[Federal Register Volume 78, Number 177 (Thursday, September 12, 2013)]
[Proposed Rules]
[Pages 56273-56504]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-20997]



[[Page 56273]]

Vol. 78

Thursday,

No. 177

September 12, 2013

Part II





Department of Labor





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Occupational Safety and Health Administration





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29 CFR Parts 1910, 1915, and 1926





Occupational Exposure to Respirable Crystalline Silica; Proposed Rule

Federal Register / Vol. 78 , No. 177 / Thursday, September 12, 2013 / 
Proposed Rules

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DEPARTMENT OF LABOR

Occupational Safety and Health Administration

29 CFR Parts 1910, 1915, and 1926

[Docket No. OSHA-2010-0034]
RIN 1218-AB70


Occupational Exposure to Respirable Crystalline Silica

AGENCY: Occupational Safety and Health Administration (OSHA), 
Department of Labor.

ACTION: Proposed rule; request for comments.

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SUMMARY: The Occupational Safety and Health Administration (OSHA) 
proposes to amend its existing standards for occupational exposure to 
respirable crystalline silica. The basis for issuance of this proposal 
is a preliminary determination by the Assistant Secretary of Labor for 
Occupational Safety and Health that employees exposed to respirable 
crystalline silica face a significant risk to their health at the 
current permissible exposure limits and that promulgating these 
proposed standards will substantially reduce that risk.
    This document proposes a new permissible exposure limit, calculated 
as an 8-hour time-weighted average, of 50 micrograms of respirable 
crystalline silica per cubic meter of air (50 [mu]g/m\3\). OSHA also 
proposes other ancillary provisions for employee protection such as 
preferred methods for controlling exposure, respiratory protection, 
medical surveillance, hazard communication, and recordkeeping. OSHA is 
proposing two separate regulatory texts--one for general industry and 
maritime, and the other for construction--in order to tailor 
requirements to the circumstances found in these sectors.

DATES: Written comments. Written comments, including comments on the 
information collection determination described in Section IX of the 
preamble (OMB Review under the Paperwork Reduction Act of 1995), must 
be submitted (postmarked, sent, or received) by December 11, 2013.
    Informal public hearings. The Agency plans to hold informal public 
hearings beginning on March 4, 2014, in Washington, DC. OSHA expects 
the hearings to last from 9:30 a.m. to 5:30 p.m., local time; a 
schedule will be released prior to the start of the hearings. The exact 
daily schedule may be amended at the discretion of the presiding 
administrative law judge (ALJ). If necessary, the hearings will 
continue at the same time on subsequent days. Peer reviewers of OSHA's 
Health Effects Literature Review and Preliminary Quantitative Risk 
Assessment will be present in Washington, DC to hear testimony on the 
second day of the hearing, March 5, 2014; see Section XV for more 
information on the peer review process.
    Notice of intention to appear at the hearings. Interested persons 
who intend to present testimony or question witnesses at the hearings 
must submit (transmit, send, postmark, deliver) a notice of their 
intention to do so by November 12, 2013. The notice of intent must 
indicate if the submitter requests to present testimony in the presence 
of the peer reviewers.
    Hearing testimony and documentary evidence. Interested persons who 
request more than 10 minutes to present testimony, or who intend to 
submit documentary evidence, at the hearings must submit (transmit, 
send, postmark, deliver) the full text of their testimony and all 
documentary evidence by December 11, 2013. See Section XV below for 
details on the format and how to file a notice of intention to appear, 
submit documentary evidence at the hearing, and request an appropriate 
amount of time to present testimony.

ADDRESSES: Written comments. You may submit comments, identified by 
Docket No. OSHA-2010-0034, by any of the following methods:
    Electronically: You may submit comments and attachments 
electronically at http://www.regulations.gov, which is the Federal e-
Rulemaking Portal. Follow the instructions on-line for making 
electronic submissions.
    Fax: If your submissions, including attachments, are not longer 
than 10 pages, you may fax them to the OSHA Docket Office at (202) 693-
1648.
    Mail, hand delivery, express mail, messenger, or courier service: 
You must submit your comments to the OSHA Docket Office, Docket No. 
OSHA-2010-0034, U.S. Department of Labor, Room N-2625, 200 Constitution 
Avenue NW., Washington, DC 20210, telephone (202) 693-2350 (OSHA's TTY 
number is (877) 889-5627). Deliveries (hand, express mail, messenger, 
or courier service) are accepted during the Department of Labor's and 
Docket Office's normal business hours, 8:15 a.m.-4:45 p.m., E.T.
    Instructions: All submissions must include the Agency name and the 
docket number for this rulemaking (Docket No. OSHA-2010-0034). All 
comments, including any personal information you provide, are placed in 
the public docket without change and may be made available online at 
http://www.regulations.gov. Therefore, OSHA cautions you about 
submitting personal information such as social security numbers and 
birthdates.
    If you submit scientific or technical studies or other results of 
scientific research, OSHA requests (but is not requiring) that you also 
provide the following information where it is available: (1) 
Identification of the funding source(s) and sponsoring organization(s) 
of the research; (2) the extent to which the research findings were 
reviewed by a potentially affected party prior to publication or 
submission to the docket, and identification of any such parties; and 
(3) the nature of any financial relationships (e.g., consulting 
agreements, expert witness support, or research funding) between 
investigators who conducted the research and any organization(s) or 
entities having an interest in the rulemaking. If you are submitting 
comments or testimony on the Agency's scientific and technical 
analyses, OSHA requests that you disclose: (1) The nature of any 
financial relationships you may have with any organization(s) or 
entities having an interest in the rulemaking; and (2) the extent to 
which your comments or testimony were reviewed by an interested party 
prior to its submission. Disclosure of such information is intended to 
promote transparency and scientific integrity of data and technical 
information submitted to the record. This request is consistent with 
Executive Order 13563, issued on January 18, 2011, which instructs 
agencies to ensure the objectivity of any scientific and technological 
information used to support their regulatory actions. OSHA emphasizes 
that all material submitted to the rulemaking record will be considered 
by the Agency to develop the final rule and supporting analyses.
    Informal public hearings. The Washington, DC hearing will be held 
in the auditorium of the U.S. Department of Labor, 200 Constitution 
Avenue NW., Washington, DC 20210.
    Notice of intention to appear, hearing testimony and documentary 
evidence. You may submit (transmit, send, postmark, deliver) your 
notice of intention to appear, hearing testimony, and documentary 
evidence, identified by docket number (OSHA-2010-0034), by any of the 
following methods:
    Electronically: http://www.regulations.gov. Follow the instructions 
online for electronic submission of materials, including attachments.

[[Page 56275]]

    Fax: If your written submission does not exceed 10 pages, including 
attachments, you may fax it to the OSHA Docket Office at (202) 693-
1648.
    Regular mail, express delivery, hand delivery, and messenger and 
courier service: Submit your materials to the OSHA Docket Office, 
Docket No. OSHA-2010-0034, U.S. Department of Labor, Room N-2625, 200 
Constitution Avenue NW., Washington, DC 20210; telephone (202) 693-2350 
(TTY number (877) 889-5627). Deliveries (express mail, hand delivery, 
and messenger and courier service) are accepted during the Department 
of Labor's and OSHA Docket Office's normal hours of operation, 8:15 
a.m. to 4:45 p.m., ET.
    Instructions: All submissions must include the Agency name and 
docket number for this rulemaking (Docket No. OSHA-2010-0034). All 
submissions, including any personal information, are placed in the 
public docket without change and may be available online at http://www.regulations.gov. Therefore, OSHA cautions you about submitting 
certain personal information, such as social security numbers and 
birthdates. Because of security-related procedures, the use of regular 
mail may cause a significant delay in the receipt of your submissions. 
For information about security-related procedures for submitting 
materials by express delivery, hand delivery, messenger, or courier 
service, please contact the OSHA Docket Office. For additional 
information on submitting notices of intention to appear, hearing 
testimony or documentary evidence, see Section XV of this preamble, 
Public Participation.
    Docket: To read or download comments, notices of intention to 
appear, and materials submitted in response to this Federal Register 
notice, go to Docket No. OSHA-2010-0034 at http://www.regulations.gov 
or to the OSHA Docket Office at the address above. All comments and 
submissions are listed in the http://www.regulations.gov index; 
however, some information (e.g., copyrighted material) is not publicly 
available to read or download through that Web site. All comments and 
submissions are available for inspection and, where permissible, 
copying at the OSHA Docket Office.
    Electronic copies of this Federal Register document are available 
at http://regulations.gov. Copies also are available from the OSHA 
Office of Publications, Room N-3101, U.S. Department of Labor, 200 
Constitution Avenue NW., Washington, DC 20210; telephone (202) 693-
1888. This document, as well as news releases and other relevant 
information, is also available at OSHA's Web site at http://www.osha.gov.

FOR FURTHER INFORMATION CONTACT: For general information and press 
inquiries, contact Frank Meilinger, Director, Office of Communications, 
Room N-3647, OSHA, U.S. Department of Labor, 200 Constitution Avenue 
NW., Washington, DC 20210; telephone (202) 693-1999. For technical 
inquiries, contact William Perry or David O'Connor, Directorate of 
Standards and Guidance, Room N-3718, OSHA, U.S. Department of Labor, 
200 Constitution Avenue NW., Washington, DC 20210; telephone (202) 693-
1950 or fax (202) 693-1678. For hearing inquiries, contact Frank 
Meilinger, Director, Office of Communications, Room N-3647, OSHA, U.S. 
Department of Labor, 200 Constitution Avenue NW., Washington, DC 20210; 
telephone (202) 693-1999; email meilinger.francis2@dol.gov.

SUPPLEMENTARY INFORMATION: 
    The preamble to the proposed standard on occupational exposure to 
respirable crystalline silica follows this outline:

I. Issues
II. Pertinent Legal Authority
III. Events Leading to the Proposed Standards
IV. Chemical Properties and Industrial Uses
V. Health Effects Summary
VI. Summary of the Preliminary Quantitative Risk Assessment
VII. Significance of Risk
VIII. Summary of the Preliminary Economic Analysis and Initial 
Regulatory Flexibility Analysis
IX. OMB Review Under the Paperwork Reduction Act of 1995
X. Federalism
XI. State Plans
XII. Unfunded Mandates
XIII. Protecting Children From Environmental Health and Safety Risks
XIV. Environmental Impacts
XV. Public Participation
XVI. Summary and Explanation of the Standards
    (a) Scope and Application
    (b) Definitions
    (c) Permissible Exposure Limit (PEL)
    (d) Exposure Assessment
    (e) Regulated Areas and Access Control
    (f) Methods of Compliance
    (g) Respiratory Protection
    (h) Medical Surveillance
    (i) Communication of Respirable Crystalline Silica Hazards to 
Employees
    (j) Recordkeeping
    (k) Dates
XVII. References
XVIII. Authority and Signature

    OSHA currently enforces permissible exposure limits (PELs) for 
respirable crystalline silica in general industry, construction, and 
shipyards. These PELs were adopted in 1971, shortly after the Agency 
was created, and have not been updated since then. The PEL for quartz 
(the most common form of crystalline silica) in general industry is a 
formula that is approximately equivalent to 100 micrograms per cubic 
meter of air ([mu]g/m\3\) as an 8-hour time-weighted average. The PEL 
for quartz in construction and shipyards is a formula based on a now-
obsolete particle count sampling method that is approximately 
equivalent to 250 [mu]g/m\3\. The current PELs for two other forms of 
crystalline silica (cristobalite and tridymite) are one-half of the 
values for quartz in general industry. OSHA is proposing a new PEL for 
respirable crystalline silica (quartz, cristobalite, and tridymite) of 
50 [mu]g/m\3\ in all industry sectors covered by the rule. OSHA is also 
proposing other elements of a comprehensive health standard, including 
requirements for exposure assessment, preferred methods for controlling 
exposure, respiratory protection, medical surveillance, hazard 
communication, and recordkeeping.
    OSHA's proposal is based on the requirements of the Occupational 
Safety and Health Act (OSH Act) and court interpretations of the Act. 
For health standards issued under section 6(b)(5) of the OSH Act, OSHA 
is required to promulgate a standard that reduces significant risk to 
the extent that it is technologically and economically feasible to do 
so. See Section II of this preamble, Pertinent Legal Authority, for a 
full discussion of OSHA legal requirements.
    OSHA has conducted an extensive review of the literature on adverse 
health effects associated with exposure to respirable crystalline 
silica. The Agency has also developed estimates of the risk of silica-
related diseases assuming exposure over a working lifetime at the 
proposed PEL and action level, as well as at OSHA's current PELs. These 
analyses are presented in a background document entitled ``Respirable 
Crystalline Silica--Health Effects Literature Review and Preliminary 
Quantitative Risk Assessment'' and are summarized in this preamble in 
Section V, Health Effects Summary, and Section VI, Summary of OSHA's 
Preliminary Quantitative Risk Assessment, respectively. The available 
evidence indicates that employees exposed to respirable crystalline 
silica well below the current PELs are at increased risk of lung cancer 
mortality and silicosis mortality and morbidity. Occupational exposures 
to respirable crystalline silica also may result in the development of 
kidney and autoimmune diseases and in death from other nonmalignant 
respiratory diseases, including chronic obstructive pulmonary disease 
(COPD).

[[Page 56276]]

As discussed in Section VII, Significance of Risk, in this preamble, 
OSHA preliminarily finds that worker exposure to respirable crystalline 
silica constitutes a significant risk and that the proposed standard 
will substantially reduce this risk.
    Section 6(b) of the OSH Act requires OSHA to determine that its 
standards are technologically and economically feasible. OSHA's 
examination of the technological and economic feasibility of the 
proposed rule is presented in the Preliminary Economic Analysis and 
Initial Regulatory Flexibility Analysis (PEA), and is summarized in 
Section VIII of this preamble. For general industry and maritime, OSHA 
has preliminarily concluded that the proposed PEL of 50 [mu]g/m\3\ is 
technologically feasible for all affected industries. For construction, 
OSHA has preliminarily determined that the proposed PEL of 50 [mu]g/
m\3\ is feasible in 10 out of 12 of the affected activities. Thus, OSHA 
preliminarily concludes that engineering and work practices will be 
sufficient to reduce and maintain silica exposures to the proposed PEL 
of 50 [mu]g/m\3\ or below in most operations most of the time in the 
affected industries. For those few operations within an industry or 
activity where the proposed PEL is not technologically feasible even 
when workers use recommended engineering and work practice controls, 
employers can supplement controls with respirators to achieve exposure 
levels at or below the proposed PEL.
    OSHA developed quantitative estimates of the compliance costs of 
the proposed rule for each of the affected industry sectors. The 
estimated compliance costs were compared with industry revenues and 
profits to provide a screening analysis of the economic feasibility of 
complying with the revised standard and an evaluation of the potential 
economic impacts. Industries with unusually high costs as a percentage 
of revenues or profits were further analyzed for possible economic 
feasibility issues. After performing these analyses, OSHA has 
preliminarily concluded that compliance with the requirements of the 
proposed rule would be economically feasible in every affected industry 
sector.
    OSHA directed Inforum--a not-for-profit corporation (based at the 
University of Maryland) well recognized for its macroeconomic 
modeling--to run its LIFT (Long-term Interindustry Forecasting Tool) 
model of the U.S. economy to estimate the industry and aggregate 
employment effects of the proposed silica rule. Inforum developed 
estimates of the employment impacts over the ten-year period from 2014-
2023 by feeding OSHA's year-by-year and industry-by-industry estimates 
of the compliance costs of the proposed rule into its LIFT model. Based 
on the resulting Inforum estimates of employment impacts, OSHA has 
preliminarily concluded that the proposed rule would have a 
negligible--albeit slightly positive--net impact on aggregate U.S. 
employment.
    OSHA believes that a new PEL, expressed as a gravimetric 
measurement of respirable crystalline silica, will improve compliance 
because the PEL is simple and relatively easy to understand. In 
comparison, the existing PELs require application of a formula to 
account for the crystalline silica content of the dust sampled and, in 
the case of the construction and shipyard PELs, a conversion from 
particle count to mg/m\3\ as well. OSHA also expects that the approach 
to methods of compliance for construction operations included in this 
proposal will improve compliance with the standard. This approach, 
which specifies exposure control methods for selected construction 
operations, gives employers a simple option to identify the control 
measures that are appropriate for these operations. Alternately, 
employers could conduct exposure assessments to determine if worker 
exposures are in compliance with the PEL. In either case, the proposed 
rule would provide a basis for ensuring that appropriate measures are 
in place to limit worker exposures.
    The Regulatory Flexibility Act, as amended by the Small Business 
Regulatory Enforcement Fairness Act (SBREFA), requires that OSHA either 
certify that a rule would not have a significant economic impact on a 
substantial number of small firms or prepare a regulatory flexibility 
analysis and hold a Small Business Advocacy Review (SBAR) Panel prior 
to proposing the rule. OSHA has determined that a regulatory 
flexibility analysis is needed and has provided this analysis in 
Section VIII.G of this preamble. OSHA also previously held a SBAR Panel 
for this rule. The recommendations of the Panel and OSHA's response to 
them are summarized in Section VIII.G of this preamble.
    Executive Orders 13563 and 12866 direct agencies to assess all 
costs and benefits of available regulatory alternatives. Executive 
Order 13563 emphasizes the importance of quantifying both costs and 
benefits, of reducing costs, of harmonizing rules, and of promoting 
flexibility. This rule has been designated an economically significant 
regulatory action under section 3(f)(1) of Executive Order 12866. 
Accordingly, the rule has been reviewed by the Office of Management and 
Budget, and the remainder of this section summarizes the key findings 
of the analysis with respect to costs and benefits of the rule and then 
presents several possible alternatives to the rule.
    Table SI-1--which, like all the tables in this section, is derived 
from material presented in Section VIII of this preamble--provides a 
summary of OSHA's best estimate of the costs and benefits of the 
proposed rule using a discount rate of 3 percent. As shown, the 
proposed rule is estimated to prevent 688 fatalities and 1,585 silica-
related illnesses annually once it is fully effective, and the 
estimated cost of the rule is $637 million annually. Also as shown in 
Table SI-1, the discounted monetized benefits of the proposed rule are 
estimated to be $5.3 billion annually, and the proposed rule is 
estimated to generate net benefits of $4.6 billion annually. These 
estimates are for informational purposes only and have not been used by 
OSHA as the basis for its decision concerning the choice of a PEL or of 
other ancillary requirements for this proposed silica rule. The courts 
have ruled that OSHA may not use benefit-cost analysis or a criterion 
of maximizing net benefits as a basis for setting OSHA health 
standards.\1\
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    \1\ Am. Textile Mfrs. Inst., Inc. v. Nat'l Cotton Council of 
Am., 452 U.S. 490, 513 (1981); Pub. Citizen Health Research Group v. 
U.S. Dep't of Labor, 557 F.3d 165, 177 (3d Cir. 2009); Friends of 
the Boundary Waters Wilderness v. Robertson, 978 F.2d 1484, 1487 
(8th Cir. 1992).

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[GRAPHIC] [TIFF OMITTED] TP12SE13.000

    Both the costs and benefits of Table SI-1 reflect the incremental 
costs and benefits associated with achieving full compliance with the 
proposed rule. They do not include (a) costs and benefits associated 
with current compliance that have already been achieved with regard to 
the new requirements, or (b) costs and benefits associated with 
achieving compliance with existing requirements, to the extent that 
some employers may currently not be fully complying with applicable 
regulatory requirements. They also do not include costs or benefits 
associated with relatively rare, extremely high exposures that can lead 
to acute silicosis.
    Subsequent to completion of the PEA, OSHA identified an industry, 
hydraulic fracturing, that would be impacted by the proposed standard. 
Hydraulic fracturing, sometimes called ``fracking,'' is a process used 
to extract natural gas and oil deposits from shale and other tight 
geologic formations. A recent cooperative study by the National 
Institute for Occupational Safety and Health (NIOSH) and industry 
partners identified overexposures to silica among workers conducting 
hydraulic fracturing operations. An industry focus group has been 
working with OSHA and NIOSH to disseminate information about this 
hazard, share best practices, and develop engineering controls to limit 
worker exposures to silica. OSHA finds that there are now sufficient 
data to provide the main elements of the economic analysis for this 
rapidly growing industry and has done so in Appendix A to the PEA.
    Based on recent data from the U.S. Census Bureau and industry 
sources, OSHA estimates that roughly 25,000 workers in 444 
establishments (operated by 200 business entities) in hydraulic 
fracturing would be affected by the proposed standard. Annual benefits 
of the proposed 50 [mu]g/m\3\ PEL include approximately 12 avoided 
fatalities--2.9 avoided lung cancers (mid-point estimate), 6.3 
prevented non-cancer respiratory illnesses, and 2.3 prevented cases of 
renal failure--and 40.8 avoided cases of silicosis morbidity. Monetized 
benefits are expected to range from $75.1 million at a seven percent 
discount rate to $105.4 million at a three percent discount rate to 
undiscounted benefits of $140.3 million. OSHA estimates that under the 
proposed standard, annualized compliance costs for the hydraulic 
fracturing industry will total $28.6 million at a discount rate of 7 
percent or $26.4 million at a discount rate of 3 percent.
    In addition to the proposed rule itself, this preamble discusses 
several regulatory alternatives to the proposed OSHA silica standard. 
These are presented below as well as in Section VIII of this preamble. 
OSHA believes that this presentation of regulatory alternatives serves 
two important functions. The first is to explore the possibility of 
less costly ways (than the proposed rule) to provide an adequate level 
of worker protection from exposure to respirable crystalline silica. 
The second is tied to the Agency's statutory requirement, which 
underlies the proposed rule, to reduce significant risk to the extent 
feasible. If, based on evidence presented during notice and comment, 
OSHA is unable to justify its preliminary findings of significant risk 
and feasibility as presented in this preamble to the proposed rule, the 
Agency must then consider regulatory alternatives that do satisfy its 
statutory obligations.

[[Page 56278]]

    Each regulatory alternative presented here is described and 
analyzed relative to the proposed rule. Where appropriate, the Agency 
notes whether the regulatory alternative, to be a legitimate candidate 
for OSHA consideration, requires evidence contrary to the Agency's 
findings of significant risk and feasibility. To facilitate comment, 
the regulatory alternatives have been organized into four categories: 
(1) Alternative PELs to the proposed PEL of 50 [mu]g/m\3\; (2) 
regulatory alternatives that affect proposed ancillary provisions; (3) 
a regulatory alternative that would modify the proposed methods of 
compliance; and (4) regulatory alternatives concerning when different 
provisions of the proposed rule would take effect.
    In addition, OSHA would like to draw attention to one possible 
modification to the proposed rule, involving methods of compliance, 
that the Agency would not consider to be a legitimate regulatory 
alternative: To permit the use of respiratory protection as an 
alternative to engineering and work practice controls as a primary 
means to achieve the PEL.
    As described in Section XVI of the preamble, Summary and 
Explanation of the Proposed Standards, OSHA is proposing to require 
primary reliance on engineering controls and work practices because 
reliance on these methods is consistent with long-established good 
industrial hygiene practice, with the Agency's experience in ensuring 
that workers have a healthy workplace, and with the Agency's 
traditional adherence to a hierarchy of preferred controls. The 
Agency's adherence to the hierarchy of controls has been successfully 
upheld by the courts (see AFL-CIO v. Marshall, 617 F.2d 636 (D.C. Cir. 
1979) (cotton dust standard); United Steelworkers v. Marshall, 647 F.2d 
1189 (D.C. Cir. 1980), cert. denied, 453 U.S. 913 (1981) (lead 
standard); ASARCO v. OSHA, 746 F.2d 483 (9th Cir. 1984) (arsenic 
standard); Am. Iron & Steel v. OSHA, 182 F.3d 1261 (11th Cir. 1999) 
(respiratory protection standard); Pub. Citizen v. U.S. Dep't of Labor, 
557 F.3d 165 (3rd Cir. 2009) (hexavalent chromium standard)).
    Engineering controls are reliable, provide consistent levels of 
protection to a large number of workers, can be monitored, allow for 
predictable performance levels, and can efficiently remove a toxic 
substance from the workplace. Once removed, the toxic substance no 
longer poses a threat to employees. The effectiveness of engineering 
controls does not generally depend on human behavior to the same extent 
as personal protective equipment does, and the operation of equipment 
is not as vulnerable to human error as is personal protective 
equipment.
    Respirators are another important means of protecting workers. 
However, to be effective, respirators must be individually selected; 
fitted and periodically refitted; conscientiously and properly worn; 
regularly maintained; and replaced as necessary. In many workplaces, 
these conditions for effective respirator use are difficult to achieve. 
The absence of any of these conditions can reduce or eliminate the 
protection that respirators provide to some or all of the employees who 
wear them.
    In addition, use of respirators in the workplace presents other 
safety and health concerns. Respirators impose substantial 
physiological burdens on some employees. Certain medical conditions can 
compromise an employee's ability to tolerate the physiological burdens 
imposed by respirator use, thereby placing the employee wearing the 
respirator at an increased risk of illness, injury, and even death. 
Psychological conditions, such as claustrophobia, can also impair the 
effective use of respirators by employees. These concerns about the 
burdens placed on workers by the use of respirators are the basis for 
the requirement that employers provide a medical evaluation to 
determine the employee's ability to wear a respirator before the 
employee is fit tested or required to use a respirator in the 
workplace. Although experience in industry shows that most healthy 
workers do not have physiological problems wearing properly chosen and 
fitted respirators, common health problems can sometime preclude an 
employee from wearing a respirator. Safety problems created by 
respirators that limit vision and communication must also be 
considered. In some difficult or dangerous jobs, effective vision or 
communication is vital. Voice transmission through a respirator can be 
difficult and fatiguing.
    Because respirators are less reliable than engineering and work 
practice controls and may create additional problems, OSHA believes 
that primary reliance on respirators to protect workers is generally 
inappropriate when feasible engineering and work practice controls are 
available. All OSHA substance-specific health standards have recognized 
and required employers to observe the hierarchy of controls, favoring 
engineering and work practice controls over respirators. OSHA's PELs, 
including the current PELs for respirable crystalline silica, also 
incorporate this hierarchy of controls. In addition, the industry 
consensus standards for crystalline silica (ASTM E 1132-06, Standard 
Practice for Health Requirements Relating to Occupational Exposure to 
Respirable Crystalline Silica, and ASTM E 2626-09, Standard Practice 
for Controlling Occupational Exposure to Respirable Crystalline Silica 
for Construction and Demolition Activities) incorporate the hierarchy 
of controls.
    It is important to note that the very concept of technological 
feasibility for OSHA standards is grounded in the hierarchy of 
controls. As indicated in Section II of this preamble, Pertinent Legal 
Authority, the courts have clarified that a standard is technologically 
feasible if OSHA proves a reasonable possibility,

. . . within the limits of the best available evidence . . . that 
the typical firm will be able to develop and install engineering and 
work practice controls that can meet the PEL in most of its 
operations. [See United Steelworkers v. Marshall, 647 F.2d 1189, 
1272 (D.C. Cir. 1980)]

    Allowing use of respirators instead of engineering and work 
practice controls would be at odds with this framework for evaluating 
the technological feasibility of a PEL.

Alternative PELs

    OSHA has examined two regulatory alternatives (named Regulatory 
Alternatives 1 and 2) that would modify the PEL for 
the proposed rule. Under Regulatory Alternative 1, the 
proposed PEL would be changed from 50 [mu]g/m\3\ to 100 [mu]g/m\3\ for 
all industry sectors covered by the rule, and the action level would be 
changed from 25 [mu]g/m\3\ to 50 [mu]g/m\3\ (thereby keeping the action 
level at one-half of the PEL). Under Regulatory Alternative 2, 
the proposed PEL would be lowered from 50 [mu]g/m\3\ to 25 [mu]g/m\3\ 
for all industry sectors covered by the rule, while the action level 
would remain at 25 [mu]g/m\3\ (because of difficulties in accurately 
measuring exposure levels below 25 [mu]g/m\3\).
    Tables SI-2 and SI-3 present, for informational purposes, the 
estimated costs, benefits, and net benefits of the proposed rule under 
the proposed PEL of 50 [mu]g/m\3\ and for the regulatory alternatives 
of a PEL of 100 [mu]g/m\3\ and a PEL of 25 [mu]g/m\3\ (Regulatory 
Alternatives 1 and 2), using alternative discount 
rates of 3 and 7 percent. These two tables also present the incremental 
costs, the incremental benefits, and the incremental net benefits of 
going from a PEL of 100 [mu]g/m\3\ to the proposed PEL of 50 [mu]g/m\3\ 
and then of going from the proposed PEL of 50 [mu]g/m\3\ to a PEL of 25 
[mu]g/m\3\. Table

[[Page 56279]]

SI-2 breaks out costs by provision and benefits by type of disease and 
by morbidity/mortality, while Table SI-3 breaks out costs and benefits 
by major industry sector.
[GRAPHIC] [TIFF OMITTED] TP12SE13.001


[[Page 56280]]


[GRAPHIC] [TIFF OMITTED] TP12SE13.002

    As Tables SI-2 and SI-3 show, going from a PEL of 100 [mu]g/m\3\ to 
a PEL of 50 [mu]g/m\3\ would prevent, annually, an additional 357 
silica-related fatalities and an additional 632 cases of silicosis. 
Based on its preliminary findings that the proposed PEL of 50 [mu]g/
m\3\ significantly reduces worker risk from silica exposure (as 
demonstrated by the number of silica-related fatalities and silicosis 
cases avoided) and is both technologically and economically

[[Page 56281]]

feasible, OSHA cannot propose a PEL of 100 [mu]g/m\3\ (Regulatory 
Alternative 1) without violating its statutory obligations 
under the OSH Act. However, the Agency will consider evidence that 
challenges its preliminary findings.
    As previously noted, Tables SI-2 and SI-3 also show the costs and 
benefits of a PEL of 25 [mu]g/m\3\ (Regulatory Alternative 2), 
as well as the incremental costs and benefits of going from the 
proposed PEL of 50 [mu]g/m\3\ to a PEL of 25 [mu]g/m\3\. Because OSHA 
preliminarily determined that a PEL of 25 [mu]g/m\3\ would not be 
feasible (that is, engineering and work practices would not be 
sufficient to reduce and maintain silica exposures to a PEL of 25 
[mu]g/m\3\ or below in most operations most of the time in the affected 
industries), the Agency did not attempt to identify engineering 
controls or their costs for affected industries to meet this PEL. 
Instead, for purposes of estimating the costs of going from a PEL of 50 
[mu]g/m\3\ to a PEL of 25 [mu]g/m\3\, OSHA assumed that all workers 
exposed between 50 [mu]g/m\3\ and 25 [mu]g/m\3\ would have to wear 
respirators to achieve compliance with the 25 [mu]g/m\3\ PEL. OSHA then 
estimated the associated additional costs for respirators, exposure 
assessments, medical surveillance, and regulated areas (the latter 
three for ancillary requirements specified in the proposed rule).
    As shown in Tables SI-2 and SI-3, going from a PEL of 50 [mu]g/m\3\ 
to a PEL of 25 [mu]g/m\3\ would prevent, annually, an additional 335 
silica-related fatalities and an additional 186 cases of silicosis. 
These estimates support OSHA's preliminarily finding that there is 
significant risk remaining at the proposed PEL of 50 [mu]g/m\3\. 
However, the Agency has preliminarily determined that a PEL of 25 
[mu]g/m\3\ (Regulatory Alternative 2) is not technologically 
feasible, and for that reason, cannot propose it without violating its 
statutory obligations under the OSH Act.

Regulatory Alternatives That Affect Ancillary Provisions

    The proposed rule contains several ancillary provisions (provisions 
other than the PEL), including requirements for exposure assessment, 
medical surveillance, training, and regulated areas or access control. 
As shown in Table SI-2, these ancillary provisions represent 
approximately $223 million (or about 34 percent) of the total 
annualized costs of the rule of $658 million (using a 7 percent 
discount rate). The two most expensive of the ancillary provisions are 
the requirements for medical surveillance, with annualized costs of $79 
million, and the requirements for exposure monitoring, with annualized 
costs of $74 million.
    As proposed, the requirements for exposure assessment are triggered 
by the action level. As described in this preamble, OSHA has defined 
the action level for the proposed standard as an airborne concentration 
of respirable crystalline silica of 25 [mu]g/m\3\ calculated as an 
eight-hour time-weighted average. In this proposal, as in other 
standards, the action level has been set at one-half of the PEL.
    Because of the variable nature of employee exposures to airborne 
concentrations of respirable crystalline silica, maintaining exposures 
below the action level provides reasonable assurance that employees 
will not be exposed to respirable crystalline silica at levels above 
the PEL on days when no exposure measurements are made. Even when all 
measurements on a given day may fall below the PEL (but are above the 
action level), there is some chance that on another day, when exposures 
are not measured, the employee's actual exposure may exceed the PEL. 
When exposure measurements are above the action level, the employer 
cannot be reasonably confident that employees have not been exposed to 
respirable crystalline silica concentrations in excess of the PEL 
during at least some part of the work week. Therefore, requiring 
periodic exposure measurements when the action level is exceeded 
provides the employer with a reasonable degree of confidence in the 
results of the exposure monitoring.
    The action level is also intended to encourage employers to lower 
exposure levels in order to avoid the costs associated with the 
exposure assessment provisions. Some employers would be able to reduce 
exposures below the action level in all work areas, and other employers 
in some work areas. As exposures are lowered, the risk of adverse 
health effects among workers decreases.
    OSHA's preliminary risk assessment indicates that significant risk 
remains at the proposed PEL of 50 [mu]g/m\3\. Where there is continuing 
significant risk, the decision in the Asbestos case (Bldg. and Constr. 
Trades Dep't, AFL-CIO v. Brock, 838 F.2d 1258, 1274 (D.C. Cir. 1988)) 
indicated that OSHA should use its legal authority to impose additional 
requirements on employers to further reduce risk when those 
requirements will result in a greater than de minimis incremental 
benefit to workers' health. OSHA's preliminary conclusion is that the 
requirements triggered by the action level will result in a very real 
and necessary, but non-quantifiable, further reduction in risk beyond 
that provided by the PEL alone. OSHA's choice of proposing an action 
level for exposure monitoring of one-half of the PEL is based on the 
Agency's successful experience with other standards, including those 
for inorganic arsenic (29 CFR 1910.1018), ethylene oxide (29 CFR 
1910.1047), benzene (29 CFR 1910.1028), and methylene chloride (29 CFR 
1910.1052).
    As specified in the proposed rule, all workers exposed to 
respirable crystalline silica above the PEL of 50 [mu]g/m\3\ are 
subject to the medical surveillance requirements. This means that the 
medical surveillance requirements would apply to 15,172 workers in 
general industry and 336,244 workers in construction. OSHA estimates 
that 457 possible silicosis cases will be referred to pulmonary 
specialists annually as a result of this medical surveillance.
    OSHA has preliminarily determined that these ancillary provisions 
will: (1) Help ensure that the PEL is not exceeded, and (2) minimize 
risk to workers given the very high level of risk remaining at the PEL. 
OSHA did not estimate, and the benefits analysis does not include, 
monetary benefits resulting from early discovery of illness.
    Because medical surveillance and exposure assessment are the two 
most costly ancillary provisions in the proposed rule, the Agency has 
examined four regulatory alternatives (named Regulatory Alternatives 
3, 4, 5, and 6) involving changes 
to one or the other of these ancillary provisions. These four 
regulatory alternatives are defined below and the incremental cost 
impact of each is summarized in Table SI-4. In addition, OSHA is 
including a regulatory alternative (named Regulatory Alternative 
7) that would remove all ancillary provisions.

[[Page 56282]]

[GRAPHIC] [TIFF OMITTED] TP12SE13.003

    Under Regulatory Alternative 3, the action level would be 
raised from 25 [mu]g/m\3\ to 50 [mu]g/m\3\ while keeping the PEL at 50 
[mu]g/m\3\. As a result, exposure monitoring requirements would be 
triggered only if workers were exposed

[[Page 56283]]

above the proposed PEL of 50 [mu]g/m\3\. As shown in Table SI-4, 
Regulatory Option 3 would reduce the annualized cost of the 
proposed rule by about $62 million, using a discount rate of either 3 
percent or 7 percent.
    Under Regulatory Alternative 4, the action level would 
remain at 25 [mu]g/m\3\ but medical surveillance would now be triggered 
by the action level, not the PEL. As a result, medical surveillance 
requirements would be triggered only if workers were exposed at or 
above the proposed action level of 25 [mu]g/m\3\. As shown in Table SI-
4, Regulatory Option 4 would increase the annualized cost of 
the proposed rule by about $143 million, using a discount rate of 3 
percent (and by about $169 million, using a discount rate of 7 
percent).
    Under Regulatory Alternative 5, the only change to the 
proposed rule would be to the medical surveillance requirements. 
Instead of requiring workers exposed above the PEL to have a medical 
check-up every three years, those workers would be required to have a 
medical check-up annually. As shown in Table SI-4, Regulatory Option 
5 would increase the annualized cost of the proposed rule by 
about $69 million, using a discount rate of 3 percent (and by about $66 
million, using a discount rate of 7 percent).
    Regulatory Alternative 6 would essentially combine the 
modified requirements in Regulatory Alternatives 4 and 
5. Under Regulatory Alternative 6, medical 
surveillance would be triggered by the action level, not the PEL, and 
workers exposed at or above the action level would be required to have 
a medical check-up annually rather than triennially. The exposure 
monitoring requirements in the proposed rule would not be affected. As 
shown in Table SI-4, Regulatory Option 6 would increase the 
annualized cost of the proposed rule by about $342 million, using a 
discount rate of either 3 percent or 7 percent.
    OSHA is not able to quantify the effects of these preceding four 
regulatory alternatives on protecting workers exposed to respirable 
crystalline silica at levels at or below the proposed PEL of 50 [mu]g/
m\3\--where significant risk remains. The Agency solicits comment on 
the extent to which these regulatory options may improve or reduce the 
effectiveness of the proposed rule.
    The final regulatory alternative affecting ancillary provisions, 
Regulatory Alternative 7, would eliminate all of the ancillary 
provisions of the proposed rule, including exposure assessment, medical 
surveillance, training, and regulated areas or access control. However, 
it should be carefully noted that elimination of the ancillary 
provisions does not mean that all costs for ancillary provisions would 
disappear. In order to meet the PEL, employers would still commonly 
need to do monitoring, train workers on the use of controls, and set up 
some kind of regulated areas to indicate where respirator use would be 
required. It is also likely that employers would increasingly follow 
the many recommendations to provide medical surveillance for employees. 
OSHA has not attempted to estimate the extent to which the costs of 
these activities would be reduced if they were not formally required, 
but OSHA welcomes comment on the issue.
    As indicated previously, OSHA preliminarily finds that there is 
significant risk remaining at the proposed PEL of 50 [mu]g/m\3\. 
However, the Agency has also preliminarily determined that 50 [mu]g/
m\3\ is the lowest feasible PEL. Therefore, the Agency believes that it 
is necessary to include ancillary provisions in the proposed rule to 
further reduce the remaining risk. OSHA anticipates that these 
ancillary provisions will reduce the risk beyond the reduction that 
will be achieved by a new PEL alone.
    OSHA's reasons for including each of the proposed ancillary 
provisions are detailed in Section XVI of this preamble, Summary and 
Explanation of the Standards. In particular, OSHA believes that 
requirements for exposure assessment (or alternately, using specified 
exposure control methods for selected construction operations) would 
provide a basis for ensuring that appropriate measures are in place to 
limit worker exposures. Medical surveillance is particularly important 
because individuals exposed above the PEL (which triggers medical 
surveillance in the proposed rule) are at significant risk of death and 
illness. Medical surveillance would allow for identification of 
respirable crystalline silica-related adverse health effects at an 
early stage so that appropriate intervention measures can be taken. 
OSHA believes that regulated areas and access control are important 
because they serve to limit exposure to respirable crystalline silica 
to as few employees as possible. Finally, OSHA believes that worker 
training is necessary to inform employees of the hazards to which they 
are exposed, along with associated protective measures, so that 
employees understand how they can minimize potential health hazards. 
Worker training on silica-related work practices is particularly 
important in controlling silica exposures because engineering controls 
frequently require action on the part of workers to function 
effectively.
    OSHA expects that the benefits estimated under the proposed rule 
will not be fully achieved if employers do not implement the ancillary 
provisions of the proposed rule. For example, OSHA believes that the 
effectiveness of the proposed rule depends on regulated areas or access 
control to further limit exposures and on medical surveillance to 
identify disease cases when they do occur.
    Both industry and worker groups have recognized that a 
comprehensive standard is needed to protect workers exposed to 
respirable crystalline silica. For example, the industry consensus 
standards for crystalline silica, ASTM E 1132-06, Standard Practice for 
Health Requirements Relating to Occupational Exposure to Respirable 
Crystalline Silica, and ASTM E 2626-09, Standard Practice for 
Controlling Occupational Exposure to Respirable Crystalline Silica for 
Construction and Demolition Activities, as well as the draft proposed 
silica standard for construction developed by the Building and 
Construction Trades Department, AFL-CIO, have each included 
comprehensive programs. These recommended standards include provisions 
for methods of compliance, exposure monitoring, training, and medical 
surveillance (ASTM, 2006; 2009; BCTD 2001). Moreover, as mentioned 
previously, where there is continuing significant risk, the decision in 
the Asbestos case (Bldg. and Constr. Trades Dep't, AFL-CIO v. Brock, 
838 F.2d 1258, 1274 (D.C. Cir. 1988)) indicated that OSHA should use 
its legal authority to impose additional requirements on employers to 
further reduce risk when those requirements will result in a greater 
than de minimis incremental benefit to workers' health. OSHA 
preliminarily concludes that the additional requirements in the 
ancillary provisions of the proposed standard clearly exceed this 
threshold.

A Regulatory Alternative That Modifies the Methods of Compliance

    The proposed standard in general industry and maritime would 
require employers to implement engineering and work practice controls 
to reduce employees' exposures to or below the PEL. Where engineering 
and/or work practice controls are insufficient, employers would still 
be required to implement them to reduce exposure as much as possible, 
and to supplement them with a respiratory protection program. Under the 
proposed construction standard, employers would

[[Page 56284]]

be given two options for compliance. The first option largely follows 
requirements for the general industry and maritime proposed standard, 
while the second option outlines, in Table 1 (Exposure Control Methods 
for Selected Construction Operations) of the proposed rule, specific 
construction exposure control methods. Employers choosing to follow 
OSHA's proposed control methods would be considered to be in compliance 
with the engineering and work practice control requirements of the 
proposed standard, and would not be required to conduct certain 
exposure monitoring activities.
    One regulatory alternative (Regulatory Alternative 8) 
involving methods of compliance would be to eliminate Table 1 as a 
compliance option in the construction sector. Under that regulatory 
alternative, OSHA estimates that there would be no effect on estimated 
benefits but that the annualized costs of complying with the proposed 
rule (without the benefit of the Table 1 option in construction) would 
increase by $175 million, totally in exposure monitoring costs, using a 
3 percent discount rate (and by $178 million using a 7 percent discount 
rate), so that the total annualized compliance costs for all affected 
establishments in construction would increase from $495 to $670 million 
using a 3 percent discount rate (and from $511 to $689 million using a 
7 percent discount rate).

Regulatory Alternatives That Affect the Timing of the Standard

    The proposed rule would become effective 60 days following 
publication of the final rule in the Federal Register. Provisions 
outlined in the proposed standard would become enforceable 180 days 
following the effective date, with the exceptions of engineering 
controls and laboratory requirements. The proposed rule would require 
engineering controls to be implemented no later than one year after the 
effective date, and laboratory requirements would be required to begin 
two years after the effective date.
    OSHA will strongly consider alternatives that would reduce the 
economic impact of the rule and provide additional flexibility for 
firms coming into compliance with the requirements of the rule. The 
Agency solicits comment and suggestions from stakeholders, particularly 
small business representatives, on options for phasing in requirements 
for engineering controls, medical surveillance, and other provisions of 
the rule (e.g., over 1, 2, 3, or more years). These options will be 
considered for specific industries (e.g., industries where first-year 
or annualized cost impacts are highest), specific size-classes of 
employers (e.g., employers with fewer than 20 employees), combinations 
of these factors, or all firms covered by the rule.
    Although OSHA did not explicitly develop or quantitatively analyze 
the multitude of potential regulatory alternatives involving longer-
term or more complex phase-ins of the standard, the Agency is 
soliciting comments on this issue. Such a particularized, multi-year 
phase-in could have several advantages, especially from the viewpoint 
of impacts on small businesses. First, it would reduce the one-time 
initial costs of the standard by spreading them out over time, a 
particularly useful mechanism for small businesses that have trouble 
borrowing large amounts of capital in a single year. Second, a 
differential phase-in for smaller firms would aid very small firms by 
allowing them to gain from the control experience of larger firms. 
Finally, a phase-in would be useful in certain industries--such as 
foundries, for example--by allowing employers to coordinate their 
environmental and occupational safety and health control strategies to 
minimize potential costs. However a phase-in would also postpone the 
benefits of the standard.
    OSHA analyzed one regulatory alternative (Regulatory Alternative 
9) involving the timing of the standard which would arise if, 
contrary to OSHA's preliminary findings, a PEL of 50 [micro]g/m\3\ with 
an action level of 25 [micro]g/m\3\ were found to be technologically 
and economically feasible some time in the future (say, in five years), 
but not feasible immediately. In that case, OSHA might issue a final 
rule with a PEL of 50 [micro]g/m\3\ and an action level of 25 [micro]g/
m\3\ to take effect in five years, but at the same time issue an 
interim PEL of 100 [micro]g/m\3\ and an action level of 50 [micro]g/
m\3\ to be in effect until the final rule becomes feasible. Under this 
regulatory alternative, and consistent with the public participation 
and ``look back'' provisions of Executive Order 13563, the Agency could 
monitor compliance with the interim standard, review progress toward 
meeting the feasibility requirements of the final rule, and evaluate 
whether any adjustments to the timing of the final rule would be 
needed. Under Regulatory Alternative 9, the estimated costs 
and benefits would be somewhere between those estimated for a PEL of 
100 [micro]g/m\3\ with an action level of 50 [micro]g/m\3\ and those 
estimated for a PEL of 50 [micro]g/m\3\ with an action level of 25 
[micro]g/m\3\, the exact estimates depending on the length of time 
until the final rule is phased in. OSHA emphasizes that this regulatory 
alternative is contrary to the Agency's preliminary findings of 
economic feasibility and, for the Agency to consider it, would require 
specific evidence introduced on the record to show that the proposed 
rule is not now feasible but would be feasible in the future.
    OSHA requests comments on these regulatory alternatives, including 
the Agency's choice of regulatory alternatives (and whether there are 
other regulatory alternatives the Agency should consider) and the 
Agency's analysis of them.

I. Issues

    OSHA requests comment on all relevant issues, including health 
effects, risk assessment, significance of risk, technological and 
economic feasibility, and the provisions of the proposed regulatory 
text. In addition, OSHA requests comments on all of the issues raised 
by the Small Business Regulatory Fairness Enforcement Act (SBREFA) 
Panel, as summarized in Table VIII-H-4 in Section VIII.H of this 
preamble.
    OSHA is including Section I on issues at the beginning of the 
document to assist readers as they review the proposal and consider any 
comments they may want to submit. However, to fully understand the 
questions in this section and provide substantive input in response to 
them, the parts of the preamble that address these issues in detail 
should be read and reviewed. These include: Section V, Health Effects 
Summary; Section VI, Summary of the Preliminary Quantitative Risk 
Assessment; Section VII, Significance of Risk; Section VIII, Summary of 
the Preliminary Economic Analysis and Initial Regulatory Flexibility 
Analysis; and Section XVI, Summary and Explanation of the Standards. In 
addition, OSHA invites comment on additional technical questions and 
discussions of economic issues presented in the Preliminary Economic 
Analysis (PEA) of the proposed standards. Section XIX is the text of 
the standards and is the final authority on what is required in them.
    OSHA requests that comments be organized, to the extent possible, 
around the following issues and numbered questions. Comment on 
particular provisions should contain a heading setting forth the 
section and the paragraph in the standard that the comment is 
addressing. Comments addressing more than one section or paragraph will 
have correspondingly more headings.
    Submitting comments in an organized manner and with clear reference 
to the issue raised will enable all participants

[[Page 56285]]

to easily see what issues the commenter addressed and how they were 
addressed. This is particularly important in a rulemaking such as 
silica, which has multiple adverse health effects and affects many 
diverse processes and industries. Many commenters, especially small 
businesses, are likely to confine their interest (and comments) to the 
issues that affect them, and they will benefit from being able to 
quickly identify comments on these issues in others' submissions. Of 
course, the Agency welcomes comments concerning this proposal that fall 
outside the issues raised in this section. However, OSHA is especially 
interested in responses, supported by evidence and reasons, to the 
following questions:

Health Effects

    1. OSHA has described a variety of studies addressing the major 
adverse health effects that have been associated with exposure to 
respirable crystalline silica. Has OSHA adequately identified and 
documented all critical health impairments associated with occupational 
exposure to respirable crystalline silica? If not, what adverse health 
effects should be added? Are there any additional studies, other data, 
or information that would affect the information discussed or 
significantly change the determination of material health impairment? 
Submit any relevant information, data, or additional studies (or the 
citations), and explain your reasoning for recommending the inclusion 
of any studies you suggest.
    2. Using currently available epidemiologic and experimental 
studies, OSHA has made a preliminary determination that respirable 
crystalline silica presents risks of lung cancer, silicosis, and non-
malignant respiratory disease (NMRD) as well as autoimmune and renal 
disease risks to exposed workers. Is this determination correct? Are 
there additional studies or other data OSHA should consider in 
evaluating any of these adverse health risks? If so, submit the studies 
(or citations) and other data and include your reasons for finding them 
germane to determining adverse health effects of exposure to 
crystalline silica.

Risk Assessment

    3. OSHA has relied upon risk models using cumulative respirable 
crystalline silica exposure to estimate the lifetime risk of death from 
occupational lung cancer, silicosis, and NMRD among exposed workers. 
Additionally, OSHA has estimated the lifetime risk of silicosis 
morbidity among exposed workers. Is cumulative exposure the correct 
metric for exposure for each of these models? If not, what exposure 
measure should be used?
    4. Some of the literature OSHA reviewed indicated that the risk of 
contracting accelerated silicosis and lung cancer may be non-linear at 
very high exposures and may be described by an exposure dose rate 
health effect model. OSHA used the more conservative model of 
cumulative exposure that is more protective to the worker. Are there 
additional data to support or rebut any of these models used by OSHA? 
Are there other models that OSHA should consider for estimating lung 
cancer, silicosis, or NMRD risk? If so, describe the models and the 
rationale for their use.
    5. Are there additional studies or sources of data that OSHA should 
have included in its qualitative and quantitative risk assessments? 
What are these studies and have they been peer-reviewed, or are they 
soon to be peer-reviewed? What is the rationale for recommending the 
studies or data?
    6. Steenland et al. (2001a) pooled data from 10 cohort studies to 
conduct an analysis of lung cancer mortality among silica-exposed 
workers. Can you provide quantitative lung cancer risk estimates from 
other data sources? Have or will the data you submit be peer-reviewed? 
OSHA is particularly interested in quantitative risk analyses that can 
be conducted using the industrial sand worker studies by McDonald, 
Hughes, and Rando (2001) and the pooled center-based case-control study 
conducted by Cassidy et al. (2007).
    7. OSHA has made a preliminary determination that the available 
data are not sufficient or suitable for quantitative analysis of the 
risk of autoimmune disease, stomach cancer, and other cancer and non-
cancer health effects. Do you have, or are you aware of, studies, data, 
and rationale that would be suitable for a quantitative risk assessment 
for these adverse health effects? Submit the studies (or citations), 
data, and rationale.

Profile of Affected Industries

    8. In its PEA of the proposed rule, summarized in Section VIII of 
this preamble, OSHA presents a profile of the affected worker 
population. The profile includes estimates of the number of affected 
workers by industry sector or operation and job category, and the 
distribution of exposures by job category. If your company has 
potential worker exposures to respirable crystalline silica, is your 
industry among those listed by North American Industry Classification 
System (NAICS) code as affected industries? Are there additional data 
that will enable the Agency to refine its profile of the worker 
population exposed to respirable crystalline silica? If so, provide or 
reference such data and explain how OSHA should use these data to 
revise the profile.

Technological and Economic Feasibility of the Proposed PEL

    9. What are the job categories in which employees are potentially 
exposed to respirable crystalline silica in your company or industry? 
For each job category, provide a brief description of the operation and 
describe the job activities that may lead to respirable crystalline 
silica exposure. How many employees are exposed, or have the potential 
for exposure, to respirable crystalline silica in each job category in 
your company or industry? What are the frequency, duration, and levels 
of exposures to respirable crystalline silica in each job category in 
your company or industry? Where responders are able to provide exposure 
data, OSHA requests that, where available, exposure data be personal 
samples with clear descriptions of the length of the sample, analytical 
method, and controls in place. Exposure data that provide information 
concerning the controls in place are more valuable than exposure data 
without such information.
    10. Please describe work environments or processes that may expose 
workers to cristobalite. Please provide supporting evidence, or explain 
the basis of your knowledge.
    11. Have there been technological changes within your industry that 
have influenced the magnitude, frequency, or duration of exposure to 
respirable crystalline silica or the means by which employers attempt 
to control such exposures? Describe in detail these technological 
changes and their effects on respirable crystalline silica exposures 
and methods of control.
    12. Has there been a trend within your industry or an effort in 
your firm to reduce or eliminate respirable crystalline silica from 
production processes, products, and services? If so, please describe 
the methods used and provide an estimate of the percentage reduction in 
respirable crystalline silica, and the extent to which respirable 
crystalline silica is still necessary in specific processes within 
product lines or production activities. If you have substituted another 
substance(s) for crystalline silica, identify the substance(s) and any 
adverse health effects associated with exposure to the substitute 
substances, and the cost impact of substitution (cost of materials, 
productivity impact). OSHA also

[[Page 56286]]

requests that responders describe any health hazards or technical, 
economic, or other deterrents to substitution.
    13. Has your industry or firm used outsourcing or subcontracting, 
or concentrated high exposure tasks in-house, in order to expose fewer 
workers to respirable crystalline silica? An example would be 
subcontracting for the removal of hardened concrete from concrete 
mixing trucks, a task done typically 2-4 times a year, to a specialty 
subcontractor. What methods have you used to reduce the number of 
workers exposed to respirable crystalline silica and how were they 
implemented? Describe any trends related to concentration of high 
exposure tasks and provide any supporting information.
    14. Does any job category or employee in your workplace have 
exposures to respirable crystalline silica that air monitoring data do 
not adequately portray due to the short duration, intermittent or non-
routine nature, or other unique characteristics of the exposure? 
Explain your response and indicate peak levels, duration, and frequency 
of exposures for employees in these job categories.
    15. OSHA requests the following information regarding engineering 
and work practice controls to control exposure to crystalline silica in 
your workplace or industry:
    a. Describe the operations and tasks in which the proposed PEL is 
being achieved most of the time by means of engineering and work 
practice controls.
    b. What engineering and work practice controls have been 
implemented in these operations and tasks?
    c. For all operations and tasks in facilities where respirable 
crystalline silica is used, what engineering and work practice controls 
have been implemented to control respirable crystalline silica? If you 
have installed engineering controls or adopted work practices to reduce 
exposure to respirable crystalline silica, describe the exposure 
reduction achieved and the cost of these controls.
    d. Where current work practices include the use of regulated areas 
and hygiene facilities, provide data on the implementation of these 
controls, including data on the costs of installation, operation, and 
maintenance associated with these controls.
    e. Describe additional engineering and work practice controls that 
could be implemented in each operation where exposure levels are 
currently above the proposed PEL to further reduce exposure levels.
    f. When these additional controls are implemented, to what levels 
can exposure be expected to be reduced, or what percent reduction is 
expected to be achieved?
    g. What amount of time is needed to develop, install, and implement 
these additional controls? Will the added controls affect productivity? 
If so, how?
    h. Are there any processes or operations for which it is not 
reasonably possible to implement engineering and work practice controls 
within one year to achieve the proposed PEL? If so, how much additional 
time would be necessary?
    16. OSHA requests information on whether there are any specific 
conditions or job tasks involving exposure to respirable crystalline 
silica where engineering and work practice controls are not available 
or are not capable of reducing exposure levels to or below the proposed 
PEL most of the time. Provide data and evidence to support your 
response.
    17. OSHA has made a preliminary determination that compliance with 
the proposed PEL can be achieved in most operations most of the time 
through the use of engineering and work practice controls. OSHA has 
further made a preliminary determination that the proposed rule is 
technologically feasible. OSHA solicits comments on the reasonableness 
of these preliminary determinations.

Compliance Costs

    18. In its PEA (summarized in Section VIII.3 of this preamble), 
OSHA developed its estimate of the costs of the proposed rule. The 
Agency requests comment on the methodological and analytical 
assumptions applied in the cost analysis. Of particular importance are 
the unit cost estimates provided in tables and text in Chapter V of the 
PEA for all major provisions of the proposed rule. OSHA requests the 
following information regarding unit and total compliance costs:
    a. If you have installed engineering controls or adopted work 
practices to reduce exposure to respirable crystalline silica, describe 
these controls and their costs. If you have substituted another 
substance(s) for crystalline silica, what has been the cost impact of 
substitution (cost of materials, productivity impact)?
    b. OSHA has proposed to limit the prohibition on dry sweeping to 
situations where this activity could contribute to exposure that 
exceeds the PEL and estimated the costs for the use of wet methods to 
control dust. OSHA requests comment on the use of wet methods as a 
substitute for dry sweeping and whether the prohibition on dry sweeping 
is feasible and cost-effective.
    c. In its PEA, OSHA presents estimated baseline levels of use of 
personal protective equipment (PPE) and the incremental PPE costs 
associated with the proposed rule. Are OSHA's estimated PPE compliance 
rates reasonable? Are OSHA's estimates of PPE costs, and the 
assumptions underlying these estimates, consistent with current 
industry practice? If not, provide data and evidence describing current 
industry PPE practices.
    d. Do you currently conduct exposure monitoring for respirable 
crystalline silica? Are OSHA's estimates of exposure assessment costs 
reasonable? Would your company require outside consultants to perform 
exposure monitoring?
    e. Are OSHA's estimates for medical surveillance costs--including 
direct medical costs, the opportunity cost of worker time for offsite 
travel and for the health screening, and recordkeeping costs--
reasonable?
    f. In its PEA, OSHA presents estimated baseline levels of training 
and information concerning respirable crystalline silica-related 
hazards and the incremental costs associated with the additional 
requirements for training and information in the proposed rule. OSHA 
requests information on information and training programs addressing 
respirable crystalline silica that are currently being implemented by 
employers and any necessary additions to those programs that are 
anticipated in response to the proposed rule. Are OSHA's baseline 
estimates and unit costs for training reasonable and consistent with 
current industry practice?
    g. Are OSHA's estimated costs for regulated areas and written 
access control plans reasonable?
    h. The cost estimates in the PEA take the much higher labor 
turnover rates in construction into account when calculating costs. For 
the proposed rule, OSHA used the most recent BLS turnover rate of 64 
percent for construction (versus a turnover rate of 27.2 percent for 
general industry). OSHA believes that the estimates in the PEA capture 
the effect of high turnover rates in construction and solicits comments 
on this issue.
    i. Has OSHA omitted any costs that would be incurred to comply with 
the proposed rule?

Effects on Small Entities

    19. OSHA has considered the effects on small entities raised during 
its SBREFA process and addressed these concerns in Chapter VIII of the 
PEA. Are there additional difficulties small

[[Page 56287]]

entities may encounter when attempting to comply with requirements of 
the proposed rule? Can any of the proposal's requirements be deleted or 
simplified for small entities, while still providing equivalent 
protection of the health of employees? Would allowing additional time 
for small entities to comply make a difference in their ability to 
comply? How much additional time would be necessary?

Economic Impacts

    20. OSHA, in its PEA, has estimated compliance costs per affected 
entity and the likely impacts on revenues and profits. OSHA requests 
that affected employers provide comment on OSHA's estimate of revenue, 
profit, and the impacts of costs for their industry or application 
group. The Agency also requests that employers provide data on their 
revenues, profits, and the impacts of cost, if available. Are there 
special circumstances--such as unique cost factors, foreign 
competition, or pricing constraints--that OSHA needs to consider when 
evaluating economic impacts for particular applications and industry 
groups?
    21. OSHA seeks comment as to whether establishments will be able to 
finance first-year compliance costs from cash flow, and under what 
circumstances a phase-in approach will assist firms in complying with 
the proposed rule.
    22. The Agency invites comment on potential employment impacts of 
the proposed silica rule, and on Inforum's estimates of the employment 
impacts of the proposed silica rule on the U.S. economy.

Outreach and Compliance Assistance

    23. If the proposed rule is promulgated, OSHA will provide outreach 
materials on the provisions of the standards in order to encourage and 
assist employers in complying. Are there particular materials that 
would make compliance easier for your company or industry? What 
materials would be especially useful for small entities? Submit 
recommendations or samples.

Benefits and Net Benefits

    24. OSHA requests comments on any aspect of its estimation of 
benefits and net benefits from the proposed rule, including the 
following:
    a. The use of willingness-to-pay measures and estimates based on 
compensating wage differentials.
    b. The data and methods used in the benefits calculations.
    c. The choice of discount rate for annualizing the monetized 
benefits of the proposed rule.
    d. Increasing the monetary value of a statistical life over time 
resulting from an increase in real per capita income and the estimated 
income elasticity of the value of life.
    e. Extending the benefits analysis beyond the 60-year period used 
in the PEA.
    f. The magnitude of non-quantified health benefits arising from the 
proposed rule and methods for better measuring these effects. An 
example would be diagnosing latent tuberculosis (TB) in the silica-
exposed population and thereby reducing the risk of TB being spread to 
the population at large.

Overlapping and Duplicative Regulations

    25. Do any federal regulations duplicate, overlap, or conflict with 
the proposed respirable crystalline silica rule? If so, provide or cite 
to these regulations.

Alternatives/Ways to Simplify a New Standard

    26. Comment on the alternative to new comprehensive standards 
(which have ancillary provisions in addition to a permissible exposure 
limit) that would be simply improved outreach and enforcement of the 
existing standards (which is only a permissible exposure limit with no 
ancillary provisions). Do you believe that improved outreach and 
enforcement of the existing permissible exposure limits would be 
sufficient to reduce significant risks of material health impairment in 
workers exposed to respirable crystalline silica? Provide information 
to support your position.
    27. OSHA solicits comments on ways to simplify the proposed rule 
without compromising worker protection from exposure to respirable 
crystalline silica. In particular, provide detailed recommendations on 
ways to simplify the proposed standard for construction. Provide 
evidence that your recommended simplifications would result in a 
standard that was effective, to the extent feasible, in reducing 
significant risks of material health impairment in workers exposed to 
respirable crystalline silica.

Environmental Impacts

    28. Submit data, information, or comments pertaining to possible 
environmental impacts of adopting this proposal, including any positive 
or negative environmental effects and any irreversible commitments of 
natural resources that would be involved. In particular, consideration 
should be given to the potential direct or indirect impacts of the 
proposal on water and air pollution, energy use, solid waste disposal, 
or land use. Would compliance with the silica rule require additional 
actions to comply with federal, state, or local environmental 
requirements?
    29. Some small entity representatives advised OSHA that the use of 
water as a control measure is limited at their work sites due to 
potential water and soil contamination. OSHA believes these limits may 
only apply in situations where crystalline silica is found with other 
toxic substances such as during abrasive blasting of metal or painted 
metal structures, or in locations where state and local requirements 
are more restrictive than EPA requirements. OSHA seeks comments on this 
issue, including cites to applicable requirements.
    a. Are there limits on the use of water controls in your operations 
due to environmental regulations? If so, are the limits due to the non-
silica components of the waste stream? What are these non-silica 
components?
    b. What metals or other toxic chemicals are in your silica waste 
streams and what are the procedures and costs to filter out these 
metals or other toxic chemicals from your waste streams? Provide 
documentation to support your cost estimates.

Provisions of the Standards

Scope

    30. OSHA's Advisory Committee on Construction Safety and Health 
(ACCSH) has historically advised the Agency to take into consideration 
the unique nature of construction work environments by either setting 
separate standards or making accommodations for the differences in work 
environments in construction as compared to general industry. ASTM, for 
example, has separate silica standards of practice for general industry 
and construction, E 1132-06 and E 2625-09, respectively. To account for 
differences in the workplace environments for these different sectors, 
OSHA has proposed separate standards for general industry/maritime and 
construction. Is this approach necessary and appropriate? What other 
approaches, if any, should the Agency consider? Provide a rationale for 
your response.
    31. OSHA has proposed that the scope of the construction standard 
include all occupational exposures to respirable crystalline silica in 
construction work as defined in 29 CFR 1910.12(b) and covered under 29 
CFR part 1926, rather

[[Page 56288]]

than restricting the application of the rule to specific construction 
operations. Should OSHA modify the scope to limit what is covered? What 
should be included and what should be excluded? Provide a rationale for 
your position. Submit your proposed language for the scope and 
application provision.
    32. OSHA has not proposed to cover agriculture because the Agency 
does not have data sufficient to determine the feasibility of the 
proposed PEL in agricultural operations. Should OSHA cover respirable 
crystalline silica exposure in agriculture? Provide evidence to support 
your position. OSHA seeks information on agricultural operations that 
involve respirable crystalline silica exposures, including information 
that identifies particular activities or crops (e.g., hand picking 
fruit and vegetables, shaking branches and trees, harvesting with 
combines, loading storage silos, planting) associated with exposure, 
information indicating levels of exposure, and information relating to 
available control measures and their effectiveness. OSHA also seeks 
information related to the development of respirable crystalline 
silica-related adverse health effects and diseases among workers in the 
agricultural sector.
    33. Should OSHA limit coverage of the rule to materials that 
contain a threshold concentration (e.g., 1%) of crystalline silica? For 
example, OSHA's Asbestos standard defines ``asbestos-containing 
material'' as any material containing more than 1% asbestos, for 
consistency with EPA regulations. OSHA has not proposed a comparable 
limitation to the definition of respirable crystalline silica. Is this 
approach appropriate? Provide the rationale for your position.
    34. OSHA has proposed to cover shipyards under the general industry 
standard. Are there any unique circumstances in shipyard employment 
that would justify development of different provisions or a separate 
standard for the shipyard industry? What are the circumstances and how 
would they not be adequately covered by the general industry standard?

Definitions

    35. Competent person. OSHA has proposed limited duties for a 
competent person relating to establishment of an access control plan. 
The Agency did not propose specific requirements for training of a 
competent person. Is this approach appropriate? Should OSHA include a 
competent person provision? If so, should the Agency add to, modify, or 
delete any of the duties of a competent person as described in the 
proposed standard? Provide the basis for your recommendations.
    36. Has OSHA defined ``respirable crystalline silica'' 
appropriately? If not, provide the definition that you believe is 
appropriate. Explain the basis for your response, and provide any data 
that you believe are relevant.
    37. The proposed rule defines ``respirable crystalline silica'' in 
part as ``airborne particles that contain quartz, cristobalite, and/or 
tridymite.'' OSHA believes that tridymite is rarely found in nature or 
in the workplace. Please describe any instances of occupational 
exposure to tridymite of which you are aware. Please provide supporting 
evidence, or explain the basis of your knowledge. Should tridymite be 
included in the scope of this proposed rule? Please provide any 
evidence to support your position.

PEL and Action Level

    38. OSHA has proposed a TWA PEL for respirable crystalline silica 
of 50 [micro]g/m\3\ for general industry, maritime, and construction. 
The Agency has made a preliminary determination that this is the lowest 
level that is technologically feasible. The Agency has also determined 
that a PEL of 50 [micro]g/m\3\ will substantially reduce, but not 
eliminate, significant risk of material health impairment. Is this PEL 
appropriate, given the Agency's obligation to reduce significant risk 
of material health impairment to the extent feasible? If not, what PEL 
would be more appropriate? The Agency also solicits comment on 
maintaining the existing PELs for respirable crystalline silica. 
Provide evidence to support your response.
    39. OSHA has proposed a single PEL for respirable crystalline 
silica (quartz, cristobalite, and tridymite). Is a single PEL 
appropriate, or should the Agency maintain separate PELs for the 
different forms of respirable crystalline silica? Provide the rationale 
for your position.
    40. OSHA has proposed an action level for respirable crystalline 
silica exposure of 25 [micro]g/m\3\ in general industry, maritime, and 
construction. Is this an appropriate approach and level, and if not, 
what approach or level would be more appropriate and why? Should an 
action level be included in the final rule? Provide the rationale for 
your position.
    41. If an action level is included in the final rule, which 
provisions, if any, should be triggered by exposure above or below the 
action level? Provide the basis for your position and include 
supporting information.
    42. If no action level is included in the final rule, which 
provisions should apply to all workers exposed to respirable 
crystalline silica? Which provisions should be triggered by the PEL? 
Are there any other appropriate triggers for the requirements of the 
rule?

Exposure Assessment

    43. OSHA is proposing to allow employers to initially assess 
employee exposures using air monitoring or objective data. Has OSHA 
defined ``objective data'' sufficiently for an employer to know what 
data may be used? If not, submit an alternative definition. Is it 
appropriate to allow employers to use objective data to perform 
exposure assessments? Explain why or why not.
    44. The proposed rule provides two options for periodic exposure 
assessment: (1) A fixed schedule option, and (2) a performance option. 
The performance option provides employers flexibility in the methods 
used to determine employee exposures, but requires employers to 
accurately characterize employee exposures. The proposed approach is 
explained in the Summary and Explanation for paragraph (d) Exposure 
Assessment. OSHA solicits comments on this proposed exposure assessment 
provision. Is the wording of the performance option in the regulatory 
text understandable and does it clearly indicate what would constitute 
compliance with the provision? If not, suggest alternative language 
that would clarify the provision, enabling employers to more easily 
understand what would constitute compliance.
    45. Do you conduct initial air monitoring or do you rely on 
objective data to determine respirable crystalline silica exposures? If 
objective data, what data do you use? Have you conducted historical 
exposure monitoring of your workforce that is representative of current 
process technology and equipment use? Describe any other approaches you 
have implemented for assessing an employee's initial exposure to 
respirable crystalline silica.
    46. OSHA is proposing specific requirements for laboratories that 
perform analyses of respirable crystalline silica samples. The 
rationale is to improve the precision in individual laboratories and 
reduce the variability of results between laboratories, so that 
sampling results will be more reliable. Are these proposed requirements 
appropriate? Will the laboratory requirements add necessary reliability 
and reduce inter-lab variability, or might they be overly proscriptive? 
Provide the basis for your response.
    47. Has OSHA correctly described the accuracy and precision of 
existing methods of sampling and analysis for

[[Page 56289]]

respirable crystalline silica at the proposed action level and PEL? Can 
worker exposures be accurately measured at the proposed action level 
and PEL? Explain the basis for your response, and provide any data that 
you believe are relevant.
    48. OSHA has not addressed the performance of the analytical method 
with respect to tridymite since we have found little available data. 
Please comment on the performance of the analytical method with respect 
to tridymite and provide any data to support your position.

Regulated Areas and Access Control

    49. Where exposures exceed the PEL, OSHA has proposed to provide 
employers with the option of either establishing a regulated area or 
establishing a written access control plan. For which types of work 
operations would employers be likely to establish a written access 
control plan? Will employees be protected by these options? Provide the 
basis for your position and include supporting information.
    50. The Summary and Explanation for paragraph (e) Regulated Areas 
and Access Control clarifies how the regulated area requirements would 
apply to multi-employer worksites in the proposed standard. OSHA 
solicits comments on this issue.
    51. OSHA is proposing limited requirements for protective clothing 
in the silica rule. Is this appropriate? Are you aware of any 
situations where more or different protective clothing would be needed 
for silica exposures? If so, what type of protective clothing and 
equipment should be required? Are there additional provisions related 
to protective clothing that should be incorporated into this rule that 
will enhance worker protection? Provide the rationale and data that 
support your conclusions.

Methods of Compliance

    52. In OSHA's cadmium standard (29 CFR 1910.1027(f)(1)(ii),(iii), 
and (iv)), the Agency established separate engineering control air 
limits (SECALs) for certain processes in selected industries. SECALs 
were established where compliance with the PEL by means of engineering 
and work practice controls was infeasible. For these industries, a 
SECAL was established at the lowest feasible level that could be 
achieved by engineering and work practice controls. The PEL was set at 
a lower level, and could be achieved by any allowable combination of 
controls, including respiratory protection. In OSHA's chromium (VI) 
standard (29 CFR 1910.1026), an exception similar to SECALs was made 
for painting airplanes and airplane parts. Should OSHA follow this 
approach for respirable crystalline silica in any industries or 
processes? If so, in what industries or processes, and at what exposure 
levels, should the SECALs be established? Provide the basis for your 
position and include supporting information.
    53. The proposed standards do not contain a requirement for a 
written exposure control program. The two ASTM standards for general 
industry and construction (E 1132-06, section 4.2.6, and E 2626-09, 
section 4.2.5) state that, where overexposures are persistent (such as 
in regulated areas or abrasive blasting operations), a written exposure 
control plan shall establish engineering and administrative controls to 
bring the area into compliance, if feasible. In addition, the proposed 
regulatory language developed by the Building and Construction Trades 
Department, AFL-CIO contains provisions for a written program. The ASTM 
standards recommend that, where there are regulated areas with 
persistent exposures or tasks, tools, or operations that tend to cause 
respirable crystalline silica exposure, the employer will conduct a 
formal analysis and implement a written control plan (an abatement 
plan) on how to bring the process into compliance. If that is not 
feasible, the employer is to indicate the respiratory protection and 
other protective procedures that will be used to protect employee(s) 
permanently or until compliance will be achieved. Should OSHA require 
employers to develop and implement a written exposure control plan and, 
if so, what should be required to be in the plans?
    54. Table 1 in the proposed construction standard specifies 
engineering and work practice controls and respiratory protection for 
selected construction operations, and exempts employers who implement 
these controls from exposure assessment requirements. Is this approach 
appropriate? Are there other operations that should be included, or 
listed operations that should not be included? Are the specified 
control measures effective? Should any other changes be made in Table 
1? How should OSHA update Table 1 in the future to account for 
development of new technologies? Provide data and information to 
support your position.
    55. OSHA requests comments on the degree of specificity used for 
the engineering and work practice controls for tasks identified in 
Table 1, including maintenance requirements. Should OSHA require an 
evaluation or inspection checklist for controls? If so, how frequently 
should evaluations or inspections be conducted? Provide any examples of 
such checklists, along with information regarding their frequency of 
use and effectiveness.
    56. In the proposed construction standard, when employees perform 
an operation listed in Table 1 and the employer fully implements the 
engineering controls, work practices, and respiratory protection 
described in Table 1 for that operation, the employer is not required 
to assess the exposure of the employees performing such operations. 
However, the employer must still ensure compliance with the proposed 
PEL for that operation. OSHA seeks comment on whether employers fully 
complying with Table 1 for an operation should still need to comply 
with the proposed PEL for that operation. Instead, should OSHA treat 
compliance with Table 1 as automatically meeting the requirements of 
the proposed PEL?
    57. Are the descriptions of the operations (specific task or tool 
descriptions) and control technologies in Table 1 clear and precise 
enough so that employers and workers will know what controls they 
should be using for the listed operations? Identify the specific 
operation you are addressing and whether your assessment is based on 
your anecdotal experience or research. For each operation, are the data 
and other supporting information sufficient to predict the range of 
expected exposures under the controlled conditions? Identify 
operations, if any, where you believe the data are not sufficient. 
Provide the reasoning and data that support your position.
    58. In one specific example from Table 1, OSHA has proposed the 
option of using a wet method for hand-operated grinders, with 
respirators required only for operations lasting four hours or more. 
Please comment and provide OSHA with additional information regarding 
wet grinding and the adequacy of this control strategy. OSHA is also 
seeking additional information on the second option (commercially 
available shrouds and dust collection systems) to confirm that this 
control strategy (including the use of half-mask respirators) will 
reduce workers' exposure to or below the PEL.
    59. For impact drilling operations lasting four hours or less, OSHA 
is proposing in Table 1 to allow workers to use water delivery systems 
without the use of respiratory protection, as the Agency believes that 
this dust suppression method alone will provide

[[Page 56290]]

consistent, sufficient protection. Is this control strategy 
appropriate? Please provide the basis for your position and any 
supporting evidence or additional information that addresses the 
appropriateness of this control strategy.
    60. In the case of rock drilling, in order to ensure that workers 
are adequately protected from the higher exposures that they would 
experience working under shrouds, OSHA is proposing in Table 1 that 
employers ensure that workers use half-mask respirators when working 
under shrouds at the point of operation. Is this specification 
appropriate? Please provide the basis for your position and any 
supporting evidence or additional information that addresses the 
appropriateness of this specification.
    61. OSHA has specified a control strategy for concrete drilling in 
Table 1 that includes use of a dust collection system as well as a low-
flow water spray. Please provide to OSHA any data that you have that 
describes the efficacy of these controls. Is the control strategy in 
Table 1 adequate? Please provide the basis for your position and any 
supporting evidence or additional information regarding the adequacy of 
this control strategy.
    62. One of the control options in Table 1 in the proposed 
construction standard for rock-crushing operations is local exhaust 
ventilation. However, OSHA is aware of difficulties in applying this 
control to this operation. Is this control strategy appropriate and 
practical for rock-crushing operations? Please provide any information 
that you have addressing this issue.
    63. OSHA has not proposed to prohibit the use of crystalline silica 
as an abrasive blasting agent. Abrasive blasting, similar to other 
operations that involve respirable crystalline silica exposures, must 
follow the hierarchy of controls, which means, if feasible, that 
substitution, engineering, or administrative controls or a combination 
of these controls must be used to minimize or eliminate the exposure 
hazard. Is this approach appropriate? Provide the basis for your 
position and any supporting evidence.
    64. The technological feasibility study (PEA, Chapter 4) indicates 
that employers use substitutes for crystalline silica in a variety of 
operations. If you are aware of substitutes for crystalline silica that 
are currently being used in any operation not considered in the 
feasibility study, please provide to OSHA relevant information that 
contains data supporting the effectiveness, in reducing exposure to 
crystalline silica, of those substitutes. Provide any information you 
may have on the health hazards associated with exposure to these 
substitutes.
    65. Information regarding the effectiveness of dust control kits 
that incorporate local exhaust ventilation in the railroad 
transportation industry in reducing worker exposure to crystalline 
silica is not available from the manufacturer. If you have any relevant 
information on the effectiveness of such kits, please provide it to 
OSHA.
    66. The proposed rule prohibits the use of compressed air and dry 
brushing and sweeping for cleaning of surfaces and clothing in general 
industry, maritime, and construction and promotes the use of wet 
methods and HEPA-filter vacuuming as alternatives. Are there any 
circumstances in general industry, maritime, or construction work where 
dry sweeping is the only kind of sweeping that can be done? Have you 
done dry sweeping and, if so, what has been your experience with it? 
What methods have you used to minimize dust when dry sweeping? Can 
exposure levels be kept below the proposed PEL when dry sweeping is 
conducted? How? Provide exposure data for periods when you conducted 
dry sweeping. If silica respirable dust samples are not available, 
provide real time respirable dust or gravimetric respirable dust data. 
Is water available at most sites to wet down dust prior to sweeping? 
How effective is the use of water? Does the use of water cause other 
problems for the worksite? Are there other substitutes that are 
effective?
    67. A 30-day exemption from the requirement to implement 
engineering and work practice controls was not included in the proposed 
standard for construction, and has been removed from the proposed 
standard for general industry and maritime. OSHA requests comment on 
this issue.
    68. The proposed prohibition on employee rotation is explained in 
the Summary and Explanation for paragraph (f) Methods of Compliance. 
OSHA solicits comment on the prohibition of employee rotation to 
achieve compliance when exposure levels exceed the PEL.

Medical Surveillance

    69. Is medical surveillance being provided for respirable 
crystalline silica-exposed employees at your worksite? If so:
    a. How do you determine which employees receive medical 
surveillance (e.g., by exposure level or other factors)?
    b. Who administers and implements the medical surveillance (e.g., 
company doctor or nurse, outside doctor or nurse)?
    c. What examinations, tests, or evaluations are included in the 
medical surveillance program? Does your medical surveillance program 
include testing for latent TB? Do you include pulmonary function 
testing in your medical surveillance program?
    d. What benefits (e.g., health, reduction in absenteeism, or 
financial) have been achieved from the medical surveillance program?
    e. What are the costs of your medical surveillance program? How do 
your costs compare with OSHA's estimated unit costs for the physical 
examination and employee time involved in the medical surveillance 
program? Are OSHA's baseline assumptions and cost estimates for medical 
surveillance consistent with your experiences providing medical 
surveillance to your employees?
    f. How many employees are included in your medical surveillance 
program?
    g. What NAICS code describes your workplace?
    70. Is the content and frequency of proposed examinations 
appropriate? If not, how should content and frequency be modified?
    71. Is the specified content of the physician or other licensed 
health care professional's (PLHCP) written medical opinion sufficiently 
detailed to enable the employer to address the employee's needs and 
potential workplace improvements, and yet appropriately limited so as 
to protect the employee's medical privacy? If not, how could the 
medical opinion be improved?
    72. Is the requirement for latent TB testing appropriate? Does the 
proposed rule implement this requirement in a cost-effective manner? 
Provide the data or cite references that support your position.
    73. Is the requirement for pulmonary function testing initially and 
at three-year intervals appropriate? Is there an alternate strategy or 
schedule for conducting follow-up testing that is better? Provide data 
or cite references to support your position.
    74. Is the requirement for chest X-rays initially and at three-year 
intervals appropriate? Is there an alternate strategy or schedule for 
conducting follow-up chest X-rays that you believe would be better? 
Provide data or cite references to support your position.
    75. Are there other tests that should be included in medical 
surveillance?
    76. Do you provide medical surveillance to employees under another 
OSHA standard or as a matter of company policy? If so, describe your 
program in terms of what standards the program addresses and such 
factors as content and frequency of examinations

[[Page 56291]]

and referrals, and reports to the employer.
    77. Is exposure for 30 days at or above the PEL the appropriate 
number of days to trigger medical surveillance? Should the appropriate 
reference for medical monitoring be the PEL or the action level? Is 30 
days from initial assignment a reasonable amount of time to provide a 
medical exam? Indicate the basis for your position.
    78. Are PLHCPs available in your geographic area to provide medical 
surveillance to workers who are covered by the proposed rule? For 
example, do you have access to qualified X-ray technicians, NIOSH-
certified B-readers, and pulmonary specialists? Describe any 
difficulties you may have with regard to access to PLHCPs to provide 
surveillance for the rule. Note what you consider your ``geographic 
area'' in responding to this question.
    79. OSHA is proposing to allow an ``equivalent diagnostic study'' 
in place of requirements to use a chest X-ray (posterior/anterior view; 
no less than 14 x 17 inches and no more than 16 x 17 inches at full 
inspiration; interpreted and classified according to the International 
Labour Organization (ILO) International Classification of Radiographs 
of Pneumoconioses by a NIOSH-certified ``B'' reader). Two other 
radiological test methods, computed tomography (CT) and high resolution 
computed tomography (HRCT), could be considered ``equivalent diagnostic 
studies'' under paragraph (h)(2)(iii) of the proposal. However, the 
benefits of CT or HRCT should be balanced with risks, including higher 
radiation doses. Also, standardized methods for interpreting and 
reporting results of CT or HRCT are not currently available. The Agency 
requests comment on whether CT and HRCT should be considered 
``equivalent diagnostic studies'' under the rule. Provide a rationale 
and evidence to support your position.
    80. OSHA has not included requirements for medical removal 
protection (MRP) in the proposed rule, because OSHA has made a 
preliminary determination that there are few instances where temporary 
worker removal and MRP will be useful. The Agency requests comment as 
to whether the respirable crystalline silica rule should include 
provisions for the temporary removal and extension of MRP benefits to 
employees with certain respirable crystalline silica-related health 
conditions. In particular, what medical conditions or findings should 
trigger temporary removal and for what maximum amount of time should 
MRP benefits be extended? OSHA also seeks information on whether or not 
MRP is currently being used by employers with respirable crystalline 
silica-exposed workers, and the costs of such programs.

Hazard Communication and Training

    81. OSHA has proposed that employers provide hazard information to 
employees in accordance with the Agency's Hazard Communication standard 
(29 CFR 1910.1200). Compliance with the Hazard Communication standard 
would mean that there would be a requirement for a warning label for 
substances that contain more than 0.1 percent crystalline silica. 
Should this requirement be changed so that warning labels would only be 
required of substances more than 1 percent by weight of silica? Provide 
the rationale for your position. The Agency also has proposed 
additional training specific to work with respirable crystalline 
silica. Should OSHA include these additional requirements in the final 
rule, or are the requirements of the Hazard Communication standard 
sufficient?
    82. OSHA is providing an abbreviated training section in this 
proposal as compared to ASTM consensus standards (see ASTM E 1132-06, 
sections 4.8.1-5). The Hazard Communication standard is comprehensive 
and covers most of the training requirements traditionally included in 
an OSHA health standard. Do you concur with OSHA that performance-based 
training specified in the Hazard Communication standard, supplemented 
by the few training requirements of this section, is sufficient in its 
scope and depth? Are there any other training provisions you would add?
    83. The proposed rule does not alter the requirements for 
substances to have warning labels, specify wording for labels, or 
otherwise modify the provisions of the OSHA's Hazard Communication 
standard. OSHA invites comment on these issues.

Recordkeeping

    84. OSHA is proposing to require recordkeeping for air monitoring 
data, objective data, and medical surveillance records. The proposed 
rule's recordkeeping requirements are discussed in the Summary and 
Explanation for paragraph (j) Recordkeeping. The Agency seeks comment 
on the utility of these recordkeeping requirements as well as the costs 
of making and maintaining these records. Provide evidence to support 
your position.

Dates

    85. OSHA requests comment on the time allowed for compliance with 
the provisions of the proposed rule. Is the time proposed appropriate, 
or should there be a longer or shorter phase-in of requirements? In 
particular, should requirements for engineering controls and/or medical 
surveillance be phased in over a longer period of time (e.g., over 1, 
2, 3, or more years)? Should an extended phase-in period be provided 
for specific industries (e.g., industries where first-year or 
annualized cost impacts are highest), specific size-classes of 
employers (e.g., employers with fewer than 20 employees), combinations 
of these factors, or all firms covered by the rule? Identify any 
industries, processes, or operations that have special needs for 
additional time, the additional time required, and the reasons for the 
request.
    86. OSHA is proposing a two-year start-up period to allow 
laboratories time to achieve compliance with the proposed requirements, 
particularly with regard to requirements for accreditation and round 
robin testing. OSHA also recognizes that requirements for monitoring in 
the proposed rule will increase the required capacity for analysis of 
respirable crystalline silica samples. Do you think that this start-up 
period is enough time for laboratories to achieve compliance with the 
proposed requirements and to develop sufficient analytic capacity? If 
you think that additional time is needed, please tell OSHA how much 
additional time is required and give your reasons for this request.

Appendices

    87. Some OSHA health standards include appendices that address 
topics such as the hazards associated with the regulated substance, 
health screening considerations, occupational disease questionnaires, 
and PLHCP obligations. In this proposed rule, OSHA has included a non-
mandatory appendix to clarify the medical surveillance provisions of 
the rule. What would be the advantages and disadvantages of including 
such an appendix in the final rule? If you believe it should be 
included, comment on the appropriateness of the information included. 
What additional information, if any, should be included in the 
appendix?

II. Pertinent Legal Authority

    The purpose of the Occupational Safety and Health Act, 29 U.S.C. 
651 et seq. (``the Act''), is to ``. . . assure so far as possible 
every working man and

[[Page 56292]]

woman in the nation safe and healthful working conditions and to 
preserve our human resources.'' 29 U.S.C. 651(b).
    To achieve this goal Congress authorized the Secretary of Labor 
(the Secretary) to promulgate and enforce occupational safety and 
health standards. 29 U.S.C. 654(b) (requiring employers to comply with 
OSHA standards), 655(a) (authorizing summary adoption of existing 
consensus and federal standards within two years of the Act's 
enactment), and 655(b) (authorizing promulgation, modification or 
revocation of standards pursuant to notice and comment).
    The Act provides that in promulgating health standards dealing with 
toxic materials or harmful physical agents, such as this proposed 
standard regulating occupational exposure to respirable crystalline 
silica, the Secretary, shall set the standard which most adequately 
assures, to the extent feasible, on the basis of the best available 
evidence that no employee will suffer material impairment of health or 
functional capacity even if such employee has regular exposure to the 
hazard dealt with by such standard for the period of his working life. 
29 U.S.C. 655(b)(5).
    The Supreme Court has held that before the Secretary can promulgate 
any permanent health or safety standard, she must make a threshold 
finding that significant risk is present and that such risk can be 
eliminated or lessened by a change in practices. Industrial Union 
Dept., AFL-CIO v. American Petroleum Institute, 448 U.S. 607, 641-42 
(1980) (plurality opinion) (``The Benzene case''). Thus, section 
6(b)(5) of the Act requires health standards to reduce significant risk 
to the extent feasible. Id.
    The Court further observed that what constitutes ``significant 
risk'' is ``not a mathematical straitjacket'' and must be ``based 
largely on policy considerations.'' The Benzene case, 448 U.S. at 655. 
The Court gave the example that if,

. . . the odds are one in a billion that a person will die from 
cancer . . . the risk clearly could not be considered significant. 
On the other hand, if the odds are one in one thousand that regular 
inhalation of gasoline vapors that are 2% benzene will be fatal, a 
reasonable person might well consider the risk significant. [Id.]

    OSHA standards must be both technologically and economically 
feasible. United Steelworkers v. Marshall, 647 F.2d 1189, 1264 (D.C. 
Cir. 1980) (``The Lead I case''). The Supreme Court has defined 
feasibility as ``capable of being done.'' Am. Textile Mfrs. Inst. v. 
Donovan, 452 U.S. 490, 509-510 (1981) (``The Cotton Dust case''). The 
courts have further clarified that a standard is technologically 
feasible if OSHA proves a reasonable possibility,

. . . within the limits of the best available evidence . . . that 
the typical firm will be able to develop and install engineering and 
work practice controls that can meet the PEL in most of its 
operations. [See The Lead I case, 647 F.2d at 1272]

    With respect to economic feasibility, the courts have held that a 
standard is feasible if it does not threaten massive dislocation to or 
imperil the existence of the industry. Id. at 1265. A court must 
examine the cost of compliance with an OSHA standard,

. . . in relation to the financial health and profitability of the 
industry and the likely effect of such costs on unit consumer prices 
. . . [T]he practical question is whether the standard threatens the 
competitive stability of an industry, . . . or whether any intra-
industry or inter-industry discrimination in the standard might 
wreck such stability or lead to undue concentration. [Id. (citing 
Indus. Union Dep't, AFL-CIO v. Hodgson, 499 F.2d 467 (D.C. Cir. 
1974))]

    The courts have further observed that granting companies reasonable 
time to comply with new PELs may enhance economic feasibility. The Lead 
I case at 1265. While a standard must be economically feasible, the 
Supreme Court has held that a cost-benefit analysis of health standards 
is not required by the Act because a feasibility analysis is required. 
The Cotton Dust case, 453 U.S. at 509.
    Finally, sections 6(b)(7) and 8(c) of the Act authorize OSHA to 
include among a standard's requirements labeling, monitoring, medical 
testing, and other information-gathering and -transmittal provisions. 
29 U.S.C. 655(b)(7), 657(c).

III. Events Leading to the Proposed Standards

    OSHA's current standards for workplace exposure to respirable 
crystalline silica were adopted in 1971, pursuant to section 6(a) of 
the OSH Act (36 FR 10466, May 29, 1971). Section 6(a) provided that in 
the first two years after the effective date of the Act, OSHA had to 
promulgate ``start-up'' standards, on an expedited basis and without 
public hearing or comment, based on national consensus or established 
Federal standards that improved employee safety or health. Pursuant to 
that authority, OSHA in 1971 promulgated approximately 425 permissible 
exposure limits (PELs) for air contaminants, including silica, derived 
principally from Federal standards applicable to government contractors 
under the Walsh-Healey Public Contracts Act, 41 U.S.C. 35, and the 
Contract Work Hours and Safety Standards Act (commonly known as the 
Construction Safety Act), 40 U.S.C. 333. The Walsh-Healey Act and 
Construction Safety Act standards, in turn, had been adopted primarily 
from recommendations of the American Conference of Governmental 
Industrial Hygienists (ACGIH).
    For general industry (see 29 CFR 1910.1000, Table Z-3), the PEL for 
crystalline silica in the form of respirable quartz is based on two 
alternative formulas: (1) A particle-count formula, PELmppcf 
= 250/(% quartz + 5); and (2) a mass formula proposed by ACGIH in 1968, 
PEL = (10 mg/m\3\)/(% quartz + 2). The general industry PELs for 
cristobalite and tridymite are one-half of the value calculated from 
either of the above two formulas. For construction (29 CFR 1926.55, 
Appendix A) and shipyards (29 CFR 1915.1000, Table Z), the formula for 
the PEL for crystalline silica in the form of quartz 
(PELmppcf = 250/(% quartz + 5)), which requires particle 
counting, is derived from the 1970 ACGIH threshold limit value 
(TLV).\2\ The formula based on particle-counting technology used in the 
general industry, construction, and shipyard PELs is now considered 
obsolete.
---------------------------------------------------------------------------

    \2\ The Mineral Dusts tables that contain the silica PELs for 
construction and shipyards do not clearly express PELs for 
cristobalite and tridymite. 29 CFR 1926.55; 29 CFR 1915.1000. This 
lack of textual clarity likely results from a transcription error in 
the Code of Federal Regulations. OSHA's current proposal provides 
the same PEL for quartz, cristobalite, and tridymite, in general 
industry, construction, and shipyards.
---------------------------------------------------------------------------

    In 1974, the National Institute for Occupational Safety and Health 
(NIOSH) evaluated crystalline silica as a workplace hazard and issued 
criteria for a recommended standard on occupational exposure to 
crystalline silica (NIOSH, 1974). NIOSH recommended that occupational 
exposure to crystalline silica be controlled so that no worker is 
exposed to a time-weighted average (TWA) of free (respirable 
crystalline) silica greater than 50 [mu]g/m\3\ as determined by a full-
shift sample for up to a 10-hour workday, 40-hour workweek. The 
document also recommended a number of ancillary provisions for a 
standard, such as exposure monitoring and medical surveillance.
    In December 1974, OSHA published an Advanced Notice of Proposed 
Rulemaking (ANPRM) based on the recommendations in the NIOSH criteria 
document (39 FR 44771, Dec. 27, 1974). In the ANPRM, OSHA solicited 
``public participation on the issues of whether a new standard for 
crystalline silica

[[Page 56293]]

should be issued on the basis of the [NIOSH] criteria or any other 
information, and, if so, what should be the contents of a proposed 
standard for crystalline silica.'' OSHA also set forth the particular 
issues of concern on which comments were requested. The Agency did not 
pursue a final rule for crystalline silica at that time.
    As information developed during the 1980s and 1990s, national and 
international classification organizations came to recognize 
crystalline silica as a human carcinogen. In June 1986, the 
International Agency for Research on Cancer (IARC) evaluated the 
available evidence regarding crystalline silica carcinogenicity and 
concluded that it was ``probably carcinogenic to humans'' (IARC, 1987). 
An IARC working group met again in October 1996 to evaluate the 
complete body of research, including research that had been conducted 
since the initial 1986 evaluation. IARC concluded that ``crystalline 
silica inhaled in the form of quartz or cristobalite from occupational 
sources is carcinogenic to humans'' (IARC, 1997).
    In 1991, in the Sixth Annual Report on Carcinogens, the U.S. 
National Toxicology Program (NTP) concluded that respirable crystalline 
silica was ``reasonably anticipated to be a human carcinogen'' (NTP, 
1991). NTP reevaluated the available evidence and concluded, in the 
Ninth Report on Carcinogens (NTP, 2000), that ``respirable crystalline 
silica (RCS), primarily quartz dust occurring in industrial and 
occupational settings, is known to be a human carcinogen, based on 
sufficient evidence of carcinogenicity from studies in humans 
indicating a causal relationship between exposure to RCS and increased 
lung cancer rates in workers exposed to crystalline silica dust'' (NTP, 
2000). ACGIH listed respirable crystalline silica (in the form of 
quartz) as a suspected human carcinogen in 2000, while lowering the TLV 
to 0.05 mg/m\3\ (ACGIH, 2001). ACGIH subsequently lowered the TLV for 
crystalline silica to 0.025 mg/m\3\ in 2006, which is the current value 
(ACGIH, 2010).
    In 1989, OSHA established 8-hour TWA PELs of 0.1 for quartz and 
0.05 mg/m\3\ for cristobalite and tridymite, as part of the Air 
Contaminants final rule for general industry (54 FR 2332, Jan. 19, 
1989). OSHA stated that these limits presented no substantial change 
from the Agency's former formula limits, but would simplify sampling 
procedures. In providing comments on the proposed rule, NIOSH 
recommended that crystalline silica be considered a potential 
carcinogen.
    In 1992, OSHA, as part of the Air Contaminants proposed rule for 
maritime, construction, and agriculture, proposed the same PELs as for 
general industry, to make the PELs consistent across all the OSHA-
regulated sectors (57 FR 26002, June 12, 1992). However, on July 7 of 
the same year, the U.S. Court of Appeals for the Eleventh Circuit 
vacated the 1989 Air Contaminants final rule for general industry (Am. 
Fed'n of Labor and Cong. of Indus. Orgs. v. OSHA, 965 F.2d 962 (1992)), 
which also mooted the proposed rule for maritime, construction, and 
agriculture. The Court's decision to vacate the rule forced the Agency 
to return to the PELs adopted in the 1970s.
    In 1994, OSHA launched a process to determine which safety and 
health hazards in the U.S. needed most attention. A priority planning 
committee included safety and health experts from OSHA, NIOSH, and the 
Mine Safety and Health Administration (MSHA). The committee reviewed 
available information on occupational deaths, injuries, and illnesses 
and held an extensive dialogue with representatives of labor, industry, 
professional and academic organizations, the States, voluntary 
standards organizations, and the public. The National Advisory 
Committee on Occupational Safety and Health and the Advisory Committee 
on Construction Safety and Health also made recommendations. Rulemaking 
for crystalline silica exposure was one of the priorities designated by 
this process. OSHA indicated that crystalline silica would be added to 
the Agency's regulatory agenda as other standards were completed and 
resources became available.
    In August 1996, the Agency initiated enforcement efforts under a 
Special Emphasis Program (SEP) on crystalline silica. The SEP was 
intended to reduce worker silica dust exposures that can cause 
silicosis. It included extensive outreach as well as inspections. Among 
the outreach materials available were slides presenting information on 
hazard recognition and crystalline silica control technology, a video 
on crystalline silica and silicosis, and informational cards for 
workers explaining crystalline silica, health effects related to 
exposure, and methods of control. The SEP provided guidance for 
targeting inspections of worksites with employees at risk of developing 
silicosis.
    As a follow-up to the SEP, OSHA undertook numerous non-regulatory 
actions to address silica exposures. For example, in October of 1996, 
OSHA launched a joint silicosis prevention effort with MSHA, NIOSH, and 
the American Lung Association (DOL, 1996). This public education 
campaign involved distribution of materials on how to prevent 
silicosis, including a guide for working safely with silica and 
stickers for hard hats to remind workers of crystalline silica hazards. 
Spanish language versions of these materials were also made available. 
OSHA and MSHA inspectors distributed materials at mines, construction 
sites, and other affected workplaces. The joint silicosis prevention 
effort included a National Conference to Eliminate Silicosis in 
Washington, DC, in March of 1997, which brought together approximately 
650 participants from labor, business, government, and the health and 
safety professions to exchange ideas and share solutions to reach the 
goal of eliminating silicosis. The conference highlighted the best 
methods of eliminating silicosis and included problem-solving workshops 
on how to prevent the disease in specific industries and job 
operations; plenary sessions with senior government, labor, and 
corporate officials; and opportunities to meet with safety and health 
professionals who had implemented successful silicosis prevention 
programs.
    In 2003, OSHA examined enforcement data for the years between 1997 
and 2002 and identified high rates of noncompliance with the OSHA 
respirable crystalline silica PEL, particularly in construction. This 
period covers the first five years of the SEP. These enforcement data, 
presented in Table 1, indicate that 24 percent of silica samples from 
the construction industry and 13 percent from general industry were at 
least three times the OSHA PEL. The data indicate that 66 percent of 
the silica samples obtained during inspections in general industry were 
in compliance with the PEL, while only 58 percent of the samples 
collected in construction were in compliance.

[[Page 56294]]



     Table III-1--Results of Time-Weighted Average (TWA) Exposure Respirable Crystalline Silica Samples for
                                        Construction and General Industry
                                       [January 1, 1997-December 31, 2002]
----------------------------------------------------------------------------------------------------------------
                                                           Construction               Other than construction
                                                 ---------------------------------------------------------------
     Exposure (severity relative to the PEL)         Number of                       Number of
                                                      samples         Percent         samples         Percent
----------------------------------------------------------------------------------------------------------------
< 1 PEL.........................................             424              58            2226              66
1 x PEL to < 2 x PEL............................              86              12             469              14
2 x PEL to < 3 x PEL............................              48               6             215               6
>= 3 x PEL and higher (3+)......................             180              24             453              13
                                                 ---------------------------------------------------------------
    Total  of samples..................             738                            3363
----------------------------------------------------------------------------------------------------------------
Source: OSHA Integrated Management Information System.

    In an effort to expand the 1996 SEP, on January 24, 2008, OSHA 
implemented a National Emphasis Program (NEP) to identify and reduce or 
eliminate the health hazards associated with occupational exposure to 
crystalline silica (OSHA, 2008). The NEP targeted worksites with 
elevated exposures to crystalline silica and included new program 
evaluation procedures designed to ensure that the goals of the NEP were 
measured as accurately as possible, detailed procedures for conducting 
inspections, updated information for selecting sites for inspection, 
development of outreach programs by each Regional and Area Office 
emphasizing the formation of voluntary partnerships to share 
information, and guidance on calculating PELs in construction and 
shipyards. In each OSHA Region, at least two percent of inspections 
every year are silica-related inspections. Additionally, the silica-
related inspections are conducted at a range of facilities reasonably 
representing the distribution of general industry and construction work 
sites in that region.
    A recent analysis of OSHA enforcement data from January 2003 to 
December 2009 (covering the period of continued implementation of the 
SEP and the first two years of the NEP) shows that considerable 
noncompliance with the PEL continues to occur. These enforcement data, 
presented in Table 2, indicate that 14 percent of silica samples from 
the construction industry and 19 percent for general industry were at 
least three times the OSHA PEL during this period. The data indicate 
that 70 percent of the silica samples obtained during inspections in 
general industry were in compliance with the PEL, and 75 percent of the 
samples collected in construction were in compliance.

     Table III-2--Results of Time-Weighted Average (TWA) Exposure Respirable Crystalline Silica Samples for
                                        Construction and General Industry
                                       [January 1, 2003-December 31, 2009]
----------------------------------------------------------------------------------------------------------------
                                                           Construction               Other than construction
                                                 ---------------------------------------------------------------
     Exposure (severity relative to the PEL)         Number of                       Number of
                                                      samples         Percent         samples         Percent
----------------------------------------------------------------------------------------------------------------
< 1 PEL.........................................             548              75             948              70
1 x PEL to < 2 x PEL............................              49               7             107               8
2 x PEL to < 3 x PEL............................              32               4              46               3
>= 3 x PEL and higher (3+)......................             103              14             254              19
                                                 ---------------------------------------------------------------
    Total  of samples..................             732                            1355
----------------------------------------------------------------------------------------------------------------
Source: OSHA Integrated Management Information System.

    Both industry and worker groups have recognized that a 
comprehensive standard is needed to protect workers exposed to 
respirable crystalline silica. For example, ASTM (originally known as 
the American Society for Testing and Materials) has published 
recommended standards for addressing the hazards of crystalline silica, 
and the Building and Construction Trades Department, AFL-CIO also has 
recommended a comprehensive program standard. These recommended 
standards include provisions for methods of compliance, exposure 
monitoring, training, and medical surveillance. The National Industrial 
Sand Association has also developed exposure assessment, medical 
surveillance, and training guidance products.
    In 1997, OSHA announced in its Unified Agenda under Long-Term 
Actions that it planned to publish a proposed rule on crystalline 
silica ``because the agency has concluded that there will be no 
significant progress in the prevention of silica-related diseases 
without the adoption of a full and comprehensive silica standard, 
including provisions for product substitution, engineering controls, 
training and education, respiratory protection and medical screening 
and surveillance. A full standard will improve worker protection, 
ensure adequate prevention programs, and further reduce silica-related 
diseases.'' (62 FR 57755, 57758, Oct. 29, 1997). In November 1998, OSHA 
moved ``Occupational Exposure to Crystalline Silica'' to the pre-rule 
stage in the Regulatory Plan (63 FR 61284, 61303-304, Nov. 9, 1998). 
OSHA held a series of stakeholder meetings in 1999 and 2000 to get 
input on the rulemaking. Stakeholder meetings for all industry sectors 
were held in Washington, Chicago, and San Francisco. A separate 
stakeholder meeting for the construction sector was held in Atlanta.

[[Page 56295]]

    OSHA initiated Small Business Regulatory Enforcement Fairness Act 
(SBREFA) proceedings in 2003, seeking the advice of small business 
representatives on the proposed rule (68 FR 30583, 30584, May 27, 
2003). The SBREFA panel, including representatives from OSHA, the Small 
Business Administration (SBA), and the Office of Management and Budget 
(OMB), was convened on October 20, 2003. The panel conferred with small 
entity representatives (SERs) from general industry, maritime, and 
construction on November 10 and 12, 2003, and delivered its final 
report, which included comments from the SERs and recommendations to 
OSHA for the proposed rule, to OSHA's Assistant Secretary on December 
19, 2003 (OSHA, 2003).
    Throughout the crystalline silica rulemaking process, OSHA has 
presented information to, and has consulted with, the Advisory 
Committee on Construction Safety and Health (ACCSH) and the Maritime 
Advisory Committee on Occupational Safety and Health (MACOSH). In 
December of 2009, OSHA representatives met with ACCSH to discuss the 
rulemaking and receive their comments and recommendations. On December 
11, ACCSH passed motions supporting the concept of Table 1 in the draft 
proposed construction rule and recognizing that the controls listed in 
Table 1 are effective. (As discussed with regard to paragraph (f) of 
the proposed rule, Table 1 presents specified control measures for 
selected construction operations.) ACCSH also recommended that OSHA 
maintain the protective clothing provision found in the SBREFA panel 
draft regulatory text and restore the ``competent person'' requirement 
and responsibilities to the proposed rule. Additionally, the group 
recommended that OSHA move forward expeditiously with the rulemaking 
process.
    In January 2010, OSHA completed a peer review of the draft Health 
Effects analysis and Preliminary Quantitative Risk Assessment following 
procedures set forth by OMB in the Final Information Quality Bulletin 
for Peer Review, published on the OMB Web site on December 16, 2004 
(see 70 FR 2664, Jan. 14, 2005). Each peer reviewer submitted a written 
report to OSHA. The Agency revised its draft documents as appropriate 
and made the revised documents available to the public as part of this 
Notice of Proposed Rulemaking. OSHA also made the written charge to the 
peer reviewers, the peer reviewers' names, the peer reviewers' reports, 
and the Agency's response to the peer reviewers' reports publicly 
available with publication of this proposed rule. OSHA will schedule 
time during the informal rulemaking hearing for participants to testify 
on the Health Effects analysis and Preliminary Quantitative Risk 
Assessment in the presence of peer reviewers and will request the peer 
reviewers to submit any amended final comments they may wish to add to 
the record. The Agency will consider amended final comments received 
from the peer reviewers during development of a final rule and will 
make them publicly available as part of the silica rulemaking record.

IV. Chemical Properties and Industrial Uses

    Silica is a compound composed of the elements silicon and oxygen 
(chemical formula SiO2). Silica has a molecular weight of 
60.08, and exists in crystalline and amorphous states, both in the 
natural environment and as produced during manufacturing or other 
processes. These substances are odorless solids, have no vapor 
pressure, and create non-explosive dusts when particles are suspended 
in air (IARC, 1997).
    Silica is classified as part of the ``silicate'' class of minerals, 
which includes compounds that are composed of silicon and oxygen and 
which may also be bonded to metal ions or their oxides (Hurlbut, 1966). 
The basic structural units of silicates are silicon tetrahedrons 
(SiO4), pyramidal structures with four triangular sides 
where a silicon atom is located in the center of the structure and an 
oxygen atom is located at each of the four corners. When silica 
tetrahedrons bond exclusively with other silica tetrahedrons, each 
oxygen atom is bonded to the silicon atom of its original ion, as well 
as to the silicon atom from another silica ion. This results in a ratio 
of one atom of silicon to two atoms of oxygen, expressed as 
SiO2. The silicon-oxygen bonds within the tetrahedrons use 
only one-half of each oxygen's total bonding energy. This leaves 
negatively charged oxygen ions available to bond with available 
positively charged ions. When they bond with metal and metal oxides, 
commonly of iron, magnesium, aluminum, sodium, potassium, and calcium, 
they form the silicate minerals commonly found in nature (Bureau of 
Mines, 1992).
    In crystalline silica, the silicon and oxygen atoms are arranged in 
a three-dimensional repeating pattern. Silica is said to be 
polymorphic, as different forms are created when the silica 
tetrahedrons combine in different crystalline structures. The primary 
forms of crystalline silica are quartz, cristobalite, and tridymite. In 
an amorphous state, silicon and oxygen atoms are present in the same 
proportions but are not organized in a repeating pattern. Amorphous 
silica includes natural and manufactured glasses (vitreous and fused 
silica, quartz glass), biogenic silica, and opals which are amorphous 
silica hydrates (IARC, 1997).
    Quartz is the most common form of crystalline silica and accounts 
for almost 12% by volume of the earth's crust. Alpha quartz, the quartz 
form that is stable below 573 [deg]C, is the most prevalent form of 
crystalline silica found in the workplace. It accounts for the 
overwhelming majority of naturally found silica and is present in 
varying amounts in almost every type of mineral. Alpha quartz is found 
in igneous, sedimentary, and metamorphic rock, and all soils contain at 
least a trace amount of quartz (Bureau of Mines, 1992). Alpha quartz is 
used in many products throughout various industries and is a common 
component of building materials (Madsen et al., 1995). Common trade 
names for commercially available quartz include: CSQZ, DQ 12, Min-U-
Sil, Sil-Co-Sil, Snowit, Sykron F300, and Sykron F600 (IARC, 1997).
    Cristobalite is a form of crystalline silica that is formed at high 
temperatures (>1470 [deg]C). Although naturally occurring cristobalite 
is relatively rare, volcanic eruptions, such as Mount St. Helens, can 
release cristobalite dust into the air. Cristobalite can also be 
created during some processes conducted in the workplace. For example, 
flux-calcined diatomaceous earth is a material used as a filtering aid 
and as a filler in other products (IARC, 1997). It is produced when 
diatomaceous earth (diatomite), a geological product of decayed 
unicellular organisms called diatoms, is heated with flux. The finished 
product can contain between 40 and 60 percent cristobalite. Also, high 
temperature furnaces are often lined with bricks that contain quartz. 
When subjected to prolonged high temperatures, this quartz can convert 
to cristobalite.
    Tridymite is another material formed at high temperatures (>870 
[deg]C) that is associated with volcanic activity. The creation of 
tridymite requires the presence of a flux such as sodium oxide. 
Tridymite is rarely found in nature and rarely reported in the 
workplace (Smith, 1998).
    When heated or cooled sufficiently, crystalline silica can 
transition between the polymorphic forms, with specific transitions 
occurring at different temperatures. At higher temperatures the 
linkages between the silica

[[Page 56296]]

tetrahedrons break and reform, resulting in new crystalline structures. 
Quartz converts to cristobalite at 1470 [deg]C, and at 1723 [deg]C 
cristobalite loses its crystalline structure and becomes amorphous 
fused silica. These high temperature transitions reverse themselves at 
extremely slow rates, with different forms co-existing for a long time 
after the crystal cools.
    Other types of transitions occur at lower temperatures when the 
silica-oxygen bonds in the silica tetrahedron rotate or stretch, 
resulting in a new crystalline structure. These low-temperature, or 
alpha to beta, transitions are readily and rapidly reversed as the 
crystal cools. At temperatures encountered by workers, only the alpha 
form of crystalline silica exists (IARC, 1997).
    Crystalline silica minerals produce distinct X-ray diffraction 
patterns, specific to their crystalline structure. The patterns can be 
used to distinguish the crystalline polymorphs from each other and from 
amorphous silica (IARC, 1997).
    The specific gravity and melting point of silica vary between 
polymorphs. Silica is insoluble in water at 20 [deg]C and in most 
acids, but its solubility increases with higher temperatures and pH, 
and it dissolves readily in hydrofluoric acid. Solubility is also 
affected by the presence of trace metals and by particle size. Under 
humid conditions water vapor in the air reacts with the surface of 
silica particles to form an external layer of silinols (SiOH). When 
these silinols are present the crystalline silica becomes more 
hydrophilic. Heating or acid washing reduces the amount of silinols on 
the surface area of crystalline silica particles. There is an external 
amorphous layer found in aged quartz, called the Beilby layer, which is 
not found on freshly cut quartz. This amorphous layer is more water 
soluble than the underlying crystalline core. Etching with hydrofluoric 
acid removes the Beilby layer as well as the principal metal impurities 
on quartz.
    Crystalline silica has limited chemical reactivity. It reacts with 
alkaline aqueous solutions, but does not readily react with most acids, 
with the exception of hydrofluoric acid. In contrast, amorphous silica 
and most silicates react with most mineral acids and alkaline 
solutions. Analytical chemists relied on this difference in acid 
reactivity to develop the silica point count analytical method that was 
widely used prior to the current X-ray diffraction and infrared methods 
(Madsen et al., 1995).
    Crystalline silica is used in industry in a wide variety of 
applications. Sand and gravel are used in road building and concrete 
construction. Sand with greater than 98% silica is used in the 
manufacture of glass and ceramics. Silica sand is used to form molds 
for metal castings in foundries, and in abrasive blasting operations. 
Silica is also used as a filler in plastics, rubber, and paint, and as 
an abrasive in soaps and scouring cleansers. Silica sand is used to 
filter impurities from municipal water and sewage treatment plants, and 
in hydraulic fracturing for oil and gas recovery. Silica is also used 
to manufacture artificial stone products used as bathroom and kitchen 
countertops, and the silica content in those products can exceed 93 
percent (Kramer et al., 2012).
    There are over thirty major industries and operations where 
exposures to crystalline silica can occur. They include such diverse 
workplaces as foundries, dental laboratories, concrete products and 
paint and coating manufacture, as well as construction activities 
including masonry cutting, grinding and tuckpointing, operating heavy 
equipment, and road work. A more detailed discussion of the industries 
affected by the proposed standard is presented in Section VIII of this 
preamble. Crystalline silica exposures can also occur in mining, and in 
agriculture during plowing and harvesting.

V. Health Effects Summary

    This section presents a summary of OSHA's review of the health 
effects literature for respirable crystalline silica. OSHA's full 
analysis is contained in Section I of the background document entitled 
``Respirable Crystalline Silica--Health Effects Literature Review and 
Preliminary Quantitative Risk Assessment,'' which has been placed in 
rulemaking docket OSHA-2010-0034. OSHA's review of the literature on 
the adverse effects associated with exposure to crystalline silica 
covers the following topics:
    (1) Silicosis (including relevant data from U.S. disease 
surveillance efforts);
    (2) Lung cancer and cancer at other sites;
    (3) Non-malignant respiratory disease (other than silicosis);
    (4) Renal and autoimmune effects; and
    (5) Physical factors affecting the toxicity of crystalline silica.
    The purpose of the Agency's scientific review is to present OSHA's 
preliminary findings on the nature of the hazards presented by exposure 
to respirable crystalline silica, and to present an adequate basis for 
the quantitative risk assessment section to follow. OSHA's review 
reflects the relevant literature identified by the Agency through 
previously published reviews, literature searches, and contact with 
outside experts. Most of the evidence that describes the health risks 
associated with exposure to silica consists of epidemiological studies 
of worker populations; in addition, animal and in vitro studies on mode 
of action and molecular toxicology are also described. OSHA's review of 
the silicosis literature focused on a few particular issues, such as 
the factors that affect progression of the disease and the relationship 
between the appearance of radiological abnormalities indicative of 
silicosis and pulmonary function decline. Exposure to respirable 
crystalline silica is the only known cause of silicosis and there are 
literally thousands of research papers and case studies describing 
silicosis among working populations. OSHA did not review every one of 
these studies, because many of them do not relate to the issues that 
are of interest to OSHA.
    OSHA's health effects literature review addresses exposure only to 
airborne respirable crystalline silica since there is no evidence that 
dermal or oral exposure presents a hazard to workers. This review is 
also confined to issues related to inhalation of respirable dust, which 
is generally defined as particles that are capable of reaching the gas-
exchange region of the lung (i.e., particles less than 10 [mu]m in 
aerodynamic diameter). The available studies include populations 
exposed to quartz or cristobalite, the two forms of crystalline silica 
most often encountered in the workplace. OSHA was unable to identify 
any relevant epidemiological literature concerning a third polymorph, 
tridymite, which is also currently regulated by OSHA and included in 
the scope of OSHA's proposed crystalline silica standard.
    OSHA's approach in this review is based on a weight-of-evidence 
approach, in which studies (both positive and negative) are evaluated 
for their overall quality, and causal inferences are drawn based on a 
determination of whether there is substantial evidence that exposure 
increases the risk of a particular effect. Factors considered in 
assessing the quality of studies include size of the cohort studied and 
power of the study to detect a sufficiently low level of disease risk; 
duration of follow-up of the study population; potential for study bias 
(such as selection bias in case-control studies or survivor effects in 
cross-sectional studies); and adequacy of underlying exposure 
information for

[[Page 56297]]

examining exposure-response relationships. Studies were deemed suitable 
for inclusion in OSHA's Preliminary Quantitative Risk Assessment where 
there was adequate quantitative information on exposure and disease 
risks and the study was judged to be sufficiently high quality 
according to the criteria described above. The Preliminary Quantitative 
Risk Assessment is included in Section II of the background document 
and is summarized in Section VI of this preamble.
    A draft health effects review document was submitted for external 
scientific peer review in accordance with the Office of Management and 
Budget's ``Final Information Quality Bulletin for Peer Review'' (OMB, 
2004). A summary of OSHA's responses to the peer reviewers' comments 
appears in Section III of the background document. Since the draft 
health effects review document was submitted for external scientific 
peer review, new studies or reviews examining possible associations 
between occupational exposure to respirable crystalline silica and lung 
cancer have been published. OSHA's analysis of that new information is 
presented in a supplemental literature review and is available in the 
docket (OSHA, 2013).

A. Silicosis and Disease Progression

1. Pathology and Diagnosis
    Silicosis is a progressive disease in which accumulation of 
respirable crystalline silica particles causes an inflammatory reaction 
in the lung, leading to lung damage and scarring, and, in some cases, 
progresses to complications resulting in disability and death. Three 
types of silicosis have been described: an acute form following intense 
exposure to respirable dust of high crystalline silica content for a 
relatively short period (i.e., a few months or years); an accelerated 
form, resulting from about 5 to 15 years of heavy exposure to 
respirable dusts of high crystalline silica content; and, most 
commonly, a chronic form that typically follows less intense exposure 
of usually more than 20 years (Becklake, 1994; Balaan and Banks, 1992). 
In both the accelerated and chronic form of the disease, lung 
inflammation leads to the formation of excess connective tissue, or 
fibrosis, in the lung. The hallmark of the chronic form of silicosis is 
the silicotic islet or nodule, one of the few agent-specific lesions in 
pathology (Balaan and Banks, 1992). As the disease progresses, these 
nodules, or fibrotic lesions, increase in density and can develop into 
large fibrotic masses, resulting in progressive massive fibrosis (PMF). 
Once established, the fibrotic process of chronic silicosis is thought 
to be irreversible (Becklake, 1994), and there is no specific treatment 
for silicosis (Davis, 1996; Banks, 2005). Unlike chronic silicosis, the 
acute form of the disease almost certainly arises from exposures well 
in excess of current OSHA standards and presents a different 
pathological picture, one of pulmonary alveolar proteinosis.
    Chronic silicosis is the most frequently observed type of silicosis 
in the U.S. today. Affected workers may have a dry chronic cough, 
sputum production, shortness of breath, and reduced pulmonary function. 
These symptoms result from airway restriction and/or obstruction caused 
by the development of fibrotic scarring in the alveolar sacs and lower 
region of the lung. The scarring can be detected by chest x-ray or 
computerized tomography (CT) when the lesions become large enough to 
appear as visible opacities. The result is restriction of lung volumes 
and decreased pulmonary compliance with concomitant reduced gas 
transfer (Balaan and Banks, 1992). Early stages of chronic silicosis 
can be referred to as either simple or nodular silicosis; later stages 
are referred to as either pulmonary massive fibrosis (PMF), 
complicated, or advanced silicosis.
    The clinical diagnosis of silicosis has three requisites (Balaan 
and Banks, 1992; Banks, 2005). The first is the recognition by the 
physician that exposure to crystalline silica adequate to cause this 
disease has occurred. The second is the presence of chest radiographic 
abnormalities consistent with silicosis. The third is the absence of 
other illnesses that could resemble silicosis on chest radiograph, 
e.g., pulmonary fungal infection or miliary tuberculosis. To describe 
the presence and severity of silicosis from chest x-ray films or 
digital radiographic images, a standardized system exists to classify 
the opacities seen on chest radiographs (the International Labor 
Organization (ILO) International Classification of Radiographs of the 
Pneumoconioses (ILO, 1980, 2002, 2011; Merchant and Schwartz, 1998; 
NIOSH, 2011). This system standardizes the description of chest x-ray 
films or digital radiographic images with respect to the size, shape, 
and density of opacities, which together indicate the severity and 
extent of lung involvement. The density of opacities seen on chest x-
ray films or digital radiographic images is classified on a 4-point 
major category scale (0, 1, 2, or 3), with each major category divided 
into three subcategories, giving a 12-point scale between 0/0 and 3/+. 
(For each subcategory, the top number indicates the major category that 
the profusion most closely resembles, and the bottom number indicates 
the major category that was given secondary consideration.) Major 
category 0 indicates the absence of visible opacities and categories 1 
to 3 reflect increasing profusion of opacities and a concomitant 
increase in severity of disease. Biopsy is not necessary to make a 
diagnosis and a diagnosis does not require that chest x-ray films or 
digital radiographic images be rated using the ILO system (NIOSH, 
2002). In addition, an assessment of pulmonary function, though not 
itself necessary to confirm a diagnosis of silicosis, is important to 
evaluate whether the individual has impaired lung function.
    Although chest x-ray is typically used to examine workers exposed 
to respirable crystalline silica for the presence of silicosis, it is a 
fairly insensitive tool for detecting lung fibrosis (Hnizdo et al., 
1993; Craighead and Vallyathan, 1980; Rosenman et al., 1997). To 
address the low sensitivity of chest x-rays for detecting silicosis, 
Hnizdo et al. (1993) recommended that radiographs consistent with an 
ILO category of 0/1 or greater be considered indicative of silicosis 
among workers exposed to a high concentration of silica-containing 
dust. In like manner, to maintain high specificity, chest x-rays 
classified as category 1/0 or 1/1 should be considered as a positive 
diagnosis of silicosis.
    Newer imaging technologies with both research and clinical 
applications include computed tomography, and high resolution 
tomography. High- resolution computed tomography (HRCT) uses thinner 
image slices and a different reconstruction algorithm to improve 
spatial resolution over CT. Recent studies of high-resolution 
computerized tomography (HRCT) have found HRCT to be superior to chest 
x-ray imaging for detecting small opacities and for identifying PMF 
(Sun et al., 2008; Lopes et al., 2008; Blum et al., 2008).
    The causal relationship between exposure to crystalline silica and 
silicosis has long been accepted in the scientific and medical 
communities. Of greater interest to OSHA is the quantitative 
relationship between exposure to crystalline silica and development of 
silicosis. A large number of cross-sectional and retrospective studies 
have been conducted to evaluate this relationship (Kreiss and Zhen, 
1996; Love et al., 1999; Ng and Chan, 1994; Rosenman et al., 1996; 
Hughes et al., 1998; Muir et al., 1989a, 1989b; Park et al., 2002; Chen

[[Page 56298]]

et al., 2001; Hnizdo and Sluis-Cremer, 1993; Miller et al., 1998; 
Buchanan et al., 2003; Steenland and Brown, 1995b). In general, these 
studies, particularly those that included retirees, have found a risk 
of radiological silicosis (usually defined as x-ray films classified 
ILO major category 1 or greater) among workers exposed near the range 
of cumulative exposure permitted by current exposure limits. These 
studies are presented in detail in OSHA's Preliminary Quantitative Risk 
Assessment (Section II of the background document and summarized in 
Section VI of this preamble).
2. Silicosis in the United States
    Unlike most occupational diseases, surveillance statistics are 
available that provide information on the prevalence of silicosis 
mortality and morbidity in the U.S. The most comprehensive and current 
source of surveillance data in the U.S. related to occupational lung 
diseases, including silicosis, is the National Institute for 
Occupational Safety and Health (NIOSH) Work-Related Lung Disease 
(WoRLD) Surveillance System; the WoRLD Surveillance Report is compiled 
from the most recent data from the WoRLD System (NIOSH, 2008c). 
National statistics on mortality associated with occupational lung 
diseases are also compiled in the National Occupational Respiratory 
Mortality System (NORMS, available on the Internet at http://webappa.cdc.gov/ords/norms.html), a searchable database administered by 
NIOSH. In addition, NIOSH published a recent review of mortality 
statistics in its MMWR Report Silicosis Mortality, Prevention, and 
Control--United States, 1968-2002 (CDC, 2005). For each of these 
sources, data are compiled from death certificates reported to state 
vital statistics offices, which are collected by the National Center 
for Health Statistics (NCHS). Data on silicosis morbidity are available 
from only a few states that administer occupational disease 
surveillance systems, and from data on hospital discharges. OSHA 
believes that the mortality and morbidity statistics compiled in these 
sources and summarized below indicate that silicosis remains a 
significant occupational health problem in the U.S. today.
    From 1968 to 2002, silicosis was recorded as an underlying or 
contributing cause of death on 16,305 death certificates; of these, a 
total of 15,944 (98 percent) deaths occurred in males (CDC, 2005). From 
1968 to 2002, the number of silicosis deaths decreased from 1,157 (8.91 
per million persons aged =15 years) to 148 (0.66 per 
million), corresponding to a 93-percent decline in the overall 
mortality rate. In its most recent WoRLD Report (NIOSH, 2008c), NIOSH 
reported that the number of silicosis deaths in 2003, 2004, and 2005 
were 179, 166, and 161, respectively, slightly higher than that 
reported in 2002. The number of silicosis deaths identified each year 
has remained fairly constant since the late 1990's.
    NIOSH cited two main factors that were likely responsible for the 
declining trend in silicosis mortality since 1968. First, many of the 
deaths in the early part of the study period occurred among persons 
whose main exposure to crystalline silica dust probably occurred before 
introduction of national standards for silica dust exposure established 
by OSHA and the Mine Safety and Health Administration (MSHA) (i.e., 
permissible exposure limits (PELs)) that likely led to reduced silica 
dust exposure. Second, there has been declining employment in heavy 
industries (e.g., foundries) where silica exposure was prevalent (CDC, 
2005). Although the factors described by NIOSH are reasonable 
explanations for the steep reduction in silicosis-related mortality, it 
should be emphasized that the surveillance data are insufficient for 
the analysis of residual risk associated with current occupational 
exposure limits for crystalline silica. Analyses designed to explore 
this question must make use of appropriate exposure-response data, as 
is presented in OSHA's Preliminary Quantitative Risk Assessment 
(summarized in Section VI of this preamble).
    Although the number of deaths from silicosis overall has declined 
since 1968, the number of silicosis-associated deaths reported among 
persons aged 15 to 44 had not declined substantially prior to 1995 (CDC 
1998). Unfortunately, it is not known to what extent these deaths among 
younger workers were caused by acute or accelerated forms of silicosis.
    Silicosis deaths among workers of all ages result in significant 
premature mortality; between 1996 and 2005, a total of 1,746 deaths 
resulted in a total of 20,234 years of life lost from life expectancy, 
with an average of 11.6 years of life lost. For the same period, among 
307 decedents who died before age 65, or the end of a working life, 
there were 3,045 years of life lost to age 65, with an average of 9.9 
years of life lost from a working life (NIOSH, 2008c).
    Data on the prevalence of silicosis morbidity are available from 
only three states (Michigan, Ohio, and New Jersey) that have 
administered disease surveillance programs over the past several years. 
These programs rely primarily on hospital discharge records, reporting 
of cases from the medical community, workers' compensation programs, 
and death certificate data. For the reporting period 1993-2002, the 
last year for which data are available, three states (Michigan, New 
Jersey and Ohio) recorded 879 cases of silicosis (NIOSH 2008c). 
Hospital discharge records represent the primary ascertainment source 
for all three states. It should be noted that hospital discharge 
records most likely include cases of acute silicosis or very advance 
chronic silicosis since it is unlikely that there would be a need for 
hospitalization in cases with early radiographic signs of silicosis, 
such as for an ILO category 1/0 x-ray. Nationwide hospital discharge 
data compiled by NIOSH (2008c) and the Council of State and Territorial 
Epidemiologists (CSTE, 2005) indicates that there are at least 1,000 
hospitalizations each year due to silicosis.
    Data on silicosis mortality and morbidity are likely to understate 
the true impact of exposure of U.S. workers to crystalline silica. This 
is in part due to underreporting that is characteristic of passive 
case-based disease surveillance systems that rely on the health care 
community to generate records (Froines et al., 1989). Health care 
professionals play the main role in such surveillance by virtue of 
their unique role in recognizing and diagnosing diseases, but most 
health care professionals do not take occupational histories (Goldman 
and Peters, 1981; Rutstein et al., 1983). In addition to the lack of 
information about exposure histories, difficulty in recognizing 
occupational illnesses that have long latency periods, like silicosis, 
contributes to under-recognition and underreporting by health care 
providers. Based on an analysis of data from Michigan's silicosis 
surveillance activities, Rosenman et al. (2003) estimated that the true 
incidence of silicosis mortality and morbidity were understated by a 
factor of between 2.5 and 5, and that there were estimated to be from 
3,600 to 7,300 new cases of silicosis occurring in the U.S. annually 
between 1987 and 1996. Taken with the surveillance data presented 
above, OSHA believes that exposure to crystalline silica remains a 
cause of significant mortality and morbidity in the U.S.
3. Progression of Silicosis and Its Associated Impairment
    As described above, silicosis is a progressive lung disease that is 
usually first detected by the appearance of a

[[Page 56299]]

diffuse nodular fibrosis on chest x-ray films. To evaluate the clinical 
significance of radiographic signs of silicosis, OSHA reviewed several 
studies that have examined how exposure affects progression of the 
disease (as seen by chest radiography) as well as the relationship 
between radiologic findings and pulmonary function. The following 
summarizes OSHA's preliminary findings from this review.
    Of the several studies reviewed by OSHA that documented silicosis 
progression in populations of workers, four studies (Hughes et al., 
1982; Hessel et al., 1988; Miller et al., 1998; Ng et al., 1987a) 
included quantitative exposure data that were based on either current 
or historical measurements of respirable quartz. The exposure variable 
most strongly associated in these studies with progression of silicosis 
was cumulative respirable quartz (or silica) exposure (Hessel et al., 
1988; Hughes et al., 1982; Miller et al., 1998; Ng et al., 1987a), 
though both average concentration of respirable silica (Hughes et al., 
1982; Ng et al., 1987a) and duration of employment in dusty jobs have 
also been found to be associated with the progression of silicosis 
(Hughes et al., 1982; Ogawa et al., 2003).
    The study reflecting average exposures most similar to current 
exposure conditions is that of Miller et al. (1998), which followed a 
group of 547 British coal miners in 1990-1991 to evaluate chest x-ray 
changes that had occurred after the mines closed in 1981. This study 
had data available from chest x-rays taken during health surveys 
conducted between 1954 and 1978, as well as data from extensive 
exposure monitoring conducted between 1964 and 1978. The mean and 
maximum cumulative exposure reported in the study correspond to average 
concentrations of 0.12 and 0.55 mg/m\3\, respectively, over the 15-year 
sampling period. However, between 1971 and 1976, workers experienced 
unusually high concentrations of respirable quartz in one of the two 
coal seams in which the miners worked. For some occupations, quarterly 
mean quartz concentrations ranged from 1 to 3 mg/m\3\, and for a brief 
period, concentrations exceeded 10 mg/m\3\ for one job. Some of these 
high exposures likely contributed to the extent of disease progression 
seen in these workers; in its Preliminary Quantitative Risk Assessment, 
OSHA reviewed a study by Buchanan et al. (2003), who found that short-
term exposures to high (>2 mg/m\3\) concentrations of silica can 
increase the silicosis risk by 3-fold over what would be predicted by 
cumulative exposure alone (see Section VI).
    Among the 504 workers whose last chest x-ray was classified as ILO 
0/0 or 0/1, 20 percent had experienced onset of silicosis (i.e., chest 
x-ray was classified as ILO 1/0 by the time of follow up in 1990-1991), 
and 4.8 percent progressed to at least category 2. However, there are 
no data available to continue following the progression of this group 
because there have been no follow-up surveys of this cohort since 1991.
    In three other studies examining the progression of silicosis, 
(Hessel et al., 1988; Hughes et al., 1982; Ng et al., 1987a) cohorts 
were comprised of silicotics (individuals already diagnosed with 
silicosis) that were followed further to evaluate disease progression. 
These studies reflect exposures of workers to generally higher average 
concentrations of respirable quartz than are permitted by OSHA's 
current exposure limit. Some general findings from this body of 
literature follow. First, size of opacities on initial radiograph is a 
determinant for further progression. Individuals with large opacities 
on initial chest radiograph have a higher probability of further 
disease progression than those with small opacities (Hughes et al., 
1982; Lee, et al., 2001; Ogawa et al., 2003). Second, although 
silicotics who continue to be exposed are more likely to progress than 
silicotics who are not exposed (Hessel et al., 1988), once silicosis 
has been detected there remains a likelihood of progression in the 
absence of additional exposure to silica (Hessel et al., 1988; Miller 
et al., 1998; Ogawa, et al., 2003; Yang et al., 2006). There is some 
evidence in the literature that the probability of progression is 
likely to decline over time following the end of the exposure, although 
this observation may also reflect a survivor effect (Hughes et al., 
1982; Lee et al., 2001). In addition, of borderline statistical 
significance was the association of tuberculosis with increased 
likelihood of silicosis progression (Lee et al., 2001).
    Of the four studies reviewed by OSHA that provided quantitative 
exposure information, two studies (Miller et al., 1998; Ng et al., 
1987a) provide the information most relevant to current exposure 
conditions. The range of average concentration of respirable 
crystalline silica to which workers were exposed in these studies (0.12 
to 0.48 mg/m\3\, respectively) is relatively narrow and is of 
particular interest to OSHA because current enforcement data indicate 
that exposures in this range or not much lower are common today, 
especially in construction and foundries, and sandblasting operations. 
These studies reported the percentage of workers whose chest x-rays 
show signs of progression at the time of follow-up; the annual rate at 
which workers showed disease progression were similar, 2 percent and 6 
percent, respectively.
    Several cross-sectional and longitudinal studies have examined the 
relationship between progressive changes observed on radiographs and 
corresponding declines in lung-function parameters. In general, the 
results are mixed: some studies have found that pulmonary function 
losses correlate with the extent of fibrosis seen on chest x-ray films, 
and others have not found such correlations. The lack of a correlation 
in some studies between degree of fibrotic profusion seen on chest x-
rays and pulmonary function have led some to suggest that pulmonary 
function loss is an independent effect of exposure to respirable 
crystalline silica, or may be a consequence of emphysematous changes 
that have been seen in conjunction with radiographic silicosis.
    Among studies that have reported finding a relationship between 
pulmonary function and x-ray abnormalities, Ng and Chan (1992) found 
that forced expiratory volume (FEV1) and forced vital 
capacity (FVC) were statistically significantly lower for workers whose 
x-ray films were classified as ILO profusion categories 2 and 3, but 
not among workers with ILO category 1 profusion compared to those with 
a profusion score of 0/0. As expected, highly significant reductions in 
FEV1, FVC, and FEV1/FVC were noted in subjects 
with large opacities. The authors concluded that chronic simple 
silicosis, except that classified as profusion category 1, is 
associated with significant lung function impairment attributable to 
fibrotic disease.
    Similarly, Moore et al. (1988) also found chronic silicosis to be 
associated with significant lung function loss, especially among 
workers with chest x-rays classified as ILO profusion categories 2 and 
3. For those classified as category 1, lung function was not 
diminished. B[eacute]gin et al. (1988) also found a correlation between 
decreased lung function (FVC and the ratio of FEV1/FVC) and 
increased profusion and coalescence of opacities as determined by CT 
scan. This study demonstrated increased impairment among workers with 
higher imaging categories (3 and 4), as expected, but also impairment 
(significantly reduced expiratory flow rates) among persons with more 
moderate pulmonary fibrosis (group 2).
    In a population of gold miners, Cowie (1998) found that lung 
function

[[Page 56300]]

declined more rapidly in men with silicosis than those without. In 
addition to the 24 ml./yr. decrements expected due to aging, this study 
found an additional loss of 8 ml. of FEV1 per year would be 
expected from continued exposure to dust in the mines. An earlier 
cross-sectional study by these authors (Cowie and Mabena, 1991), which 
examined 1,197 black underground gold miners who had silicosis, found 
that silicosis (analyzed as a continuous variable based on chest x-ray 
film classification) was associated with reductions in FVC, 
FEV1, FEV1/FVC, and carbon monoxide diffusing 
capacity (DLco), and these relationships persisted after 
controlling for duration and intensity of exposure and smoking.
    In contrast to these studies, other investigators have reported 
finding pulmonary function decrements in exposed workers independent of 
radiological evidence of silicosis. Hughes et al. (1982) studied a 
representative sample of 83 silicotic sandblasters, 61 of whom were 
followed for one to seven years. A multiple regression analysis showed 
that the annual reductions in FVC, FEV1 and DLco 
were related to average silica concentrations but not duration of 
exposure, smoking, stage of silicosis, or time from initial exposure. 
Ng et al. (1987b) found that, among male gemstone workers in Hong Kong 
with x-rays classified as either Category 0 or 1, declines in 
FEV1 and FVC were not associated with radiographic category 
of silicosis after adjustment for years of employment. The authors 
concluded that there was an independent effect of respirable dust 
exposure on pulmonary function. In a population of 61 gold miners, 
Wiles et al. (1992) also found that radiographic silicosis was not 
associated with lung function decrements. In a re-analysis and follow-
up of an earlier study, Hnizdo (1992) found that silicosis was not a 
significant predictor of lung function, except for FEV1 for 
non-smokers.
    Wang et al. (1997) observed that silica-exposed workers (both 
nonsmokers and smokers), even those without radiographic evidence of 
silicosis, had decreased spirometric parameters and diffusing capacity 
(DLco). Pulmonary function was further decreased in the 
presence of silicosis, even those with mild to moderate disease (ILO 
categories 1 and 2). The authors concluded that functional 
abnormalities precede radiographic changes of silicosis.
    A number of studies were conducted to examine the role of 
emphysematous changes in the presence of silicosis in reducing lung 
function; these have been reviewed by Gamble et al. (2004), who 
concluded that there is little evidence that silicosis is related to 
development of emphysema in the absence of PMF. In addition, Gamble et 
al. (2004) found that, in general, studies found that the lung function 
of those with radiographic silicosis in ILO category 1 was 
indistinguishable from those in category 0, and that those in category 
2 had small reductions in lung function relative to those with category 
0 and little difference in the prevalence of emphysema. There were 
slightly greater decrements in lung function with category 3 and more 
significant reductions with progressive massive fibrosis. In studies 
for which information was available on both silicosis and emphysema, 
reduced lung function was more strongly related to emphysema than to 
silicosis.
    In conclusion, many studies reported finding an association between 
pulmonary function decrements and ILO category 2 or 3 background 
profusion of small opacities; this appears to be consistent with the 
histopathological view, in which individual fibrotic nodules 
conglomerate to form a massive fibrosis (Ng and Chan, 1992). Emphysema 
may also play a role in reducing lung function in workers with higher 
grades of silicosis. Pulmonary function decrements have not been 
reported in some studies among workers with silicosis scored as ILO 
category 1. However, a number of other studies have documented declines 
in pulmonary function in persons exposed to silica and whose radiograph 
readings are in the major ILO category 1 (i.e. 1/0, 1/1, 1/2), or even 
before changes were seen on chest x-ray (B[eacute]gin et al., 1988; 
Cowie, 1998; Cowie and Mabena, 1991; Ng et al., 1987a; Wang et al., 
1997). It may also be that studies designed to relate x-ray findings 
with pulmonary function declines are further confounded by pulmonary 
function declines caused by chronic obstructive pulmonary disease 
(COPD) seen among silica-exposed workers absent radiological silicosis, 
as has been seen in many investigations of COPD. OSHA's review of the 
literature on crystalline silica exposure and development of COPD 
appears in section II.D of the background document and is summarized in 
section V.D below.
    OSHA believes that the literature reviewed above demonstrates 
decreased lung function among workers with radiological evidence of 
silicosis consistent with an ILO classification of major category 2 or 
higher. Also, given the evidence of functional impairment in some 
workers prior to radiological evidence of silicosis, and given the low 
sensitivity of radiography, particularly in detecting early silicosis, 
OSHA believes that exposure to silica impairs lung function in at least 
some individuals before silicosis can be detected on chest radiograph.
4. Pulmonary Tuberculosis
    As silicosis progresses, it may be complicated by severe 
mycobacterial infections, the most common of which is pulmonary 
tuberculosis (TB). Active tuberculosis infection is a well-recognized 
complication of chronic silicosis, and such infections are known as 
silicotuberculosis (IARC, 1997; NIOSH, 2002). The risk of developing TB 
infection is higher in silicotics than non-silicotics (Balmes, 1990; 
Cowie, 1994; Hnizdo and Murray, 1998; Kleinschmidt and Churchyard, 
1997; and Murray et al., 1996). There also is evidence that exposure to 
silica increases the risk for pulmonary tuberculosis independent of the 
presence of silicosis (Cowie, 1994; Hnizdo and Murray, 1998; 
teWaterNaude et al., 2006). In a summary of the literature on silica-
related disease mechanisms, Ding et al. (2002) noted that it is well 
documented that exposure to silica can lead to impaired cell-mediated 
immunity, increasing susceptibility to mycobacterial infection. Reduced 
numbers of T-cells, increased numbers of B-cells, and alterations of 
serum immunoglobulin levels have been observed in workers with 
silicosis. In addition, according to Ng and Chan (1991), silicosis and 
TB act synergistically to increase fibrotic scar tissue (leading to 
massive fibrosis) or to enhance susceptibility to active mycobacterial 
infection. Lung fibrosis is common to both diseases and both diseases 
decrease the ability of alveolar macrophages to aid in the clearance of 
dust or infectious particles.

B. Carcinogenic Effects of Silica (Cancer of the Lung and Other Sites)

    OSHA conducted an independent review of the epidemiological 
literature on exposure to respirable crystalline silica and lung 
cancer, covering more than 30 occupational groups in over a dozen 
industrial sectors. In addition, OSHA reviewed a pooled case-control 
study, a large national death certificate study, two national cancer 
registry studies, and six meta-analyses. In all, OSHA's review included 
approximately 60 primary epidemiological studies.
    Based on its review, OSHA preliminarily concludes that the human 
data summarized in this section

[[Page 56301]]

provides ample evidence that exposure to respirable crystalline silica 
increases the risk of lung cancer among workers. The strongest evidence 
comes from the worldwide cohort and case-control studies reporting 
excess lung cancer mortality among workers exposed to respirable 
crystalline silica dust as quartz in various industrial sectors, 
including the granite/stone quarrying and processing, industrial sand, 
mining, and pottery and ceramic industries, as well as to cristobalite 
in diatomaceous earth and refractory brick industries. The 10-cohort 
pooled case-control analysis by Steenland et al. (2001a) confirms these 
findings. A more recent clinic-based pooled case-control analysis of 
seven European countries by Cassidy et al. (2007) as well as two 
national death certificate registry studies (Pukkala et al., 2005 in 
Finland; Calvert et al., 2003 in the United States) support the 
findings from the cohort and case-control analysis.
1. Overall and Industry Sector-Specific Findings
    Associations between exposure to respirable crystalline silica and 
lung cancer have been reported in worker populations from many 
different industrial sectors. IARC (1997) concluded that crystalline 
silica is a confirmed human carcinogen based largely on nine studies of 
cohorts in four industry sectors that IARC considered to be the least 
influenced by confounding factors (sectors included quarries and 
granite works, gold mining, ceramic/pottery/refractory brick 
industries, and the diatomaceous earth industry). IARC (2012) recently 
reaffirmed that crystalline silica is a confirmed human carcinogen. 
NIOSH (2002) also determined that crystalline silica is a human 
carcinogen after evaluating updated literature.
    OSHA believes that the strongest evidence for carcinogenicity comes 
from studies in five industry sectors. These are:
     Diatomaceous Earth Workers (Checkoway et al., 1993, 1996, 
1997, and 1999; Seixas et al., 1997);
     British Pottery Workers (Cherry et al., 1998; McDonald et 
al., 1995);
     Vermont Granite Workers (Attfield and Costello, 2004; 
Graham et al., 2004; Costello and Graham, 1988; Davis et al., 1983);
     North American Industrial Sand Workers (Hughes et al., 
2001; McDonald et al., 2001, 2005; Rando et al., 2001; Sanderson et 
al., 2000; Steenland and Sanderson, 2001); and
     British Coal Mining (Miller et al., 2007; Miller and 
MacCalman, 2009).
    The studies above were all retrospective cohort or case-control 
studies that demonstrated positive, statistically significant exposure-
response relationships between exposure to crystalline silica and lung 
cancer mortality. Except for the British pottery studies, where 
exposure-response trends were noted for average exposure only, lung 
cancer risk was found to be related to cumulative exposure. OSHA 
credits these studies because in general, they are of sufficient size 
and have adequate years of follow up, and have sufficient quantitative 
exposure data to reliably estimate exposures of cohort members. As part 
of their analyses, the authors of these studies also found positive 
exposure-response relationships for silicosis, indicating that 
underlying estimates of worker exposures were not likely to be 
substantially misclassified. Furthermore, the authors of these studies 
addressed potential confounding due to other carcinogenic exposures 
through study design or data analysis.
    A series of studies of the diatomaceous earth industry (Checkoway 
et al., 1993, 1996, 1997, 1999) demonstrated positive exposure-response 
trends between cristobalite exposures and lung cancer as well as non-
malignant respiratory disease mortality (NMRD). Checkoway et al. (1993) 
developed a ``semi-quantitative'' cumulative exposure estimate that 
demonstrated a statistically significant positive exposure-response 
trend (p = 0.026) between duration of employment or cumulative exposure 
and lung cancer mortality. The quartile analysis showed a monotonic 
increase in lung cancer mortality, with the highest exposure quartile 
having a RR of 2.74 for lung cancer mortality. Checkoway et al. (1996) 
conducted a re-analysis to address criticisms of potential confounding 
due to asbestos and again demonstrated a positive exposure response 
risk gradient when controlling for asbestos exposure and other 
variables. Rice et al. (2001) conducted a re-analysis and quantitative 
risk assessment of the Checkoway et al. (1997) study, which OSHA has 
included as part of its assessment of lung cancer mortality risk (See 
Section II, Preliminary Quantitative Risk Assessment).
    In the British pottery industry, excess lung cancer risk was found 
to be associated with crystalline silica exposure among workers in a 
PMR study (McDonald et al., 1995) and in a cohort and nested case-
control study (Cherry et al., 1998). In the PMR study, elevated PMRs 
for lung cancer were found after adjusting for potential confounding by 
asbestos exposure. In the study by Cherry et al., odds ratios for lung 
cancer mortality were statistically significantly elevated after 
adjusting for smoking. Odds ratios were related to average, but not 
cumulative, exposure to crystalline silica. The findings of the British 
pottery studies are supported by other studies within their industrial 
sector. Studies by Winter et al. (1990) of British pottery workers and 
by McLaughlin et al. (1992) both reported finding suggestive trends of 
increased lung cancer mortality with increasing exposure to respirable 
crystalline silica.
    Costello and Graham (1988) and Graham et al. (2004) in a follow-up 
study found that Vermont granite workers employed prior to 1930 had an 
excess risk of lung cancer, but lung cancer mortality among granite 
workers hired after 1940 (post-implementation of controls) was not 
elevated in the Costello and Graham (1988) study and was only somewhat 
elevated (not statistically significant) in the Graham et al. (2004) 
study. Graham et al. (2004) concluded that their results did not 
support a causal relationship between granite dust exposure and lung 
cancer mortality. Looking at the same population, Attfield and Costello 
(2004) developed a quantitative estimate of cumulative exposure (8 
exposure categories) adapted from a job exposure matrix developed by 
Davis et al. (1983). They found a statistically significant trend with 
log-transformed cumulative exposure. Lung cancer mortality rose 
reasonably consistently through the first seven increasing exposure 
groups, but fell in the highest cumulative exposure group. With the 
highest exposure group omitted, a strong positive dose-response trend 
was found for both untransformed and log-transformed cumulative 
exposures. Attfield and Costello (2004) concluded that exposure to 
crystalline silica in the range of cumulative exposures typically 
experienced by contemporarily exposed workers causes an increased risk 
of lung cancer mortality. The authors explained that the highest 
exposure group would have included the most unreliable exposure 
estimates being reconstructed from exposures 20 years prior to study 
initiation when exposure estimation was less precise. Also, even though 
the highest exposure group consisted of only 15 percent of the study 
population, it had a disproportionate effect on dampening the exposure-
response relationship.
    OSHA believes that the study by Attfield and Costello (2004) is of 
superior design in that it was a categorical analysis that used

[[Page 56302]]

quantitative estimates of exposure and evaluated lung cancer mortality 
rates by exposure group. In contrast, the findings by Graham et al. 
(2004) are based on a dichotomous comparison of risk among high- versus 
low-exposure groups, where date-of-hire before and after implementation 
of ventilation controls is used as a surrogate for exposure. 
Consequently, OSHA believes that the study by Attfield and Costello is 
the more convincing study, and is one of the studies used by OSHA for 
quantitative risk assessment of lung cancer mortality due to 
crystalline silica exposure.
    The conclusions of the Vermont granite worker study (Attfield and 
Costello, 2004) are supported by the findings in studies of workers in 
the U.S. crushed stone industry (Costello et al., 1995) and Danish 
stone industry (Gu[eacute]nel et al., 1989a, 1989b). Costello et al. 
(1995) found a non-statistically significant increase in lung cancer 
mortality among limestone quarry workers and a statistically 
significant increased lung cancer mortality in granite quarry workers 
who worked 20 years or more since first exposure. Gu[eacute]nel et al. 
(1989b), in a Danish cohort study, found statistically significant 
increases in lung cancer incidence among skilled stone workers and 
skilled granite stone cutters. A study of Finnish granite workers that 
initially showed increasing risk of lung cancer with increasing silica 
exposure, upon extended follow-up, did not show an association and is 
therefore considered a negative study (Toxichemica, Inc., 2004).
    Studies of two overlapping cohorts in the industrial sand industry 
(Hughes et al., 2001; McDonald et al., 2001, 2005; Rando et al., 2001; 
Sanderson et al., 2000; Steenland and Sanderson, 2001) reported 
comparable results. These studies found a statistically significantly 
increased risk of lung cancer mortality with increased cumulative 
exposure in both categorical and continuous analyses. McDonald et al. 
(2001) examined a cohort that entered the workforce, on average, a 
decade earlier than the cohorts that Steenland and Sanderson (2001) 
examined. The McDonald cohort, drawn from eight plants, had more years 
of exposure in the industry (19 versus 8.8 years). The Steenland and 
Sanderson (2001) cohort worked in 16 plants, 7 of which overlapped with 
the McDonald, et al. (2001) cohort. McDonald et al. (2001), Hughes et 
al. (2001), and Rando et al. (2001) had access to smoking histories, 
plant records, and exposure measurements that allowed for historical 
reconstruction and the development of a job exposure matrix. Steenland 
and Sanderson (2001) had limited access to plant facilities, less 
detailed historic exposure data, and used MSHA enforcement records for 
estimates of recent exposure. These studies (Hughes et al., 2001; 
McDonald et al., 2005; Steenland and Sanderson, 2001) show very similar 
exposure response patterns of increased lung cancer mortality with 
increased exposure. OSHA included the quantitative exposure-response 
analysis from the Hughes et al. (2001) study in its Preliminary 
Quantitative Risk Assessment (Section II).
    Brown and Rushton (2005a, 2005b) found no association between risk 
of lung cancer mortality and exposure to respirable crystalline silica 
among British industrial sand workers. However, the small sample size 
and number of years of follow-up limited the statistical power of the 
analysis. Additionally, as Steenland noted in a letter review (2005a), 
the cumulative exposures of workers in the Brown and Ruston (2005b) 
study were over 10 times lower than the cumulative exposures 
experienced by the cohorts in the pooled analysis that Steenland et al. 
(2001b) performed. The low exposures experienced by this cohort would 
have made detecting a positive association with lung cancer mortality 
even more difficult.
    Excess lung cancer mortality was reported in a large cohort study 
of British coal miners (Miller et al., 2007; Miller and MacCalman, 
2009). These studies examined the mortality experience of 17,800 miners 
through the end of 2005. By that time, the cohort had accumulated 
516,431 person years of observation (an average of 29 years per miner), 
with 10,698 deaths from all causes. Overall lung cancer mortality was 
elevated (SMR=115.7, 95% C.I. 104.8-127.7), and a positive exposure-
response relationship with crystalline silica exposure was determined 
from Cox regression after adjusting for smoking history. Three of the 
strengths of this study are the detailed time-exposure measurements of 
both quartz and total mine dust, detailed individual work histories, 
and individual smoking histories. For lung cancer, analyses based on 
the Cox regression provide strong evidence that, for these coal miners, 
quartz exposures were associated with increased lung cancer risk but 
that simultaneous exposures to coal dust did not cause increased lung 
cancer risk. Because of these strengths, OSHA included the quantitative 
analysis from this study in its Preliminary Quantitative Risk 
Assessment (Section II).
    Studies of lung cancer mortality in metal ore mining populations 
reflect mixed results. Many of these mining studies were subject to 
confounding due to exposure to other potential carcinogens such as 
radon and arsenic. IARC (1997) noted that in only a few ore mining 
studies was confounding from other occupational carcinogens taken into 
account. IARC (1997) also noted that, where confounding was absent or 
accounted for in the analysis (gold miners in the U.S., tungsten miners 
in China, and zinc and lead miners in Sardinia, Italy), an association 
between silica exposure and lung cancer was absent. Many of the studies 
conducted since IARC's (1997) review more strongly implicate 
crystalline silica as a human carcinogen. Pelucchi et al. (2006), in a 
meta-analysis of studies conducted since IARC's (1997) review, reported 
statistically significantly elevated relative risks of lung cancer 
mortality in underground and surface miners in three cohort and four 
case-control studies (See Table I-15). Cassidy et al. (2007), in a 
pooled case-control analysis, showed a statistically significant 
increased risk of lung cancer mortality among miners (OR = 1.48). 
Cassidy et al. (2007) also demonstrated a clear linear trend of 
increasing odds ratios for lung cancer with increasing exposures.
    Among workers in Chinese tungsten and iron mines, mortality from 
lung cancer was not found to be statistically significantly increased 
(Chen et al., 1992; McLaughlin et al., 1992). In contrast, studies of 
Chinese tin miners found increased lung cancer mortality rates and 
positive exposure-response associations with increased silica exposure 
(Chen et al., 1992). Unfortunately, in many of these Chinese tin mines, 
there was potential confounding from arsenic exposure, which was highly 
correlated with exposure to crystalline silica (Chen and Chen, 2002; 
Chen et al., 2006). Two other studies (Carta et al. (2001) of Sardinian 
miners and stone quarrymen; Finkelstein (1998) primarily of Canadian 
miners) were limited to silicotics. The Sardinian study found a non-
statistically significant association between crystalline silica 
exposure and lung cancer mortality but no apparent exposure-response 
trend with silica exposure. The authors attributed the increased lung 
cancer to increased radon exposure and smoking among cases as compared 
to controls. Finkelstein (1998) found a positive association between 
silica exposure and lung cancer.
    Gold mining has been extensively studied in the United States, 
South

[[Page 56303]]

Africa, and Australia in four cohort and associated nested case-control 
studies, and in two separate case-control studies conducted in South 
Africa. As with metal ore mining, gold mining involves exposure to 
radon and other carcinogenic agents, which may confound the 
relationship between silica exposure and lung cancer. The U.S. gold 
miner study (Steenland and Brown, 1995a) did not find an increased risk 
of lung cancer, while the western Australian gold miner study (de Klerk 
and Musk, 1998) showed a SMR of 149 (95% CI 1.26-1.76) for lung cancer. 
Logistic regression analysis of the western Australian case control 
data showed that lung cancer mortality was statistically significantly 
associated with log cumulative silica exposure after adjusting for 
smoking and bronchitis. After additionally adjusting for silicosis, the 
relative risk remained elevated but was no longer statistically 
significant. The authors concluded that their findings showed 
statistically significantly increased lung cancer mortality in this 
cohort but that the increase in lung cancer mortality was restricted to 
silicotic members of the cohort.
    Four studies of gold miners were conducted in South Africa. Two 
case control studies (Hessel et al., 1986, 1990) reported no 
significant association between silica exposure and lung cancer, but 
these two studies may have underestimated risk, according to Hnizdo and 
Sluis-Cremer (1991). Two cohort studies (Reid and Sluis-Cremer, 1996; 
Hnizdo and Sluis-Cremer, 1991) and their associated nested case-control 
studies found elevated SMRs and odds ratios, respectively, for lung 
cancer. Reid and Sluis-Cremer (1996) attributed the increased mortality 
due to lung cancer and other non-malignant respiratory diseases to 
cohort members' lifestyle choices (particularly smoking and alcohol 
consumption). However, OSHA notes that the study reported finding a 
positive, though not statistically significant, association between 
cumulative crystalline silica exposure and lung cancer, as well as 
statistically significant association with renal failure, COPD, and 
other respiratory diseases that have been implicated with silica 
exposure.
    In contrast, Hnizdo and Sluis-Cremer (1991) found a positive 
exposure-response relationship between cumulative exposure and lung 
cancer mortality among South African gold miners after accounting for 
smoking. In a nested case-control study from the same cohort, Hnizdo et 
al. (1997) found a statistically significant increase in lung cancer 
mortality that was associated with increased cumulative dust exposure 
and time spent underground. Of the studies examining silica and lung 
cancer among South African gold miners, these two studies were the 
least likely to have been affected by exposure misclassification, given 
their rigorous methodologies and exposure measurements. Although not 
conclusive in isolation, OSHA considers the mining study results, 
particularly the gold mining and the newer mining studies, as 
supporting evidence of a causal relationship between exposure to silica 
and lung cancer risk.
    OSHA has preliminarily determined that the results of the studies 
conducted in three industry sectors (foundry, silicon carbide, and 
construction sectors) were confounded by the presence of exposures to 
other carcinogens. Exposure data from these studies were not sufficient 
to distinguish between exposure to silica dust and exposure to other 
occupational carcinogens. Thus, elevated rates of lung cancer found in 
these industries could not be attributed to silica. IARC previously 
made a similar determination in reference to the foundry industry. 
However, with respect to the construction industry, Cassidy et al. 
(2007), in a large, European community-based case-control study, 
reported finding a clear linear trend of increasing odds ratio with 
increasing cumulative exposure to crystalline silica (estimated semi-
quantitatively) after adjusting for smoking and exposure to insulation 
and wood dusts. Similar trends were found for workers in the 
manufacturing and mining industries as well. This study was a very 
large multi-national study that utilized information on smoking 
histories and exposure to silica and other occupational carcinogens. 
OSHA believes that this study provides further evidence that exposure 
to crystalline silica increases the risk of lung cancer mortality and, 
in particular, in the construction industry.
    In addition, a recent analysis of 4.8 million death certificates 
from 27 states within the U.S. for the years 1982 to 1995 showed 
statistically significant excesses in lung cancer mortality, silicosis 
mortality, tuberculosis, and NMRD among persons with occupations 
involving medium and high exposure to respirable crystalline silica 
(Calvert et al., 2003). A national records and death certificate study 
was also conducted in Finland by Pukkala et al. (2005), who found a 
statistically significant excess of lung cancer incidence among men and 
women with estimated medium and heavy exposures. OSHA believes that 
these large national death certificate studies and the pooled European 
community-based case-control study are strongly supportive of the 
previously reviewed epidemiologic data and supports the conclusion that 
occupational exposure to crystalline silica is a risk factor for lung 
cancer mortality.
    One of the more compelling studies evaluated by OSHA is the pooled 
analysis of 10 occupational cohorts (5 mines and 5 industrial 
facilities) conducted by Steenland et al. (2001a), which demonstrated 
an overall positive exposure-response relationship between cumulative 
exposure to silica and lung cancer mortality. These ten cohorts 
included 65,980 workers and 1,072 lung cancer deaths, and were selected 
because of the availability of raw data on exposure to crystalline 
silica and health outcomes. The investigators used a nested case 
control design and found lung cancer risk increased with increasing 
cumulative exposure, log cumulative exposure, and average exposure. 
Exposure-response trends were similar between mining and non-mining 
cohorts. From their analysis, the authors concluded that ``[d]espite 
this relatively shallow exposure-response trend, overall our results 
tend to support the recent conclusion by IARC (1997) that inhaled 
crystalline silica in occupational settings is a human carcinogen, and 
suggest that existing permissible exposure limits for silica need to be 
lowered (Steenland et al., 2001a). To evaluate the potential effect of 
random and systematic errors in the underlying exposure data from these 
10 cohort studies, Steenland and Bartell (Toxichemica, Inc., 2004) 
conducted a series of sensitivity analyses at OSHA's request. OSHA's 
Preliminary Quantitative Risk Assessment (Section II) presents 
additional information on the Steenland et al. (2001a) pooled cohort 
study and the sensitivity analysis performed by Steenland and Bartell 
(Toxichemica, Inc., 2004).
2. Smoking, Silica Exposure, and Lung Cancer
    Smoking is known to be a major risk factor for lung cancer. 
However, OSHA believes it is unlikely that smoking explains the 
observed exposure-response trends in the studies described above, 
particularly the retrospective cohort or nested case-control studies of 
diatomaceous earth, British pottery, Vermont granite, British coal, 
South African gold, and industrial sand workers. Also, the positive 
associations between silica exposure and lung cancer in multiple 
studies in multiple sectors indicates that exposure to crystalline

[[Page 56304]]

silica independently increases the risk of lung cancer.
    Studies by Hnizdo et al. (1997), McLaughlin et al. (1992), Hughes 
et al. (2001), McDonald et al. (2001, 2005), Miller and MacCalman 
(2009), and Cassidy et al. (2007) had detailed smoking histories with 
sufficiently large populations and a sufficient number of years of 
follow-up time to quantify the interaction between crystalline silica 
exposure and cigarette smoking. In a cohort of white South African gold 
miners (Hnizdo and Sluis-Cremer, 1991) and in the follow-up nested 
case-control study (Hnizdo et al., 1997) found that the combined effect 
of exposure to respirable crystalline silica and smoking was greater 
than additive, suggesting a multiplicative effect. This synergy 
appeared to be greatest for miners with greater than 35 pack-years of 
smoking and higher cumulative exposure to silica. In the Chinese nested 
case-control studies reported by McLaughlin et al. (1992), cigarette 
smoking was associated with lung cancer, but control for smoking did 
not influence the association between silica and lung cancer in the 
mining and pottery cohorts studied. The studies of industrial sand 
workers by Hughes et al. (2001) and British coal workers by Miller and 
MacCalman (2009) found positive exposure-response trends after 
adjusting for smoking histories, as did Cassidy et al. (2007) in their 
community-based case-control study of exposed European workers.
    In reference to control of potential confounding by cigarette 
smoking in crystalline silica studies, Stayner (2007), in an invited 
journal commentary, stated:

    Of particular concern in occupational cohort studies is the 
difficulty in adequately controlling for confounding by cigarette 
smoking. Several of the cohort studies that adjusted for smoking 
have demonstrated an excess of lung cancer, although the control for 
smoking in many of these studies was less than optimal. The results 
of the article by Cassidy et al. presented in this journal appear to 
have been well controlled for smoking and other workplace exposures. 
It is quite implausible that residual confounding by smoking or 
other risk factors for lung cancer in this or other studies could 
explain the observed excess of lung cancer in the wide variety of 
populations and study designs that have been used. Also, it is 
generally considered very unlikely that confounding by smoking could 
explain the positive exposure-response relationships observed in 
these studies, which largely rely on comparisons between workers 
with similar socioeconomic backgrounds.

    Given the findings of investigators who have accounted for the 
impact of smoking, the weight of the evidence reviewed here implicates 
respirable crystalline silica as an independent risk factor for lung 
cancer mortality. This finding is further supported by animal studies 
demonstrating that exposure to silica alone can cause lung cancer 
(e.g., Muhle et al., 1995).
3. Silicosis and Lung Cancer Risk
    In general, studies of workers with silicosis, as well as meta-
analyses that include these studies, have shown that workers with 
radiologic evidence of silicosis have higher lung cancer risk than 
those without radiologic abnormalities or mixed cohorts. Three meta-
analyses attempted to look at the association of increasing ILO 
radiographic categories of silicosis with increasing lung cancer 
mortality. Two of these analyses (Kurihara and Wada, 2004; Tsuda et 
al., 1997) showed no association with increasing lung cancer mortality, 
while Lacasse et al. (2005) demonstrated a positive dose-response for 
lung cancer with increasing ILO radiographic category. A number of 
other studies, discussed above, found increased lung cancer risk among 
exposed workers absent radiological evidence of silicosis (Cassidy et 
al., 2007; Checkoway et al., 1999; Cherry et al., 1998; Hnizdo et al., 
1997; McLaughlin et al., 1992). For example, the diatomaceous earth 
study by Checkoway et al. (1999) showed a statistically significant 
exposure-response for lung cancer among non-silicotics. Checkoway and 
Franzblau (2000), reviewing the international literature, found all 
epidemiological studies conducted to that date were insufficient to 
conclusively determine the role of silicosis in the etiology of lung 
cancer. OSHA preliminarily concludes that the more recent pooled and 
meta-analyses do not provide compelling evidence that silicosis is a 
necessary precursor to lung cancer. The analyses that do suggest an 
association between silicosis and lung cancer may simply reflect that 
more highly exposed individuals are at a higher risk for lung cancer.
    Animal and in vitro studies have demonstrated that the early steps 
in the proposed mechanistic pathways that lead to silicosis and lung 
cancer seem to share some common features. This has led some of these 
researchers to also suggest that silicosis is a prerequisite to lung 
cancer. Some have suggested that any increased lung cancer risk 
associated with silica may be a consequence of the inflammation (and 
concomitant oxidative stress) and increased epithelial cell 
proliferation associated with the development of silicosis. However, 
other researchers have noted that other key factors and proposed 
mechanisms, such as direct damage to DNA by silica, inhibition of p53, 
loss of cell cycle regulation, stimulation of growth factors, and 
production of oncogenes, may also be involved in carcinogenesis induced 
by silica (see Section II.F of the background document for more 
information on these studies). Thus, OSHA preliminarily concludes that 
available animal and in vitro studies do not support the hypothesis 
that development of silicosis is necessary for silica exposure to cause 
lung cancer.
4. Relationship Between Silica Polymorphs and Lung Cancer Risk
    OSHA's current PELs for respirable crystalline silica reflects a 
once-held belief that cristobalite is more toxic than quartz (i.e., the 
existing general industry PEL for cristobalite is one-half the general 
industry PEL for quartz). Available evidence indicates that this does 
not appear to be the case with respect to the carcinogenicity of 
crystalline silica. A comparison between cohorts having principally 
been exposed to cristobalite (the diatomaceous earth study and the 
Italian refractory brick study) with other well conducted studies of 
quartz-exposed cohorts suggests no difference in the toxicity of 
cristobalite versus quartz. The data indicates that the SMRs for lung 
cancer mortality among workers in the diatomaceous earth (SMR = 141) 
and refractory brick (SMR=151) cohort studies are within the range of 
the SMR point estimates of other cohort studies with principally quartz 
exposures (quartz exposure of Vermont granite workers yielding an SMR 
of 117; quartz and possible post-firing cristobalite exposure of 
British pottery workers yielding an SMR of 129; quartz exposure among 
industrial sand workers yielding SMRs of 129, (McDonald et al., 2001) 
and 160 (Steenland and Sanderson, 2001)). Also, the SMR point estimates 
for the diatomaceous earth and refractory brick studies are similar to, 
and fall within the 95 percent confidence interval of, the odds ratio 
(OR=1.37, 95% CI 1.14-1.65) of the recently conducted multi-center 
case-control study in Europe (Cassidy et al., 2007).
    OSHA believes that the current epidemiological literature provides 
little, if any, support for treating cristobalite as presenting a 
greater lung cancer risk than comparable exposure to respirable quartz. 
Furthermore, the weight of the available toxicological literature no 
longer supports the hypothesis that cristobalite has a higher toxicity 
than quartz, and quantitative

[[Page 56305]]

estimates of lung cancer risk do not suggest that cristobalite is more 
carcinogenic than quartz. (See Section I.F of the background document, 
Physical Factors that May Influence Toxicity of Crystalline Silica, for 
a fuller discussion of this issue.) OSHA preliminary concludes that 
respirable cristobalite and quartz dust have similar potencies for 
increasing lung cancer risk. Both IARC (1997) and NIOSH (2002) reached 
similar conclusions.
5. Cancers of Other Sites
    Respirable crystalline silica exposure has also been investigated 
as a potential risk factor for cancer at other sites such as the 
larynx, nasopharynx and the digestive system including the esophagus 
and stomach. Although many of these studies suggest an association 
between exposure to crystalline silica and an excess risk of cancer 
mortality, most are too limited in terms of size, study design, or 
potential for confounding to be conclusive. Other than for lung cancer, 
cancer mortality studies demonstrating a dose-response relationship are 
quite limited. In their silica hazard review, NIOSH (2002) concluded 
that, exclusive of the lung, an association has not been established 
between silica exposure and excess mortality from cancer at other 
sites. A brief summary of the relevant literature is presented below.
a. Cancer of the Larynx and Nasopharynx
    Several studies, including three of the better-quality lung cancer 
studies (Checkoway et al., 1997; Davis et al., 1983; McDonald et al., 
2001) suggest an association between exposure to crystalline silica and 
increased mortality from laryngeal cancer. However, the evidence for an 
association is not strong due to the small number of cases reported and 
lack of statistical significance of most of the findings.
b. Gastric (Stomach) Cancer
    In their 2002 hazard review of respirable crystalline silica, NIOSH 
identified numerous epidemiological studies and reported statistically 
significant increases in death rates due to gastric or stomach cancer. 
OSHA preliminarily concurs with observations made previously by Cocco 
et al. (1996) and the NIOSH (2002) crystalline silica hazard review 
that the vast majority of epidemiology studies of silica and stomach 
cancer have not sufficiently adjusted for the effects of confounding 
factors or have not been sufficiently designed to assess a dose-
response relationship (e.g., Finkelstein and Verma, 2005; Moshammer and 
Neuberger, 2004; Selikoff, 1978, Stern et al., 2001). Other studies did 
not demonstrate a statistically significant dose-response relationship 
(e.g., Calvert et al., 2003; Tsuda et al., 2001). Therefore, OSHA 
believes the evidence is insufficient to conclude that silica is a 
gastric carcinogen.
c. Esophageal Cancer
    Three well-conducted nested case-control studies of Chinese workers 
indicated an increased risk of esophageal cancer mortality attributed 
by the study's authors to respirable crystalline silica exposure in 
refractory brick production, boiler repair, and foundry workers (Pan et 
al., 1999; Wernli et al., 2006) and caisson construction work (Yu et 
al., 2005). Each study demonstrated a dose-response association with 
some surrogate measure of exposure, but confounding due to other 
occupational exposures is possible in all three work settings (heavy 
metal exposure in the repair of boilers in steel plants, PAH exposure 
in foundry workers, radon and radon daughter exposure in Hong Kong 
caisson workers). Other less well-constructed studies also indicated 
elevated rates of esophageal cancer mortality with silica exposure 
(Tsuda et al., 2001; Xu et al., 1996a).
    In contrast, two large national mortality studies in Finland and 
the United States, using qualitatively ranked exposure estimates, did 
not show a positive association between silica exposure and esophageal 
cancer mortality (Calvert et al., 2003; Weiderpass et al., 2003). OSHA 
preliminarily concludes that the epidemiological literature is not 
sufficiently robust to attribute increased esophageal cancer mortality 
to exposure to respirable crystalline silica.
d. Other Miscellaneous Cancers
    In 2002, NIOSH conducted a thorough literature review of the health 
effects potentially associated with crystalline silica exposure 
including a review of lung cancer and other carcinogens. NIOSH noted 
that for workers who may have been exposed to crystalline silica, there 
have been infrequent reports of statistically significant excesses of 
deaths for other cancers. A summary of these cancer studies as cited in 
NIOSH (2002) have been reported in the following organ systems (see 
NIOSH, 2002 for full bibliographic references): salivary gland; liver; 
bone; pancreatic; skin; lymphopoetic or hematopoietic; brain; and 
bladder.
    According to NIOSH (2002), an association has not been established 
between these cancers and exposure to crystalline silica. OSHA believes 
that these isolated reports of excess cancer mortality at these sites 
are not sufficient to draw any inferences about the role of silica 
exposure. The findings have not been consistently seen among 
epidemiological studies and there is no evidence of an exposure 
response relationship.

C. Other Nonmalignant Respiratory Disease

    In addition to causing silicosis, exposure to crystalline silica 
has been associated with increased risks of other non-malignant 
respiratory diseases (NMRD), primarily chronic obstructive pulmonary 
disease (COPD). COPD is a disease state characterized by airflow 
limitation that is not fully reversible. The airflow limitation is 
usually progressive and is associated with an abnormal inflammatory 
response of the lungs to noxious particles or gases. In patients with 
COPD, either chronic bronchitis or emphysema may be present or both 
conditions may be present together. The following presents OSHA's 
discussion of the literature describing the relationships between 
silica exposure and non-malignant respiratory disease.
1. Emphysema
    OSHA has considered a series of longitudinal studies of white South 
African gold miners conducted by Hnizdo and co-workers. Hnizdo et al. 
(1991) found a significant association between emphysema (both 
panacinar and centriacinar) and years of employment in a high dust 
occupation (respirable dust was estimated to contain 30 percent free 
silica). There was no such association found for non-smokers, as there 
were only four non-smokers with a significant degree of emphysema found 
in the cohort. A further study by Hnizdo et al. (1994) looked at only 
life-long non-smoking South African gold miners. In this population, no 
significant degree of emphysema or association with years of exposure 
or cumulative dust exposure was found. However, the degree of emphysema 
was significantly associated with the degree of hilar gland nodules, 
which the authors suggested might act as a surrogate for exposure to 
silica. The authors concluded that the minimal degree of emphysema seen 
in non-smoking miners exposed to the cumulative dust levels found in 
this study (mean 6.8 mg/m\3\, SD 2.4, range 0.5 to 20.2, 30 percent 
crystalline silica) was unlikely to cause meaningful impairment of lung 
function.

[[Page 56306]]

    From the two studies above, Hnizdo et al. (1994) concluded that the 
statistically significant association between exposure to silica dust 
and the degree of emphysema in smokers suggests that tobacco smoking 
potentiates the effect of silica dust. In contrast to their previous 
studies, a later study by Hnizdo et al. (2000) of South African gold 
miners found that emphysema prevalence was decreased in relation to 
dust exposure. The authors suggested that selection bias was 
responsible for this finding.
    The findings of several cross-sectional and case-control studies 
were more mixed. Becklake et al. (1987), in an unmatched case-control 
study of white South African gold miners, determined that a miner who 
had worked in high dust for 20 years had a greater chance of getting 
emphysema than a miner who had never worked in high dust. A reanalysis 
of this data (de Beer et al., 1992) including added-back cases and 
controls (because of possible selection bias in the original study), 
still found an increased risk for emphysema, although the reported odds 
ratio was smaller than previously reported by Becklake et al. (1987). 
Begin et al. (1995), in a study of the prevalence of emphysema in 
silica-exposed workers with and without silicosis, found that silica-
exposed smokers without silicosis had a higher prevalence of emphysema 
than a group of asbestos-exposed workers with similar smoking history. 
In non-smokers, the prevalence of emphysema was much higher in those 
with silicosis than in those without silicosis. A study of black 
underground gold miners found that the presence and grade of emphysema 
were statistically significantly associated with the presence of 
silicosis but not with years of mining (Cowie et al., 1993).
    Several of the above studies (Becklake et al., 1987; Begin et al., 
1995; Hnizdo et al., 1994) found that emphysema can occur in silica-
exposed workers who do not have silicosis and suggest that a causal 
relationship may exist between exposure to silica and emphysema. The 
findings of experimental (animal) studies that emphysema occurs at 
lower silica doses than does fibrosis in the airways or the appearance 
of early silicotic nodules (e.g., Wright et al., 1988) tend to support 
the findings in human studies that silica-induced emphysema can occur 
absent signs of silicosis.
    Others have also concluded that there is a relationship between 
emphysema and exposure to crystalline silica. Green and Vallyathan 
(1996) reviewed several studies of emphysema in workers exposed to 
silica. The authors stated that these studies show an association 
between cumulative dust exposure and death from emphysema. IARC (1997) 
has also briefly reviewed studies on emphysema in its monograph on 
crystalline silica carcinogenicity and concluded that exposure to 
crystalline silica increases the risk of emphysema. In their 2002 
Hazard Review, NIOSH concluded that occupational exposure to respirable 
crystalline silica is associated with emphysema but that some 
epidemiologic studies suggested that this effect may be less frequent 
or absent in non-smokers.
    Hnizdo and Vallyathan (2003) also conducted a review of studies 
addressing COPD due to occupational silica exposure and concluded that 
chronic exposure to silica dust at levels that do not cause silicosis 
may cause emphysema.
    Based on these findings, OSHA preliminarily concludes that exposure 
to respirable crystalline silica or silica-containing dust can increase 
the risk of emphysema, regardless of whether silicosis is present. This 
appears to be clearly the case for smokers. It is less clear whether 
nonsmokers exposed to silica would also be at higher risk and if so, at 
what levels of exposure. It is also possible that smoking potentiates 
the effect of silica dust in increasing emphysema risk.
2. Chronic Bronchitis
    There were no longitudinal studies available designed to 
investigate the relationship between silica exposure and bronchitis. 
However, several cross-sectional studies provide useful information. 
Studies are about equally divided between those that have reported a 
relationship between silica exposure and bronchitis and those that have 
not. Several studies demonstrated a qualitative or semiquantitative 
relationship between silica exposure and chronic bronchitis. Sluis-
Cremer et al. (1967) found a significant difference between the 
prevalence of chronic bronchitis in dust-exposed and non-dust exposed 
male residents of a South African gold mining town who smoked, but 
found no increased prevalence among non-smokers. In contrast, a 
different study of South African gold miners found that the prevalence 
of chronic bronchitis increased significantly with increasing dust 
concentration and cumulative dust exposure in smokers, nonsmokers, and 
ex-smokers (Wiles and Faure, 1977). Similarly, a study of Western 
Australia gold miners found that the prevalence of chronic bronchitis, 
as indicated by odds ratios (controlled for age and smoking), was 
significantly increased in those that had worked in the mines for 1 to 
9 years, 10 to 19 years, and more than 20 years, as compared to 
lifetime non-miners (Holman et al., 1987). Chronic bronchitis was 
present in 62 percent of black South African gold miners and 45 percent 
of those who had never smoked in a study by Cowie and Mabena (1991). 
The prevalence of what the researchers called ``chronic bronchitic 
symptom complex'' reflected the intensity of dust exposure. A higher 
prevalence of respiratory symptoms, independent of smoking and age, was 
also found for granite quarry workers in Singapore in a high exposure 
group as compared to low exposure and control groups, even after 
excluding those with silicosis from the analysis (Ng et al., 1992b).
    Other studies found no relationship between silica exposure and the 
prevalence of chronic bronchitis. Irwig and Rocks (1978) compared 
silicotic and non-silicotic South African gold miners and found no 
significant difference in symptoms of chronic bronchitis. The 
prevalence of symptoms of chronic bronchitis were also not found to be 
associated with years of mining, after adjusting for smoking, in a 
population of current underground uranium miners (Samet et al., 1984). 
Silica exposure was described in the study to be ``on occasion'' above 
the TLV. It was not possible to determine, however, whether miners with 
respiratory diseases had left the workforce, making the remaining 
population unrepresentative. Hard-rock (molybdenum) miners, with 27 and 
49 percent of personal silica samples greater than 100 and 55 [mu]g/
m\3\, respectively, also showed no increase in prevalence of chronic 
bronchitis in association with work in that industry (Kreiss et al., 
1989). However, the authors thought that differential out-migration of 
symptomatic miners and retired miners from the industry and town might 
explain that finding. Finally, grinders of agate stones (with resulting 
dust containing 70.4 percent silica) in India also had no increase in 
the prevalence of chronic bronchitis compared to controls matched by 
socioeconomic status, age and smoking, although there was a 
significantly higher prevalence of acute bronchitis in female grinders. 
A significantly higher prevalence and increasing trend with exposure 
duration for pneumoconiosis in the agate workers indicated that had an 
increased prevalence in chronic bronchitis been present, it would have 
been detected (Rastogi et al., 1991). However, control workers in this 
study may also have been exposed to silica and the study and control 
workers both

[[Page 56307]]

had high tuberculosis prevalence, possibly masking an association of 
exposure with bronchitis (NIOSH, 2002). Furthermore, exposure durations 
were very short.
    Thus, some prevalence studies supported a finding of increased 
bronchitis in workers exposed to silica-containing dust, while other 
studies did not support such a finding. However, OSHA believes that 
many of the studies that did not find such a relationship were likely 
to be biased towards the null. For example, some of the molybdenum 
miners studied by Kreiss et al. (1989), particularly retired and 
symptomatic miners, may have left the town and the industry before the 
time that the cross-sectional study was conducted, resulting in a 
survivor effect that could have interfered with detection of a possible 
association between silica exposure and bronchitis. This survivor 
effect may also have been operating in the study of uranium miners in 
New Mexico (Samet et al., 1984). In two of the negative studies, 
members of comparison and control groups were also exposed to 
crystalline silica (Irwig and Rocks, 1978; Rastogi et al., 1991), 
creating a potential bias toward the null. Additionally, tuberculosis 
in both exposed and control groups in the agate worker study (Rastogi 
et al., 1991)) may have masked an effect (NIOSH, 2002), and the 
exposure durations were very short. Several of the positive studies 
demonstrated a qualitative or semi-quantitative relationship between 
silica exposure and chronic bronchitis.
    Others have reviewed relevant studies and also concluded that there 
is a relationship between exposure to crystalline silica and the 
development of bronchitis. The American Thoracic Society (ATS) (1997) 
published an official statement on the adverse effects of crystalline 
silica exposure that included a section that discussed studies on 
chronic bronchitis (defined by chronic sputum production). According to 
the ATS review, chronic bronchitis was found to be common among worker 
groups exposed to dusty environments contaminated with silica. In 
support of this conclusion, ATS cited studies with what they viewed as 
positive findings of South African (Hnizdo et al., 1990) and Australian 
(Holman et al., 1987) gold miners, Indonesian granite workers (Ng et 
al., 1992b), and Indian agate workers (Rastogi et al., 1991). ATS did 
not mention studies with negative findings.
    A review published by NIOSH in 2002 discussed studies related to 
silica exposure and development of chronic bronchitis. NIOSH concluded, 
based on the same studies reviewed by OSHA, that occupational exposure 
to respirable crystalline silica is associated with bronchitis, but 
that some epidemiologic studies suggested that this effect may be less 
frequent or absent in non-smokers.
    Hnizdo and Vallyathan (2003) also reviewed studies addressing COPD 
due to occupational silica exposure and concluded that chronic exposure 
to silica dust at levels that do not cause silicosis may cause chronic 
bronchitis. They based this conclusion on studies that they cited as 
showing that the prevalence of chronic bronchitis increases with 
intensity of exposure. The cited studies were also reviewed by OSHA 
(Cowie and Mabena, 1991; Holman et al., 1987; Kreiss et al., 1989; 
Sluis-Cremer et al., 1967; Wiles and Faure, 1977).
    OSHA preliminarily concludes that exposure to respirable 
crystalline silica may cause chronic bronchitis and an exposure-
response relationship may exist. Smokers may be at increased risk as 
compared to non-smokers. Chronic bronchitis may occur in silica-exposed 
workers who do not have silicosis.
3. Pulmonary Function Impairment
    OSHA has reviewed numerous studies on the relationship of silica 
exposure to pulmonary function impairment as measured by spirometry. 
There were several longitudinal studies available. Two groups of 
researchers conducted longitudinal studies of lung function impairment 
in Vermont granite workers and reached opposite conclusions. Graham et 
al (1981, 1994) examined stone shed workers, who had the highest 
exposures to respirable crystalline silica (between 50 and 100 [mu]g/
m\3\), along with quarry workers (presumed to have lower exposure) and 
office workers (expected to have negligible exposure). The longitudinal 
losses of FVC and FEV1 were not correlated with years 
employed, did not differ among shed, quarry, and office workers, and 
were similar, according to the authors, to other blue collar workers 
not exposed to occupational dust.
    Eisen et al. (1983, 1995) found the opposite. They looked at lung 
function in two groups of granite workers: ``survivors'', who 
participated in each of five annual physical exams, and ``dropouts'', 
who did not participate in the final exam. There was a significant 
exposure-response relationship between exposure to crystalline silica 
and FEV1 decline among the dropouts but not among the 
survivors. The dropout group had a steeper FEV1 loss, and 
this was true for each smoking category. The authors concluded that 
exposures of about 50 ug/m\3\ produced a measurable effect on pulmonary 
function in the dropouts. Eisen et al. (1995) felt that the ``healthy 
worker effect'' was apparent in this study and that studies that only 
looked at ``survivors'' would be less likely to see any effect of 
silica on pulmonary function.
    A 12-year follow-up of age- and smoking-matched granite crushers 
and referents in Sweden found that over the follow-up period, the 
granite crushers had significantly greater decreases in 
FEV1, FEV1/FVC, maximum expiratory flow, and 
FEF50 than the referents (Malmberg et al., 1993). A 
longitudinal study of South African gold miners conducted by Hnizdo 
(1992) found that cumulative dust exposure was a significant predictor 
of most indices of decreases in lung function, including 
FEV1 and FVC. A multiple linear regression analysis showed 
that the effects of silica exposure and smoking were additive. Another 
study of South African gold miners (Cowie, 1998) also found a loss of 
FEV1 in those without silicosis. Finally, a study of U.S. 
automotive foundry workers (Hertzberg et al., 2002) found a consistent 
association with increased pulmonary function abnormalities and 
estimated measures of cumulative silica exposure within 0.1 mg/m\3\. 
The Hnizdo (1992), Cowie et al. (1993), and Cowie (1998) studies of 
South African gold miners and the Malmberg et al. (1993) study of 
Swedish granite workers found very similar reductions in 
FEV1 attributable to silica dust exposure.
    A number of prevalence studies have described relationships between 
lung function loss and silica exposure or exposure measurement 
surrogates (e.g., duration of exposure). These findings support those 
of the longitudinal studies. Such results have been found in studies of 
white South African gold miners (Hnizdo et al., 1990; Irwig and Rocks, 
1978), black South African gold miners (Cowie and Mabena, 1991), Quebec 
silica-exposed workers (Begin, et al., 1995), Singapore rock drilling 
and crushing workers (Ng et al., 1992b), Vermont granite shed workers 
(Theriault et al., 1974a, 1974b), aggregate quarry workers and coal 
miners in Spain (Montes et al., 2004a, 2004b), concrete workers in The 
Netherlands (Meijer et al., 2001), Chinese refractory brick 
manufacturing workers in an iron-steel plant (Wang et al., 1997), 
Chinese gemstone workers (Ng et al., 1987b), hard-rock miners in 
Manitoba, Canada (Manfreda et al., 1982) and Colorado (Kreiss et al., 
1989), pottery workers in France (Neukirch et al., 1994), potato 
sorters exposed to diatomaceous earth containing crystalline silica in 
The Netherlands

[[Page 56308]]

(Jorna et al., 1994), slate workers in Norway (Suhr et al., 2003), and 
men in a Norwegian community (Humerfelt et al., 1998). Two of these 
prevalence studies also addressed the role of smoking in lung function 
impairment associated with silica exposure. In contrast to the 
longitudinal study of South African gold miners discussed above 
(Hnizdo, 1992), another study of South African gold miners (Hnizdo et 
al., 1990) found that the joint effect of dust and tobacco smoking on 
lung function impairment was synergistic, rather than additive. Also, 
Montes et al. (2004b) found that the criteria for dust-tobacco 
interactions were satisfied for FEV1 decline in a study of 
Spanish aggregate quarry workers.
    One of the longitudinal studies and many of the prevalence studies 
discussed above directly addressed the question of whether silica-
exposed workers can develop pulmonary function impairment in the 
absence of silicosis. These studies found that pulmonary function 
impairment: (1) Can occur in silica-exposed workers in the absence of 
silicosis, (2) was still evident when silicosis was controlled for in 
the analysis, and (3) was related to the magnitude and duration of 
silica exposure rather than to the presence or severity of silicosis.
    Many researchers have concluded that a relationship exists between 
exposure to silica and lung function impairment. IARC (1997) has 
briefly reviewed studies on airways disease (i.e., chronic airflow 
limitation and obstructive impairment of lung function) in its 
monograph on crystalline silica carcinogenicity and concluded that 
exposure to crystalline silica causes these effects. In its official 
statement on the adverse effects of crystalline silica exposure, the 
American Thoracic Society (ATS) (1997) included a section on airflow 
obstruction. The ATS noted that, in most of the studies reviewed, 
airflow limitation was associated with chronic bronchitis. The review 
of Hnizdo and Vallyathan (2003) also addressed COPD due to occupational 
silica exposure. They examined the epidemiological evidence for an 
exposure-response relationship for airflow obstruction in studies where 
silicosis was present or absent. Hnizdo and Vallyathan (2003) concluded 
that chronic exposure to silica dust at levels that do not cause 
silicosis may cause airflow obstruction.
    Based on the evidence discussed above from a number of longitudinal 
studies and numerous cross-sectional studies, OSHA preliminarily 
concludes that there is an exposure-response relationship between 
exposure to respirable crystalline silica and the development of 
impaired lung function. The effect of tobacco smoking on this 
relationship may be additive or synergistic. Also, pulmonary function 
impairment has been shown to occur among silica-exposed workers who do 
not show signs of silicosis.
4. Non-malignant Respiratory Disease Mortality
    In this section, OSHA reviews studies on NMRD mortality that 
focused on causes of death other than from silicosis. Two studies of 
gold miners, a study of diatomaceous earth workers, and a case-control 
analysis of death certificate data provide useful information.
    Wyndham et al. (1986) found a significant excess mortality for 
chronic respiratory diseases in a cohort of white South African gold 
miners. Although these data did include silicosis mortality, the 
authors found evidence demonstrating that none of the miners certified 
on the death certificate as dying from silicosis actually died from 
that disease. Instead, pneumoconiosis was always an incidental finding 
in those dying from some other cause, the most common of which was 
chronic obstructive lung disease. A case-referent analysis found that, 
although the major risk factor for chronic respiratory disease was 
smoking, there was a statistically significant additional effect of 
cumulative dust exposure, with the relative risk estimated to be 2.48 
per ten units of 1000 particle years of exposure.
    A synergistic effect of smoking and cumulative dust exposure on 
mortality from COPD was found in another study of white South African 
gold miners (Hnizdo, 1990). Analysis of various combinations of dust 
exposure and smoking found a trend in odds ratios that indicated this 
synergism. There was a statistically significant increasing trend for 
dust particle-years and for cigarette-years of smoking. For cumulative 
dust exposure, an exposure-response relationship was found, with the 
analysis estimating that those with exposures of 10,000, 17,500, or 
20,000 particle-years of exposure had a 2.5-, 5.06-, or 6.4-times 
higher mortality risk for COPD, respectively, than those with the 
lowest dust exposure of less than 5000 particle-years. The authors 
concluded that dust alone would not lead to increased COPD mortality 
but that dust and smoking act synergistically to cause COPD and were 
thus the main risk factor for death from COPD in their study.
    Park et al. (2002) analyzed the California diatomaceous earth 
cohort data originally studied by Checkoway et al. (1997), consisting 
of 2,570 diatomaceous earth workers employed for 12 months or more from 
1942 to 1994, to quantify the relationship between exposure to 
cristobalite and mortality from chronic lung disease other than cancer 
(LDOC). Diseases in this category included pneumoconiosis (which 
included silicosis), chronic bronchitis, and emphysema, but excluded 
pneumonia and other infectious diseases. Smoking information was 
available for about 50 percent of the cohort and for 22 of the 67 LDOC 
deaths available for analysis, permitting Park et al. (2002) to at 
least partially adjust for smoking. Using the exposure estimates 
developed for the cohort by Rice et al. (2001) in their exposure-
response study of lung cancer risks, Park et al. (2002) evaluated the 
quantitative exposure-response relationship for LDOC mortality and 
found a strong positive relationship with exposure to respirable 
crystalline silica. OSHA finds this study particularly compelling 
because of the strengths of the study design and availability of 
smoking history data on part of the cohort and high-quality exposure 
and job history data; consequently, OSHA has included this study in its 
Preliminary Quantitative Risk Assessment.
    In a case-control analysis of death certificate data drawn from 27 
U.S. states, Calvert et al. (2003) found increased mortality odds 
ratios among those in the medium and higher crystalline silica exposure 
categories, a significant trend of increased risk for COPD mortality 
with increasing silica exposures, and a significantly increased odds 
ratio for COPD mortality in silicotics as compared to those without 
silicosis.
    Green and Vallyathan (1996) also reviewed several studies of NMRD 
mortality in workers exposed to silica. The authors stated that these 
studies showed an association between cumulative dust exposure and 
death from the chronic respiratory diseases.
    Based on the evidence presented in the studies above, OSHA 
preliminarily concludes that respirable crystalline silica increases 
the risk for mortality from non-malignant respiratory disease (not 
including silicosis) in an exposure-related manner. However, it appears 
that the risk is strongly influenced by smoking, and the effects of 
smoking and silica exposure may be synergistic.

D. Renal and Autoimmune Effects

    In recent years, evidence has accumulated that suggests an 
association between exposure to crystalline silica and an increased 
risk

[[Page 56309]]

of renal disease. Over the past 10 years, epidemiologic studies have 
been conducted that provide evidence of exposure-response trends to 
support this association. There is also suggestive evidence that silica 
can increase the risk of rheumatoid arthritis and other autoimmune 
diseases (Steenland, 2005b). In fact, an autoimmune mechanism has been 
postulated for some silica-associated renal disease (Calvert et al., 
1997). This section will discuss the evidence supporting an association 
of silica exposure with renal and autoimmune diseases.
    Overall, there is substantial evidence suggesting an association 
between exposure to crystalline silica and increased risks of renal and 
autoimmune diseases. In addition to a number of case reports, 
epidemiologic studies have found statistically significant associations 
between occupational exposure to silica dust and chronic renal disease 
(e.g., Calvert et al., 1997), subclinical renal changes (e.g., Ng et 
al., 1992c), end-stage renal disease morbidity (e.g., Steenland et al., 
1990), chronic renal disease mortality (Steenland et al., 2001b, 
2002a), and Wegener's granulomatosis (Nuyts et al., 1995). In other 
findings, silica-exposed individuals, both with and without silicosis, 
had an increased prevalence of abnormal renal function (Hotz et al., 
1995), and renal effects have been reported to persist after cessation 
of silica exposure (Ng et al., 1992c). Possible mechanisms suggested 
for silica-induced renal disease include a direct toxic effect on the 
kidney, deposition in the kidney of immune complexes (IgA) following 
silica-related pulmonary inflammation, or an autoimmune mechanism 
(Calvert et al., 1997; Gregorini et al., 1993).
    Several studies of exposed worker populations reported finding 
excess renal disease mortality and morbidity. Wyndham et al. (1986) 
reported finding excess mortality from acute and chronic nephritis 
among South African goldminers that had been followed for 9 years. 
Italian ceramic workers experienced an overall increase in the 
prevalence of end-stage renal disease (ESRD) cases compared to regional 
rates; the six cases that occurred among the workers had cumulative 
exposures to crystalline silica of between 0.2 and 3.8 mg/m\3\-years 
(Rapiti et al., 1999).
    Calvert et al. (1997) found an increased incidence of non-systemic 
ESRD cases among 2,412 South Dakota gold miners exposed to a median 
crystalline silica concentration of 0.09 mg/m\3\. In another study of 
South Dakota gold miners, Steenland and Brown (1995a) reported a 
positive trend of chronic renal disease mortality risk and cumulative 
exposure to respirable crystalline silica, but most of the excess 
deaths were concentrated among workers hired before 1930 when exposures 
were likely higher than in more recent years.
    Excess renal disease mortality has also been described among North 
American industrial sand workers. McDonald et al., (2001, 2005) found 
that nephritis/nephrosis mortality was elevated overall among 2,670 
industrial sand workers hired 20 or more years prior to follow-up, but 
there was no apparent relationship with either cumulative or average 
exposure to crystalline silica. However, Steenland et al. (2001b) did 
find that increased mortality from acute and chronic renal disease was 
related to increasing quartiles of cumulative exposure among a larger 
cohort of 4,626 industrial sand workers. In addition, they also found a 
positive trend for ESRD case incidence and quartiles of cumulative 
exposure.
    In a pooled cohort analysis, Steenland et al. (2002a) combined the 
industrial sand cohort from Steenland et al. (2001b), gold mining 
cohort from Steenland and Brown (1995a), and the Vermont granite cohort 
studies by Costello and Graham (1988). In all, the combined cohort 
consisted of 13,382 workers with exposure information available for 
12,783. The exposure estimates were validated by the monotonically 
increasing exposure-response trends seen in analyses of silicosis, 
since cumulative silica levels are known to predict silicosis risk. The 
mean duration of exposure, cumulative exposure, and concentration of 
respirable silica for the cohort were 13.6 years, 1.2 mg/m\3\-years, 
and 0.07 mg/m\3\, respectively.
    The analysis demonstrated statistically significant exposure-
response trends for acute and chronic renal disease mortality with 
quartiles of cumulative exposure to respirable crystalline silica. In a 
nested case-control study design, a positive exposure-response 
relationship was found across the three cohorts for both multiple-cause 
mortality (i.e., any mention of renal disease on the death certificate) 
and underlying cause mortality. Renal disease risk was most prevalent 
among workers with cumulative exposures of 0.5 mg/m\3\ or more 
(Steenland et al., 2002a).
    Other studies failed to find an excess renal disease risk among 
silica-exposed workers. Davis et al. (1983) found an elevated, but not 
a statistically significant increase, in mortality from diseases of the 
genitourinary system among Vermont granite shed workers. There was no 
observed relationship between mortality from this cause and cumulative 
exposure. A similar finding was reported by Koskela et al. (1987) among 
Finnish granite workers, where there were 4 deaths due to urinary tract 
disease compared to 1.8 expected. Both Carta et al. (1994) and Cocco et 
al. (1994) reported finding no increased mortality from urinary tract 
disease among workers in an Italian lead mine and a zinc mine. However, 
Cocco et al. (1994) commented that exposures to respirable crystalline 
silica were low, averaging 0.007 and 0.09 mg/m\3\ in the two mines, 
respectively, and that their study in particular had low statistical 
power to detect excess mortality.
    There are many case series, case-control, and cohort studies that 
provide support for a causal relationship between exposure to 
respirable crystalline silica and an increased renal disease risk 
(Kolev et al., 1970; Osorio et al., 1987; Steenland et al., 1990; 
Gregorini et al., 1993; Nuyts et al., 1995). In addition, a number of 
studies have demonstrated early clinical signs of renal dysfunction 
(i.e., urinary excretion of low- and high-molecular weight proteins and 
other markers of renal glomerular and tubular disruption) in workers 
exposed to crystalline silica, both with and without silicosis (Ng et 
al., 1992c; Hotz et al., 1995; Boujemaa, 1994; Rosenman et al., 2000).
    OSHA believes that there is substantial evidence on which to base a 
finding that exposure to respirable crystalline silica increases the 
risk of renal disease mortality and morbidity. In particular, OSHA 
believes that the 3-cohort pooled analysis conducted by Steenland et 
al. (2002a) is particularly convincing. OSHA believes that the findings 
of this pooled analysis seem credible because the analysis involved a 
large number of workers from three cohorts with well-documented, 
validated job-exposure matrices and found a positive and monotonic 
increase in renal disease risk with increasing exposure for both 
underlying and multiple cause data. However, there are considerably 
less data, and thus the findings based on them are less robust, than 
what is available for silicosis mortality or lung cancer mortality. 
Nevertheless, OSHA preliminarily concludes that the underlying data are 
sufficient to provide useful estimates of risk and has included the 
Steenland et al. (2002a) analysis in its Preliminary Quantitative Risk 
Assessment.
    Several studies of different designs, including case series, 
cohort, registry linkage and case-control, conducted in a variety of 
exposed groups suggest an association between silica exposure and

[[Page 56310]]

increased risk of systemic autoimmune disease (Parks et al., 1999). 
Studies have found that the most common autoimmune diseases associated 
with silica exposure are scleroderma (e.g., Sluis-Cremer et al., 1985); 
rheumatoid arthritis (e.g. Klockars et al., 1987; Rosenman and Zhu, 
1995); and systemic lupus erythematosus (e.g., Brown et al., 1997). 
Mechanisms suggested for silica-related autoimmune disease include an 
adjuvant effect of silica (Parks et al., 1999), activation of the 
immune system by the fibrogenic proteins and growth factors released as 
a result of the interaction of silica particles with macrophages (e.g., 
Haustein and Anderegg, 1998), and a direct local effect of non-
respirable silica particles penetrating the skin and producing 
scleroderma (Green and Vallyathan, 1996). However, there are no 
quantitative exposure-response data available at this time on which to 
base a quantitative risk assessment for autoimmune diseases.
    Therefore, OSHA preliminarily concludes that there is substantial 
evidence that silica exposure increases the risks of renal and 
autoimmune disease. The positive and monotonic exposure-response trends 
demonstrated for silica exposure and renal disease risk more strongly 
suggest a causal link. The studies by Steenland et al. (2001b, 2002a) 
and Steenland and Brown (1995a) provide evidence of a positive 
exposure-response relationship. For autoimmune diseases, the available 
data did not provide an adequate basis for assessing exposure-response 
relationships. However, OSHA believes that the available exposure-
response data on silica exposure and renal disease is sufficient to 
allow for quantitative estimates of risk.

E. Physical Factors That May Influence Toxicity of Crystalline Silica

    Much research has been conducted to investigate the influence of 
various physical factors on the toxicologic potency of crystalline 
silica. Such factors examined include crystal polymorphism; the age of 
fractured surfaces of the crystal particle; the presence of impurities, 
particularly metals, on particle surfaces; and clay occlusion of the 
particle. These factors likely vary among different workplace settings 
suggesting that the risk to workers exposed to a given level of 
respirable crystalline silica may not be equivalent in different work 
environments. In this section, OSHA examines the research demonstrating 
the effects of these factors on the toxicologic potency of silica.
    The modification of surface characteristics by the physical factors 
noted above may alter the toxicity of silica by affecting the physical 
and biochemical pathways of the mechanistic process. Thus, OSHA has 
reviewed the proposed mechanisms by which silica exposure leads to 
silicosis and lung cancer. It has been proposed that silicosis results 
from a cycle of cell damage, oxidant generation, inflammation, scarring 
and fibrosis. A silica particle entering the lung can cause lung damage 
by two major mechanisms: direct damage to lung cells due to the silica 
particle's unique surface properties or by the activation or 
stimulation of alveolar macrophages (after phagocytosis) and/or 
alveolar epithelial cells. In either case, an elevated production of 
reactive oxygen and nitrogen species (ROS/RNS) results in oxidant 
damage to lung cells. The oxidative stress and lung injury stimulates 
alveolar macrophages and/or alveolar epithelial cells to produce growth 
factors and fibrogenic mediators, resulting in fibroblast activation 
and pulmonary fibrosis. A continuous ingestion-reingestion cycle, with 
cell activation and death, is established.
    OSHA has examined evidence on the comparative toxicity of the 
silica polymorphs (quartz, cristobalite, and tridymite). A number of 
animal studies appear to suggest that cristobalite and tridymite are 
more toxic to the lung than quartz and more tumorigenic (e.g., King et 
al., 1953; Wagner et al., 1980). However, in contrast to these 
findings, several authors have reviewed the studies done in this area 
and concluded that cristobalite and tridymite are not more toxic than 
quartz (e.g., Bolsaitis and Wallace, 1996; Guthrie and Heaney, 1995). 
Furthermore, a difference in toxicity between cristobalite and quartz 
has not been observed in epidemiologic studies (tridymite has not been 
studied) (NIOSH, 2002). In an analysis of exposure-response for lung 
cancer, Steenland et al. (2001a) found similar exposure-response trends 
between cristobalite-exposed workers and other cohorts exposed to 
quartz.
    A number of studies have compared the toxicity of freshly fractured 
versus aged silica. Although animal studies have demonstrated that 
freshly fractured silica is more toxic than aged silica, aged silica 
still retains significant toxicity (Porter et al., 2002; Shoemaker et 
al., 1995; Vallyathan et al., 1995). Studies of workers exposed to 
freshly fractured silica have demonstrated that these workers exhibit 
the same cellular effects as seen in animals exposed to freshly 
fractured silica (Castranova et al., 1998; Goodman et al., 1992). There 
have been no studies, however, comparing workers exposed to freshly 
fractured silica to those exposed to aged silica. Animal studies also 
suggest that pulmonary reactions of rats to short-duration exposure to 
freshly fractured silica mimic those seen in acute silicosis in humans 
(Vallyathan et al., 1995).
    Surface impurities, particularly metals, have been shown to alter 
silica toxicity. Iron, depending on its state and quantity, has been 
shown to either increase or decrease toxicity. Aluminum has been shown 
to decrease toxicity (Castranova et al., 1997; Donaldson and Borm, 
1998; Fubini, 1998). Silica coated with aluminosilicate clay exhibits 
lower toxicity, possibly as a result of reduced bioavailability of the 
silica particle surface (Donaldson and Borm, 1998; Fubini, 1998). This 
reduced bioavailability may be due to aluminum ions left on the silica 
surface by the clay (Bruch et al., 2004; Cakmak et al., 2004; Fubini et 
al., 2004). Aluminum and other metal ions are thought to modify silanol 
groups on the silica surface, thus decreasing the membranolytic and 
cytotoxic potency and resulting in enhanced particle clearance from the 
lung before damage can take place (Fubini, 1998). An epidemiologic 
study found that the risk of silicosis was less in pottery workers than 
in tin and tungsten miners (Chen et al., 2005; Harrison et al., 2005), 
possibly reflecting that pottery workers were exposed to silica 
particles having less biologically available, non-clay-occluded surface 
area than was the case for miners. The authors concluded that clay 
occlusion of silica particles can be a factor in reducing disease risk.
    Although it is evident that a number of factors can act to mediate 
the toxicological potency of crystalline silica, it is not clear how 
such considerations should be taken into account to evaluate lung 
cancer and silicosis risks to exposed workers. After evaluating many in 
vitro studies that had been conducted to investigate the surface 
characteristics of crystalline silica particles and their influence on 
fibrogenic activity, NIOSH (2002) concluded that further research is 
needed to associate specific surface characteristics that can affect 
toxicity with specific occupational exposure situations and consequent 
health risks to workers. According to NIOSH (2002), such exposures may 
include work processes that produce freshly fractured silica surfaces 
or that involve quartz contaminated with trace elements such as iron. 
NIOSH called for further in vitro and in vivo studies of the toxicity 
and pathogenicity of alpha quartz compared with its polymorphs, quartz

[[Page 56311]]

contaminated with trace elements, and further research on the 
association of surface properties with specific work practices and 
health effects.
    In discussing the ``considerable'' heterogeneity shown across the 
10 studies used in the pooled lung cancer risk analysis, Steenland et 
al. (2001a) pointed to hypotheses that physical differences in silica 
exposure (e.g., freshness of particle cleavage) between cohorts may be 
a partial explanation of observed differences in exposure-response 
coefficients derived from those cohort studies. However, the authors 
did not have specific information on whether or how these factors might 
have actually influenced the observed differences. Similarly, in the 
pooled analysis and risk assessments for silicosis mortality conducted 
by Mannetje et al. (2002b), differences in biological activity of 
different types of silica dust could not be specifically taken into 
account. Mannetje et al. (2002b) determined that the exposure-response 
relationship between silicosis and log-transformed cumulative exposure 
to crystalline silica was comparable between studies and no significant 
heterogeneity was found. The authors therefore concluded that their 
findings were relevant for different circumstances of occupational 
exposure to crystalline silica. Both the Steenland et al. (2001a) and 
Mannetje et al. (2002b) studies are discussed in detail in OSHA's 
Preliminary Quantitative Risk Assessment (section II of the background 
document and summarized in section VI of this preamble).
    OSHA preliminarily concludes that there is considerable evidence to 
support the hypothesis that surface activity of crystalline silica 
particles plays an important role in producing disease, and that 
several environmental influences can modify surface activity to either 
enhance or diminish the toxicity of silica. However, OSHA believes that 
the available information is insufficient to determine in any 
quantitative way how these influences may affect disease risk to 
workers in any particular workplace setting.

VI. Summary of OSHA's Preliminary Quantitative Risk Assessment

A. Introduction

    The Occupational Safety and Health Act (OSH Act or Act) and some 
landmark court cases have led OSHA to rely on quantitative risk 
assessment, to the extent possible, to support the risk determinations 
required to set a permissible exposure limit (PEL) for a toxic 
substance in standards under the OSH Act. A determining factor in the 
decision to perform a quantitative risk assessment is the availability 
of suitable data for such an assessment. In the case of crystalline 
silica, there has been extensive research on its health effects, and 
several quantitative risk assessments have been published in the peer-
reviewed scientific literature that describe the risk to exposed 
workers of lung cancer mortality, silicosis mortality and morbidity, 
non-malignant respiratory disease mortality, and renal disease 
mortality. These assessments were based on several studies of 
occupational cohorts in a variety of industry sectors, the underlying 
studies of which are described in OSHA's review of the health effects 
literature (see section V of this preamble). In this section, OSHA 
summarizes its Preliminary Quantitative Risk Assessment (QRA) for 
crystalline silica, which is presented in Section II of the background 
document entitled ``Respirable Crystalline Silica--Health Effects 
Literature Review and Preliminary Quantitative Risk Assessment'' 
(placed in Docket OSHA-2010-0034).
    OSHA has done what it believes to be a comprehensive review of the 
literature to provide quantitative estimates of risk for crystalline 
silica-related diseases. Quantitative risk assessments for lung cancer 
and silicosis mortality were published after the International Agency 
for Research on Cancer (IARC) determined more than a decade ago that 
there was sufficient evidence to regard crystalline silica as a human 
carcinogen (IARC, 1997). This finding was based on several studies of 
worker cohorts demonstrating associations between exposure to 
crystalline silica and an increased risk of lung cancer. Although IARC 
judged the overall evidence as being sufficient to support this 
conclusion, IARC also noted that some studies of crystalline silica-
exposed workers did not demonstrate an excess risk of lung cancer and 
that exposure-response trends were not always consistent among studies 
that were able to describe such trends. These findings led Steenland et 
al. (2001a) and Mannetje et al. (2002b) to conduct comprehensive 
exposure-response analyses of the risk of lung cancer and silicosis 
mortality associated with exposure to crystalline silica. These 
studies, referred to as the IARC multi-center studies of lung cancer 
and silicosis mortality, relied on all available cohort data from 
previously published epidemiological studies for which there were 
adequate quantitative data on worker exposures to crystalline silica to 
derive pooled estimates of disease risk. In addition, OSHA identified 
four single-cohort studies of lung cancer mortality that it judged 
suitable for quantitative risk assessment; two of these cohorts 
(Attfield and Costello, 2004; Rice et al., 2001) were included among 
the 10 used in the IARC multi-center study and studies of two other 
cohorts appeared later (Hughes et al., 2001; McDonald et al., 2001, 
2005; Miller and MacCalman, 2009). For non-malignant respiratory 
disease mortality, in addition to the silicosis mortality study by 
Mannetje et al. (2002b), Park et al. (2002) conducted an exposure-
response analysis of non-malignant respiratory disease mortality 
(including silicosis and other chronic obstructive pulmonary diseases) 
among diatomaceous earth workers. Exposure-response analyses for 
silicosis morbidity have been published in several single-cohort 
studies (Chen et al., 2005; Hnizdo and Sluis-Cremer, 1993; Steenland 
and Brown, 1995b; Miller et al., 1998; Buchanan et al., 2003). Finally, 
a quantitative assessment of end-stage renal disease mortality based on 
data from three worker cohorts was developed by Steenland et al. 
(2002a).
    In addition to these published studies, OSHA's contractor, 
Toxichemica, Inc., commissioned Drs. Kyle Steenland and Scott Bartell 
of Emory University to perform an uncertainty analysis to examine the 
effect on lung cancer and silicosis mortality risk estimates of 
uncertainties that exist in the exposure assessments underlying the two 
IARC multi-center analyses (Toxichemica, Inc., 2004).
    OSHA's Preliminary QRA presents estimates of the risk of silica-
related diseases assuming exposure over a working life (45 years) to 
the proposed 8-hour time-weighted average (TWA) PEL and action level of 
0.05 and 0.025 mg/m\3\, respectively, of respirable crystalline silica, 
as well as to OSHA's current PELs. OSHA's current general industry PEL 
for respirable quartz is expressed both in terms of a particle count 
formula and a gravimetric concentration formula, while the current 
construction and shipyard employment PELs for respirable quartz are 
only expressed in terms of a particle count formula. The current PELs 
limit exposure to respirable dust; the specific limit in any given 
instance depends on the concentration of crystalline silica in the 
dust. For quartz, the gravimetric general industry PEL approaches a 
limit of 0.1 mg/m\3\ as respirable quartz as the quartz content 
increases (see discussion in Section XVI of this preamble, Summary and 
Explanation for paragraph (c)). OSHA's Preliminary QRA presents risk 
estimates for

[[Page 56312]]

exposure over a working lifetime to 0.1 mg/m\3\ to represent the risk 
associated with exposure to the current general industry PEL. OSHA's 
current PEL for construction and shipyard employment is a formula PEL 
that limits exposure to respirable dust expressed as a respirable 
particle count concentration. As with the gravimetric general industry 
PEL, the limit varies depending on quartz content of the dust. There is 
no single mass concentration equivalent for the construction and 
shipyard PELs; OSHA's Preliminary QRA reviews several studies that 
suggest that the current construction/shipyard PEL likely lies in the 
range between 0.25 and 0.5 mg/m\3\ respirable quartz, and OSHA presents 
risk estimates for this range of exposure to represent the risks 
associated with exposure to the current construction/shipyard PEL. In 
general industry, for both the gravimetric and particle count PELs, 
OSHA's current PEL for cristobalite and tridymite are half the value 
for quartz. Thus, OSHA's Preliminary QRA presents risk estimates 
associated with exposure over a working lifetime to 0.025, 0.05, 0.1, 
0.25, and 0.5 mg/m\3\ respirable silica (corresponding to cumulative 
exposures over 45 years to 1.125, 2.25, 4.5, 11.25, and 22.5 mg/m\3\-
years).
    Risk estimates for lung cancer mortality, silicosis and non-
malignant respiratory disease mortality, and renal disease mortality 
are presented in terms of lifetime (up to age 85) excess risk per 1,000 
workers for exposure over an 8-hour working day, 250 days per year, and 
a 45-year working life. For silicosis morbidity, OSHA based its risk 
estimates on cumulative risk models used by the various investigators 
to develop quantitative exposure-response relationships. These models 
characterized the risk of developing silicosis (as detected by chest 
radiography) up to the time that cohort members (including both active 
and retired workers) were last examined. Thus, risk estimates derived 
from these studies represent less-than-lifetime risks of developing 
radiographic silicosis. OSHA did not attempt to estimate lifetime risk 
(i.e., up to age 85) for silicosis morbidity because the relationships 
between age, time, and disease onset post-exposure have not been well 
characterized.
    A draft preliminary quantitative risk assessment document was 
submitted for external scientific peer review in accordance with the 
Office of Management and Budget's ``Final Information Quality Bulletin 
for Peer Review'' (OMB, 2004). A summary of OSHA's responses to the 
peer reviewers' comments appears in Section III of the background 
document.
    In the sections below, OSHA describes the studies and the published 
risk assessments it uses to estimate the occupational risk of 
crystalline silica-related disease. (The Preliminary QRA itself also 
discusses several other available studies that OSHA does not include 
and OSHA's reasons for not including these studies.)

B. Lung Cancer Mortality

1. Summary of Studies
    In its Preliminary QRA, OSHA discusses risk assessments from six 
published studies that quantitatively analyzed exposure-response 
relationships for crystalline silica and lung cancer; some of these 
also provided estimates of risks associated with exposure to OSHA's 
current PEL or NIOSH's Recommended Exposure Limit (REL) of 0.05 mg/
m\3\. These studies include: (1) A quantitative analysis by Steenland 
et al. (2001a) of worker cohort data pooled from ten studies; (2) an 
exposure-response analysis by Rice et al. (2001) of a cohort of 
diatomaceous earth workers primarily exposed to cristobalite; (3) an 
analysis by Attfield and Costello (2004) of U.S. granite workers; (4) a 
risk assessment by Kuempel et al. (2001), who employed a kinetic rat 
lung model to describe the relationship between quartz lung burden and 
cancer risk, then calibrated and validated that model using the 
diatomaceous earth worker and granite worker cohort mortality data; (5) 
an exposure-response analysis by Hughes et al., (2001) of U.S. 
industrial sand workers; and (6) a risk analysis by Miller et al. 
(2007) and Miller and MacCalman (2009) of British coal miners. These 
six studies are described briefly below and are followed by a summary 
of the lung cancer risk estimates derived from these studies.
a. Steenland et al. (2001a) Pooled Cohort Analysis
    OSHA considers the lung cancer analysis conducted by Steenland et 
al. (2001a) to be of prime importance for risk estimation because of 
its size, incorporation of data from multiple cohorts, and availability 
of detailed exposure and job history data. Subsequent to its 
publication, Steenland and Bartell (Toxichemica, Inc., 2004) conducted 
a quantitative uncertainty analysis on the pooled data set to evaluate 
the potential impact on the risk estimates of random and systematic 
exposure misclassification, and Steenland (personal communication, 
2010) conducted additional exposure-response modeling.
    The original study consisted of a pooled exposure-response analysis 
and risk assessment based on raw data obtained from ten cohorts of 
silica-exposed workers (65,980 workers, 1,072 lung cancer deaths). 
Steenland et al. (2001a) initially identified 13 cohort studies as 
containing exposure information sufficient to develop a quantitative 
exposure assessment; the 10 studies included in the pooled analysis 
were those for which data on exposure and health outcome could be 
obtained for individual workers. The cohorts in the pooled analysis 
included U.S. gold miners (Steenland and Brown, 1995a), U.S. 
diatomaceous earth workers (Checkoway et al., 1997), Australian gold 
miners (de Klerk and Musk, 1998), Finnish granite workers (Koskela et 
al., 1994), U.S. industrial sand employees (Steenland and Sanderson, 
2001), Vermont granite workers (Costello and Graham, 1988), South 
African gold miners (Hnizdo and Sluis-Cremer, 1991; Hnizdo et al., 
1997), and Chinese pottery workers, tin miners, and tungsten miners 
(Chen et al., 1992).
    The exposure assessments developed for the pooled analysis are 
described by Mannetje et al. (2002a). The exposure information and 
measurement methods used to assess exposure from each of the 10 cohort 
studies varied by cohort and by time and included dust measurements 
representing particle counts, mass of total dust, and respirable dust 
mass. All exposure information was converted to units of mg/m\3\ 
respirable crystalline silica by generating cohort-specific conversion 
factors based on the silica content of the dust to which workers were 
exposed.
    A case-control study design was employed for which cases and 
controls were matched for race, sex, age (within 5 years) and study; 
100 controls were matched to each case. To test the reasonableness of 
the cumulative exposure estimates for cohort members, Mannetje et al. 
(2002a) examined exposure-response relationships for silicosis 
mortality by performing a nested case-control analysis for silicosis or 
unspecified pneumoconiosis using conditional logistic regression. Each 
cohort was stratified into quartiles by cumulative exposure, and 
standardized rate ratios (SRR) for silicosis were calculated using the 
lowest-exposure quartile as the baseline. Odds ratios (OR) for 
silicosis were also calculated for the pooled data set overall, which 
was stratified into quintiles based on cumulative exposure.

[[Page 56313]]

    For the pooled data set, the relationship between odds ratio for 
silicosis mortality and increasing cumulative exposure was ``positive 
and reasonably monotonic'', ranging from 3.1 for the lowest quartile of 
exposure to 4.8 for the highest. In addition, in seven of the ten 
individual cohorts, there were statistically significant trends between 
silicosis mortality rate ratios (SRR) and cumulative exposure. For two 
of the cohorts (U.S. granite workers and U.S. gold miners), the trend 
test was not statistically significant (p=0.10). A trend analysis could 
not be performed on the South African gold miner cohort since silicosis 
was not coded as an underlying cause of death in that country. A more 
rigorous analysis of silicosis mortality on pooled data from six of 
these cohorts also showed a strong, statistically significant 
increasing trend with increasing decile of cumulative exposure 
(Mannetje et al., 2002b), providing additional evidence for the 
reasonableness of the exposure assessment used for the Steenland et al 
(2001a) lung cancer analysis.
    For the pooled lung cancer mortality analysis, Steenland et al. 
(2001a) conducted a nested case-control analysis via Cox regression, in 
which there were 100 controls chosen for each case randomly selected 
from among cohort members who survived past the age at which the case 
died, and matched on age (the time variable in Cox regression), study, 
race/ethnicity, sex, and date of birth within 5 years (which, in 
effect, matched on calendar time given the matching on age). Using 
alternative continuous exposure variables in a log-linear relative risk 
model (log RR=[beta]x, where x represents the exposure variable and 
[beta] the coefficient to be estimated), Steenland et al. (2001a) found 
that the use of either 1) cumulative exposure with a 15-year lag, 2) 
the log of cumulative exposure with a 15-year lag, or 3) average 
exposure resulted in positive statistically significant (p<=0.05) 
exposure-response coefficients. The models that provided the best fit 
to the data were those that used cumulative exposure and log-
transformed cumulative exposure. The fit of the log-linear model with 
average exposure was clearly inferior to those using cumulative and 
log-cumulative exposure metrics.
    There was significant heterogeneity among studies (cohorts) using 
either cumulative exposure or average exposure. The authors suggested a 
number of possible reasons for such heterogeneity, including errors in 
measurement of high exposures (which tends to have strong influence on 
the exposure-response curve when untransformed exposure measures are 
used), the differential toxicity of silica depending on the crystalline 
polymorph, the presence of coatings or trace minerals that alter the 
reactivity of the crystal surfaces, and the age of the fractured 
surfaces. Models that used the log transform of cumulative exposure 
showed no statistically significant heterogeneity among cohorts 
(p=0.36), possibly because they are less influenced by very high 
exposures than models using untransformed cumulative exposure. For this 
reason, as well as the good fit of the model using log-cumulative 
exposure, Steenland et al. (2001a) conducted much of their analysis 
using log-transformed cumulative exposure. The sensitivity analysis by 
Toxichemica, Inc. (2004) repeated this analysis after correcting some 
errors in the original coding of the data set. At OSHA's request, 
Steenland (2010) also conducted a categorical analysis of the pooled 
data set and additional analyses using linear relative risk models 
(with and without log-transformation of cumulative exposure) as well as 
a 2-piece spline model.
    The cohort studies included in the pooled analysis relied in part 
on particle count data and the use of conversion factors to estimate 
exposures of workers to mass respirable quartz. A few studies were able 
to include at least some respirable mass sampling data. OSHA believes 
that uncertainty in the exposure assessments that underlie each of the 
10 studies included in the pooled analysis is likely to represent one 
of the most important sources of uncertainty in the risk estimates. To 
evaluate the potential impact of uncertainties in the underlying 
exposure assessments on estimates of the risk, OSHA's contractor, 
Toxichemica, Inc. (2004), commissioned Drs. Kyle Steenland and Scott 
Bartell of Emory University to conduct an uncertainty analysis using 
the raw data from the pooled cancer risk assessment. The uncertainty 
analysis employed a Monte Carlo technique in which two kinds of random 
exposure measurement error were considered; these were (1) random 
variation in respirable dust measurements and (2) random error in 
estimating respirable quartz exposures from historical data on particle 
count concentration, total dust mass concentration, and respirable dust 
mass concentration measurements. Based on the results of this 
uncertainty analysis, OSHA does not have reason to believe that random 
error in the underlying exposure estimates in the Steenland et al. 
(2001a) pooled cohort study of lung cancer is likely to have 
substantially influenced the original findings, although a few 
individual cohorts (particularly the South African and Australian gold 
miner cohorts) appeared to be sensitive to measurement errors.
    The sensitivity analysis also examined the potential effect of 
systematic bias in the use of conversion factors to estimate respirable 
crystalline silica exposures from historical data. Absent a priori 
reasons to suspect bias in a specific direction (with the possible 
exception of the South African cohort), Toxichemica, Inc. (2004) 
considered possible biases in either direction by assuming that 
exposure was under-estimated by 100% (i.e., the true exposure was twice 
the estimated) or over-estimated by 100% (i.e., the true exposure was 
half the estimated) for any given cohort in the original pooled 
dataset. For the conditional logistic regression model using log 
cumulative exposure with a 15-year lag, doubling or halving the 
exposure for a specific study resulted in virtually no change in the 
exposure-response coefficient for that study or for the pooled analysis 
overall. Therefore, based on the results of the uncertainty analysis, 
OSHA believes that misclassification errors of a reasonable magnitude 
in the estimation of historical exposures for the 10 cohort studies 
were not likely to have substantially biased risk estimates derived 
from the exposure-response model used by Steenland et al. (2001a).
b. Rice et al. (2001) Analysis of Diatomaceous Earth Workers
    Rice et al. (2001) applied a variety of exposure-response models to 
the same California diatomaceous earth cohort data originally reported 
on by Checkoway et al. (1993, 1996, 1997) and included in the pooled 
analysis conducted by Steenland et al. (2001a) described above. The 
cohort consisted of 2,342 white males employed for at least one year 
between 1942 and 1987 in a California diatomaceous earth mining and 
processing plant. The cohort was followed until 1994, and included 77 
lung cancer deaths. Rice et al. (2001) relied on the dust exposure 
assessment developed by Seixas et al. (1997) from company records of 
over 6,000 samples collected from 1948 to 1988; cristobalite was the 
predominate form of crystalline silica to which the cohort was exposed. 
Analysis was based on both Poisson regression models Cox's proportional 
hazards models with various functions of cumulative silica exposure in 
mg/m\3\-years to estimate the relationship between silica exposure and 
lung cancer mortality rate. Rice et al. (2001) reported that exposure 
to crystalline silica was a significant predictor of lung cancer

[[Page 56314]]

mortality for nearly all of the models employed, with the linear 
relative risk model providing the best fit to the data in the Poisson 
regression analysis.
c. Attfield and Costello (2004) Analysis of Granite Workers
    Attfield and Costello (2004) analyzed the same U.S. granite cohort 
originally studied by Costello and Graham (1988) and Davis et al. 
(1983) and included in the Steenland et al. (2001a) pooled analysis, 
consisting of 5,414 male granite workers who were employed in the 
Vermont granite industry between 1950 and 1982 and who had received at 
least one chest x-ray from the surveillance program of the Vermont 
Department of Industrial Hygiene. Their 2004 report extended follow-up 
from 1982 to 1994, and found 201 deaths. Workers' cumulative exposures 
were estimated by Davis et al. (1983) based on historical exposure data 
collected in six environmental surveys conducted between 1924 and 1977, 
plus work history information.
    Using Poisson regression models and seven cumulative exposure 
categories, the authors reported that the results of the categorical 
analysis showed a generally increasing trend of lung cancer rate ratios 
with increasing cumulative exposure, with seven lung cancer death rate 
ratios ranging from 1.18 to 2.6. A complication of this analysis was 
that the rate ratio for the highest exposure group in the analysis 
(cumulative exposures of 6.0 mg/m\3\-years or higher) was substantially 
lower than those for other exposure groups. Attfield and Costello 
(2004) reported that the best-fitting model was based on a 15-year lag, 
use of untransformed cumulative exposure, and omission of the highest 
exposure group.
    The authors argued that it was appropriate to base their risk 
estimates on a model that was fitted without the highest exposure group 
for several reasons. They believed the underlying exposure data for the 
high-exposure group was weaker than for the others, and that there was 
a greater likelihood that competing causes of death and misdiagnoses of 
causes of death attenuated the lung cancer death rate. Second, all of 
the remaining groups comprised 85 percent of the deaths in the cohort 
and showed a strong linear increase in lung cancer mortality with 
increasing exposure. Third, Attfield and Costello (2004) believed that 
the exposure-response relationship seen in the lower exposure groups 
was more relevant given that the exposures of these groups were within 
the range of current occupational standards. Finally, the authors 
stated that risk estimates derived from the model after excluding the 
highest exposure group were more consistent with other published risk 
estimates than was the case for estimates derived from the model using 
all exposure groups. Because of these reasons, OSHA believes it is 
appropriate to rely on the model employed by Attfield and Costello 
(2004) after omitting the highest exposure group.
d. Kuempel et al. (2001) Rat-Based Model for Human Lung Cancer
    Kuempel et al. (2001) published a rat-based toxicokinetic/
toxicodynamic model for silica exposure for predicting human lung 
cancer, based on lung burden concentrations necessary to cause the 
precursor events that can lead to adverse physiological effects in the 
lung. These adverse physiological effects can then lead to lung 
fibrosis and an indirect genotoxic cause of lung cancer. The 
hypothesized first step, or earliest expected response, in these 
disease processes is chronic lung inflammation, which the authors 
consider as a disease limiting step. Since the NOAEL of lung burden 
associated with this inflammation, based on the authors' rat-to-human 
lung model conversion, is the equivalent of exposure to 0.036 mg/m\3\ 
(Mcrit) for 45 years, exposures below this level would 
presumably not lead to (based on an indirect genotoxic mechanism) lung 
cancer, at least in the ``average individual.'' Since silicosis also is 
inflammation mediated, this exposure could also be considered to be an 
average threshold level for that disease as well.
    Kuempel et al. (2001) have used their rat-based lung cancer model 
with human data, both to validate their model and to estimate the lung 
cancer risk as a function of quartz lung burden. First they 
``calibrated'' human lung burdens from those in rats based on exposure 
estimates and lung autopsy reports of U.S. coal miners. Then they 
validated these lung burden estimates using quartz exposure data from 
U.K. coal miners. Using these human lung burden/exposure concentration 
equivalence relationships, they then converted the cumulative exposure-
lung cancer response slope estimates from both the California 
diatomaceous earth workers (Rice et al., 2001) and Vermont granite 
workers (Attfield and Costello, 2001) to lung burden-lung cancer 
response slope estimates. Finally, they used these latter slope 
estimates in a life table program to estimate lung cancer risk 
associated with their ``threshold'' exposure of 0.036 mg/m\3\ and to 
the OSHA PEL and NIOSH REL. Comparing the estimates from the two 
epidemiology studies with those based on a male rat chronic silica 
exposure study the authors found that, '' the lung cancer excess risk 
estimates based on male rat data are approximately three times higher 
than those based on the male human data.'' Based on this modeling and 
validation exercise, Keumpel et al. concluded, ``the rat-based 
estimates of excess lung cancer risk in humans exposed to crystalline 
silica are reasonably similar to those based on two human occupational 
epidemiology studies.''
    Toxichemica, Inc. (2004) investigated whether use of the dosimetry 
model would substantially affect the results of the pooled lung cancer 
data analysis initially conducted by Steenland et al. (2001a). They 
replicated the lung dosimetry model using Kuempel et al.'s (2001) 
reported median fit parameter values, and compared the relationship 
between log cumulative exposure and 15-year lagged lung burden at the 
age of death in case subjects selected for the pooled case-control 
analysis. The two dose metrics were found to be highly correlated 
(r=0.99), and models based on either log silica lung burden or log 
cumulative exposure were similarly good predictors of lung cancer risk 
in the pooled analysis (nearly identical log-likelihoods of -4843.96 
and--4843.996, respectively). OSHA believes that the Kuempel et al. 
(2001) analysis is a credible attempt to quantitatively describe the 
retention and accumulation of quartz in the lung, and to relate the 
external exposure and its associated lung burden to the inflammatory 
process. However, using the lung burden model to convert the cumulative 
exposure coefficients to a different exposure metric appears to add 
little additional information or insight to the risk assessments 
conducted on the diatomaceous earth and granite cohort studies. 
Therefore, for the purpose of quantitatively evaluating lung cancer 
risk in exposed workers, OSHA has chosen to rely on the epidemiology 
studies themselves and the cumulative exposure metrics used in those 
studies.
e. Hughes et al. (2001), McDonald et al. (2001), and McDonald et al. 
(2005) Study of North American Industrial Sand Workers
    McDonald et al. (2001), Hughes et al. (2001) and McDonald et al. 
(2005) followed up on a cohort study of North American industrial sand 
workers that overlapped with the industrial sand cohort (18 plants, 
4,626 workers) studied by Steenland and Sanderson (2001) and included 
in Steenland et al.'s (2001a) pooled cohort analysis. The McDonald et 
al. (2001) follow-up cohort

[[Page 56315]]

included 2,670 men employed before 1980 for three years or more in one 
of nine North American (8 U.S. and 1 Canadian) sand-producing plants, 
including 1 large associated office complex. Information on cause of 
death was obtained, from 1960 through 1994, for 99 percent of the 
deceased workers for a total 1,025 deaths representing 38 percent of 
the cohort. A nested case-control study and analysis based on 90 lung 
cancer deaths from this cohort was also conducted by Hughes et al. 
(2001). A later update through 2000, of both the cohort and nested 
case-control studies by McDonald et al. (2005), eliminated the Canadian 
plant, following 2,452 men from the eight U.S. plants. For the lung 
cancer case-control part of the study the update included 105 lung 
cancer deaths. Both the initial and updated case control studies used 
up to two controls per case.
    Although the cohort studies provided evidence of increased risk of 
lung cancer (SMR = 150, p = 0.001, based on U.S. rates) for deaths 
occurring 20 or more years from hire, the nested case-control studies, 
Hughes et al. (2001) and McDonald et al. (2005), allowed for individual 
job, exposure, and smoking histories to be taken into account in the 
exposure-response analysis for lung cancer. Both of these case-control 
analyses relied on an analysis of exposure information reported by 
Sanderson et al. (2000) and by Rando et al. (2001) to provide 
individual estimates of average and cumulative exposure. Statistically 
significant positive exposure-response trends for lung cancer were 
found for both cumulative exposure (lagged 15 years) and average 
exposure concentration, but not for duration of employment, after 
controlling for smoking. A monotonic increase was seen for both lagged 
and unlagged cumulative exposure when the four upper exposure 
categories were collapsed into two. With exposure lagged 15 years and 
after adjusting for smoking, increasing quartiles of cumulative silica 
exposure were associated with lung cancer mortality (odds ratios of 
1.00, 0.84, 2.02 and 2.07, p-value for trend=0.04). There was no 
indication of an interaction effect of smoking and cumulative silica 
exposure (Hughes et al., 2001).
    OSHA considers this Hughes et al. (2001) study and analysis to be 
of high enough quality to provide risk estimates for excess lung cancer 
for silica exposure to industrial sand workers. Using the median 
cumulative exposure levels of 0, 0.758, 2.229 and 6.183 mg/m\3\-years, 
Hughes et al. estimated lung cancer odds ratios, ORs (no. of deaths), 
for these categories of 1.00 (14), 0.84 (15), 2.02 (31), and 2.07 (30), 
respectively, on a 15-year lag basis (p-value for trend=0.04.) For the 
updated nested case control analysis, McDonald et al. (2005) found very 
similar results, with exposure lagged 15 years and, after adjusting for 
smoking, increasing quartiles of cumulative silica exposure were 
associated with lung cancer ORs (no. of deaths) of 1.00 (13), 0.94 
(17), 2.24 (38), and 2.66 (37) (p-value for trend=0.006). Because the 
Hughes et al. (2001) report contained information that allowed OSHA to 
better calculate exposure-response estimates and because of otherwise 
very similar results in the two papers, OSHA has chosen to base its 
lifetime excess lung cancer risk estimate for these industrial sand 
workers on the Hughes et al. (2001) case-control study. Using the 
median exposure levels of 0, 0.758, 2.229 and 6.183 mg-years/m\3\, 
respectively, for each of the four categories described above, and 
using the model: ln OR = [alpha] + [beta] x Cumulative Exposure, the 
coefficient for the exposure estimate was [beta] = 0.13 per (mg/m\3\-
years), with a standard error of [beta] = 0.074 (calculated from the 
trend test p-value in the same paper). In this model, with background 
lung cancer risks of about 5 percent, the OR provides a suitable 
estimate of the relative risk.
f. Miller et al. (2007) and Miller and MacCalman (2009) Study of 
British Coal Workers Exposed to Respirable Quartz
    Miller et al. (2007) and Miller and MacCalman (2009) continued a 
follow-up mortality study, begun in 1970, of 18,166 coalminers from 10 
British coalmines initially followed through the end of 1992 (Miller et 
al., 1997). The two recent reports on mortality analyzed the cohort of 
17,800 miners and extended the analysis through the end of 2005. By 
that time there were 516,431 person years of observation, an average of 
29 years per miner, with 10,698 deaths from all causes. Causes of 
deaths of interest included pneumoconiosis, other non-malignant 
respiratory diseases (NMRD), lung cancer, stomach cancer, and 
tuberculosis. Three of the strengths of this study are its use of 
detailed time-exposure measurements of both quartz and total mine dust, 
detailed individual work histories, and individual smoking histories. 
However, the authors noted that no additional exposure measurements 
were included in the updated analysis, since all the mines had closed 
by the mid 1980's.
    For this cohort mortality study there were analyses using both 
external (regional age-time and cause specific mortality rates) 
internal controls. For the analysis from external mortality rates, the 
all-cause mortality SMR from 1959 through 2005 was 100.9 (95% C.I., 
99.0-102.8), based on all 10,698 deaths. However, these death ratios 
were not uniform over time. For the period from 1990 to 2005, the all-
cause SMR was 109.6 (95% C.I., 106.5-112.8), while the ratios for 
previous periods were less than 100. This pattern of recent increasing 
SMRs was also seen in the recent cause-specific death rate for lung 
cancer, SMR=115.7 (95% C.I., 104.8-127.7). For the analysis based on 
internal rates and using Cox regression methods, the relative risk for 
lung cancer risk based on a cumulative quartz exposure equivalent to 
approximately 0.055 mg/m\3\ for 45 years was RR = 1.14 (95% C.I., 1.04 
to 1.25). This risk is adjusted for concurrent coal dust exposure and 
smoking status, and incorporated a 15-year lag in quartz exposures. The 
analysis showed a strong effect for smoking (independent of quartz 
exposure) on lung cancer. For lung cancer, OSHA believes that the 
analyses based on the Cox regression method provides strong evidence 
that for these coal miners' quartz exposures were associated with 
increased lung cancer risk, but that simultaneous exposures to coal 
dust did not cause increased lung cancer risk. To estimate lung cancer 
risk from this study, OSHA estimated the regression slope for a log-
linear relative risk model based on the Miller and MacCalman's (2009) 
finding of a relative risk of 1.14 for a cumulative exposure of 0.055 
mg/m\3\-years.
2. Summary of OSHA's Estimates of Lung Cancer Mortality Risk
    Tables VI-1 and VI-2 summarize the excess lung cancer risk 
estimates from occupational exposure to crystalline silica, based on 
five of the six lung cancer risk assessments discussed above. OSHA's 
estimates of lifetime excess lung cancer risk associated with 45 years 
of exposure to crystalline silica at 0.1 mg/m\3\ (approximately the 
current general industry PEL) range from 13 to 60 deaths per 1,000 
workers. For exposure to the proposed PEL of 0.05 mg/m\3\, the lifetime 
risk estimates calculated by OSHA are in the range of 6 to 26 deaths 
per 1,000 workers. For a 45-year exposure at the proposed action level 
of 0.025 mg/m\3\, OSHA estimates the risk to range from 3 to 23 deaths 
per 1,000 workers. The results from these assessments are reasonably 
consistent despite the use of data from different cohorts and the 
reliance on different analytical techniques for evaluating dose-
response relationships. Furthermore, OSHA notes that in this range of 
exposure, 0.025--0.1 mg/m\3\, there is statistical consistency between

[[Page 56316]]

the risk estimates, as evidenced by the considerable overlap in the 95-
percent confidence intervals of the risk estimates presented in Table 
VI-1.
    OSHA also estimates the lung cancer risk associated with 45 years 
of exposure to the current construction/shipyard PEL (in the range of 
0.25 to 0.5 mg/m\3\) to range from 37 to 653 deaths per 1,000 workers. 
Exposure to 0.25 or 0.5 mg/m\3\ over 45 years represents cumulative 
exposures of 11.25 and 22.5 mg-years/m\3\, respectively. This range of 
cumulative exposure is well above the median cumulative exposure for 
most of the cohorts used in the risk assessment, primarily because most 
of the individuals in these cohorts had not been exposed for as long as 
45 years. Thus, estimating lung cancer excess risks over this higher 
range of cumulative exposures of interest to OSHA required some degree 
of extrapolation and adds uncertainty to the estimates.

C. Silicosis and Non-Malignant Respiratory Disease Mortality

    There are two published quantitative risk assessment studies of 
silicosis and non-malignant respiratory disease (NMRD) mortality; a 
pooled analysis of silicosis mortality by Mannetje et al. (2002b) of 
data from six epidemiological studies, and an exposure-response 
analysis of NMRD mortality among diatomaceous earth workers (Park et 
al., 2002).
1. Mannetje et al. (2002b) Six Cohort Pooled Analysis
    The Mannetje et al. (2002b) silicosis analysis was part of the IARC 
ten cohort pooled study included in the Steenland et al. (2001a) lung 
cancer mortality analysis above. These studies included 18,634 subjects 
and 170 silicosis deaths (n = 150 for silicosis, and n = 20 unspecified 
pneumoconiosis). The silicosis deaths had a median duration of exposure 
of 28 years, a median cumulative exposure of 7.2 mg/m\3\-years, and a 
median average exposure of 0.26 mg/m\3\, while the respective values of 
the whole cohort were 10 years, 0.62 mg/m\3\-years, and 0.07 mg/m\3\. 
Rates for silicosis adjusted for age, calendar time, and study were 
estimated by Poisson regression; rates increased nearly monotonically 
with deciles of cumulative exposure, from a mortality rate of 5/100,000 
person-years in the lowest exposure category (0-0.99 mg/m\3\-years) to 
299/100,000 person-years in the highest category (>28.10 mg/m\3\-
years). Quantitative estimates of exposure to respirable silica (mg/
m\3\) were available for all six cohorts (Mannetje et al. 2002a). 
Lifetime risk of silicosis mortality was estimated by accumulating 
mortality rates over time using the formula
    Risk = 1 - exp(-[sum]time * rate).
    To estimate the risk of silicosis mortality at the current and 
proposed PELs, OSHA used the model described by Mannetje et al. (2002b) 
to estimate risk to age 85 but used rate ratios that were estimated 
from a nested case-control design that was part of a sensitivity 
analysis conducted by Toxichemica, Inc. (2004), rather than the Poisson 
regression originally conducted by Mannetje et al. (2002b). The case-
control design was selected because it was expected to better control 
for age; in addition, the rate ratios derived from the case-control 
study reflect exposure measurement uncertainty via conduct of a Monte 
Carlo analysis (Toxichemica, Inc., 2004).
2. Park et al. (2002) Study of Diatomaceous Earth Workers
    Park et al. (2002) analyzed the California diatomaceous earth 
cohort data originally studied by Checkoway et al. (1997), consisting 
of 2,570 diatomaceous earth workers employed for 12 months or more from 
1942 to 1994, to quantify the relationship between exposure to 
cristobalite and mortality from chronic lung disease other than cancer 
(LDOC). Diseases in this category included pneumoconiosis (which 
included silicosis), chronic bronchitis, and emphysema, but excluded 
pneumonia and other infectious diseases. Industrial hygiene data for 
the cohort were available from the employer for total dust, silica 
(mostly cristobalite), and asbestos. Park et al. (2002) used the 
exposure assessment previously reported by Seixas et al. (1997) and 
used by Rice et al. (2001) to estimate cumulative crystalline silica 
exposures for each worker in the cohort based on detailed work history 
files. The mean silica concentration for the cohort overall was 0.29 
mg/m\3\ over the period of employment (Seixas et al., 1997). The mean 
cumulative exposure values for total respirable dust and respirable 
crystalline silica were 7.31 and 2.16 mg/m\3\-year, respectively. 
Similar cumulative exposure estimates were made for asbestos. Smoking 
information was available for about 50 percent of the cohort and for 22 
of the 67 LDOC deaths available for analysis, permitting Park et al. 
(2002) to at least partially adjust for smoking. Estimates of LDOC 
mortality risks were derived via Poisson and Cox's proportional hazards 
models; a variety of relative rate model forms were fit to the data, 
with a linear relative rate model being selected for risk estimation.
3. Summary Risk Estimates for Silicosis and NMRD Mortality
    Table VI-2 presents OSHA's risk estimates for silicosis and NMRD 
mortality derived from the Mannetje et al. (2002b) and Park et al. 
(2002) studies, respectively. For 45 years of exposure to the current 
general industry PEL (approximately 0.1 mg/m\3\ respirable crystalline 
silica), OSHA's estimates of excess lifetime risk are 11 deaths per 
1,000 workers for the pooled analysis and 83 deaths per 1,000 workers 
based on Park et al.'s (2002) estimates. At the proposed PEL, estimates 
of silicosis and NMRD mortality are 7 and 43 deaths per 1,000, 
respectively. For exposures up to 0.25 mg/m\3\, the estimates based on 
Park et al. are about 5 to 11 times as great as those calculated for 
the pooled analysis of silicosis mortality (Mannetje et al., 2002b). 
However, these two sets of risk estimates are not directly comparable. 
First, the Park et al. analysis used untransformed cumulative exposure 
as the exposure metric, whereas the Mannertje et al. analysis used log 
cumulative exposure, which causes the exposure-response to flatten out 
in the higher exposure ranges. Second, the mortality endpoint for the 
Park et al. (2002) analysis is death from all non-cancer lung diseases, 
including pneumoconiosis, emphysema, and chronic bronchitis, whereas 
the pooled analysis by Mannetje et al. (2002b) included only deaths 
coded as silicosis or other pneumoconiosis. Less than 25 percent of the 
LDOC deaths in the Park et al. (2002) analysis were coded as silicosis 
or other pneumoconiosis (15 of 67). As noted by Park et al. (2002), it 
is likely that silicosis as a cause of death is often misclassified as 
emphysema or chronic bronchitis; thus, Mannetje et al.'s (2002b) 
selection of deaths may tend to underestimate the true risk of 
silicosis mortality, and Park et al.'s (2002) analysis would more 
fairly capture the total respiratory mortality risk from all non-
malignant causes, including silicosis and chronic obstructive pulmonary 
disease.

D. Renal Disease Mortality

    Steenland et al. (2002a) examined renal disease mortality in three 
cohorts and evaluated exposure-response relationships from the pooled 
cohort data. The three cohorts included U.S. gold miners (Steenland and 
Brown, 1995a), U.S. industrial sand workers (Steenland et al., 2001b), 
and Vermont granite workers (Costello and Graham, 1988), all three of 
which are included in both the lung cancer mortality and silicosis 
mortality pooled analyses reported above. Follow up for the U.S.

[[Page 56317]]

gold miners study was extended six years from that in the other pooled 
analyses. Steenland et al. (2002a) reported that these cohorts were 
chosen because data were available for both underlying cause mortality 
and multiple cause mortality; this was believed important because renal 
disease is often listed on death certificates without being identified 
as an underlying cause of death. In the three cohorts, there were 51 
total renal disease deaths using underlying cause, and 204 total renal 
deaths using multiple cause mortality.
    The combined cohort for the pooled analysis (Steenland et al., 
2002a) consisted of 13,382 workers with exposure information available 
for 12,783 (95 percent). Exposure matrices for the three cohorts had 
been used in previous studies (Steenland and Brown, 1995a; Attfield and 
Costello, 2001; Steenland et al., 2001b). The mean duration of 
exposure, the mean cumulative exposure, and the mean concentration of 
respirable silica for the pooled cohort were 13.6 years, 1.2 mg/m\3\-
years, and 0.07 mg/m\3\, respectively. SMRs (compared to the U.S. 
population) for renal disease (acute and chronic glomerulonephritis, 
nephrotic syndrome, acute and chronic renal failure, renal sclerosis, 
and nephritis/nephropathy) were statistically significantly elevated 
using multiple cause data (SMR 1.29, 95% CI 1.10-1.47, 193 deaths) and 
underlying cause data (SMR 1.41, 95% CI 1.05-1.85, 51 observed deaths).
    OSHA's estimates of renal disease mortality appear in Table VI-2. 
Based on the life table analysis, OSHA estimates that exposure to the 
current (0.10 mg/m\3\) and proposed general industry PEL (0.0.05 mg/
m\3\) over a working life would result in a lifetime excess renal 
disease risk of 39 (95% CI 2-200) and 32 (95% CI 1.7-147) deaths per 
1,000, respectively. For exposure to the current construction/shipyard 
PEL, OSHA estimates the excess lifetime risk to range from 52 (95% CI 
2.2-289) to 63 (95% CI 2.5-368) deaths per 1,000 workers.

E. Silicosis Morbidity

    OSHA's Preliminary QRA summarizes the principal cross-sectional and 
cohort studies that have quantitatively characterized relationships 
between exposure to crystalline silica and development of radiographic 
evidence of silicosis. Each of these studies relied on estimates of 
cumulative exposure to evaluate the relationship between exposure and 
silicosis prevalence in the worker populations examined. The health 
endpoint of interest in these studies is the appearance of opacities on 
chest roentgenograms indicative of pulmonary fibrosis.
    The International Labour Organization's (ILO) 1980 International 
Classification of Radiographs of the Pneumoconioses is accepted as the 
standard against which chest radiographs are measured in epidemiologic 
studies, for medical surveillance and for clinical evaluation. 
According to this standard, if radiographic findings are or may be 
consistent with pneumoconiosis, then the size, shape, and extent of 
profusion of opacities are characterized by comparing the radiograph to 
standard films. Classification by shape (rounded vs. irregular) and 
size involves identifying primary and secondary types of small 
opacities on the radiograph and classifying them into one of six size/
shape categories. The extent of profusion is judged from the 
concentrations of opacities as compared with that on the standard 
radiographs and is graded on a 12-point scale of four major categories 
(0-3, with Category 0 representing absence of opacities), each with 
three subcategories. Most of the studies reviewed by OSHA considered a 
finding consistent with an ILO classification of 1/1 to be a positive 
diagnosis of silicosis, although some also considered an x-ray 
classification of 1/0 or 0/1 to be positive.
    Chest radiography is not the most sensitive tool used to diagnose 
or detect silicosis. In 1993, Hnizdo et al. reported the results of a 
study that compared autopsy and radiological findings of silicosis in a 
cohort of 557 white South African gold miners. The average period from 
last x-ray to autopsy was 2.7 years. Silicosis was not diagnosed 
radiographically for over 60 percent of the miners for whom 
pathological examination of lung tissue showed slight to marked 
silicosis. The likelihood of false negatives (negative by x-ray, but 
silicosis is actually present) increased with years of mining and 
average dust exposure of the miners. The low sensitivity seen for 
radiographic evaluation suggests that risk estimates derived from 
radiographic evidence likely understate the true risk of developing 
fibrotic lesions as a result of exposure to crystalline silica.
    OSHA's Preliminary QRA examines multiple studies from which 
silicosis occupational morbidity risks can be estimated. The studies 
evaluated fall into three major types. Some are cross-sectional studies 
in which radiographs taken at a point in time were examined to 
ascertain cases (Kreiss and Zhen, 1996; Love et al., 1999; Ng and Chan, 
1994; Rosenman et al., 1996; Churchyard et al., 2003, 2004); these 
radiographs may have been taken as part of a health survey conducted by 
the investigators or represent the most recent chest x-ray available 
for study subjects. Other studies were designed to examine radiographs 
over time in an effort to determine onset of disease. Some of these 
studies examined primarily active, or current, workers (Hughes et al., 
1998; Muir et al., 1989a, 1989b; Park et al., 2002), while others 
included both active and retired workers (Chen et al., 2001, 2005; 
Hnizdo and Sluis-Cremer, 1993; Miller et al., 1998; Buchanan et al., 
2003; Steenland and Brown, 1995b).
    Even though OSHA has presented silicosis risk estimates for all of 
the studies identified, the Agency is relying primarily on those 
studies that examined radiographs over time and included both active 
and retired workers. It has been pointed out by others (Chen et al., 
2001; Finkelstein, 2000; NIOSH, 2002) that lack of follow-up of retired 
workers consistently resulted in lower risk estimates compared to 
studies that included retired workers. OSHA believes that the most 
reliable estimates of silicosis morbidity, as detected by chest 
radiographs, come from the studies that evaluated radiographs over 
time, included radiographic evaluation of workers after they left 
employment, and derived cumulative or lifetime estimates of silicosis 
disease risk. Brief descriptions of these cumulative risk studies used 
to estimate silicosis morbidity risks are presented below.
1. Hnizdo and Sluis Cremer (1993) Study of South African White Gold 
Miners
    Hnizdo and Sluis-Cremer (1993) described the results of a 
retrospective cohort study of 2,235 white gold miners in South Africa. 
These workers had received annual examinations and chest x-rays while 
employed; most returned for occasional examinations after employment. A 
case was defined as one with an x-ray classification of ILO 1/1 or 
greater. A total of 313 miners had developed silicosis and had been 
exposed for an average of 27 years at the time of diagnosis. Forty-
three percent of the cases were diagnosed while employed and the 
remaining 57 percent were diagnosed an average of 7.4 years after 
leaving the mines. The average latency for the cohort was 35 years 
(range of 18-50 years) from start of exposure to diagnosis.
    The average respirable dust exposure for the cohort overall was 
0.29 mg/m\3\ (range 0.11-0.47), corresponding to an estimated average 
respirable silica concentration of 0.09 mg/m\3\ (range

[[Page 56318]]

0.033-0.14). The average cumulative dust exposure for the overall 
cohort was 6.6 mg/m\3\-years (range 1.2-18.7), or an average cumulative 
silica exposure of 1.98 mg/m\3\-years (range 0.36-5.61). OSHA believes 
that the exposure estimates for the cohort are uncertain given the need 
to rely on particle count data generated over a fairly narrow 
production period.
    Silicosis risk increased exponentially with cumulative exposure to 
respirable dust and was modeled using log-logistic regression. Using 
the exposure-response relationship developed by Hnizdo and Sluis-Cremer 
(1993), and assuming a quartz content of 30 percent in respirable dust, 
Rice and Stayner (1995) and NIOSH (2002) estimated the risk of 
silicosis to be 70 percent and 13 percent for a 45-year exposure to 0.1 
and 0.05 mg/m\3\ respirable crystalline silica, respectively.
2. Steenland and Brown (1995b) Study of South Dakota Gold Miners
    Three thousand three hundred thirty South Dakota gold miners who 
had worked at least a year underground between 1940 and 1965 were 
studied by Steenland and Brown (1995b). Workers were followed though 
1990 with 1,551 having died; loss to follow up was low (2 percent). 
Chest x-rays taken in cross-sectional surveys in 1960 and 1976 and 
death certificates were used to ascertain cases of silicosis. One 
hundred twenty eight cases were found via death certificate, 29 by x-
ray (defined as ILO 1/1 or greater), and 13 by both. Nine percent of 
deaths had silicosis mentioned on the death certificate. Inclusion of 
death certificate diagnoses probably increases the risk estimates from 
this study compared to those that rely exclusively on radiographic 
findings to evaluate silicosis morbidity risk (see discussion of Hnizdo 
et al. (1993) above).
    Exposure was estimated by conversion of impinger (particle count) 
data and was based on measurements indicating an average of 13 percent 
silica in the dust. Based on these data, the authors estimated the mean 
exposure concentration to be 0.05 mg/m\3\ for the overall cohort, with 
those hired before 1930 exposed to an average of 0.15 mg/m\3\. The 
average duration of exposure for cases was 20 years (s.d = 8.7) 
compared to 8.2 years (s.d = 7.9) for the rest of the cohort. This 
study found that cumulative exposure was the best disease predictor, 
followed by duration of exposure and average exposure. Lifetime risks 
were estimated from Poisson regression models using standard life table 
techniques. The authors estimated a risk of 47 percent associated with 
45 years of exposure to 0.09 mg/m\3\ respirable crystalline silica, 
which reduced to 35 percent after adjustment for age and calendar time.
3. Miller et al. (1995, 1998) and Buchanan et al. (2003) Study of 
Scottish Coal Miners
    Miller et al. (1995, 1998) and Buchanan et al. (2003) reported on a 
1990/1991 follow-up study of 547 survivors of a 1,416 member cohort of 
Scottish coal workers from a single mine. These men had all worked in 
the mine during a period between early 1971 and mid 1976, during which 
they had experienced ``unusually high concentrations of freshly cut 
quartz in mixed coalmine dust. The population's exposures to both coal 
and quartz dust had been measured in unique detail, for a substantial 
proportion of the men's working lives.'' Thus, this cohort allowed for 
the study of the effects of both higher and lower silica 
concentrations, and exposure-rate effects on the development of 
silicosis. The 1,416 men had all had previous radiographs dating from 
before, during, or just after this high concentration period, and the 
547 participating survivors received their follow-up chest x-rays 
between November 1990 and April 1991. Follow-up interviews consisted of 
questions on current and past smoking habits, and occupational history 
since leaving the coal mine, which closed in 1981.
    Silicosis cases were identified as such if the median 
classification of the three readers indicated an ILO (1980) 
classification of 1/0 or greater, plus a progression from the earlier 
reading. Of the 547 men, 203 (38 percent) showed progression of at 
least one ILO category from the 1970's surveys to the 1990-91 survey; 
in 128 of these (24 percent) there was progression of two or more 
steps. In the 1970's survey 504 men had a profusion score of 0; of 
these, 120 (24 percent) progressed to an ILO classification of 1/0 or 
greater. Of the 36 men who had shown earlier profusions of 1/0 or 
greater, 27 (75 percent) showed further progression at the 1990/1991 
follow-up. Only one subject showed a regression from any earlier 
reading, and that was slight, from ILO 1/0 to 0/1.
    To study the effects of exposure to high concentrations of quartz 
dust, the Buchanan et al. (2003) analysis presented the results of 
logistic regression modeling that incorporated two independent terms 
for cumulative exposure, one arising from exposure to concentrations 
less than 2 mg/m\3\ respirable quartz and the other from exposure to 
concentrations greater than or equal to 2 mg/m\3\. Both of the 
cumulative quartz exposure concentration variables were ``highly 
statistically significant in the presence of the other,'' and 
independent of the presence of coal dust. Since these quartz variables 
were in the same units, g-hr/m\3\, the authors noted that coefficient 
for exposure concentrations equal to or above 2.0 mg/m\3\ was 3 times 
that of the coefficient for concentrations less than 2.0 mg/m\3\. From 
this, the authors concluded that their analysis showed that ``the risk 
of silicosis over a working lifetime can rise dramatically with 
exposure to such high concentrations over a timescale of merely a few 
months.''
    Buchanan et al., (2003) provided analysis and risk estimates only 
for silicosis cases defined as having an x-ray classified as ILO 2/1+, 
after adjusting for the disproportionately severe effect of exposure to 
high concentrations on silicosis risk. Estimating the risk of acquiring 
a chest x-ray classified as ILO 1/0+ from the Buchanan (2003) or the 
earlier Miller et al. (1995, 1998) publications can only be roughly 
approximated because of the limited summary information included; this 
information suggests that the risk of silicosis defined as an ILO 
classification of 1/0+ could be about three times higher than the risk 
of silicosis defined as an ILO 2/1+ x-ray. OSHA has a high degree of 
confidence in the estimates of progression to stages 2/1+ from this 
Scotland coal mine study, mainly because of the highly detailed and 
extensive exposure measurements, the radiographic records, and the 
detailed analyses of high exposure-rate effects.
4. Chen et al. (2001) Study of Tin Miners
    Chen et al. (2001) reported the results of a retrospective study of 
a Chinese cohort of 3,010 underground miners who had worked in tin 
mines at least one year between 1960 and 1965. They were followed 
through 1994, by which time 2,426 (80.6%) workers had either retired or 
died, and only 400 (13.3%) remained employed at the mines.
    The study incorporated occupational histories, dust measurements 
and medical examination records. Exposure data consisted of high-flow, 
short-term gravimetric total dust measurements made routinely since 
1950; the authors used data from 1950 to represent earlier exposures 
since dust control measures were not implemented until 1958. Results 
from a 1998-1999 survey indicated that respirable silica measurements 
were 3.6 percent (s.d = 2.5 percent) of total dust measurements. Annual 
radiographs were taken since 1963 and all cohort members continued

[[Page 56319]]

to have chest x-rays taken every 2 or 3 years after leaving work. 
Silicosis was diagnosed when at least 2 of 3 radiologists classified a 
radiograph as being a ``suspected case'' or at Stage I, II, or III 
under the 1986 Chinese pneumoconiosis roentgen diagnostic criteria. 
According to Chen et al. (2001), these four categories under the 
Chinese system were found to agree closely with ILO categories 0/1, 
Category 1, Category 2, and Category 3, respectively, based on studies 
comparing the Chinese and ILO classification systems. Silicosis was 
observed in 33.7 percent of the group; 67.4 percent of the cases 
developed after exposure ended.
5. Chen et al. (2005) Study of Chinese Pottery Workers, Tin Miners, and 
Tungsten Miners
    In a later study, Chen et al. (2005) investigated silicosis 
morbidity risks among three cohorts to determine if the risk varied 
among workers exposed to silica dust having different characteristics. 
The cohorts consisted of 4,547 pottery workers, 4,028 tin miners, and 
14,427 tungsten miners selected from a total of 20 workplaces. Cohort 
members included all males employed after January 1, 1950 and who 
worked for at least one year between 1960 and 1974. Radiological 
follow-up was through December 31, 1994 and x-rays were scored 
according to the Chinese classification system as described above by 
Chen et al. (2001) for the tin miner study. Exposure estimates of 
cohort members to respirable crystalline silica were based on the same 
data as described by Chen et al. (2001). In addition, the investigators 
measured the extent of surface occlusion of crystalline silica 
particles by alumino-silicate from 47 dust samples taken at 13 
worksites using multiple-voltage scanning electron microscopy and 
energy dispersive X-ray spectroscopy (Harrison et al., 2005); this 
method yielded estimates of the percent of particle surface that is 
occluded.
    Compared to tin and tungsten miners, pottery workers were exposed 
to significantly higher mean total dust concentrations (8.2 mg/m\3\, 
compared to 3.9 mg/m\3\ for tin miners and 4.0 mg/m\3\ for tungsten 
miners), worked more net years in dusty occupations (mean of 24.9 years 
compared to 16.4 years for tin miners and 16.5 years for tungsten 
miners), and had higher mean cumulative dust exposures (205.6 mg/m\3\-
years compared to 62.3 mg/m\3\-years for tin miners and 64.9 mg/m\3\-
years for tungsten miners) (Chen et al., 2005). Applying the authors' 
conversion factors to estimate respirable crystalline silica from 
Chinese total dust measurements, the approximate mean cumulative 
exposures to respirable silica for pottery, tin, and tungsten workers 
are 6.4 mg/m\3\-years, 2.4 mg/m\3\-years, and 3.2 mg/m\3\-years, 
respectively. Measurement of particle surface occlusion indicated that, 
on average, 45 percent of the surface area of respirable particles 
collected from pottery factory samples was occluded, compared to 18 
percent of the particle surface area for tin mine samples and 13 
percent of particle surface area for tungsten mines.
    Based on Chen et al. (2005), OSHA estimated the cumulative 
silicosis risk associated with 45 years of exposure to 0.1 mg/m\3\ 
respirable crystalline silica (a cumulative exposure of 4.5 mg/m\3\-
years) to be 6 percent for pottery workers, 12 percent for tungsten 
miners, and 40 percent for tin miners. For a cumulative exposure of 
2.25 mg/m\3\-years (i.e., 45 years of exposure to 0.05 mg/m\3\), 
cumulative silicosis morbidity risks were estimated to be 2, 2, and 10 
percent for pottery workers, tungsten miners, and tin miners, 
respectively. When cumulative silica exposure was adjusted to reflect 
exposure to surface-active quartz particles (i.e., not occluded), the 
estimated cumulative risk among pottery workers more closely 
approximated those of the tin and tungsten miners, suggesting to the 
authors that alumino-silicate occlusion of the crystalline particles in 
pottery factories at least partially explained the lower risk seen 
among workers, despite their having been more heavily exposed.
6. Summary of Silicosis Morbidity Risk Estimates.
    Table VI-2 presents OSHA's risk estimates for silicosis morbidity 
that are derived from each of the studies described above. Estimates of 
silicosis morbidity derived from the seven cohorts in cumulative risk 
studies with post-employment follow-up range from 60 to 773 per 1,000 
workers for 45-year exposures to the current general industry PEL of 
0.10 mg/m\3\, and from 20 to 170 per 1,000 workers for a 45-year 
exposure to the proposed PEL of 0.05 mg/m\3\. The study results provide 
substantial evidence that the disease can progress for years after 
exposure ends. Results from an autopsy study (Hnizdo et al., 1993), 
which found pathological evidence of silicosis absent radiological 
signs, suggest that silicosis cases based on radiographic diagnosis 
alone tend to underestimate risk since pathological evidence of 
silicosis. Other results (Chen et al., 2005) suggest that surface 
properties among various types of silica dusts can have different 
silicosis potencies. Results from the Buchanan et al. (2003) study of 
Scottish coal miners suggest that short-term exposures to >2 mg/m\3\ 
silica can cause a disproportionately higher risk of silicosis than 
would be predicted by cumulative exposure alone, suggesting a dose-rate 
effect for exposures to concentrations above this level. OSHA believes 
that, given the consistent finding of a monotonic exposure-response 
relationship for silicosis morbidity with cumulative exposure in the 
studies reviewed, that cumulative exposure is a reasonable exposure 
metric upon which to base risk estimates in the exposure range of 
interest to OSHA (i.e., between 0.025 and 0.5 mg/m\3\ respirable 
crystalline silica).

F. Other Considerations in OSHA's Risk Analysis

    Uncertainties are inherent to any risk modeling process and 
analysis; assessing risk and associated complexities of silica exposure 
among workers is no different. However, the Agency has a high level of 
confidence that the preliminary risk assessment results reasonably 
reflect the range of risks experienced by workers exposed to silica in 
all occupational settings. First, the preliminary assessment is based 
on an analysis of a wide range of studies, conducted in multiple 
industries across a wide range of exposure distributions, which 
included cumulative exposures equivalent to 45 years of exposure to and 
below the current PEL.
    Second, risk models employed in this assessment are based on a 
cumulative exposure metric, which is the product of average daily 
silica concentration and duration of worker exposure for a specific 
job. Consequently, these models predict the same risk for a given 
cumulative exposure regardless of the pattern of exposure. For example, 
a manufacturing plant worker exposed to silica at 0.05 mg/m\3\ for 
eight hours per day will have the same cumulative exposure over a given 
period of time as a construction worker who is exposed each day to 
silica at 0.1 mg/m\3\ for one hour, at 0.075 mg/m\3\ for four hours and 
not exposed to silica for three hours. The cumulative exposure metric 
thus reflects a worker's long-term average exposure without regard to 
the pattern of exposure experienced by the worker, and is therefore 
generally applicable to all workers who are exposed to silica in the 
various industries. For example, at construction sites, conditions may 
change often since the nature of work can be intermittent and involve 
working with a variety of materials that contain different 
concentrations of quartz. Additionally, workers may perform

[[Page 56320]]

construction operations for relatively short periods of time where they 
are exposed to concentrations of silica that may be significantly 
higher than many continuous operations in general industry. However, 
these differences are taken into account by the use of the cumulative 
exposure metric that relates exposure to disease risk. OSHA believes 
that use of cumulative exposure is the most appropriate dose-metric 
because each of the studies that provide the basis for the risk 
assessment demonstrated strong exposure-response relationships between 
cumulative exposure and disease risk. This metric is especially 
important in terms of progression of silica-related disease, as 
discussed in Section VII of the preamble, Significance of Risk, in 
section B.1.a.
    OSHA's risk assessment relied upon many studies that utilized 
cumulative exposures of cohort members. Table VI-3 summarizes these 
lung cancer studies, including worker exposure quartile data across a 
number of industry sectors. The cumulative exposures exhibited in these 
studies are equivalent to the cumulative exposure that would result 
from 45 years of exposure to the current and proposed PELs (i.e., 4.5 
and 2,25 mg/m\3\, respectively). For this reason, OSHA has a high 
degree of confidence in the risk estimates associated with exposure to 
the current and proposed PELs; additionally, the risk assessment does 
not require significant low-dose extrapolation of the model beyond the 
observed range of exposures. OSHA acknowledges there is greater 
uncertainty in the risk estimates for the proposed action level of 
0.025 mg/m\3\, particularly given some evidence of a threshold for 
silicosis between the proposed PEL and action level. Given the Agency's 
findings that controlling exposures below the proposed PEL would not be 
technologically feasible for employers, OSHA believes that estimating 
risk for exposures below the proposed action level, which becomes 
increasingly more uncertain, is not necessary to further inform the 
Agency's regulatory action.
    Although the Agency believes that the results of its risk 
assessment are broadly relevant to all occupational exposure situations 
involving crystalline silica, OSHA acknowledges that differences exist 
in the relative toxicity of crystalline silica particles present in 
different work settings due to factors such as the presence of mineral 
or metal impurities on quartz particle surfaces, whether the particles 
have been freshly fractured or are aged, and size distribution of 
particles. At this time, however, OSHA preliminarily concludes that it 
is not yet possible to use available information on factors that 
mediate the potency of silica to refine available quantitative 
estimates of the lung cancer and silicosis mortality risks, and that 
the estimates from the studies and analyses relied upon are fairly 
representative of a wide range of workplaces reflecting differences in 
silica polymorphism, surface properties, and impurities.

                                   Table VI-1--Estimates of Lifetime \a\ Lung Cancer Mortality Risk Resulting from 45-Years of Exposure to Crystalline Silica
                                                                      [Deaths per 1,000 workers (95% confidence interval)]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                             Exposure level (mg/m\3\)
                  Cohort                              Model               Exposure    Model parameters (standard -------------------------------------------------------------------------------
                                                                        lag (years)             error)                 0.025           0.05            0.10            0.25            0.50
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Ten pooled cohorts (see Table II-1)......  Log-linear \b\.............           15  [beta] = 0.60 (0.015)......      22 (11-36)      26 (12-41)      29 (13-48)      34 (15-56)      38 (17-63)
                                           Linear \b\.................           15  [beta] = 0.074950                 23 (9-38)      26 (10-43)      29 (11-47)      33 (12-53)      36 (14-58)
                                                                                      (0.024121).
                                           Linear.....................           15  [beta]1 = 0.16498 (0.0653)         9 (2-16)       18 (4-31)       22 (6-38)      27 (12-43)      36 (20-51)
                                                                                      and.
                                           SplineSec.  \c\ \d\........  ...........  [beta]2 = -0.1493 (0.0657).  ..............  ..............  ..............  ..............  ..............
Range from 10 cohorts....................  ...........................           15  Various....................         0.21-13         0.41-28         0.83-69         2.1-298         4.2-687
                                           Log-linear \c\.............  ...........                               ..............  ..............  ..............  ..............  ..............
Diatomaceous earth workers...............  Linear \c\.................           10  [beta] = 0.1441 \e\........        9 (2-21)       17 (5-41)      34 (10-79)     81 (24-180)    152 (46-312)
U.S.Granite workers......................  Log-linear \c\.............           15  [beta] = 0.19 \e\..........       11 (4-18)       25 (9-42)     60 (19-111)    250 (59-502)   653 (167-760)
North American industrial sand workers...  Log-linear \c\.............           15  [beta] = 0.13 (0.074) \f\..        7 (0-16)       15 (0-37)       34 (0-93)     120 (0-425)     387 (0-750)
British coal miners......................  Log-linear \c\.............           15  [Bgr] = 0.0524 (0.0188)....         3 (1-5)        6 (2-11)       13 (4-23)       37 (9-75)     95 (20-224)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Risk to age 85 and based on 2006 background mortality rates for all males (see Appendix for life table method).
\b\ Model with log cumulative exposure (mg/m\3\-days + 1).
\c\ Model with cumulative exposure (mg/m\3\-years).
\d\ 95% confidence interval calculated as follows (where CE = cumulative exposure in mg/m\3\-years and SE is standard error of the parameter estimate):
For CE <= 2.19: 1 + [([beta]1  (1.96*SE1)) * CE].
For CE > 2.19: 1 + [([beta]1 * CE) + ([beta]2 * (CE-2.19))]  1.96 * SQRT[ (CE\2\ * SE1\2\) + ((CE-2.19)\2\* SE2\2\) + (2*CE*(CE-3.29)*-0.00429)].
\e\ Standard error not reported, upper and lower confidence limit on beta estimated from confidence interval of risk estimate reported in original article.
\f\ Standard error of the coefficient was estimated from the p-value for trend.


               Table VI-2--Summary of Lifetime or Cumulative Risk Estimates for Crystalline Silica
----------------------------------------------------------------------------------------------------------------
                                    Risk associated with 45 years of occupational exposure (per 1,000 workers)
                                 -------------------------------------------------------------------------------
    Health endpoint (source)                  Respirable crystalline silica exposure level (mg/m\3\)
                                 -------------------------------------------------------------------------------
                                       0.025           0.05            0.100           0.250           0.500
----------------------------------------------------------------------------------------------------------------
Lung Cancer Mortality (Lifetime
 Risk):
    Pooled Analysis,                        9-23           18-26           22-29           27-34           36-38
     Toxichemica, Inc (2004) \a\
     \b\........................

[[Page 56321]]

 
    Diatomaceous Earth Worker                  9              17              34              81             152
     study (Rice et al., 2001)
     \a\ \c\....................
    U.S. Granite Worker study                 11              25              60             250             653
     (Attfield and Costello,
     2004) \a\ \d\..............
    North American Industrial                  7              15              34             120             387
     Sand Worker study (Hughes
     et al., 2001) \a\ \e\......
    British Coal Miner study                   3               6              13              37              95
     (Miller and MacCalman,
     2009) \a\ \f\..............
Silicosis and Non-Malignant Lung
 Disease Mortality (Lifetime
 Risk):
    Pooled Analysis                            4               7              11              17              22
     (Toxichemica, Inc., 2004)
     (silicosis) \g\............
    Diatomaceous Earth Worker                 22              43              83             188             321
     study (Park et al., 2002)
     (NMRD) \h\.................
Renal Disease Mortality
 (Lifetime Risk):
    Pooled Cohort study                       25              32              39              52              63
     (Steenland et al., 2002a)..
Silicosis Morbidity (Cumulative
 Risk):
    Chest x-ray category of 2/1               21              55             301             994            1000
     or greater (Buchanan et
     al., 2003) \j\.............
    Silicosis mortality and/or x-             31              74             431             593             626
     ray of 1/1 or greater
     (Steenland and Brown,
     1995b) \k\.................
    Chest x-ray category of 1/1                6             127             773             995            1000
     or greater (Hnizdo and
     Sluis-Cremer, 1993) \l\....
    Chest x-ray category of 1 or              40             170             590            1000            1000
     greater (Chen et al., 2001)
     \m\........................
    Chest x-ray category of 1 or  ..............  ..............  ..............  ..............  ..............
     greater (Chen et al., 2005)
     \n\
        Tin miners..............              40             100             400             950            1000
        Tungsten miners.........               5              20             120             750            1000
        Pottery workers.........               5              20              60             300             700
----------------------------------------------------------------------------------------------------------------
From Table II-12, ``Respirable Crystalline Silica--Health Effects Literature Review and Preliminary Quantitative
  Risk Assessment'' (Docket OSHA-2010-0034).


                                                                    Table VI-3--Exposure Distribution in Lung Cancer Studies
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                        Cum(exp) (mg/m\3\-y)                 Average* exposure (mg/m\3\)        Mean respirable
                                                                                     No. of   --------------------------------------------------------------------------------    crystalline
                                                         Primary  exposure (as       deaths                                                                                     silica exposure
                  Study                        n          described  in study)      from lung             median                         25th     median     75th               over employment
                                                                                     cancer      q\1\     (q\2\)     q\3\       max     (q\1\)    (q\2\)    (q\3\)      max       period (mg/
                                                                                                                                                                                   m[caret]3)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
U.S. diatomaceous earth workers \1\            2,342  cristobalite...............          77      0.37      1.05      2.48     62.52      0.11      0.18      0.46      2.43                n/a
 (Checkoway et al., 1997).
S. African gold miners \1\ (Hnizdo and         2,260  quartz and other silicates.          77       n/a      4.23       n/a       n/a      0.15      0.19      0.22      0.31                n/a
 Sluis-cremer, 1991 & Hnizdo et al.,
 1997).
U.S. gold miners \1\ (Steenland and            3,328  silica dust................         156       0.1      0.23      0.74       6.2      0.02      0.05       0.1      0.24                n/a
 Brown, 1995a).
Australian gold miners \1\ (de Klerk and       2,297  silica dust................         135      6.52     11.37     17.31     50.22      0.25      0.43      0.65      1.55                n/a
 Musk, 1998).
U.S. granite workers (Costello and             5,414  silica dust from granite...         124      0.14      0.71      2.19        50      0.02      0.05      0.08      1.01                n/a
 Graham, 1988).
Finnish granite workers (Koskela et al.,       1,026  quartz dust................          38      0.84      4.63     15.42    100.98      0.39      0.59      1.29       3.6                n/a
 1994).

[[Page 56322]]

 
U.S. industrial sand workers \1\               4,626  silica dust................          85      0.03      0.13       5.2     8.265      0.02      0.04      0.06       0.4                n/a
 (Steenland et al., 2001b).
North American industrial sand workers            90  crystalline silica.........          95      1.11      2.73      5.20       n/a     0.069      0.15     0.025       n/a                n/a
 \1\ (Hughes et al., 2001).
Ch. Tungsten (Chen et al., 1992).........     28,442  silica dust................         174      3.49      8.56     29.79    232.26      0.15      0.32      1.28      4.98                6.1
Ch. Pottery (Chen et al., 1992)..........     13,719  silica dust................          81      3.89      6.07      9.44     63.15      0.18      0.22      0.34       2.1               11.4
Ch. Tin (Chen et al., 1992)..............      7,849  silica dust................         119      2.79      5.27      5.29     83.09      0.12      0.19      0.49      1.95                7.7
British coal workers \1\ (Miller and          17,820  quartz.....................         973       n/a       n/a       n/a       n/a       n/a       n/a       n/a       n/a                n/a
 MacCalman, 2009).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Study adjusted for effects smoking.
* Average exposure is cumulative exposure averaged over the entire exposure period.
n/a Data not available.

VII. Significance of Risk

A. Legal Requirements

    To promulgate a standard that regulates workplace exposure to toxic 
materials or harmful physical agents, OSHA must first determine that 
the standard reduces a ``significant risk'' of ``material impairment.'' 
The first part of this requirement, ``significant risk,'' refers to the 
likelihood of harm, whereas the second part, ``material impairment,'' 
refers to the severity of the consequences of exposure.
    The Agency's burden to establish significant risk derives from the 
OSH Act, 29 U.S.C. 651 et seq. Section 3(8) of the Act requires that 
workplace safety and health standards be ``reasonably necessary and 
appropriate to provide safe or healthful employment.'' 29 U.S.C. 
652(8). The Supreme Court, in the ``benzene'' decision, stated that 
section 3(8) ``implies that, before promulgating any standard, the 
Secretary must make a finding that the workplaces in question are not 
safe.'' Indus. Union Dep't, AFL-CIO v. Am. Petroleum Inst., 448 U.S. 
607, 642 (1980). Examining section 3(8) more closely, the Court 
described OSHA's obligation to demonstrate significant risk:

``[S]afe'' is not the equivalent of ``risk-free.'' A workplace can 
hardly be considered ``unsafe'' unless it threatens the workers with 
a significant risk of harm. Therefore, before the Secretary can 
promulgate any permanent health or safety standard, he must make a 
threshold finding that the place of employment is unsafe in the 
sense that significant risks are present and can be eliminated or 
lessened by a change in practices.

    Id. While clarifying OSHA's responsibilities, the Court emphasized 
the Agency's discretion in determining what constitutes significant 
risk, stating, ``[the Agency's] determination that a particular level 
of risk is `significant' will be based largely on policy 
considerations.'' Benzene, 448 U.S. at 655, n. 62. The Court explained 
that significant risk is not a ``mathematical straitjacket,'' and 
maintained that OSHA could meet its burden without ``wait[ing] for 
deaths to occur before taking any action.'' Benzene, 448 U.S. at 655.
    Because section 6(b)(5) of the Act requires that the Agency base 
its findings on the ``best available evidence,'' a reviewing court must 
``give OSHA some leeway where its findings must be made on the 
frontiers of scientific knowledge.'' Benzene, 448 U.S. at 656. Thus, 
while OSHA's significant risk determination must be supported by 
substantial evidence, the Agency ``is not required to support the 
finding that a significant risk exists with anything approaching 
scientific certainty.'' Id. Furthermore, ``the Agency is free to use 
conservative assumptions in interpreting the data with respect to 
carcinogens, risking error on the side of over protection rather than 
under protection,'' so long as such assumptions are based in ``a body 
of reputable scientific thought.'' Id.
    The Act also requires that the Agency make a finding that the toxic 
material or harmful physical agent at issue causes material impairment 
to workers' health. Section 6(b)(5) of the Act directs the Secretary of 
Labor to ``set the standard which most adequately assures, to the 
extent feasible, on the basis of the best available evidence, that no 
employee will suffer material impairment of health or functional 
capacity even if such employee has regular exposure to the hazard . . . 
for the period of his working life.'' 29 U.S.C. 655(b)(5). As with 
significant risk, what constitutes material impairment in any given 
case is a policy determination for which OSHA is given substantial 
leeway. ``OSHA is not required to state with scientific certainty or 
precision the exact point at which each type of [harm] becomes a 
material impairment.'' AFL-CIO v. OSHA, 965 F.2d 962, 975 (11th Cir. 
1992). Courts have also noted that OSHA should consider all forms and 
degrees of material impairment--not just death or serious physical 
harm--and that OSHA may act with a ``pronounced bias towards worker 
safety.'' Id; Bldg & Constr. Trades Dep't v. Brock, 838 F.2d 1258, 1266 
(D.C. Cir. 1988).
    It is the Agency's practice to estimate risk to workers by using 
quantitative

[[Page 56323]]

risk assessment and determining the significance of that risk based on 
judicial guidance, the language of the OSH Act, and Agency policy 
considerations. Thus, using the best available evidence, OSHA 
identifies material health impairments associated with potentially 
hazardous occupational exposures, and, when possible, provides a 
quantitative assessment of exposed workers' risk of these impairments. 
The Agency then evaluates whether these risks are severe enough to 
warrant regulatory action and determines whether a new or revised rule 
will substantially reduce these risks.
    In this case, OSHA has reviewed extensive toxicological, 
epidemiological, and experimental research pertaining to adverse health 
effects of occupational exposure to respirable crystalline silica, 
including silicosis, other non-malignant respiratory disease, lung 
cancer, and autoimmune and renal diseases. As a result of this review, 
the Agency has developed preliminary quantitative estimates of the 
excess risk of mortality and morbidity that is attributable to 
currently allowable respirable crystalline silica exposure 
concentrations. The Agency is proposing a new PEL of 0.05 mg/m\3\ 
because exposures at and above this level present a significant risk to 
workers' health. Even though OSHA's preliminary risk assessment 
indicates that a significant risk exists at the proposed action level 
of 0.025 mg/m\3\, the Agency is not proposing a PEL below the proposed 
0.05 mg/m\3\ limit because OSHA must also consider technological and 
economic feasibility in determining exposure limits. As explained in 
the Summary and Explanation for paragraph (c), Permissible Exposure 
Limit (PEL), OSHA has preliminary determined that the proposed PEL of 
0.05 mg/m\3\ is technologically and economically feasible, but that a 
lower PEL of 0.025 mg/m\3\ is not technologically feasible. OSHA has 
preliminarily determined that long-term exposure at the current PEL 
presents a significant risk of material harm to workers' health, and 
that adoption of the proposed PEL will substantially reduce this risk 
to the extent feasible.
    As discussed in Section V of this preamble (Health Effects 
Summary), inhalation exposure to respirable crystalline silica 
increases the risk of a variety of adverse health effects, including 
silicosis, chronic obstructive pulmonary disease (COPD), lung cancer, 
immunological effects, kidney disease, and infectious tuberculosis 
(TB). OSHA considers each of these conditions to be a material 
impairment of health. These diseases result in significant discomfort, 
permanent functional limitations including permanent disability or 
reduced ability to work, reduced quality of life, and decreased life 
expectancy. When these diseases coexist, as is common, the effects are 
particularly debilitating (Rice and Stayner, 1995; Rosenman et al., 
1999). Based on these findings and on the scientific evidence that 
respirable crystalline silica substantially increases the risk of each 
of these conditions, OSHA preliminarily concludes that workers who are 
exposed to respirable crystalline silica at the current PEL are at 
significant risk of material impairment of health or functional 
capacity.

B. OSHA's Preliminary Findings

1. Material Impairments of Health
    Section I of OSHA's Health Effects Literature Review and 
Preliminary Quantitative Risk Assessment (available in Docket OSHA-
2010-0034) describes in detail the adverse health conditions that 
workers who are exposed to respirable crystalline silica are at risk of 
developing. The Agency's findings are summarized in Section V of this 
preamble (Health Effects Summary). The adverse health effects discussed 
include lung cancer, silicosis, other non-malignant respiratory disease 
(NMRD), and immunological and renal effects.
a. Silicosis
    Silicosis refers to a spectrum of lung diseases attributable to the 
inhalation of respirable crystalline silica. As described in Section V 
(Health Effects Summary), the three types of silicosis are acute, 
accelerated, and chronic. Acute silicosis can occur within a few weeks 
to months after inhalation exposure to extremely high levels of 
respirable crystalline silica. Death from acute silicosis can occur 
within months to a few years of disease onset, with the exposed person 
drowning in their own lung fluid (NIOSH, 1996). Accelerated silicosis 
results from exposure to high levels of airborne respirable crystalline 
silica, and disease usually occurs within 5 to 10 years of initial 
exposure (NIOSH, 1996). Both acute and accelerated silicosis are 
associated with exposures that are substantially above the current 
general industry PEL, although precise information on the relationships 
between exposure and occurrence of disease are not available.
    Chronic silicosis is the most common form of silicosis seen today, 
and is a progressive and irreversible condition characterized as a 
diffuse nodular pulmonary fibrosis (NIOSH, 1996). Chronic silicosis 
generally occurs after 10 years or more of inhalation exposure to 
respirable crystalline silica at levels below those associated with 
acute and accelerated silicosis. Affected workers may have a dry 
chronic cough, sputum production, shortness of breath, and reduced 
pulmonary function. These symptoms result from airway restriction 
caused by the development of fibrotic scarring in the alveolar sacs and 
the ends of the lung tissue. The scarring can be detected in chest x-
ray films when the lesions become large enough to appear as visible 
opacities. The result is restriction of lung volumes and decreased 
pulmonary compliance with concomitant reduced gas transfer (Balaan and 
Banks, 1992). Chronic silicosis is characterized by small, rounded 
opacities that are symmetrically distributed in the upper lung zones on 
chest radiograph.
    The diagnosis of silicosis is based on a history of exposure to 
respirable crystalline silica, chest radiograph findings, and the 
exclusion of other conditions, including tuberculosis (TB). Because 
workers affected by early stages of chronic silicosis are often 
asymptomatic, the finding of opacities in the lung is key to detecting 
silicosis and characterizing its severity. The International Labour 
Organization (ILO) International Classification of Radiographs of 
Pneumoconioses (ILO, 1980, 2002, 2011) is the currently accepted 
standard against which chest radiographs are evaluated in epidemiologic 
studies, for medical surveillance, and for clinical evaluation. The ILO 
system standardizes the description of chest x-rays, and is based on a 
12-step scale of severity and extent of silicosis as evidenced by the 
size, shape, and density of opacities seen on the x-ray film. Profusion 
(frequency) of small opacities is classified on a 4-point major 
category scale (0-3), with each major category divided into three, 
giving a 12-point scale between 0/- and 3/+. Large opacities are 
defined as any opacity greater than 1 cm that is present in a film.
    The small rounded opacities seen in early stage chronic silicosis 
(i.e., ILO major category 1 profusion) may progress (through ILO major 
categories 2 and/or 3) and develop into large fibrotic masses that 
destroy the lung architecture, resulting in progressive massive 
fibrosis (PMF). This stage of advanced silicosis is usually 
characterized by impaired pulmonary function, disability, and premature 
death. In cases involving PMF, death is commonly attributable to 
progressive respiratory insufficiency (Balaan and Banks, 1992).

[[Page 56324]]

    The appearance of ILO category 2 or 3 background profusion of small 
opacities has been shown to increase the risk of developing large 
opacities characteristic of PMF. In one study of silicosis patients in 
Hong Kong, Ng and Chan (1991) found the risk of PMF increased by 42 and 
64 percent among patients whose chest x-ray films were classified as 
ILO major category 2 or 3, respectively. Research has shown that people 
with silicosis advanced beyond ILO major category 1 have reduced median 
survival times compared to the general population (Infante-Rivard et 
al., 1991; Ng et al., 1992a; Westerholm, 1980).
    Silicosis is the oldest known occupational lung disease and is 
still today the cause of significant premature mortality. In 2005, 
there were 161 deaths in the U.S. where silicosis was recorded as an 
underlying or contributing cause of death on a death certificate 
(NIOSH, 2008c). Between 1996 and 2005, deaths attributed to silicosis 
resulted in an average of 11.6 years of life lost by affected workers 
(NIOSH, 2007). In addition, exposure to respirable crystalline silica 
remains an important cause of morbidity and hospitalizations. State-
based hospital discharge data show that in the year 2000, 1,128 
silicosis-related hospitalizations occurred, indicating that silicosis 
continues to be a significant health issue in the U.S. (CSTE, 2005). 
Although there is no national silicosis disease surveillance system in 
the U.S., a published analysis of state-based surveillance data from 
the time period 1987-1996 estimated that between 3,600-7,000 new cases 
of silicosis occurred in the U.S. each year (Rosenman et al., 2003). It 
has been widely reported that available statistics on silicosis-related 
mortality and morbidity are likely to be understated due to 
misclassification of causes of death (for example, as tuberculosis, 
chronic bronchitis, emphysema, or cor pulmonale), errors in recording 
occupation on death certificates, or misdiagnosis of disease by health 
care providers (Goodwin, 2003; Windau et al., 1991; Rosenman et al., 
2003). Furthermore, reliance on chest x-ray findings may miss cases of 
silicosis because fibrotic changes in the lung may not be visible on 
chest radiograph; thus, silicosis may be present absent x-ray signs or 
may be more severe than indicated by x-ray (Hnizdo et al., 1993; 
Craighead and Vallyathan, 1980; Rosenman et al., 1997).
    Although most workers with early-stage silicosis (ILO categories 0/
1 or 1/0) typically do not experience respiratory symptoms, the primary 
risk to the affected worker is progression of disease with progressive 
decline of lung function. Several studies of workers exposed to 
crystalline silica have shown that, once silicosis is detected by x-
ray, a substantial proportion of affected workers can progress beyond 
ILO category 1 silicosis, even after exposure has ceased (for example, 
Hughes et al., 1982; Hessel et al., 1988; Miller et al., 1998; Ng et 
al., 1987a; Yang et al., 2006). In a population of coal miners whose 
last chest x-ray while employed was classified as major category 0, and 
who were examined again 10 years after the mine had closed, 20 percent 
had developed opacities consistent with a classification of at least 1/
0, and 4 percent progressed further to at least 2/1 (Miller et al., 
1998). Although there were periods of extremely high exposure to 
respirable quartz in the mine (greater than 2 mg/m\3\ in some jobs 
between 1972 and 1976, and more than 10 percent of exposures between 
1969 and 1977 were greater than 1 mg/m\3\), the mean cumulative 
exposure for the cohort over the period 1964-1978 was 1.8 mg/m\3\-
years, corresponding to an average silica concentration of 0.12 mg/
m\3\. In a population of granite quarry workers exposed to an average 
respirable silica concentration of 0.48 mg/m\3\ (mean length of 
employment was 23.4 years), 45 percent of those diagnosed with simple 
silicosis showed radiological progression of disease after 2 to 10 
years of follow up (Ng et al., 1987a). Among a population of gold 
miners, 92 percent progressed in 14 years; exposures of high-, medium-, 
and low-exposure groups were 0.97, 0.45, and 0.24 mg/m\3\, respectively 
(Hessel et al., 1988). Chinese mine and factory workers categorized 
under the Chinese system of x-ray classification as ``suspected'' 
silicosis cases (analogous to ILO 0/1) had a progression rate to stage 
I (analogous to ILO major category 1) of 48.7 percent and the average 
interval was about 5.1 years (Yang et al., 2006). These and other 
studies discussed in the Health Effects section are of populations of 
workers exposed to average concentrations of respirable crystalline 
silica above those permitted by OSHA's current general industry PEL. 
The studies, however, are of interest to OSHA because the Agency's 
current enforcement data indicate that exposures in this range are 
still common in some industry sectors. Furthermore, the Agency's 
preliminary risk assessment is based on use of an exposure metric that 
is less influenced by exposure pattern and, instead, characterizes the 
accumulated exposure of workers over time. Further, the use of a 
cumulative exposure metric reflects the progression of silica-related 
diseases: While it is not known that silicosis is a precursor to lung 
cancer, continued exposure to respirable crystalline silica among 
workers with silicosis has been shown to be associated with malignant 
respiratory disease (Chen et al., 1992). The Chinese pottery workers 
study offers an example of silicosis-associated lung cancer among 
workers in the clay industry, reflecting the variety of health outcomes 
associated with diverse silica exposures across industrial settings.
    The risk of silicosis, and particularly its progression, carries 
with it an increased risk of reduced lung function. There is strong 
evidence in the literature for the finding that lung function 
deteriorates more rapidly in workers exposed to silica, especially 
those with silicosis, than what is expected from a normal aging process 
(Cowie 1998; Hughes et al., 1982; Malmberg et al., 1993; Ng and Chan, 
1992). The rates of decline in lung function are greater in those whose 
disease showed evidence of radiologic progression (B[eacute]gin et al., 
1987a; Cowie 1998; Ng and Chan, 1992; Ng et al., 1987a). Additionally, 
the average deterioration of lung function exceeds that in smokers 
(Hughes et al., 1982).
    Several studies have reported no decrease in pulmonary function 
with an ILO category 1 level of profusion of small opacities but found 
declines in pulmonary function with categories 2 and 3 (Ng et al., 
1987a; Begin et al., 1988; Moore et al., 1988). A study by Cowie 
(1998), however, found a statistically significantly greater annual 
loss in FVC and FEV1 among those with category 1 profusion 
compared to category 0. In another study, Cowie and Mabena (1991) found 
that the degree of profusion of opacities was associated with 
reductions in several pulmonary function metrics. Still, other studies 
have reported no associations between radiographic silicosis and 
decreases in pulmonary function (Ng et al., 1987a; Wiles et al., 1992; 
Hnizdo, 1992), with some studies (Ng et al., 1987a; Wang et al., 1997) 
finding that measurable changes in pulmonary function are evident well 
before the changes seen on chest x-ray. This may reflect the general 
insensitivity of chest radiography in detecting lung fibrosis, and/or 
may reflect that exposure to respirable silica has also been shown to 
increase the risk of chronic obstructive pulmonary disease (COPD) (see 
Section V, Health Effects Summary).
    Finally, silicosis, and exposure to respirable crystalline silica 
in and of itself, increases the risk that latent

[[Page 56325]]

tuberculosis infection can convert to active disease. Early 
descriptions of dust diseases of the lung did not distinguish between 
TB and silicosis, and most fatal cases described in the first half of 
this century were a combination of silicosis and TB (Castranova et al., 
1996). More recent findings demonstrate that exposure to silica, even 
without silicosis, increases the risk of infectious (i.e., active) 
pulmonary TB (Sherson et al., 1990; Cowie, 1994; Hnizdo and Murray, 
1998; WaterNaude et al., 2006). Both conditions together can hasten the 
development of respiratory impairment and increase mortality risk even 
beyond that experienced by unexposed persons with active TB (Banks, 
2005).
    Based on the information presented above and in its review of the 
health literature, OSHA preliminarily concludes that silicosis remains 
a significant cause of early mortality and of serious morbidity, 
despite the existence of an enforceable exposure limit over the past 40 
years. Silicosis in its later stages of progression (i.e., with chest 
x-ray findings of ILO category 2 or 3 profusion of small opacities, or 
the presence of large opacities) is characterized by the likely 
appearance of respiratory symptoms and decreased pulmonary function, as 
well as increased risk of progression to PMF, disability, and early 
mortality. Early-stage silicosis, although without symptoms among many 
who are affected, nevertheless reflects the formation of fibrotic 
lesions in the lung and increases the risk of progression to later 
stages, even after exposure to respirable crystalline silica ceases. In 
addition, the presence of silicosis increases the risk of pulmonary 
infections, including conversion of latent TB infection to active TB. 
Silicosis is not a reversible condition and there is no specific 
treatment for the disease, other than administration of drugs to 
alleviate inflammation and maintain open airways, or administration of 
oxygen therapy in severe cases. Based on these considerations, OSHA 
preliminarily finds that silicosis of any form, and at any stage, is a 
material impairment of health and that fibrotic scarring of the lungs 
represents loss of functional respiratory capacity.
b. Lung Cancer
    OSHA considers lung cancer, an irreversible and usually fatal 
disease, to be a clear material impairment of health. According to the 
National Cancer Institute (Horner et al., 2009), the five-year survival 
rate for all forms of lung cancer is only 15.6 percent, a rate that has 
not improved in nearly two decades. OSHA's preliminary finding that 
respirable crystalline silica exposure substantially increases the risk 
of lung cancer mortality is based on the best available toxicological 
and epidemiological data, reflects substantial supportive evidence from 
animal and mechanistic research, and is consistent with the conclusions 
of other government and public health organizations, including the 
International Agency for Research on Cancer (IARC, 1997), the National 
Toxicology Program (NTP, 2000), the National Institute for Occupational 
Safety and Health (NIOSH, 2002), the American Thoracic Society (1997), 
and the American Conference of Governmental Industrial Hygienists 
(ACGIH, 2001). The Agency's primary evidence comes from evaluation of 
more than 50 studies of occupational cohorts from many different 
industry sectors in which exposure to respirable crystalline silica 
occurs, including granite and stone quarrying; the refractory brick 
industry; gold, tin, and tungsten mining; the diatomaceous earth 
industry; the industrial sand industry; and construction. Studies key 
to OSHA's risk assessment are outlined in Table VII-1, which summarizes 
exposure characterization and related lung cancer risk across several 
different industries. In addition, the association between exposure to 
respirable crystalline silica and lung cancer risk was reported in a 
national mortality surveillance study (Calvert et al., 2003) and in two 
community-based studies (Pukkala et al., 2005; Cassidy et al., 2007), 
as well as in a pooled analysis of 10 occupational cohort studies 
(Steenland et al., 2001a).

                                                    Table VII-1-- Summary of Key Lung Cancer Studies
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                  Type of study and
   Industry sector/population      description of          Exposure       No. of lung cancer   Risk ratios (95%       Additional            Source
                                     population        characterization      deaths/cases             CI)             information
--------------------------------------------------------------------------------------------------------------------------------------------------------
U.S. Diatomaceous earth workers  Cohort study. Same  Assessment based on  77................  SMR 129 (CI 101-    Smoking history     Checkoway et al.,
                                  as Checkoway et     almost 6,400                             161) based on       available for       1997.
                                  al., 1993,          samples taken from                       national rates,     half cohort.
                                  excluding 317       1948-1988; about                         and SMR 144 (CI     Under worst-case
                                  workers whose       57 percent of                            114-180) based on   assumptions, the
                                  exposures could     samples                                  local rates. Risk   risk ratio for
                                  not be              represented                              ratios by           the high-exposure
                                  characterized,      particle counts,                         exposure quintile   group would be
                                  and including 89    17 percent were                          were 1.00, 0.96,    reduced to 1.67
                                  workers with        personal                                 0.77, 1.26, and     after accounting
                                  asbestos exposure   respirable dust                          2.15, with the      for smoking.
                                  who were            samples. JEM                             latter being
                                  previously          included 135 jobs                        stat. sig. RR=
                                  excluded from the   over 4 time                              2.15 and 1.67.
                                  1993 study.         periods (Seixas et
                                  Follow up through   al., 1997).
                                  1994.
South African gold miners......  Cohort study.       Particle count data  77................  RR 1.023 (CI 1.005- Model adjusted for  Hnizdo and Sluis-
                                  N=2,209 white       from Beadle (1971).                      1.042) per 1,000    smoking and year    Cremer, 1991.
                                  male miners                                                  particle-years of   of birth. Lung
                                  employed between                                             exposure based on   cancer was
                                  1936 and 1943.                                               Cox proportional    associated with
                                  Followed from                                                hazards model.      silicosis of the
                                  1968-1986.                                                                       hilar glands not
                                                                                                                   silicosis of lung
                                                                                                                   or pleura.
                                                                                                                   Possible
                                                                                                                   confounding by
                                                                                                                   radon exposure
                                                                                                                   among miners with
                                                                                                                   20 or more years
                                                                                                                   experience.

[[Page 56326]]

 
South African gold miners......  Nested case-        Particle count data  78................  RR 2.45 (CI 1.2-    Lung cancer         Hnizdo et al.,
                                  control study       converted to                             5.2) when           mortality           1997.
                                  from population     respirable dust                          silicosis was       associated with
                                  study by Hnizdo     mass (Beadle and                         included in model.  smoking,
                                  and Sluis-          Bradley, 1970, and                                           cumulative dust
                                  Cremer,1991. N=78   Page-Shipp and                                               exposure, and
                                  cases, 386          Harris, 1972).                                               duration of
                                  controls.                                                                        underground work.
                                                                                                                   Latter two
                                                                                                                   factors were most
                                                                                                                   significantly
                                                                                                                   associated with
                                                                                                                   lung cancer with
                                                                                                                   exposure lagged
                                                                                                                   20 years.
US gold miners.................  Cohort and nested   Particle count       115...............  SMR 113 (CI 94-     Smoking data        Steenland and
                                  case-control        data, conversion                         136) overall.       available for       Brown, 1995a,
                                  study, same         to mass                                  SMRs increased      part of cohort,     1995b
                                  population as       concentration                            for workers with    habits comparable
                                  Brown et al.        based on Vt.                             30 or more years    to general US
                                  (1986); workers     Granite study,                           of latency, and     population;
                                  with at least 1     construction of                          when local cancer   attributable
                                  year underground    JEM. Median quartz                       rates used as       smoking-related
                                  work between 1940   exposures were                           referents. Case-    cancer risk
                                  and 1965. Follow    0.15, 0.07, and                          control study       estimated to be
                                  up through 1990.    0.02 mg/m\3\ prior                       showed no           1.07.
                                                      to 1930, from 1930-                      relationship of
                                                      1950, and after                          risk to
                                                      1950 respectively.                       cumulative
                                                                                               exposure to dust.
Australian gold miners.........  Cohort and nested   Expert ranking of    Nested case         SMR 126 (CI 107-    Association         de Klerk and Musk,
                                  case-control        dustiness by job.    control of 138      159) lower bound;   between exposure    1998
                                  study. N=2,297,                          lung cancer         SMR 149 (CI 126-    and lung cancer
                                  follow up of                             deaths.             176) upper bound.   mortality not
                                  Armstrong et al.                                             From case-          stat. sig. after
                                  (1979). Follow up                                            control, RR 1.31    adjusting for
                                  through 1993.                                                (CI 1.10-1.7) per   smoking,
                                                                                               unit exposure       bronchitis, and
                                                                                               score.              silicosis.
                                                                                                                   Authors concluded
                                                                                                                   lung cancer
                                                                                                                   restricted to
                                                                                                                   miners who
                                                                                                                   received
                                                                                                                   compensation for
                                                                                                                   silicosis..
U.S. (Vermont) granite shed and  Cohort study.       Exposure data not    53 deaths among     SMR 129 for pre-    Dust controls       Costello and
 quarry workers -.                N=5,414 employed    used in analysis.    those hired         1930 hires (not     employed between    Graham, 1988.
                                  at least 1 year                          before 1930; 43     stat. sig.); SMR    1938 and 1940
                                  between 1950 and                         deaths among        95 for post-1940    with continuing
                                  1982.                                    those hired after   hires (not stat.    improvement
                                                                           1940.               sig). SMR 181       afterwards.
                                                                                               (stat. sig) for
                                                                                               shed workers
                                                                                               hired before 1930
                                                                                               and with long
                                                                                               tenure and
                                                                                               latency.
Finnish granite workers........  Cohort and nested   Personal sampling    31 through 1989...  Through 1989, SMR   Smoking habits      Koskela et al.,
                                  case-control        data collected                           140 (CI 98-193).    similar to other    1987, 1990, 1994.
                                  studies. N=1,026,   from 1970-1972                           For workers in      Finnish
                                  follow up from      included total and                       two regions where   occupational
                                  1972-1981,          respirable dust                          silica content of   groups. Minimal
                                  extended to 1985    and respirable                           rock was highest,   work-related
                                  (Koskella et al.,   silica sampling.                         SMRs were 126 (CI   exposures to
                                  1990) and 1989      Average silica                           71-208) and 211     other carcinogens.
                                  (Koskella et al.,   concentrations                           (CI 120-342),
                                  1994).              ranged form 0.3-                         respectively.
                                                      4.9 mg/m\3\.
North American industrial sand   Case-control study  Assessment based on  95 cases, two       OR 1.00, 0.84,      Adjusted for        Hughes et al.,
 workers.                         from McDonald et    14,249 respirable    controls per case.  2.02 and 2.07 for   smoking. Positive   2001.
                                  al. (2001) cohort.  dust and silica                          increasing          association
                                                      samples taken from                       quartiles of        between silica
                                                      1974 to 1998.                            exposure p for      exposure and lung
                                                      Exposures prior to                       trend=0.04).        cancer. Median
                                                      this based on                                                exposure for
                                                      particle count                                               cases and
                                                      data. Adjustments                                            controls were
                                                      made for                                                     0.148 and 0.110
                                                      respirator use                                               mg/m\3\
                                                      (Rando et al.,                                               respirable
                                                      2001).                                                       silica,
                                                                                                                   respectively.

[[Page 56327]]

 
U.S. industrial sand workers...  Cohort and nested   Exposure assessment  109 deaths overall  SMR 160 (CI 131-    Smoking data from   Steenland and
                                  case-control        based on 4,269                           193) overall.       358 workers         Sanderson, 2001.
                                  study. N=4,626      compliance dust                          Positive trends     suggested that
                                  workers. Follow     samples taken from                       seen with           smoking could not
                                  up from 1960-1996.  1974-1996 and                            cumulative silica   explain the
                                                      analyzed for                             exposure (p=0.04    observed increase
                                                      respirable quartz.                       for unlagged,       in lung cancer
                                                      Exposures prior to                       p=0.08 for          mortality rates.
                                                      1974 based on                            lagged).
                                                      particle count
                                                      data and quartz
                                                      analysis of
                                                      settled dust and
                                                      dust collected by
                                                      high-volume air
                                                      samplers, and use
                                                      of a conversion
                                                      factor (1
                                                      mppcf=0.1 mg/m\3\).
Chinese Tin, Tungsten, and       Cohort study.       Measurements for     ..................  SMRs 198 for tin    Non-statistically   Chen et al., 1992.
 Copper miners.                   N=54,522 workers    total dust, quartz                       workers (no CI      significantly
                                  employed 1 yr. or   content, and                             reported but        increased risk
                                  more between 1972   particle size                            stat. sig.). No     ratio for lung
                                  and 1974. Follow    taken from 1950's-                       stat. sig.          cancer among
                                  up through 1989.    1980's. Exposures                        increased SMR for   silicotics. No
                                                      categorized as                           tungsten or         increased
                                                      high, medium, low,                       copper miners.      gradient in risk
                                                      or non-exposed.                                              observed with
                                                                                                                   exposure.
Chinese Pottery workers........  Cohort study.       Measurements of job- ..................  SMR 58 (p<0.05)     No reported         Chen et al., 1992.
                                  N=13,719 workers    specific total                           overall. RR 1.63    increase in lung
                                  employed in 1972-   dust and quartz                          (CI 0.8-3.4)        cancer with
                                  1974. Follow up     content of settled                       among silicotics    increasing
                                  through 1989.       dust used to                             compared to non-    exposure.
                                                      classify workers                         silicotics.
                                                      into one of four
                                                      total dust
                                                      exposure groups.
British Coal workers...........  Cohort study.       Quartz exposure      973...............  Significant         Adjusted for        Miller et al,
                                  N=17,820 miners     assessed from                            relationship        smoking.            2007; Miller and
                                  from 10             personal                                 between                                 MacCalman, 2009
                                  collieries..        respirable dust                          cumulative silica
                                                      samples.                                 exposure (lagged
                                                                                               15 years) and
                                                                                               lung cancer
                                                                                               mortality VIA Cox
                                                                                               regression.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Toxicity studies provide additional evidence of the carcinogenic 
potential of crystalline silica (Health Effects Summary, Section V). 
Acellular studies using DNA exposed directly to freshly fractured 
crystalline silica demonstrate the direct effect silica has on DNA 
breakage. Cell culture research has investigated the processes by which 
crystalline silica disrupts normal gene expression and replication 
(Section V). Studies demonstrate that chronic inflammatory and fibrotic 
processes resulting in oxidative and cellular damage set up another 
possible mechanism that leads to neoplastic changes in the lung 
(Goldsmith, 1997; see also Health Effects discussion in Section V). In 
addition, the biologically damaging physical characteristics of 
crystalline silica, and the direct and indirect genotoxicity of 
crystalline silica (Schins, 2002; Borm and Driscoll, 1996), support the 
Agency's preliminary position that respirable crystalline silica should 
be considered as an occupational carcinogen that causes lung cancer, a 
clear material impairment of health.
c. Non-Malignant Respiratory Disease (Other Than Silicosis)
    Exposure to respirable crystalline silica increases the risk of 
developing chronic obstructive pulmonary disease (COPD), in particular 
chronic bronchitis and emphysema. COPD results in loss of pulmonary 
function that restricts normal activity in individuals afflicted with 
these conditions (ATS, 2003). Both chronic bronchitis and emphysema can 
occur in conjunction with development of silicosis. Several studies 
have documented increased prevalence of chronic bronchitis and 
emphysema among silica-exposed workers even absent evidence of 
silicosis (see Section I of the Health Effects Literature Review and 
Preliminary Quantitative Risk Assessment; NIOSH, 2002; ATS, 1997). 
There is evidence that smoking may have an additive or synergistic 
effect on silica-related COPD morbidity or mortality (Hnizdo, 1990; 
Hnizdo et al., 1990; Wyndham et al., 1986; NIOSH, 2002). In a study of 
diatomaceous earth workers, Park et al. (2002) found a positive 
exposure-response relationship between exposure to respirable 
cristobalite and increased mortality from non-malignant respiratory 
disease.
    Decrements in pulmonary function have often been found among 
workers exposed to respirable crystalline silica absent radiologic 
evidence of silicosis. Several cross-sectional studies have reported 
such findings among granite workers (Theriault, 1974a, 1974b; Ng et 
al., 1992b; Montes et al., 2004b), South African gold miners (Irwig and 
Rocks, 1978; Hnizdo et al., 1990; Cowie and Mabena, 1991), gemstone 
cutters (Ng et al., 1987b), concrete workers (Meijer et al., 2001), 
refractory brick workers (Wang et al., 1997), hard rock miners 
(Manfreda et al., 1982; Kreiss et al., 1989), pottery workers (Neukirch 
et al., 1994), slate workers (Suhr et al., 2003), and potato sorters 
(Jorna et al., 1994).
    OSHA also evaluated several longitudinal studies where exposed 
workers were examined over a period of time to track changes in 
pulmonary function. Among both active and retired Vermont granite 
workers exposed to an average of 60 [mu]g/m\3\, Graham did not find 
exposure-related decrements in pulmonary function (Graham et al., 1981, 
1994). However, Eisen et al.

[[Page 56328]]

(1995) did find significant pulmonary decrements among a subset of 
granite workers (termed ``dropouts'') who left work and consequently 
did not voluntarily participate in the last of a series of annual 
pulmonary function tests. This group of workers experienced steeper 
declines in FEV1 compared to the subset of workers who 
remained at work and participated in all tests (termed ``survivors''), 
and these declines were significantly related to dust exposure. Thus, 
in this study, workers who had left work had exposure-related declines 
in pulmonary function to a greater extent than did workers who remained 
on the job, clearly demonstrating a survivor effect among the active 
workers. Exposure-related changes in lung function were also reported 
in a 12-year study of granite workers (Malmberg et al., 1993), in two 
5-year studies of South African miners (Hnizdo, 1992; Cowie, 1998), and 
in a study of foundry workers whose lung function was assessed between 
1978 and 1992 (Hertzberg et al., 2002).
    Each of these studies reported their findings in terms of rates of 
decline in any of several pulmonary function measures, such as FVC, 
FEV1, and FEV1/FVC. To put these declines in 
perspective, Eisen et al. (1995), reported that the rate of decline in 
FEV1 seen among the dropout subgroup of Vermont granite 
workers was 4 ml per mg/m\3\-year of exposure to respirable granite 
dust; by comparison, FEV1 declines at a rate of 10 ml/year 
from smoking one pack of cigarettes daily. From their study of foundry 
workers, Hertzberg et al., (2002) reported finding a 1.1 ml/year 
decline in FEV1 and a 1.6 ml/year decline in FVC for each 
mg/m\3\-year of respirable silica exposure after controlling for 
ethnicity and smoking. From these rates of decline, they estimated that 
exposure to the current OSHA quartz standard of 0.1 mg/m\3\ for 40 
years would result in a total loss of FEV1 and FVC that is 
less than but still comparable to smoking a pack of cigarettes daily 
for 40 years. Hertzberg et al. (2002) also estimated that exposure to 
the current standard for 40 years would increase the risk of developing 
abnormal FEV1 or FVC by factors of 1.68 and 1.42, 
respectively. OSHA believes that this magnitude of reduced pulmonary 
function, as well as the increased morbidity and mortality from non-
malignant respiratory disease that has been documented in the studies 
summarized above, constitute material impairments of health and loss of 
functional respiratory capacity.
d. Renal and Autoimmune Effects
    OSHA's review of the literature summarized in Section V, Health 
Effects Summary, reflects substantial evidence that exposure to 
crystalline silica increases the risk of renal and autoimmune diseases. 
Epidemiologic studies have found statistically significant associations 
between occupational exposure to silica dust and chronic renal disease 
(e.g., Calvert et al., 1997), subclinical renal changes including 
proteinurea and elevated serum creatinine (e.g., Ng et al., 1992c; 
Rosenman et al., 2000; Hotz et al., 1995), end-stage renal disease 
morbidity (e.g., Steenland et al., 1990), chronic renal disease 
mortality (Steenland et al., 2001b, 2002a), and Wegener's 
granulomatosis (Nuyts et al., 1995), the latter of which represents 
severe injury to the glomeruli that, if untreated, rapidly leads to 
renal failure. Possible mechanisms suggested for silica-induced renal 
disease include a direct toxic effect on the kidney, deposition in the 
kidney of immune complexes (IgA) following silica-related pulmonary 
inflammation, or an autoimmune mechanism (Calvert et al., 1997; 
Gregorini et al., 1993). Steenland et al. (2002a) demonstrated a 
positive exposure-response relationship between exposure to respirable 
crystalline silica and end-stage renal disease mortality.
    In addition, there are a number of studies that show exposure to be 
related to increased risks of autoimmune disease, including scleroderma 
(e.g., Sluis-Cremer et al., 1985), rheumatoid arthritis (e.g. Klockars 
et al., 1987; Rosenman and Zhu, 1995), and systemic lupus erythematosus 
(e.g., Brown et al., 1997). Scleroderma is a degenerative disorder that 
leads to over-production of collagen in connective tissue that can 
cause a wide variety of symptoms including skin discoloration and 
ulceration, joint pain, swelling and discomfort in the extremities, 
breathing problems, and digestive problems. Rheumatoid arthritis is 
characterized by joint pain and tenderness, fatigue, fever, and weight 
loss. Systemic lupus erythematosus is a chronic disease of connective 
tissue that can present a wide range of symptoms including skin rash, 
fever, malaise, joint pain, and, in many cases, anemia and iron 
deficiency. OSHA believes that chronic renal disease, end-stage renal 
disease mortality, Wegener's granulomatosis, scleroderma, rheumatoid 
arthritis, and systemic lupus erythematosus clearly represent material 
impairments of health.
2. Significance of Risk
    To evaluate the significance of the health risks that result from 
exposure to hazardous chemical agents, OSHA relies on toxicological, 
epidemiological, and experimental data, as well as statistical methods. 
The Agency uses these data and methods to characterize the risk of 
disease resulting from workers' exposure to a given hazard over a 
working lifetime at levels of exposure reflecting both compliance with 
current standards and compliance with the new standard being proposed. 
In the case of crystalline silica, the current general industry, 
construction, and shipyard PELs are formulas that limit 8-hour TWA 
exposures to respirable dust; the limit on exposure decreases with 
increasing crystalline silica content of the dust. OSHA's current 
general industry PEL for respirable quartz is expressed both in terms 
of a particle count as well as a gravimetric concentration, while the 
current construction and shipyard employment PELs for respirable quartz 
are only expressed in terms of a particle count formula. For general 
industry, the gravimetric formula PEL for quartz approaches 0.1 mg/m\3\ 
(100 [mu]g/m\3\) of respirable crystalline silica when the quartz 
content of the dust is about 10 percent or greater. For the 
construction and shipyard industries, the current PEL is a formula that 
is based on concentration of respirable particles in the air; on a mass 
concentration basis, it is believed by OSHA to lie within a range of 
between about 0.25 mg/m\3\ (250 [mu]g/m\3\) to 0.5 mg/m\3\ (500 [mu]g/
m\3\) expressed as respirable quartz (see Section VI). In general 
industry, the current PELs for cristobalite and tridymite are one-half 
the PEL for quartz.
    OSHA is proposing to revise the current PELs for general industry, 
construction, and shipyards to 0.05 mg/m\3\ (50 [mu]g/m\3\) of 
respirable crystalline silica. OSHA is also proposing an action level 
of 0.025 mg/m\3\ (25 [mu]g/m\3\). In the Summary of the Preliminary 
Quantitative Risk Assessment (Section VI of the preamble), OSHA 
presents estimates of health risks associated with 45 years of exposure 
to 0.025, 0.05, and 0.1 mg/m\3\ respirable crystalline silica to 
represent the risks associated with exposure over a working lifetime to 
the proposed action level, proposed PEL, and current general industry 
PEL, respectively. OSHA also presents estimates associated with 
exposure to 0.25 and 0.5 mg/m\3\ to represent a range of risks likely 
to be associated with exposure to the current construction and shipyard 
PELs. Risk estimates are

[[Page 56329]]

presented for mortality due to lung cancer, silicosis and other non-
malignant lung disease, and end-stage renal disease, as well as 
silicosis morbidity. The preliminary findings from this assessment are 
summarized below.
a. Summary of Excess Risk Estimates for Excess Lung Cancer Mortality
    For preliminary estimates of lung cancer risk from crystalline 
silica exposure, OSHA has relied upon studies of exposure-response 
relationships presented in a pooled analysis of 10 cohort studies 
(Steenland, et al. 2001a; Toxichemica, Inc., 2004) as well as on 
individual studies of granite (Attfield and Costello, 2004), 
diatomaceous earth (Rice et al., 2001), and industrial sand (Hughes et 
al., 2001) worker cohorts, and a study of coal miners exposed to 
respirable quartz (Miller et al., 2007; Miller and MacCalman, 2009). 
OSHA believes these studies are suitable for use to quantitatively 
characterize health risks to exposed workers because (1) study 
populations were of sufficient size to provide adequate power to detect 
low levels of risk, (2) sufficient quantitative exposure data were 
available to characterize cumulative exposures of cohort members to 
respirable crystalline silica, (3) the studies either adjusted for or 
otherwise adequately addressed confounding factors such as smoking and 
exposure to other carcinogens, and (4) investigators developed 
quantitative assessments of exposure-response relationships using 
appropriate statistical models or otherwise provided sufficient 
information that permits OSHA to do so. Where investigators estimated 
excess lung cancer risks associated with exposure to the current PEL or 
NIOSH recommended exposure limit, OSHA provided these estimates in its 
Preliminary Quantitative Risk Assessment. However, OSHA implemented all 
risk models in its own life table analysis so that the use of 
background lung cancer rates and assumptions regarding length of 
exposure and lifetime were constant across each of the models, and so 
OSHA could estimate lung cancer risks associated with exposure to 
specific levels of silica of interest to the Agency.
    The Steenland et al. (2001a) study consisted of a pooled exposure-
response analysis and risk assessment based on raw data obtained for 
ten cohorts of silica-exposed workers (65,980 workers, 1,072 lung 
cancer deaths). The cohorts in this pooled analysis include U.S. gold 
miners (Steenland and Brown, 1995a), U.S. diatomaceous earth workers 
(Checkoway et al., 1997), Australian gold miners (deKlerk and Musk, 
1998), Finnish granite workers (Koskela et al., 1994), South African 
gold miners (Hnizdo et al., 1997), U.S. industrial sand employees 
(Steenland et al., 2001b), Vermont granite workers (Costello and 
Graham, 1988), and Chinese pottery workers, tin miners, and tungsten 
miners (Chen et al., 1992). The investigators used a nested case-
control design with cases and controls matched for race, sex, age 
(within five years) and study; 100 controls were matched for each case. 
An extensive exposure assessment for this pooled analysis was developed 
and published by Mannetje et al. (2002a). Exposure measurement data 
were available for all 10 cohorts and included measurements of particle 
counts, total dust mass, respirable dust mass, and, for one cohort, 
respirable quartz. Cohort-specific conversion factors were used to 
estimate cumulative exposures to respirable crystalline silica. A case-
control analysis of silicosis mortality (Mannetje et al., 2002b) showed 
a strong positive exposure-response trend, indicating that cumulative 
exposure estimates for the cohorts were not subject to random 
misclassification errors of such a magnitude so as to obscure observing 
an exposure-response relationship between silica and silicosis despite 
the variety of dust measurement metrics relied upon and the need to 
make assumptions to convert the data to a single exposure metric (i.e., 
mass concentration of respirable crystalline silica). In effect, the 
known relationship between exposure to respirable silica and silicosis 
served as a positive control to assess the validity of exposure 
estimates. Quantitative assessment of lung cancer risks were based on 
use of a log-linear model (log RR = [beta]x, where x represents the 
exposure variable and [beta] the coefficient to be estimated) with a 
15-year exposure lag providing the best fit. Models based on 
untransformed or log-transformed cumulative dose metrics provided an 
acceptable fit to the pooled data, with the model using untransformed 
cumulative dose providing a slightly better fit. However, there was 
substantial heterogeneity among the exposure-response coefficients 
derived from the individual cohorts when untransformed cumulative dose 
was used, which could result in one or a few of the cohorts unduly 
influencing the pooled exposure-response coefficient. For this reason, 
the authors preferred the use of log-transformed cumulative exposure in 
the model to derive the pooled coefficient since heterogeneity was 
substantially reduced.
    OSHA's implementation of this model is based on a re-analysis 
conducted by Steenland and Bartow (Toxichemica, 2004), which corrected 
small errors in the assignment of exposure estimates in the original 
analysis. In addition, subsequent to the Toxichemica report, and in 
response to suggestions made by external peer reviewers, Steenland and 
Bartow conducted additional analyses based on use of a linear relative 
risk model having the general form RR = 1 + [beta]x, as well as a 
categorical analysis (personal communication, Steenland 2010). The 
linear model was implemented with both untransformed and log-
transformed cumulative exposure metrics, and was also implemented as a 
2-piece spline model.
    The categorical analysis indicates that, for the pooled data set, 
lung cancer relative risks increase steeply at low exposures, after 
which the rate of increase in relative risk declines and the exposure-
response curve becomes flat (see Figure II-2 of the Preliminary 
Quantitative Risk Assessment). Use of either the linear relative risk 
or log-linear relative risk model with untransformed cumulative 
exposure (with or without a 15-year lag) failed to capture this initial 
steep slope, resulting in an underestimate of the relative risk 
compared to that suggested by the categorical analysis. In contrast, 
use of log-transformed cumulative exposure with the linear or log-
linear model, and use of the 2-piece linear spline model with 
untransformed exposure, better reflected the initial rise and 
subsequent leveling out of the exposure-response curve, with the spline 
model fitting somewhat better than either the linear or log-linear 
models (all models incorporated a 15-year exposure lag). Of the three 
models that best reflect the shape of the underlying exposure-response 
curve suggested by the categorical analysis, there is no clear 
rationale to prefer one over the other. Use of log-transformed 
cumulative exposure in either the linear or log-linear models has the 
advantage of reducing heterogeneity among the 10 pooled studies, 
lessening the likelihood that the pooled coefficient would be overtly 
influenced by outliers; however, use of a log-transformed exposure 
metric complicates comparing results with those from other risk 
analyses considered by OSHA that are based on untransformed exposure 
metrics. Since all three of these models yield comparable estimates of 
risk the choice of model is not critical for the purpose of assessing 
significance of the risk, and therefore OSHA believes that the risk 
estimates derived from the pooled study

[[Page 56330]]

are best represented as a range of estimates based on all three of 
these models.
    From these models, the estimated lung cancer risk associated with 
45 years of exposure to 0.1 mg/m\3\ (about equal to the current general 
industry PEL) is between 22 and 29 deaths per 1,000 workers. The 
estimated risk associated with exposure to silica concentrations in the 
range of 0.25 and 0.5 mg/m\3\ (about equal to the current construction 
and shipyard PELs) is between 27 and 38 deaths per 1,000. At the 
proposed PEL of 0.05 mg/m\3\, the estimated excess risk ranges from 18 
to 26 deaths per 1,000, and, at the proposed action level of 0.025 mg/
m\3\, from 9 to 23 deaths per 1,000.
    As previously discussed, the exposure-response coefficients derived 
from each of the 10 cohorts exhibited significant heterogeneity; risk 
estimates based on the coefficients derived from the individual studies 
for untransformed cumulative exposure varied by almost two orders of 
magnitude, with estimated risks associated with exposure over a working 
lifetime to the current general industry PEL ranging from a low of 0.8 
deaths per 1,000 (from the Chinese pottery worker study) to a high of 
69 deaths per 1,000 (from the South African miner study). It is 
possible that the differences seen in the slopes of the exposure-
response relationships reflect physical differences in the nature of 
crystalline silica particles generated in these workplaces and/or the 
presence of different substances on the crystal surfaces that could 
mitigate or enhance their toxicity (see Section V, Health Effects 
Summary). It may also be that exposure estimates for some cohorts were 
subject to systematic misclassification errors resulting in under- or 
over-estimation of exposures due to the use of assumptions and 
conversion factors that were necessary to estimate mass respirable 
crystalline silica concentrations from exposure samples analyzed as 
particle counts or total and respirable dust mass. OSHA believes that, 
given the wide range of risk estimates derived from these 10 studies, 
use of log-transformed cumulative exposure or the 2-piece spline model 
is a reasonable approach for deriving a single summary statistic that 
represents the lung cancer risk across the range of workplaces and 
exposure conditions represented by the studies. However, use of these 
approaches results in a non-linear exposure-response and suggests that 
the relative risk of silica-related lung cancer begins to attenuate at 
cumulative exposures in the range of those represented by the current 
PELs. Although such exposure-response relationships have been described 
for some carcinogens (for example, from metabolic saturation or a 
healthy worker survivor effect, see Staynor et al., 2003), OSHA is not 
aware of any specific evidence that would suggest that such a result is 
biologically plausible for silica, except perhaps the possibility that 
lung cancer risks increase more slowly with increasing exposure because 
of competing risks from other silica-related diseases. Attenuation of 
the exposure-response can also result from misclassification of 
exposure estimates for the more highly-exposed cohort members (Staynor 
et al., 2003). OSHA's evaluation of individual cohort studies discussed 
below indicates that, with the exception of the Vermont granite cohort, 
attenuation of exposure-related lung cancer response has not been 
directly observed.
    In addition to the pooled cohort study, OSHA's Preliminary 
Quantitative Risk Assessment presents risk estimates derived from four 
individual studies where investigators presented either lung cancer 
risk estimates or exposure-response coefficients. Two of these studies, 
one on diatomaceous earth workers (Rice et al., 2001) and one on 
Vermont granite workers (Attfield and Costello, 2004), were included in 
the 10-cohort pooled study (Steenland et al., 2001a; Toxichemica, 
2004). The other two were of British coal miners (Miller et al., 2007; 
Miller and MacCalman, 2010) and North American industrial sand workers 
(Hughes et al., 2001).
    Rice et al. (2001) presents an exposure-response analysis of the 
diatomaceous worker cohort studied by Checkoway et al. (1993, 1996, 
1997), who found a significant relationship between exposure to 
respirable cristobalite and increased lung cancer mortality. The cohort 
consisted of 2,342 white males employed for at least one year between 
1942 and 1987 in a California diatomaceous earth mining and processing 
plant. The cohort was followed until 1994, and included 77 lung cancer 
deaths. The risk analysis relied on an extensive job-specific exposure 
assessment developed by Sexias et al. (1997), which included use of 
over 6,000 samples taken during the period 1948 through 1988. The mean 
cumulative exposure for the cohort was 2.16 mg/m\3\-years for 
respirable crystalline silica dust. Rice et al. (2001) evaluated 
several model forms for the exposure-response analysis and found 
exposure to respirable cristobalite to be a significant predictor of 
lung cancer mortality with the best-fitting model being a linear 
relative risk model (with a 15-year exposure lag). From this model, the 
estimates of the excess risk of lung cancer mortality are 34, 17, and 9 
deaths per 1,000 workers for 45-years of exposure to 0.1, 0.05, and 
0.025 mg/m\3\, respectively. For exposures in the range of the current 
construction and shipyard PELs over 45 years, estimated risks lie in a 
range between 81 and 152 deaths per 1,000 workers.
    Somewhat higher risk estimates are derived from the analysis 
presented by Attfield and Costello (2004) of Vermont granite workers. 
This study involved a cohort of 5,414 male granite workers who were 
employed in the Vermont granite industry between 1950 and 1982 and who 
were followed through 1994. Workers' cumulative exposures were 
estimated by Davis et al. (1983) based on historical exposure data 
collected in six environmental surveys conducted between 1924 and 1977. 
A categorical analysis showed an increasing trend of lung cancer risk 
ratios with increasing exposure, and Poisson regression was used to 
evaluate several exposure-response models with varying exposure lags 
and use of either untransformed or log-transformed exposure metrics. 
The best-fitting model was based on use of a 15-year lag, use of 
untransformed cumulative exposure, and omission of the highest exposure 
group. The investigators believed that the omission of the highest 
exposure group was appropriate since: (1) The underlying exposure data 
for the high-exposure group was weaker than for the others; (2) there 
was a greater likelihood that competing causes of death and 
misdiagnoses of causes of death attenuated the lung cancer death rate 
in the highest exposure group; (3) all of the remaining groups 
comprised 85 percent of the deaths in the cohort and showed a strong 
linear increase in lung cancer mortality with increasing exposure; and 
(4) the exposure-response relationship seen in the lower exposure 
groups was more relevant given that the exposures of these groups were 
within the range of current occupational standards. OSHA's use of the 
exposure coefficient from this analysis in a log-linear relative risk 
model yielded a risk estimate of 60 deaths per 1,000 workers for 45 
years of exposure to the current general industry PEL of 0.1 mg/m\3\, 
25 deaths per 1,000 for 45 years of exposure to the proposed PEL of 
0.05 mg/m\3\, and 11 deaths per 1,000 for 45 years of exposure at the 
proposed action level of 0.025 mg/m\3\. Estimated risks associated with 
45 years of exposure at the current construction PEL range from 250 to 
653 deaths per 1,000.
    Hughes et al. (2001) conducted a nested case-control study of 95 
lung cancer deaths from a cohort of 2,670

[[Page 56331]]

industrial sand workers in the U.S. and Canada studied by McDonald et 
al. (2001). (This cohort overlaps with the cohort studied by Steenland 
and Sanderson (2001), which was included in the 10-cohort pooled study 
by Steenland et al., 2001a). Both categorical analyses and conditional 
logistic regression were used to examine relationships with cumulative 
exposure, log of cumulative exposure, and average exposure. Exposure 
levels over time were estimated via a job-exposure matrix developed for 
this study (Rando et al., 2001). The 50th percentile (median) exposure 
level of cases and controls for lung cancer were 0.149 and 0.110 mg/
m\3\ respirable crystalline silica, respectively, slightly above the 
current OSHA general industry standard. There did not appear to be 
substantial misclassification of exposures, as evidenced by silicosis 
mortality showing a positive exposure-response trend with cumulative 
exposure and average exposure concentration. Statistically significant 
positive exposure-response trends for lung cancer were found for both 
cumulative exposure (lagged 15 years) and average exposure 
concentration, but not for duration of employment, after controlling 
for smoking. There was no indication of an interaction effect of 
smoking and cumulative silica exposure. Hughes et al. (2001) reported 
the exposure coefficients for both lagged and unlagged cumulative 
exposure; there was no significant difference between the two (0.13 per 
mg/m\3\-year for lagged vs. 0.14 per mg/m\3\-year for unlagged). Use of 
the coefficient from Hughes et al. (2001) that incorporated a 15-year 
lag generates estimated cancer risks of 34, 15, and 7 deaths per 1,000 
for 45 years exposure to the current general industry PEL of 0.1, the 
proposed PEL of 0.05 mg/m\3\, and the proposed action level of 0.025 
mg/m\3\ respirable silica, respectively. For 45 years of exposure to 
the construction PEL, estimated risks range from 120 to 387 deaths per 
1,000 workers.
    Miller and MacCalman (2010, also reported in Miller et al., 2007) 
extended the follow-up of a previously published cohort mortality study 
(Miller and Buchanan, 1997). The follow-up study included 17,800 miners 
from 10 coal mines in the U.K. who were followed through the end of 
2005; observation in the original study began in 1970. By 2005, there 
were 516,431 person years of observation, an average of 29 years per 
miner, with 10,698 deaths from all causes. Exposure estimates of cohort 
members were not updated from the earlier study since the mines closed 
in the 1980s; however, some of these men might have had additional 
exposure at other mines or facilities. An analysis of cause-specific 
mortality was performed using external controls; it demonstrated that 
lung cancer mortality was statistically significantly elevated for coal 
miners exposed to silica. An analysis using internal controls was 
performed via Cox proportional hazards regression methods, which 
allowed for each individual miner's measurements of age and smoking 
status, as well as the individual's detailed dust and quartz time-
dependent exposure measurements. From the Cox regression, Miller and 
MacCalman (2009) estimated that cumulative exposure of 5 g-h/m\3\ 
respirable quartz (incorporating a 15-year lag) was associated with a 
relative risk of 1.14 for lung cancer. This cumulative exposure is 
about equivalent to 45 years of exposure to 0.055 mg/m\3\ respirable 
quartz, or a cumulative exposure of 2.25 mg/m\3\-yr, assuming 2,000 
hours of exposure per year. OSHA applied this slope factor in a log-
relative risk model and estimated the lifetime lung cancer mortality 
risk to be 13 per 1,000 for 45 years of exposure to 0.1 mg/m\3\ 
respirable crystalline silica. For the proposed PEL of 0.05 mg/m\3\ and 
proposed action level of 0.025 mg/m\3\, the lifetime risks are 
estimated to be 6 and 3 deaths per 1,000, respectively. The range of 
risks estimated to result from 45 years of exposure to the current 
construction and shipyard PELs is from 37 to 95 deaths per 1,000 
workers.
    The analysis from the Miller and MacCalman (2009) study yields risk 
estimates that are lower than those obtained from the other cohort 
studies described above. Possible explanations for this include: (1) 
Unlike the studies on diatomaceous earth workers and granite workers, 
the mortality analysis of the coal miners was adjusted for smoking; (2) 
lung cancer risks might have been lower among the coal miners due to 
high competing mortality risks observed in the cohort (mortality was 
significantly increased for several diseases, including tuberculosis, 
chronic bronchitis, and non-malignant respiratory disease); and (3) the 
lower risk estimates derived from the coal miner study could reflect an 
actual difference in the cancer potency of the quartz dust in the coal 
mines compared to that present in the work environments studied 
elsewhere. OSHA believes that the risk estimates derived from this 
study are credible. In terms of design, the cohort was based on union 
rolls with very good participation rates and good reporting. The study 
group was the largest of any of the individual cohort studies reviewed 
here (over 17,000 workers) and there was an average of nearly 30 years 
of follow-up, with about 60 percent of the cohort having died by the 
end of follow-up. Just as important were the high quality and detail of 
the exposure measurements, both of total dust and quartz.
b. Summary of Risk Estimates for Silicosis and Other Chronic Lung 
Disease Mortality
    OSHA based its quantitative assessment of silicosis mortality risks 
on a pooled analysis conducted by Mannetje et al. (2002b) of data from 
six of the ten epidemiological studies in the Steenland et al. (2001a) 
pooled analysis of lung cancer mortality. Cohorts included in the 
silicosis study were U.S. diatomaceous earth workers (Checkoway et al., 
1997); Finnish granite workers (Koskela et al., 1994); U.S. granite 
workers (Costello and Graham, 1988); U.S. industrial sand workers 
(Steenland and Sanderson, 2001); U.S. gold miners (Steenland and Brown, 
1995b); and Australian gold miners (deKlerk and Musk, 1998). These six 
cohorts contained 18,634 subjects and 170 silicosis deaths, where 
silicosis mortality was defined as death from silicosis (ICD-9 502, 
n=150) or from unspecified pneumoconiosis (ICD-9 505, n = 20). Analysis 
of exposure-response was performed in a categorical analysis where the 
cohort was divided into cumulative exposure deciles and Poisson 
regression was used to estimate silicosis rate ratios for each 
category, adjusted for age, calendar period, and study. Exposure-
response was examined in more detail using a nested case-control design 
and logistic regression. Although Mannetje et al. (2002b) estimated 
silicosis risks at the current OSHA PEL from the Poisson regression, a 
subsequent analysis based on the case-control design was conducted by 
Steenland and Bartow (Toxichemica, 2004), which resulted in slightly 
lower estimates of risk. Based on the Toxichemica analysis, OSHA 
estimates that the lifetime risk (over 85 years) of silicosis mortality 
associated with 45 years of exposure to the current general industry 
PEL of 0.1 mg/m\3\ is 11 deaths per 1,000 workers. Exposure for 45 
years to the proposed PEL of 0.05 mg/m\3\ and action level of 0.025 mg/
m\3\ results in an estimated 7 and 4 silicosis deaths per 1,000, 
respectively. Lifetime risks associated with exposure at the current 
construction and shipyard PELs range from 17 to 22 deaths per 1,000 
workers.
    To study non-malignant respiratory diseases, of which silicosis is 
one, Park et al. (2002) analyzed the California

[[Page 56332]]

diatomaceous earth cohort data originally studied by Checkoway et al. 
(1997), consisting of 2,570 diatomaceous earth workers employed for 12 
months or more from 1942 to 1994. The authors quantified the 
relationship between exposure to cristobalite and mortality from 
chronic lung disease other than cancer (LDOC). Diseases in this 
category included pneumoconiosis (which included silicosis), chronic 
bronchitis, and emphysema, but excluded pneumonia and other infectious 
diseases. Less than 25 percent of the LDOC deaths in the analysis were 
coded as silicosis or other pneumoconiosis (15 of 67). As noted by Park 
et al. (2002), it is likely that silicosis as a cause of death is often 
misclassified as emphysema or chronic bronchitis. Exposure-response 
relationships were explored using both Poisson regression models and 
Cox's proportional hazards models fit to the same series of relative 
rate exposure-response models that were evaluated by Rice et al. (2001) 
for lung cancer (i.e., log-linear, log-square root, log-quadratic, 
linear relative rate, a power function, and a shape function). Relative 
or excess rates were modeled using internal controls and adjusting for 
age, calendar time, ethnicity (Hispanic versus white), and time since 
first entry into the cohort, or using age- and calendar time-adjusted 
external standardization to U.S. population mortality rates. There were 
no LDOC deaths recorded among workers having cumulative exposures above 
32 mg/m\3\-years, causing the response to level off or decline in the 
highest exposure range; possible explanations considered included 
survivor selection, depletion of susceptible populations in high dust 
areas, and/or a higher degree of misclassification of exposures in the 
earlier years where exposure data were lacking and when exposures were 
presumably the highest. Therefore, Park et al. (2002) performed 
exposure-response analyses that restricted the dataset to observations 
where cumulative exposures were below 10 mg/m\3\-years, a level more 
than four times higher than that resulting from 45 years of exposure to 
the current general industry PEL for cristobalite (which is about 0.05 
mg/m\3\), as well as analyses using the full dataset. Among the models 
based on the restricted dataset, the best-fitting model with a single 
exposure term was the linear relative rate model using external 
adjustment.
    OSHA's estimates of the lifetime chronic lung disease mortality 
risk based on this model are substantially higher than those that OSHA 
derived from the Mannetje et al. (2002b) silicosis analysis. For the 
current general industry PEL of 0.1 mg/m\3\, exposure for 45 years is 
estimated to result in 83 deaths per 1,000 workers. At the proposed PEL 
of 0.05 mg/m\3\ and action level of 0.025 mg/m\3\, OSHA estimates the 
lifetime risk from 45 years of exposure to be 43 and 22 deaths per 
1,000, respectively. The range of risks associated with exposure at the 
construction and shipyard PELs over a working lifetime is from 188 to 
321 deaths per 1,000 workers. It should be noted that the Mannetje 
study (2002b) was not adjusted for smoking while the Park study (2002) 
had data on smoking habits for about one-third of the workers who died 
from LDOC and about half of the entire cohort. The Poisson regression 
on which the risk model is based was partially stratified on smoking. 
Furthermore, analyses without adjustment for smoking suggested to the 
authors that smoking was acting as a negative confounder.
c. Summary of Risk Estimates for Renal Disease Mortality
    OSHA's analysis of the health effects literature included several 
studies that have demonstrated that exposure to crystalline silica 
increases the risk of renal and autoimmune disease (see Section V, 
Health Effects Summary). Studies have found statistically significant 
associations between occupational exposure to silica dust and chronic 
renal disease, sub-clinical renal changes, end-stage renal disease 
morbidity, chronic renal disease mortality, and Wegener's 
granulomatosis. A strong exposure-response association for renal 
disease mortality and silica exposure has also been demonstrated.
    OSHA's assessment of the renal disease risks that result from 
exposure to respirable crystalline silica are based on an analysis of 
pooled data from three cohort studies (Steenland et al., 2002a). The 
combined cohort for the pooled analysis (Steenland et al., 2002a) 
consisted of 13,382 workers and included industrial sand workers 
(Steenland et al., 2001b), U.S. gold miners (Steenland and Brown, 
1995a), and Vermont granite workers (Costello and Graham, 1998). 
Exposure data were available for 12,783 workers and analyses conducted 
by the original investigators demonstrated monotonically increasing 
exposure-response trends for silicosis, indicating that exposure 
estimates were not likely subject to significant random 
misclassification. The mean duration of exposure, cumulative exposure, 
and concentration of respirable silica for the combined cohort were 
13.6 years, 1.2 mg/m\3\-years, and 0.07 mg/m\3\, respectively. There 
were highly statistically significant trends for increasing renal 
disease mortality with increasing cumulative exposure for both multiple 
cause analysis of mortality (p<0.000001) and underlying cause analysis 
(p = 0.0007). Exposure-response analysis was also conducted as part of 
a nested case-control study, which showed statistically significant 
monotonic trends of increasing risk with increasing exposure again for 
both multiple cause (p = 0.004 linear trend, 0.0002 log trend) and 
underlying cause (p = 0.21 linear trend, 0.03 log trend) analysis. The 
authors found that use of log-cumulative dose in a log relative risk 
model fit the pooled data better than cumulative exposure, average 
exposure, or lagged exposure. OSHA's estimates of renal disease 
mortality risk, which are based on the log relative risk model with log 
cumulative exposure, are 39 deaths per 1,000 for 45 years of exposure 
at the current general industry PEL of 0.1 mg/m\3\, 32 deaths per 1,000 
for exposure at the proposed PEL of 0.05 mg/m\3\, and 25 deaths per 
1,000 at the proposed action level of 0.025 mg/m\3\. OSHA also 
estimates that 45 years of exposure at the current construction and 
shipyard PELs would result in a renal disease mortality risk ranging 
from 52 to 63 deaths per 1,000 workers.
d. Summary of Risk Estimates for Silicosis Morbidity
    OSHA's Preliminary Quantitative Risk Assessment reviewed several 
cross-sectional studies designed to characterize relationships between 
exposure to respirable crystalline silica and development of silicosis 
as determined by chest radiography. Several of these studies could not 
provide information on exposure or length of employment prior to 
disease onset. Others did have access to sufficient historical medical 
data to retrospectively determine time of disease onset but included 
medical examination at follow up of primarily active workers with 
little or no post-employment follow-up. Although OSHA presents 
silicosis risk estimates that were reported by the investigators of 
these studies, OSHA believes that such estimates are likely to 
understate lifetime risk of developing radiological silicosis; in fact, 
the risk estimates reported in these studies are generally lower than 
those derived from studies that included retired workers in follow up 
medical examinations.
    Therefore, OSHA believes that the most useful studies for 
characterizing lifetime risk of silicosis morbidity are retrospective 
cohort studies that

[[Page 56333]]

included a large proportion of retired workers in the cohort and that 
were able to evaluate disease status over time, including post-
retirement. OSHA identified studies of six cohorts for which the 
inclusion of retirees was deemed sufficient to adequately characterize 
silicosis morbidity risks well past employment (Hnizdo and Sluis-
Cremer, 1993; Steenland and Brown, 1995b; Miller et al., 1998; Buchanan 
et al., 2003; Chen et al., 2001; Chen et al., 2005). Study populations 
included five mining cohorts and a Chinese pottery worker cohort. 
Except for the Chinese studies (Chen et al., 2001; Chen et al., 2005), 
chest radiographs were interpreted in accordance with the ILO system 
described earlier in this section, and x-ray films were read by panels 
of B-readers. In the Chinese studies, films were evaluated using a 
Chinese system of classification that is analogous to the ILO system. 
In addition, the Steenland and Brown (1995b) study of U.S. gold miners 
included silicosis mortality as well as morbidity in its analysis. 
OSHA's estimates of silicosis morbidity risks are based on implementing 
the various exposure-response models reported by the investigators; 
these are considered to be cumulative risk models in the sense that 
they represent the risk observed in the cohort at the time of the last 
medical evaluation and do not reflect all of the risk that may become 
manifest over a lifetime. With the exception of a coal miner study 
(Buchanan et al., 2003), risk estimates reflect the risk that a worker 
will acquire an abnormal chest x-ray classified as ILO major category 1 
or greater; the coal miner study evaluated the risk of acquiring an 
abnormal chest x-ray classified as major category 2 or higher.
    For miners exposed to freshly cut crystalline silica, the estimated 
risk of developing lesions consistent with an ILO classification of 
category 1 or greater is estimated to range from 120 to 773 cases per 
1,000 workers exposed at the current general industry PEL of 0.1 mg/
m\3\ for 45 years. For 45 years of exposure to the proposed PEL of 0.05 
mg/m\3\, the range in estimated risk is from 20 to 170 cases per 1,000 
workers. The risk predicted from exposure to the proposed action level 
of 0.025 mg/m\3\ ranges from 5 to 40 cases per 1,000. From the coal 
miner study of Buchanan et al. (2003), the estimated risks of acquiring 
an abnormal chest x-ray classified as ILO category 2 or higher are 301, 
55, and 21 cases per 1,000 workers exposed for 45 years to 0.1, 0.05, 
and 0.025 mg/m\3\, respectively. These estimates are within the range 
of risks obtained from the other mining studies. At exposures at or 
above 0.25 mg/m\3\ for 45 years (equivalent to the current construction 
and shipyard PELs), the risk of acquiring an abnormal chest x-ray 
approaches unity. Risk estimates based on the pottery cohort are 60, 
20, and 5 cases per 1,000 workers exposed for 45 years to 0.1, 0.05, 
and 0.025 mg/m\3\, respectively, which is generally below the range of 
risks estimated from the other studies and may reflect a lower toxicity 
of quartz particles in that work environment due to the presence of 
alumino-silicates on the particle surfaces. According to Chen et al. 
(2005), adjustment of the exposure metric to reflect the unoccluded 
surface area of silica particles resulted in an exposure-response of 
pottery workers that was similar to the mining cohorts. The finding of 
a reduced silicosis risk among pottery workers is consistent with other 
studies of clay and brick industries that have reported finding a lower 
prevalence of silicosis compared to that experienced in other industry 
sectors (Love et al., 1999; Hessel, 2006; Miller and Soutar, 2007) as 
well as a lower silicosis risk per unit of cumulative exposure (Love et 
al., 1999; Miller and Soutar, 2007).
3. Significance of Risk and Risk Reduction
    The Supreme Court's benzene decision of 1980, discussed above in 
this section, states that ``before he can promulgate any permanent 
health or safety standard, the Secretary [of Labor] is required to make 
a threshold finding that a place of employment is unsafe--in the sense 
that significant risks are present and can be eliminated or lessened by 
a change in practices.'' Benzene, 448 U.S. at 642. While making it 
clear that it is up to the Agency to determine what constitutes a 
significant risk, the Court offered general guidance on the level of 
risk OSHA might determine to be significant.

    It is the Agency's responsibility to determine in the first 
instance what it considers to be a ``significant'' risk. Some risks 
are plainly acceptable and others are plainly unacceptable. If, for 
example, the odds are one in a billion that a person will die from 
cancer by taking a drink of chlorinated water, the risk clearly 
could not be considered significant. On the other hand, if the odds 
are one in a thousand that regular inhalation of gasoline vapors 
that are 2% benzene will be fatal, a reasonable person might well 
consider the risk significant and take appropriate steps to decrease 
or eliminate it.

Benzene, 448 U.S. at 655. The Court further stated that the 
determination of significant risk is not a mathematical straitjacket 
and that ``the Agency has no duty to calculate the exact probability of 
harm.'' Id.
    In this section, OSHA presents its preliminary findings with 
respect to the significance of the risks summarized above, and the 
potential of the proposed standard to reduce those risks. Findings 
related to mortality risk will be presented first, followed by 
silicosis morbidity risks.
a. Mortality Risks
    OSHA's Preliminary Quantitative Risk Assessment (and the Summary of 
the Preliminary Quantitative Risk Assessment in section VI) presents 
risk estimates for four causes of excess mortality: Lung cancer, 
silicosis, non-malignant respiratory disease (including silicosis and 
COPD), and renal disease. Table VII-2 presents the estimated excess 
lifetime risks (i.e., to age 85) of these fatal diseases associated 
with various levels of crystalline silica exposure allowed under the 
current rule, based on OSHA's risk assessment and assuming 45 years of 
occupational exposure to crystalline silica.

                              Table VII-2--Expected Excess Deaths per 1,000 Workers
----------------------------------------------------------------------------------------------------------------
                                                                                   Current
                                                             Current general    construction/
                   Fatal health outcome                       industry PEL      shipyard PEL      Proposed PEL
                                                              (0.1 mg/m\3\)     (0.25-0.5 mg/    (0.05 mg/m\3\)
                                                                                    m\3\)
----------------------------------------------------------------------------------------------------------------
Lung Cancer:
    10-cohort pooled analysis.............................             22-29             27-38             18-26
    Single cohort study-lowest estimate...................                13             37-95                 6
    Single cohort study-highest estimate..................                60           250-653                25
Silicosis.................................................                11             17-22                 7
Non-Malignant Respiratory Disease (including silicosis)...                83           188-321                43

[[Page 56334]]

 
Renal Disease.............................................                39             52-63                32
----------------------------------------------------------------------------------------------------------------

    The purpose of the OSH Act, as stated in Section 6(b), is to ensure 
``that no employee will suffer material impairment of health or 
functional capacity even if such employee has regular exposure to the 
hazard . . . for the period of his working life.'' 29 U.S.C. 655(b)(5). 
Assuming a 45-year working life, as OSHA has done in significant risk 
determinations for previous standards, the Agency preliminarily finds 
that the excess risk of disease mortality related to exposure to 
respirable crystalline silica at levels permitted by current OSHA 
standards is clearly significant. The Agency's estimate of such risk 
falls well above the level of risk the Supreme Court indicated a 
reasonable person might consider unacceptable. Benzene, 448 U.S. at 
655. For lung cancer, OSHA estimates the range of risk at the current 
general industry PEL to be between 13 and 60 deaths per 1,000 workers. 
The estimated risk for silicosis mortality is lower, at 11 deaths per 
1,000 workers; however, the estimated lifetime risk for non-malignant 
respiratory disease mortality, including silicosis, is about 8-fold 
higher than that for silicosis alone, at 83 deaths per 1,000. OSHA 
believes that the estimate for non-malignant respiratory disease 
mortality is better than the estimate for silicosis mortality at 
capturing the total respiratory disease burden associated with exposure 
to crystalline silica dust. The former captures deaths related to COPD, 
for which there is strong evidence of a causal relationship with 
exposure to silica, and is also more likely to capture those deaths 
where silicosis was a contributing factor but where the cause of death 
was misclassified. Finally, there is an estimated lifetime risk of 
renal disease mortality of 39 deaths per 1,000. Exposure for 45 years 
at levels of respirable crystalline silica in the range of the current 
limits for construction and shipyards result in even higher risk 
estimates, as presented in Table VII-2.
    To further demonstrate significant risk, OSHA compares the risk 
from currently permissible crystalline silica exposures to risks found 
across a broad variety of occupations. The Agency has used similar 
occupational risk comparisons in the significant risk determination for 
substance-specific standards promulgated since the benzene decision. 
This approach is supported by evidence in the legislative record, with 
regard to Section 6(b)(5) of the Act (29 U.S.C. 655(b)(5)), that 
Congress intended the Agency to regulate unacceptably severe 
occupational hazards, and not ``to establish a utopia free from any 
hazards'' or to address risks comparable to those that exist in 
virtually any occupation or workplace. 116 Cong. Rec. 37614 (1970), 
Leg. Hist. 480-82. It is also consistent with Section 6(g) of the OSH 
Act, which states: ``In determining the priority for establishing 
standards under this section, the Secretary shall give due regard to 
the urgency of the need for mandatory safety and health standards for 
particular industries, trades, crafts, occupations, businesses, 
workplaces or work environments.'' 29 U.S.C. 655(g).
    Fatal injury rates for most U.S. industries and occupations may be 
obtained from data collected by the Bureau of Labor Statistics. Table 
VII-3 shows annual fatality rates per 1,000 employees for several 
industries for 2007, as well as projected fatalities per 1,000 
employees assuming exposure to workplace hazards for 45 years based on 
these annual rates (BLS, 2010). While it is difficult to meaningfully 
compare aggregate industry fatality rates to the risks estimated in the 
quantitative risk assessment for crystalline silica, which address one 
specific hazard (inhalation exposure to respirable crystalline silica) 
and several health outcomes (lung cancer, silicosis, NMRD, renal 
disease mortality), these rates provide a useful frame of reference for 
considering risk from inhalation exposure to crystalline silica. For 
example, OSHA's estimated range of 6-60 excess lung cancer deaths per 
1,000 workers from regular occupational exposure to respirable 
crystalline silica in the range of 0.05--0.1 mg/m\3\ is roughly 
comparable to, or higher than, the expected risk of fatal injuries over 
a working life in high-risk occupations such as mining and construction 
(see Table VII-3). Regular exposures at higher levels, including the 
current construction and shipyard PELs for respirable crystalline 
silica, are expected to cause substantially more deaths per 1,000 
workers from lung cancer (ranging from 37 to 653 per 1,000) than result 
from occupational injuries in most private industry. At the proposed 
PEL of 0.05 mg/m\3\ respirable crystalline silica, the Agency's 
estimate of excess lung cancer mortality, from 6 to 26 deaths per 1,000 
workers, is still 3- to10-fold or more higher than private industry's 
average fatal injury rate, given the same employment time, and 
substantially exceeds those rates found in lower-risk industries such 
as finance and educational and health services.

  Table VII-3--Fatal Injuries per 1000 Employees, by Industry or Sector
------------------------------------------------------------------------
                                            Over 1 year    Over 45 years
------------------------------------------------------------------------
All Private Industry....................           0.043             1.9
Mining (General)........................           0.214             9.6
Construction............................           0.108             4.8
Manufacturing...........................           0.024             1.1
Wholesale Trade.........................           0.045             2.0
Transportation and Warehousing..........           0.165             7.4
Financial Activities....................           0.012             0.5
Educational and Health Services.........           0.008             0.4
------------------------------------------------------------------------
Source: BLS (2010).


[[Page 56335]]

    Because there is little available information on the incidence of 
occupational cancer across all industries, risk from crystalline silica 
exposure cannot be compared with overall risk from other workplace 
carcinogens. However, OSHA's previous risk assessments provide 
estimates of risk from exposure to certain carcinogens. These risk 
assessments, as with the current assessment for crystalline silica, 
were based on animal or human data of reasonable or high quality and 
used the best information then available. Table VII-4 shows the 
Agency's best estimates of cancer risk from 45 years of occupational 
exposure to several carcinogens, as published in the preambles to final 
rules promulgated since the benzene decision in 1980. These risks were 
judged by the Agency to be significant.

                      Table VII-4--Selected OSHA Risk Estimates for Prior and Current PELs
                                        [Excess Cancers per 1000 workers]
----------------------------------------------------------------------------------------------------------------
             Standard                Risk at prior PEL    Risk at current PEL        Federal Register date
----------------------------------------------------------------------------------------------------------------
Ethylene Oxide...................  63-109 per 1000.....  1.2-2.3 per 1000....  June 22, 1984.
Asbestos.........................  64 per 1000.........  6.7 per 1000........  June 20, 1986.
Benzene..........................  95 per 1000.........  10 per 1000.........  September 11, 1987.
Formaldehyde.....................  0.4-6.2 per 1000....  0.0056 per 1000.....  December 4, 1987.
Methylenedianiline...............  *6-30 per 1000......  0.8 per 1000........  August 10, 1992.
Cadmium..........................  58-157 per 1000.....  3-15 per 1000.......  September 14, 1992.
1,3-Butadiene....................  11.2-59.4 per 1000..  1.3-8.1 per 1000....  November 4, 1996.
Methylene Chloride...............  126 per 1000........  3.6 per 1000........  January 10, 1997.
Chromium VI......................  101-351 per 1000....  10-45 per 1000......  February 28, 2006
Crystalline Silica:
    General Industry PEL.........  **13-60 per 1000....  ***6-26 per 1000....  N/A
    Construction/Shipyard PEL....  **27-653 per 1000...  ***6-26 per 1000....  .................................
----------------------------------------------------------------------------------------------------------------
* no prior standard; reported risk is based on estimated exposures at the time of the rulemaking
** estimated excess lung cancer risks at the current PEL
*** estimated excess lung cancer risks at the proposed new PEL

    The estimated excess lung cancer risks associated with respirable 
crystalline silica at the current general industry PEL, 13-60 deaths 
per 1,000 workers, are comparable to, and in some cases higher than, 
the estimated excess cancer risks for many other workplace carcinogens 
for which OSHA made a determination of significant risk (see Table VII-
4, ``Selected OSHA Risk Estimates for Prior and Current PELs''). The 
estimated excess lung cancer risks associated with exposure to the 
current construction and shipyard PELs are even higher. The estimated 
risk from lifetime occupational exposure to respirable crystalline 
silica at the proposed PEL is 6-26 excess lung cancer deaths per 1,000 
workers, a range still higher than the risks from exposure to many 
other carcinogens regulated by OSHA (see Table VII-4, ``Selected OSHA 
Risk Estimates for Prior and Current PELs'').
    OSHA's preliminary risk assessment also shows that reduction of the 
current PELs to the proposed level of 0.05 mg/m\3\ will result in 
substantial reduction in risk, although quantification of that 
reduction is subject to model uncertainty. Risk models that reflect 
attenuation of the risk with increasing exposure, such as those 
relating risk to a log transformation of cumulative exposure, will 
result in lower estimates of risk reduction compared to linear risk 
models. Thus, for lung cancer risks, the assessment based on the 10-
cohort pooled analysis by Steenland et al. (2001; also Toxichemica, 
2004; Steenland 2010) suggests risk will be reduced by about 14 percent 
from the current general industry PEL and by 28-41 percent from the 
current construction/shipyard PEL (based on the midpoint of the ranges 
of estimated risk derived from the three models used for the pooled 
cohort data). These risk reduction estimates, however, are much lower 
than those derived from the single cohort studies (Rice et al., 2001; 
Attfield and Costello, 2004; Hughes et al., 2001; Miller and MacCalman, 
2009), which used linear or log-linear relative risk models with 
untransformed cumulative exposure as the dose metric. These single 
cohort studies suggest that reducing the current PELs to the proposed 
PEL will reduce lung cancer risk by more than 50 percent in general 
industry and by more than 80 percent in construction and shipyards.
    For silicosis mortality, OSHA's assessment indicates that risk will 
be reduced by 36 percent and by 58-68 percent as a result of reducing 
the current general industry and construction/shipyard PELs, 
respectively. Non-malignant respiratory disease mortality risks will be 
reduced by 48 percent and by 77-87 percent from reducing the general 
industry and construction/shipyard PELs, respectively, to the proposed 
PEL. There is also a substantial reduction in renal disease mortality 
risks; an 18-percent reduction associated with reducing the general 
industry PEL and a 38- to 49-percent reduction associated with reducing 
the construction/shipyard PEL.
    Thus, OSHA believes that the proposed PEL of 0.05 mg/m\3\ 
respirable crystalline silica will substantially reduce the risk of 
material health impairments associated with exposure to silica. 
However, even at the proposed PEL, as well as the action level of 0.025 
mg/m\3\, the risk posed to workers with 45 years of regular exposure to 
respirable crystalline silica is greater than 1 per 1,000 workers and 
is still clearly significant.
b. Silicosis Morbidity Risks
    OSHA's Preliminary Risk Assessment characterizes the risk of 
developing lung fibrosis as detected by chest x-ray. For 45 years of 
exposure at the current general industry PEL, OSHA estimates that the 
risk of developing lung fibrosis consistent with an ILO category 1+ 
degree of small opacity profusion ranges from 60 to 773 cases per 
1,000. For exposure at the construction and shipyard PELs, the risk 
approaches unity. The wide range of risk estimates derived from the 
underlying studies relied on for the risk assessment may reflect 
differences in the relative toxicity of quartz particles in different 
workplaces; nevertheless, OSHA believes that each of these risk 
estimates clearly represent a significant risk of developing fibrotic 
lesions in the lung. Exposure to the proposed PEL of 0.05 mg/m\3\ 
respirable crystalline silica for 45 years yields an estimated risk of

[[Page 56336]]

between 20 and 170 cases per 1,000 for developing fibrotic lesions 
consistent with an ILO category of 1+. These risk estimates indicate 
that promulgation of the proposed PEL would result in a reduction in 
risk by about two-thirds or more, which the Agency believes is a 
substantial reduction of the risk of developing abnormal chest x-ray 
findings consistent with silicosis.
    One study of coal miners also permitted the agency to evaluate the 
risk of developing lung fibrosis consistent with an ILO category 2+ 
degree of profusion of small opacities (Buchanan et al., 2003). This 
level of profusion has been shown to be associated with a higher 
prevalence of lung function decrement and an increased rate of early 
mortality (Ng et al., 1987a; Begin et al., 1998; Moore et al., 1988; Ng 
et al., 1992a; Infante-Rivard et al., 1991). From this study, OSHA 
estimates that the risk associated with 45 years of exposure to the 
current general industry PEL is 301 cases per 1,000 workers, again a 
clearly significant risk. Exposure to the proposed PEL of 0.05 mg/m\3\ 
respirable crystalline silica for 45 years yields an estimated risk of 
55 cases per 1,000 for developing lesions consistent with an ILO 
category 2+ degree of small opacity profusion. This represents a 
reduction in risk of over 80 percent, again a clearly substantial 
reduction of the risk of developing radiologic silicosis consistent 
with ILO category 2+ degree of small opacity profusion.
    As is the case for other health effects addressed in the 
preliminary risk assessment (i.e., lung cancer, silicosis morbidity 
defined as ILO 1+ level of profusion), there is some evidence that this 
risk will vary according to the nature of quartz particles present in 
different workplaces. In particular, risk may vary depending on whether 
quartz is freshly fractured during work operations and the co-existence 
of other minerals and substances that could alter the biological 
activity of quartz. Using medical and exposure data taken from a cohort 
of heavy clay workers first studied by Love et al. (1999), Miller and 
Soutar (2007) compared the silicosis prevalence within the cohort to 
that predicted by the exposure-response model derived by Buchanan et 
al. (2003) and used by OSHA to estimate the risk of radiologic 
silicosis with a classification of ILO 2+. They found that the model 
predicted about a 4-fold higher prevalence of workers having an 
abnormal x-ray than was actually seen in the clay cohort (31 cases 
predicted vs. 8 observed). Unlike the coal miner study, the clay worker 
cohort included only active workers and not retirees (Love et al., 
1999); however, Miller and Soutar believed this could not explain the 
magnitude of the difference between the model prediction and observed 
silicosis prevalence in the clay worker cohort. OSHA believes that the 
result obtained by Miller and Soutar (2007) likely does reflect 
differences in the toxic potency of quartz particles in different work 
settings. Nevertheless, even if the risk estimates predicted by the 
model derived from the coal worker study were reduced substantially, 
even by more than a factor of 10, the resulting risk estimate would 
still reflect the presence of a significant risk.
    The Preliminary Quantitative Risk Assessment also discusses the 
question of a threshold exposure level for silicosis. There is little 
quantitative data available with which to estimate a threshold exposure 
level for silicosis or any of the other silica-related diseases 
addressed in the risk assessment. The risk assessment discussed one 
study that perhaps provides the best information. This is an analysis 
by Kuempel et al. (2001) who used a rat-based toxicokinetic/
toxicodynamic model along with a human lung deposition/clearance model 
to estimate a minimum lung burden necessary to cause the initial 
inflammatory events that can lead to lung fibrosis and an indirect 
genotoxic cause of lung cancer. They estimated that the threshold 
effect level of lung burden associated with this inflammation 
(Mcrit) is the equivalent of exposure to 0.036 mg/m\3\ for 
45 years; thus, exposures below this level would presumably not lead to 
an excess lung cancer risk (based on an indirect genotoxic mechanism) 
nor to silicosis, at least in the ``average individual.'' This might 
suggest that exposures to a concentration of silica at the proposed 
action level would not be associated with a risk of silicosis, and 
possibly not of lung cancer. However, OSHA does not believe that the 
analysis by Kuemple et al. is definitive with respect to a threshold 
for silica-related disease. First, since the critical quartz burden is 
a mean value derived from the model, the authors estimated that a 45-
year exposure to a concentration as low as 0.005 mg/m\3\, or 5 times 
below the proposed action level, would result in a lung quartz burden 
that was equal to the 95-percent lower confidence limit on 
Mcrit. Due to the statistical uncertainty in Kuemple et 
al.'s estimate of critical lung burden, OSHA cannot rule out the 
existence of a threshold lung burden that is below that resulting from 
exposure to the proposed action level. In addition, with respect to 
silica-related lung cancer, if at least some of the risk is from a 
direct genotoxic mechanism (see section II.F of the Health Effects 
Literature Review), then this threshold value is not relevant to the 
risk of lung cancer. Supporting evidence comes from Steenland and 
Deddens (2002), who found that, for the 10-cohort pooled data set, a 
risk model that incorporated a threshold did fit better than a no-
threshold model, but the estimated threshold was very low, 0.010 mg/
m\3\ (10 [mu]g/m\3\). OSHA acknowledges that a threshold exposure level 
might lie within the range of the proposed action level, as suggested 
by the work of Kuempel et al. (2001) and that this possibility adds 
uncertainty to the estimated risks associated with exposure to the 
action level. However, OSHA believes that available information cannot 
firmly establish a threshold exposure level for silica-related effects, 
and there is no empirical evidence that a threshold exists at or above 
the proposed PEL of 0.05 mg/m\3\ for respirable crystalline silica.

VIII. Summary of the Preliminary Economic Analysis and Initial 
Regulatory Flexibility Analysis

A. Introduction and Summary

    OSHA's Preliminary Economic Analysis and Initial Regulatory 
Flexibility Analysis (PEA) addresses issues related to the costs, 
benefits, technological and economic feasibility, and the economic 
impacts (including impacts on small entities) of this proposed 
respirable crystalline silica rule and evaluates regulatory 
alternatives to the proposed rule. Executive Orders 13563 and 12866 
direct agencies to assess all costs and benefits of available 
regulatory alternatives and, if regulation is necessary, to select 
regulatory approaches that maximize net benefits (including potential 
economic, environmental, and public health and safety effects; 
distributive impacts; and equity). Executive Order 13563 emphasized the 
importance of quantifying both costs and benefits, of reducing costs, 
of harmonizing rules, and of promoting flexibility. The full PEA has 
been placed in OSHA rulemaking docket OSHA-2010-0034. This rule is an 
economically significant regulatory action under Sec. 3(f)(1) of 
Executive Order 12866 and has been reviewed by the Office of 
Information and Regulatory Affairs in the Office of Management and 
Budget, as required by executive order.
    The purpose of the PEA is to:
     Identify the establishments and industries potentially 
affected by the proposed rule;

[[Page 56337]]

     Estimate current exposures and the technologically 
feasible methods of controlling these exposures;
     Estimate the benefits resulting from employers coming into 
compliance with the proposed rule in terms of reductions in cases of 
silicosis, lung cancer, other forms of chronic obstructive pulmonary 
disease, and renal failure;
     Evaluate the costs and economic impacts that 
establishments in the regulated community will incur to achieve 
compliance with the proposed rule;
     Assess the economic feasibility of the proposed rule for 
affected industries; and
     Assess the impact of the proposed rule on small entities 
through an Initial Regulatory Flexibility Analysis (IRFA), to include 
an evaluation of significant regulatory alternatives to the proposed 
rule that OSHA has considered.
    The Preliminary Economic Analysis contains the following chapters:

Chapter I. Introduction
Chapter II. Assessing the Need for Regulation
Chapter III. Profile of Affected Industries
Chapter IV. Technological Feasibility
Chapter V. Costs of Compliance
Chapter VI. Economic Impacts
Chapter VII. Benefits and Net Benefits
Chapter VIII. Regulatory Alternatives
Chapter IX. Initial Regulatory Flexibility Analysis
Chapter X. Environmental Impacts

    Key findings of these chapters are summarized below and in sections 
VIII.B through VIII.I of this PEA summary.
Profile of Affected Industries
    The proposed rule would affect employers and employees in many 
different industries across the economy. As described in Section VIII.C 
and reported in Table VIII-3 of this preamble, OSHA estimates that a 
total of 2.1 million employees in 550,000 establishments and 533,000 
firms (entities) are potentially at risk from exposure to respirable 
crystalline silica. This total includes 1.8 million employees in 
477,000 establishments and 486,000 firms in the construction industry 
and 295,000 employees in 56,000 establishments and 47,000 firms in 
general industry and maritime.
Technological Feasibility
    As described in more detail in Section VIII.D of this preamble and 
in Chapter IV of the PEA, OSHA assessed, for all affected sectors, the 
current exposures and the technological feasibility of the proposed PEL 
of 50 [micro]g/m\3\ and, for analytic purposes, an alternative PEL of 
25 [micro]g/m\3\.
    Tables VIII-6 and VIII-7 in section VIII.D of this preamble 
summarize all the industry sectors and construction activities studied 
in the technological feasibility analysis and show how many operations 
within each can achieve levels of 50 [mu]g/m\3\ through the 
implementation of engineering and work practice controls. The table 
also summarizes the overall feasibility finding for each industry 
sector or construction activity based on the number of feasible versus 
infeasible operations. For the general industry sector, OSHA has 
preliminarily concluded that the proposed PEL of 50 [mu]g/m\3\ is 
technologically feasible for all affected industries. For the 
construction activities, OSHA has determined that the proposed PEL of 
50 [mu]g/m\3\ is feasible in 10 out of 12 of the affected activities. 
Thus, OSHA preliminarily concludes that engineering and work practices 
will be sufficient to reduce and maintain silica exposures to the 
proposed PEL of 50 [mu]g/m\3\ or below in most operations most of the 
time in the affected industries. For those few operations within an 
industry or activity where the proposed PEL is not technologically 
feasible even when workers use recommended engineering and work 
practice controls (seven out of 108 operations, see Tables VIII-6 and 
VIII-7), employers can supplement controls with respirators to achieve 
exposure levels at or below the proposed PEL.
    Based on the information presented in the technological feasibility 
analysis, the Agency believes that 50 [mu]g/m\3\ is the lowest feasible 
PEL. An alternative PEL of 25 [mu]g/m\3\ would not be feasible because 
the engineering and work practice controls identified to date will not 
be sufficient to consistently reduce exposures to levels below 25 
[mu]g/m\3\ in most operations most of the time. OSHA believes that an 
alternative PEL of 25 [mu]g/m\3\ would not be feasible for many 
industries, and that the use of respiratory protection would be 
necessary in most operations most of the time to achieve compliance. 
Additionally, the current methods of sampling analysis create higher 
errors and lower precision in measurement as concentrations of silica 
lower than the proposed PEL are analyzed. However, the Agency 
preliminarily concludes that these sampling and analytical methods are 
adequate to permit employers to comply with all applicable requirements 
triggered by the proposed action level and PEL.
Costs of Compliance
    As described in more detail in Section VIII.E and reported by 
industry in Table VIII-8 of this preamble, the total annualized cost of 
compliance with the proposed standard is estimated to be about $658 
million. The major cost elements associated with the revisions to the 
standard are costs for engineering controls, including controls for 
abrasive blasting ($344 million); medical surveillance ($79 million); 
exposure monitoring ($74 million); respiratory protection ($91 
million); training ($50 million) and regulated areas or access control 
($19 million). Of the total cost, $511 million would be borne by firms 
in the construction industry and $147 million would be borne by firms 
in general industry and maritime.
    The compliance costs are expressed as annualized costs in order to 
evaluate economic impacts against annual revenue and annual profits, to 
be able to compare the economic impact of the rulemaking with other 
OSHA regulatory actions, and to be able to add and track Federal 
regulatory compliance costs and economic impacts in a consistent 
manner. Annualized costs also represent a better measure for assessing 
the longer-term potential impacts of the rulemaking. The annualized 
costs were calculated by annualizing the one-time costs over a period 
of 10 years and applying discount rates of 7 and 3 percent as 
appropriate.
    The estimated costs for the proposed silica standard rule include 
the additional costs necessary for employers to achieve full 
compliance. They do not include costs associated with current 
compliance that has already been achieved with regard to the new 
requirements or costs necessary to achieve compliance with existing 
silica requirements, to the extent that some employers may currently 
not be fully complying with applicable regulatory requirements.
    OSHA's exposure profile represents the Agency's best estimate of 
current exposures (i.e., baseline exposures). OSHA did not attempt to 
determine the extent to which current exposures in compliance with the 
current silica PELs are the result of baseline engineering controls or 
the result of circumstances leading to low exposures. This information 
is not needed to estimate the costs of (additional) engineering 
controls needed to comply with the proposed standard.
    Because of the severe health hazards involved, the Agency expects 
that the estimated 15,446 abrasive blasters in the construction sector 
and the estimated 4,550 abrasive blasters in the maritime sector are 
currently wearing respirators in compliance with OSHA's abrasive 
blasting provisions. Furthermore, for the construction baseline, an 
estimated 241,269 workers, including abrasive blasters, will need to 
use respirators to achieve compliance with the proposed

[[Page 56338]]

rule, and, based on the NIOSH/BLS respirator use survey (NIOSH/BLS, 
2003), an estimated 56 percent of construction employers currently 
require such respiratory use and have respirator programs that meet 
OSHA's respirator standard. OSHA has not taken any costs for employers 
and their workers currently in compliance with the respiratory 
provisions in the proposed rule.
    In addition, under both the general industry and construction 
baselines, an estimated 50 percent of employers have pre-existing 
training programs that address silica-related risks (as required under 
OSHA's hazard communication standard) and partially satisfy the 
proposed rule's training requirements (for costing purposes, estimated 
to satisfy 50 percent of the training requirements in the proposed 
rule). These employers will need fewer resources to achieve full 
compliance with the proposed rule than those employers without pre-
existing training programs that address silica-related risks.
    Other than respiratory protection and worker training concerning 
silica-related risks, OSHA did not assume baseline compliance with any 
ancillary provisions, even though some employers have reported that 
they do currently monitor silica exposure and some employers have 
reported conducting medical surveillance.
Economic Impacts
    To assess the nature and magnitude of the economic impacts 
associated with compliance with the proposed rule, OSHA developed 
quantitative estimates of the potential economic impact of the new 
requirements on entities in each of the affected industry sectors. The 
estimated compliance costs were compared with industry revenues and 
profits to provide an assessment of the economic feasibility of 
complying with the revised standard and an evaluation of the potential 
economic impacts.
    As described in greater detail in Section VIII.F of this preamble, 
the costs of compliance with the proposed rulemaking are not large in 
relation to the corresponding annual financial flows associated with 
each of the affected industry sectors. The estimated annualized costs 
of compliance represent about 0.02 percent of annual revenues and about 
0.5 percent of annual profits, on average, across all firms in general 
industry and maritime, and about 0.05 percent of annual revenues and 
about 1.0 percent of annual profits, on average, across all firms in 
construction. Compliance costs do not represent more than 0.39 percent 
of revenues or more than 8.8 percent of profits in any affected 
industry in general industry or maritime, or more than 0.13 percent of 
revenues or more than 3 percent of profits in any affected industry in 
construction.
    Based on its analysis of international trade effects, OSHA 
concluded that most or all costs arising from this proposed silica rule 
would be passed on in higher prices rather than absorbed in lost 
profits and that any price increases would result in minimal loss of 
business to foreign competition.
    Given the minimal potential impact on prices or profits in the 
affected industries, OSHA has preliminarily concluded that compliance 
with the requirements of the proposed rulemaking would be economically 
feasible in every affected industry sector.
    In addition, OSHA directed Inforum--a not-for-profit corporation 
with over 40 years of experience in the design and application of 
macroeconomic models--to run its LIFT (Long-term Interindustry 
Forecasting Tool) model of the U.S. economy to estimate the industry 
and aggregate employment effects of the proposed silica rule. Inforum 
developed estimates of the employment impacts over the ten-year period 
from 2014-2023 by feeding OSHA's year-by-year and industry-by-industry 
estimates of the compliance costs of the proposed rule into its LIFT 
model. The most important Inforum result is that the proposed silica 
rule would have a negligible--albeit slightly positive--net effect on 
aggregate U.S. employment.
    Based on its analysis of the costs and economic impacts associated 
with this rulemaking and on Inforum's estimates of associated 
employment and other macroeconomic impacts, OSHA preliminarily 
concludes that the effect of the proposed standard on employment, 
wages, and economic growth for the United States would be negligible.
Benefits, Net Benefits, and Cost-Effectiveness
    As described in more detail in Section VIII.G of this preamble, 
OSHA estimated the benefits, net benefits, and incremental benefits of 
the proposed silica rule. That section also contains a sensitivity 
analysis to show how robust the estimates of net benefits are to 
changes in various cost and benefit parameters. A full explanation of 
the derivation of the estimates presented there is provided in Chapter 
VII of the PEA for the proposed rule. OSHA invites comments on any 
aspect of its estimation of the benefits and net benefits of the 
proposed rule.
    OSHA estimated the benefits associated with the proposed PEL of 50 
[mu]g/m\3\ and, for analytical purposes to comply with OMB Circular A-
4, with an alternative PEL of 100 [mu]g/m\3\ for respirable crystalline 
silica by applying the dose-response relationship developed in the 
Agency's quantitative risk assessment--summarized in Section VI of this 
preamble--to current exposure levels. OSHA determined current exposure 
levels by first developing an exposure profile (presented in Chapter IV 
of the PEA) for industries with workers exposed to respirable 
crystalline silica, using OSHA inspection and site-visit data, and then 
applying this exposure profile to the total current worker population. 
The industry-by-industry exposure profile is summarized in Table VIII-5 
in Section VIII.C of this preamble.
    By applying the dose-response relationship to estimates of current 
exposure levels across industries, it is possible to project the number 
of cases of the following diseases expected to occur in the worker 
population given current exposure levels (the ``baseline''):
     Fatal cases of lung cancer,
     fatal cases of non-malignant respiratory disease 
(including silicosis),
     fatal cases of end-stage renal disease, and
     cases of silicosis morbidity.
    Table VIII-1 provides a summary of OSHA's best estimate of the 
costs and benefits of the proposed rule using a discount rate of 3 
percent. As shown, the proposed rule is estimated to prevent 688 
fatalities and 1,585 silica-related illnesses annually once it is fully 
effective, and the estimated cost of the rule is $637 million annually. 
Also as shown in Table VIII-1, the discounted monetized benefits of the 
proposed rule are estimated to be $5.3 billion annually, and the 
proposed rule is estimated to generate net benefits of $4.6 billion 
annually. Table VIII-1 also presents the estimated costs and benefits 
of the proposed rule using a discount rate of 7 percent. The estimated 
costs and benefits of the proposed rule, disaggregated by industry 
sector, were previously presented in Table SI-3 in this preamble.

[[Page 56339]]



  Table VIII-1--Annualized Benefits, Costs and Net Benefits of OSHA's Proposed Silica Standard of 50 [mu]g/m\3\
----------------------------------------------------------------------------------------------------------------
                       Discount rate                                                 3%                7%
----------------------------------------------------------------------------------------------------------------
Annualized Costs
    Engineering Controls (includes Abrasive Blasting).....                        $329,994,068      $343,818,700
    Respirators...........................................                          90,573,449        90,918,741
    Exposure Assessment...................................                          72,504,999        74,421,757
    Medical Surveillance..................................                          76,233,932        79,069,527
    Training..............................................                          48,779,433        50,266,744
    Regulated Area or Access Control......................                          19,243,500        19,396,743
                                                           -----------------------------------------------------
        Total Annualized Costs (point estimate)...........                         637,329,380       657,892,211
Annual Benefits: Number of Cases Prevented
    Fatal Lung Cancers (midpoint estimate)................               162
    Fatal Silicosis & other Non-Malignant Respiratory                    375
     Diseases.............................................
    Fatal Renal Disease...................................               151
                                                           ------------------
    Silica-Related Mortality..............................               688     3,203,485,869     2,101,980,475
    Silicosis Morbidity...................................             1,585     1,986,214,921     1,363,727,104
                                                                             -----------------------------------
        Monetized Annual Benefits (midpoint estimate).....                       5,189,700,790     3,465,707,579
        Net Benefits......................................                       4,552,371,410     2,807,815,368
----------------------------------------------------------------------------------------------------------------

Initial Regulatory Flexibility Analysis
    OSHA has prepared an Initial Regulatory Flexibility Analysis (IRFA) 
in accordance with the requirements of the Regulatory Flexibility Act, 
as amended in 1996. Among the contents of the IRFA are an analysis of 
the potential impact of the proposed rule on small entities and a 
description and discussion of significant alternatives to the proposed 
rule that OSHA has considered. The IRFA is presented in its entirety 
both in Chapter IX of the PEA and in Section VIII.I of this preamble.
    The remainder of this section (Section VIII) of the preamble is 
organized as follows:

B. The Need for Regulation
C. Profile of Affected Industry
D. Technological Feasibility
E. Costs of Compliance
F. Economic Feasibility Analysis and Regulatory Flexibility 
Determination
G. Benefits and Net Benefits
H. Regulatory Alternatives
I. Initial Regulatory Flexibility Analysis.

B. Need for Regulation

    Employees in work environments addressed by the proposed silica 
rule are exposed to a variety of significant hazards that can and do 
cause serious injury and death. As described in Chapter II of the PEA 
in support of the proposed rule, the risks to employees are excessively 
large due to the existence of various types of market failure, and 
existing and alternative methods of overcoming these negative 
consequences--such as workers' compensation systems, tort liability 
options, and information dissemination programs--have been shown to 
provide insufficient worker protection.
    After carefully weighing the various potential advantages and 
disadvantages of using a regulatory approach to improve upon the 
current situation, OSHA concludes that, in the case of silica exposure, 
the proposed mandatory standards represent the best choice for reducing 
the risks to employees. In addition, rulemaking is necessary in this 
case in order to replace older existing standards with updated, clear, 
and consistent health standards.

C. Profile of Affected Industries

1. Introduction
    Chapter III of the PEA presents profile data for industries 
potentially affected by the proposed silica rule. The discussion below 
summarizes the findings in that chapter. As a first step, OSHA 
identifies the North American Industrial Classification System (NAICS) 
industries, both in general industry and maritime and in the 
construction sector, with potential worker exposure to silica. Next, 
OSHA provides summary statistics for the affected industries, including 
the number of affected entities and establishments, the number of at-
risk workers, and the average revenue for affected entities and 
establishments. \3\ Finally, OSHA presents silica exposure profiles for 
at-risk workers. These data are presented by sector and job category. 
Summary data are also provided for the number of workers in each 
affected industry who are currently exposed above the proposed silica 
PEL of 50 [mu]g/m\3\, as well as above an alternative PEL of 100 [mu]g/
m\3\ for economic analysis purposes.
---------------------------------------------------------------------------

    \3\ An establishment is a single physical location at which 
business is conducted or services or industrial operations are 
performed. An entity is an aggregation of all establishments owned 
by a parent company within an industry with some annual payroll.
---------------------------------------------------------------------------

    The methodological basis for the industry and at-risk worker data 
presented here comes from ERG (2007a, 2007b, 2008a, and 2008b). The 
actual data presented here comes from the technological feasibility 
analyses presented in Chapter IV of the PEA and from ERG (2013), which 
updated ERG's earlier spreadsheets to reflect the most recent industry 
data available. The technological feasibility analyses identified the 
job categories with potential worker exposure to silica. ERG (2007a, 
2007b) matched the BLS Occupational Employment Survey (OES) 
occupational titles in NAICS industries with the at-risk job categories 
and then calculated the percentages of production employment 
represented by each at-risk job title.\4\ These percentages were then 
used to project the number of employees in the at-risk job categories 
by NAICS industry. OSHA welcomes additional information and data that 
might help improve the accuracy and usefulness of the industry profile 
presented here and in Chapter III of the PEA.
---------------------------------------------------------------------------

    \4\ Production employment includes workers in building and 
grounds maintenance; forestry, fishing, and farming; installation 
and maintenance; construction; production; and material handling 
occupations.
---------------------------------------------------------------------------

2. Selection of NAICS Industries for Analysis
    The technological feasibility analyses presented in Chapter IV of 
the PEA identify the general industry and maritime sectors and the 
construction activities potentially affected by the proposed silica 
standard.

[[Page 56340]]

a. General Industry and Maritime
    Employees engaged in various activities in general industry and 
maritime routinely encounter crystalline silica as a molding material, 
as an inert mineral additive, as a refractory material, as a 
sandblasting abrasive, or as a natural component of the base materials 
with which they work. Some industries use various forms of silica for 
multiple purposes. As a result, employers are challenged to limit 
worker exposure to silica in dozens of job categories throughout the 
general industry and maritime sectors.
    Job categories in general industry and maritime were selected for 
analysis based on data from the technical industrial hygiene 
literature, evidence from OSHA Special Emphasis Program (SEP) results, 
and, in several cases, information from ERG site visit reports. These 
data sources provided evidence of silica exposures in numerous sectors. 
While the available data are not entirely comprehensive, OSHA believes 
that silica exposures in other sectors are quite limited.
    The 25 industry subsectors in the overall general industry and 
maritime sectors that OSHA identified as being potentially affected by 
the proposed silica standard are as follows:

 Asphalt Paving Products
 Asphalt Roofing Materials
 Industries with Captive Foundries
 Concrete Products
 Cut Stone
 Dental Equipment and Supplies
 Dental Laboratories
 Flat Glass
 Iron Foundries
 Jewelry
 Mineral Processing
 Mineral Wool
 Nonferrous Sand Casting Foundries
 Non-Sand Casting Foundries
 Other Ferrous Sand Casting Foundries
 Other Glass Products
 Paint and Coatings
 Porcelain Enameling
 Pottery
 Railroads
 Ready-Mix Concrete
 Refractories
 Refractory Repair
 Shipyards
 Structural Clay

    In some cases, affected industries presented in the technological 
feasibility analysis have been disaggregated to facilitate the cost and 
economic impact analysis. In particular, flat glass, mineral wool, and 
other glass products are subsectors of the glass industry described in 
Chapter IV of the PEA, and captive foundries,\5\ iron foundries, 
nonferrous sand casting foundries, non-sand cast foundries, and other 
ferrous sand casting foundries are subsectors of the overall foundries 
industry presented in Chapter IV of the PEA.
---------------------------------------------------------------------------

    \5\ Captive foundries include establishments in other industries 
with foundry processes incidental to the primary products 
manufactured. ERG (2008b) provides a discussion of the 
methodological issues involved in estimating the number of captive 
foundries and in identifying the industries in which they are found.
---------------------------------------------------------------------------

    As described in ERG (2008b), OSHA identified the six-digit NAICS 
codes for these subsectors to develop a list of industries potentially 
affected by the proposed silica standard. Table VIII-2 presents the 
sectors listed above with their corresponding six-digit NAICS 
industries.
BILLING CODE 4510-26-P

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b. Construction
    The construction sector is an integral part of the nation's 
economy, accounting for almost 6 percent of total employment. 
Establishments in this industry are involved in a wide variety of 
activities, including land development and subdivision, homebuilding, 
construction of nonresidential buildings and other structures, heavy 
construction work (including roadways and bridges), and a myriad of 
special trades such as plumbing, roofing, electrical, excavation, and 
demolition work.
    Construction activities were selected for analysis based on 
historical data of recorded samples of construction worker exposures 
from the OSHA Integrated Management Information System (IMIS) and the 
National Institute for Occupational Safety and Health (NIOSH). In 
addition, OSHA reviewed the industrial hygiene literature across the 
full range of construction activities, and focused on dusty operations 
where silica sand was most likely to be fractured or abraded by work 
operations. These physical processes have been found to cause the 
silica exposures that pose the greatest risk of silicosis for workers.
    The 12 construction activities, by job category, that OSHA 
identified as being potentially affected by the proposed silica 
standard are as follows:

 Abrasive Blasters
 Drywall Finishers
 Heavy Equipment Operators
 Hole Drillers Using Hand-Held Drills
 Jackhammer and Impact Drillers
 Masonry Cutters Using Portable Saws
 Masonry Cutters Using Stationary Saws
 Millers Using Portable or Mobile Machines
 Rock and Concrete Drillers
 Rock-Crushing Machine Operators and Tenders
 Tuckpointers and Grinders
 Underground Construction Workers

    As shown in ERG (2008a) and in Chapter IV of the PEA, these 
construction activities occur in the following construction industries, 
accompanied by their four-digit NAICS codes: \6\ \7\
---------------------------------------------------------------------------

    \6\ ERG and OSHA used the four-digit NAICS codes for the 
construction sector both because the BLS's Occupational Employment 
Statistics survey only provides data at this level of detail and 
because, unlike the case in general industry and maritime, job 
categories in the construction sector are task-specific, not 
industry-specific. Furthermore, as far as economic impacts are 
concerned, IRS data on profitability are reported only at the four-
digit NAICS code level of detail.
    \7\ In addition, some public employees in state and local 
governments are exposed to elevated levels of respirable crystalline 
silica. These exposures are included in the construction sector 
because they are the result of construction activities.

 2361 Residential Building Construction
 2362 Nonresidential Building Construction
 2371 Utility System Construction
 2372 Land Subdivision
 2373 Highway, Street, and Bridge Construction
 2379 Other Heavy and Civil Engineering Construction
 2381 Foundation, Structure, and Building Exterior Contractors
 2382 Building Equipment Contractors
 2383 Building Finishing Contractors
 2389 Other Specialty Trade Contractors
Characteristics of Affected Industries
    Table VIII-3 provides an overview of the industries and estimated 
number of workers affected by the proposed rule. Included in Table 
VIII-3 are summary statistics for each of the affected industries, 
subtotals for construction and for general industry and maritime, and 
grand totals for all affected industries combined.
    The first five columns in Table VIII-3 identify each industry in 
which workers are routinely exposed to respirable crystalline silica 
(preceded by the industry's NAICS code) and the total number of 
entities, establishments, and employees for that industry. Note that 
not all entities, establishments, and employees in these affected 
industries necessarily engage in activities involving silica exposure.
    The next three columns in Table VIII-3 show, for each affected 
industry, OSHA's estimate of the number of affected entities, 
establishments, and workers--that is, the number of entities and 
establishments in which workers are actually exposed to silica and the 
total number of workers exposed to silica. Based on ERG (2007a, 2007b), 
OSHA's methodology focused on estimation of the number of affected 
workers. The number of affected establishments was set equal to the 
total number of establishments in an industry (based on Census data) 
unless the number of affected establishments would exceed the number of 
affected employees in the industry. In that case, the number of 
affected establishments in the industry was set equal to the number of 
affected employees, and the number of affected entities in the industry 
was reduced so as to maintain the same ratio of entities to 
establishments in the industry.\8\
---------------------------------------------------------------------------

    \8\ OSHA determined that removing this assumption would have a 
negligible impact on total costs and would reduce the cost and 
economic impact on the average affected establishment or entity.

[[Page 56344]]



                                            Table VIII-3--Characteristics of Industries Affected by OSHA's Proposed Standard for Silica--All Entities
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Total                                      Total affected                     Total FTE
    NAICS          Industry      Total entities    establish-         Total      Total affected  establishments  Total affected     affected      Total revenues   Revenues per    Revenues per
                                       \a\          ments \a\    employment \a\   entities \b\         \b\       employment \b\   employees \b\    ($1,000) \c\       entity       establishment
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                          Construction
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
236100.......  Residential              197,600         198,912         966,198          54,973          55,338          55,338          27,669     $374,724,410      $1,896,379      $1,883,870
                Building
                Construction.
236200.......  Nonresidential            43,634          44,702         741,978          43,634          44,702         173,939          34,788      313,592,140       7,186,876       7,015,170
                Building
                Construction.
237100.......  Utility System            20,236          21,232         496,628          20,236          21,232         217,070          96,181       98,129,343       4,849,246       4,621,766
                Construction.
237200.......  Land Subdivision          12,383          12,469          77,406           6,466           6,511           6,511           3,255       24,449,519       1,974,442       1,960,824
237300.......  Highway, Street,          11,081          11,860         325,182          11,081          11,860         204,899          66,916       96,655,241       8,722,610       8,149,683
                and Bridge
                Construction.
237900.......  Other Heavy and            5,326           5,561          90,167           5,326           5,561          46,813          18,835       19,456,230       3,653,066       3,498,693
                Civil
                Engineering
                Construction.
238100.......  Foundation,              116,836         117,456       1,167,986         116,836         117,456         559,729         111,946      157,513,197       1,348,156       1,341,040
                Structure, and
                Building
                Exterior
                Contractors.
238200.......  Building                 179,051         182,368       1,940,281          19,988          20,358          20,358          10,179      267,537,377       1,494,196       1,467,019
                Equipment
                Contractors.
238300.......  Building                 132,219         133,343         975,335         119,000         120,012         120,012          60,006      112,005,298         847,120         839,979
                Finishing
                Contractors.
238900.......  Other Specialty           73,922          74,446         557,638          73,922          74,446         274,439         137,219       84,184,953       1,138,835       1,130,819
                Trade
                Contractors.
999000.......  State and local           14,397             N/A       5,762,939          14,397              NA         170,068          85,034              N/A             N/A             N/A
                governments \d\.
                                ----------------------------------------------------------------------------------------------------------------------------------------------------------------
                  Subtotals--Co         806,685         802,349      13,101,738         485,859         477,476       1,849,175         652,029    1,548,247,709       1,954,148       1,929,644
                   nstruction.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                  General Industry and Maritime
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
324121.......  Asphalt paving               480           1,431          14,471             480           1,431           5,043  ..............        8,909,030      18,560,480       6,225,737
                mixture and
                block
                manufacturing.
324122.......  Asphalt shingle              121             224          12,631             121             224           4,395  ..............        7,168,591      59,244,556      32,002,640
                and roofing
                materials.
325510.......  Paint and                  1,093           1,344          46,209           1,093           1,344           3,285  ..............       24,113,682      22,061,923      17,941,728
                coating
                manufacturing
                \e\.
327111.......  Vitreous china                31              41           5,854              31              41           2,802  ..............          818,725      26,410,479      19,968,899
                plumbing
                fixtures &
                bathroom
                accessories
                manufacturing.
327112.......  Vitreous china,              728             731           9,178             728             731           4,394  ..............          827,296       1,136,395       1,131,731
                fine
                earthenware, &
                other pottery
                product
                manufacturing.
327113.......  Porcelain                    110             125           6,168             110             125           2,953  ..............          951,475       8,649,776       7,611,802
                electrical
                supply mfg.
327121.......  Brick and                    104             204          13,509             104             204           5,132  ..............        2,195,641      21,111,931      10,762,945
                structural clay
                mfg.
327122.......  Ceramic wall and             180             193           7,094             180             193           2,695  ..............        1,217,597       6,764,429       6,308,794
                floor tile mfg.
327123.......  Other structural              45              49           1,603              45              49             609  ..............          227,406       5,053,461       4,640,933
                clay product
                mfg.
327124.......  Clay refractory              108             129           4,475             108             129           1,646  ..............          955,377       8,846,082       7,406,022
                manufacturing.
327125.......  Nonclay                       81             105           5,640              81             105           2,075  ..............        1,453,869      17,948,999      13,846,371
                refractory
                manufacturing.
327211.......  Flat glass                    56              83          11,003              56              83             271  ..............        3,421,674      61,101,328      41,224,993
                manufacturing.
327212.......  Other pressed                457             499          20,625             457             499           1,034  ..............        3,395,635       7,430,274       6,804,880
                and blown glass
                and glassware
                manufacturing.
327213.......  Glass container               32              72          14,392              32              72             722  ..............        4,365,673     136,427,289      60,634,351
                manufacturing.
327320.......  Ready-mixed                2,470           6,064         107,190           2,470           6,064          43,920  ..............       27,904,708      11,297,453       4,601,700
                concrete
                manufacturing.
327331.......  Concrete block               599             951          22,738             599             951          10,962  ..............        5,127,518       8,560,131       5,391,712
                and brick mfg.
327332.......  Concrete pipe                194             385          14,077             194             385           6,787  ..............        2,861,038      14,747,620       7,431,268
                mfg.
327390.......  Other concrete             1,934           2,281          66,095           1,934           2,281          31,865  ..............       10,336,178       5,344,456       4,531,424
                product mfg.
327991.......  Cut stone and              1,885           1,943          30,633           1,885           1,943          12,085  ..............        3,507,209       1,860,588       1,805,048
                stone product
                manufacturing.
327992.......  Ground or                    171             271           6,629             171             271           5,051  ..............        2,205,910      12,900,061       8,139,891
                treated mineral
                and earth
                manufacturing.
327993.......  Mineral wool                 195             321          19,241             195             321           1,090  ..............        5,734,226      29,406,287      17,863,633
                manufacturing.
327999.......  All other misc.              350             465          10,028             350             465           4,835  ..............        2,538,560       7,253,028       5,459,268
                nonmetallic
                mineral product
                mfg.
331111.......  Iron and steel               686             805         108,592             523             614             614  ..............       53,496,748      77,983,597      66,455,587
                mills.
331112.......  Electrometallurg              22              22           2,198              12              12              12  ..............        1,027,769      46,716,774      46,716,774
                ical ferroalloy
                product
                manufacturing.
331210.......  Iron and steel               186             240          21,543              94             122             122  ..............        7,014,894      37,714,484      29,228,725
                pipe and tube
                manufacturing
                from purchased
                steel.
331221.......  Rolled steel                 150             170          10,857              54              61              61  ..............        4,494,254      29,961,696      26,436,790
                shape
                manufacturing.
331222.......  Steel wire                   232             288          14,669              67              83              83  ..............        3,496,143      15,069,584      12,139,387
                drawing.
331314.......  Secondary                    119             150           7,381              33              42              42  ..............        4,139,263      34,783,724      27,595,088
                smelting and
                alloying of
                aluminum.
331423.......  Secondary                     29              31           1,278               7               7               7  ..............          765,196      26,386,082      24,683,755
                smelting,
                refining, and
                alloying of
                copper.
331492.......  Secondary                    195             217           9,383              48              53              53  ..............        3,012,985      15,451,203      13,884,721
                smelting,
                refining, and
                alloying of
                nonferrous
                metal (except
                cu & al).
331511.......  Iron foundries..             457             527          59,209             457             527          22,111  ..............        9,753,093      21,341,560      18,506,818
331512.......  Steel investment             115             132          16,429             115             132           5,934  ..............        2,290,472      19,917,147      17,352,060
                foundries.
331513.......  Steel foundries              208             222          17,722             208             222           6,618  ..............        3,640,441      17,502,121      16,398,383
                (except
                investment).
331524.......  Aluminum                     441             466          26,565             441             466           9,633  ..............        3,614,233       8,195,541       7,755,866
                foundries
                (except die-
                casting).
331525.......  Copper foundries             251             256           6,120             251             256           2,219  ..............          747,437       2,977,835       2,919,674
                (except die-
                casting).
331528.......  Other nonferrous             119             124           4,710             119             124           1,708  ..............          821,327       6,901,910       6,623,607
                foundries
                (except die-
                casting).
332111.......  Iron and steel               358             398          26,596             135             150             150  ..............        5,702,872      15,929,811      14,328,825
                forging.
332112.......  Nonferrous                    67              77           8,814              43              50              50  ..............        2,080,000      31,044,783      27,012,993
                forging.
332115.......  Crown and                     50              59           3,243              15              18              18  ..............          905,206      18,104,119      15,342,473
                closure
                manufacturing.
332116.......  Metal stamping..           1,556           1,641          64,724             347             366             366  ..............       10,418,233       6,695,523       6,348,710
332117.......  Powder                       111             129           8,362              41              47              47  ..............        1,178,698      10,618,900       9,137,193
                metallurgy part
                manufacturing.
332211.......  Cutlery and                  138             141           5,779              32              33              33  ..............        1,198,675       8,686,049       8,501,240
                flatware
                (except
                precious)
                manufacturing.
332212.......  Hand and edge              1,056           1,155          36,622             189             207             207  ..............        6,382,593       6,044,123       5,526,055
                tool
                manufacturing.
332213.......  Saw blade and                127             136           7,304              39              41              41  ..............        1,450,781      11,423,474      10,667,509
                handsaw
                manufacturing.
332214.......  Kitchen utensil,              64              70           3,928              20              22              22  ..............        1,226,230      19,159,850      17,517,577
                pot, and pan
                manufacturing.
332323.......  Ornamental and             2,408           2,450          39,947              53              54              54  ..............        6,402,565       2,658,873       2,613,292
                architectural
                metal work.
332439.......  Other metal                  364             401          15,195              78              86              86  ..............        2,817,120       7,739,340       7,025,236
                container
                manufacturing.

[[Page 56345]]

 
332510.......  Hardware                     734             828          45,282             227             256             256  ..............        9,268,800      12,627,793      11,194,203
                manufacturing.
332611.......  Spring (heavy                109             113           4,059              22              23              23  ..............          825,444       7,572,882       7,304,815
                gauge)
                manufacturing.
332612.......  Spring (light                270             340          15,336              69              87              87  ..............        2,618,283       9,697,344       7,700,832
                gauge)
                manufacturing.
332618.......  Other fabricated           1,103           1,198          36,364             189             205             205  ..............        5,770,701       5,231,823       4,816,946
                wire product
                manufacturing.
332710.......  Machine shops...          21,135          21,356         266,597           1,490           1,506           1,506  ..............       32,643,382       1,544,518       1,528,534
332812.......  Metal coating              2,363           2,599          56,978           2,363           2,599           4,695  ..............       11,010,624       4,659,595       4,236,485
                and allied
                services.
332911.......  Industrial valve             394             488          38,330             175             216             216  ..............        8,446,768      21,438,497      17,308,951
                manufacturing.
332912.......  Fluid power                  306             381          35,519             161             201             201  ..............        8,044,008      26,287,608      21,112,882
                valve and hose
                fitting
                manufacturing.
332913.......  Plumbing fixture             126             144          11,513              57              65              65  ..............        3,276,413      26,003,281      22,752,871
                fitting and
                trim
                manufacturing.
332919.......  Other metal                  240             268          18,112              91             102             102  ..............        3,787,626      15,781,773      14,132,931
                valve and pipe
                fitting
                manufacturing.
332991.......  Ball and roller              107             180          27,197              91             154             154  ..............        6,198,871      57,933,374      34,438,172
                bearing
                manufacturing.
332996.......  Fabricated pipe              711             765          27,201             143             154             154  ..............        4,879,023       6,862,198       6,377,808
                and pipe
                fitting
                manufacturing.
332997.......  Industrial                   459             461           5,281              30              30              30  ..............          486,947       1,060,887       1,056,285
                pattern
                manufacturing.
332998.......  Enameled iron                 72              76           5,655              72              76              96  ..............        1,036,508      14,395,940      13,638,259
                and metal
                sanitary ware
                manufacturing.
332999.......  All other                  3,043           3,123          72,201             397             408             408  ..............       12,944,345       4,253,811       4,144,843
                miscellaneous
                fabricated
                metal product
                manufacturing.
333319.......  Other commercial           1,253           1,349          53,012             278             299             299  ..............       12,744,730      10,171,373       9,447,539
                and service
                industry
                machinery
                manufacturing.
333411.......  Air purification             303             351          14,883              72              84              84  ..............        2,428,159       8,013,727       6,917,833
                equipment
                manufacturing.
333412.......  Industrial and               142             163          10,506              52              59              59  ..............        1,962,040      13,817,181      12,037,053
                commercial fan
                and blower
                manufacturing.
333414.......  Heating                      377             407          20,577             108             116             116  ..............        4,266,536      11,317,071      10,482,888
                equipment
                (except warm
                air furnaces)
                manufacturing.
333511.......  Industrial mold            2,084           2,126          39,917             221             226             226  ..............        4,963,915       2,381,917       2,334,861
                manufacturing.
333512.......  Machine tool                 514             530          17,220              94              97              97  ..............        3,675,264       7,150,320       6,934,461
                (metal cutting
                types)
                manufacturing.
333513.......  Machine tool                 274             285           8,556              46              48              48  ..............        1,398,993       5,105,812       4,908,746
                (metal forming
                types)
                manufacturing.
333514.......  Special die and            3,172           3,232          57,576             319             325             325  ..............        7,232,706       2,280,172       2,237,842
                tool, die set,
                jig, and
                fixture
                manufacturing.
333515.......  Cutting tool and           1,482           1,552          34,922             188             197             197  ..............        4,941,932       3,334,637       3,184,235
                machine tool
                accessory
                manufacturing.
333516.......  Rolling mill                  70              73           3,020              17              17              17  ..............          652,141       9,316,299       8,933,437
                machinery and
                equipment
                manufacturing.
333518.......  Other                        362             383          12,470              67              70              70  ..............        2,605,582       7,197,740       6,803,086
                metalworking
                machinery
                manufacturing.
333612.......  Speed changer,               197             226          12,374              61              70              70  ..............        2,280,825      11,577,790      10,092,145
                industrial high-
                speed drive,
                and gear
                manufacturing.
333613.......  Mechanical power             196             231          15,645              75              88              88  ..............        3,256,010      16,612,294      14,095,280
                transmission
                equipment
                manufacturing.
333911.......  Pump and pumping             413             490          30,764             147             174             174  ..............        7,872,517      19,061,785      16,066,362
                equipment
                manufacturing.
333912.......  Air and gas                  272             318          21,417             104             121             121  ..............        6,305,944      23,183,616      19,830,011
                compressor
                manufacturing.
333991.......  Power-driven                 137             150           8,714              45              49              49  ..............        3,115,514      22,740,979      20,770,094
                handtool
                manufacturing.
333992.......  Welding and                  250             275          15,853              82              90              90  ..............        4,257,678      17,030,713      15,482,466
                soldering
                equipment
                manufacturing.
333993.......  Packaging                    583             619          21,179             113             120             120  ..............        4,294,579       7,366,345       6,937,931
                machinery
                manufacturing.
333994.......  Industrial                   312             335          10,720              56              61              61  ..............        1,759,938       5,640,828       5,253,548
                process furnace
                and oven
                manufacturing.
333995.......  Fluid power                  269             319          19,887              95             112             112  ..............        3,991,832      14,839,523      12,513,579
                cylinder and
                actuator
                manufacturing.
333996.......  Fluid power pump             146             178          13,631              63              77              77  ..............        3,019,188      20,679,367      16,961,728
                and motor
                manufacturing.
333997.......  Scale and                     95             102           3,748              20              21              21  ..............          694,419       7,309,671       6,808,027
                balance (except
                laboratory)
                manufacturing.
333999.......  All other                  1,630           1,725          52,454             280             296             296  ..............        9,791,511       6,007,062       5,676,238
                miscellaneous
                general purpose
                machinery
                manufacturing.
334518.......  Watch, clock,                104             106           2,188              12              12              12  ..............          491,114       4,722,250       4,633,151
                and part
                manufacturing.
335211.......  Electric                      99             105           7,425              20              22              22  ..............        2,175,398      21,973,717      20,718,076
                housewares and
                household fans.
335221.......  Household                    116             125          16,033              43              47              47  ..............        4,461,008      38,456,968      35,688,066
                cooking
                appliance
                manufacturing.
335222.......  Household                     18              26          17,121              18              26              50  ..............        4,601,594     255,644,105     176,984,380
                refrigerator
                and home
                freezer
                manufacturing.
335224.......  Household                     17              23          16,269              17              23              47  ..............        4,792,444     281,908,445     208,367,112
                laundry
                equipment
                manufacturing.
335228.......  Other major                   39              45          12,806              32              37              37  ..............        4,549,859     116,663,058     101,107,984
                household
                appliance
                manufacturing.
336111.......  Automobile                   167             181          75,225             167             181             425  ..............       87,308,106     522,803,033     482,365,229
                manufacturing.
336112.......  Light truck and               63              94         103,815              63              94             587  ..............      139,827,543   2,219,484,812   1,487,527,055
                utility vehicle
                manufacturing.
336120.......  Heavy duty truck              77              95          32,122              77              95             181  ..............       17,387,065     225,806,042     183,021,739
                manufacturing.
336211.......  Motor vehicle                728             820          47,566             239             269             269  ..............       11,581,029      15,908,007      14,123,206
                body
                manufacturing.
336212.......  Truck trailer                353             394          32,260             163             182             182  ..............        6,313,133      17,884,229      16,023,179
                manufacturing.
336213.......  Motor home                    79              91          21,533              79              91             122  ..............        5,600,569      70,893,283      61,544,718
                manufacturing.
336311.......  Carburetor,                  102             116          10,537              52              60              60  ..............        2,327,226      22,815,945      20,062,296
                piston, piston
                ring, and valve
                manufacturing.
336312.......  Gasoline engine              810             876          66,112             345             373             373  ..............       30,440,351      37,580,680      34,749,259
                and engine
                parts
                manufacturing.
336322.......  Other motor                  643             697          62,016             323             350             350  ..............       22,222,133      34,560,082      31,882,544
                vehicle
                electrical and
                electronic
                equipment
                manufacturing.
336330.......  Motor vehicle                214             257          39,390             185             223             223  ..............       10,244,934      47,873,524      39,863,557
                steering and
                suspension
                components
                (except spring)
                manufacturing.
336340.......  Motor vehicle                188             241          33,782             149             191             191  ..............       11,675,801      62,105,323      48,447,306
                brake system
                manufacturing.
336350.......  Motor vehicle                432             535          83,756             382             473             473  ..............       31,710,273      73,403,409      59,271,538
                transmission
                and power train
                parts
                manufacturing.
336370.......  Motor vehicle                635             781         110,578             508             624             624  ..............       24,461,822      38,522,554      31,321,154
                metal stamping.
336399.......  All other motor            1,189           1,458         149,251             687             843             843  ..............       42,936,991      36,111,851      29,449,239
                vehicle parts
                manufacturing.
336611.......  Ship building                575             635          87,352             575             635           2,798  ..............       14,650,189      25,478,589      23,071,163
                and repair.
336612.......  Boat building...           1,066           1,129          54,705           1,066           1,129           1,752  ..............       10,062,908       9,439,876       8,913,116
336992.......  Military armored              47              57           6,899              32              39              39  ..............        2,406,966      51,212,047      42,227,477
                vehicle, tank,
                and tank
                component
                manufacturing.
337215.......  Showcase,                  1,647           1,733          59,080             317             334             334  ..............        8,059,533       4,893,462       4,650,625
                partition,
                shelving, and
                locker
                manufacturing.
339114.......  Dental equipment             740             763          15,550             399             411             411  ..............        3,397,252       4,590,881       4,452,493
                and supplies
                manufacturing.
339116.......  Dental                     7,028           7,261          47,088           7,028           7,261          33,214  ..............        3,852,293         548,135         530,546
                laboratories.
339911.......  Jewelry (except            1,760           1,777          25,280           1,760           1,777           7,813  ..............        6,160,238       3,500,135       3,466,650
                costume)
                manufacturing.
339913.......  Jewelers'                    261             264           5,199             261             264           1,607  ..............          934,387       3,580,028       3,539,346
                materials and
                lapidary work
                manufacturing.
339914.......  Costume jewelry              590             590           6,775             590             590           1,088  ..............          751,192       1,273,206       1,273,206
                and novelty
                manufacturing.

[[Page 56346]]

 
339950.......  Sign                       6,291           6,415          89,360             487             496             496  ..............       11,299,429       1,796,126       1,761,407
                manufacturing.
423840.......  Industrial                 7,016          10,742         111,198             250             383             383  ..............       19,335,522       2,755,918       1,799,993
                supplies,
                wholesalers.
482110.......  Rail                         N/A             N/A             N/A             N/A             N/A          16,895  ..............              N/A             N/A             N/A
                transportation.
621210.......  Dental offices..         119,471         124,553         817,396           7,655           7,980           7,980  ..............       88,473,742         740,546         710,330
                                ----------------------------------------------------------------------------------------------------------------------------------------------------------------
                  Subtotals--Ge         219,203         238,942       4,406,990          47,007          56,121         294,886  ..............    1,101,555,989       5,025,278       4,610,140
                   neral
                   Industry and
                   maritime.
                                ----------------------------------------------------------------------------------------------------------------------------------------------------------------
                  Totals--All         1,025,888       1,041,291      17,508,728         532,866         533,597       2,144,061         652,029   $2,649,803,698      $2,619,701      $2,544,729
                   Industries.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
a U.S. Census Bureau, Statistics of U.S. Businesses, 2006.
\b\ OSHA estimates of employees potentially exposed to silica and associated entities and establishments. Affected entities and establishments constrained to be less than or equal to the
  number of affected employees.
\c\ Estimates based on 2002 receipts and payroll data from U.S. Census Bureau, Statistics of U.S. Businesses, 2002, and payroll data from the U.S. Census Bureau, Statistics of U.S. Businesses,
  2006. Receipts are not reported for 2006, but were estimated assuming the ratio of receipts to payroll remained unchanged from 2002 to 2006.
\d\ State-plan states only. State and local governments are included under the construction sector because the silica risks for public employees are the result of construction-related
  activities.
\e\ OSHA estimates that only one-third of the entities and establishments in this industry, as reported above, use silica-containing inputs.
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG, 2013.


[[Page 56347]]

    As shown in Table VIII-3, OSHA estimates that a total of 533,000 
entities (486,000 in construction; 47,000 in general industry and 
maritime), 534,000 establishments (477,500 in construction; 56,100 in 
general industry and maritime), and 2.1 million workers (1.8 million in 
construction; 0.3 million in general industry and maritime) would be 
affected by the proposed silica rule. Note that only slightly more than 
50 percent of the entities and establishments, and about 12 percent of 
the workers in affected industries, actually engage in activities 
involving silica exposure.\9\
---------------------------------------------------------------------------

    \9\ It should be emphasized that these percentages vary 
significantly depending on the industry sector and, within an 
industry sector, depending on the NAICS industry. For example, about 
14 percent of the workers in construction, but only 7 percent of 
workers in general industry, actually engage in activities involving 
silica exposure. As an example within construction, about 63 percent 
of workers in highway, street, and bridge construction, but only 3 
percent of workers in state and local governments, actually engage 
in activities involving silica exposure.
---------------------------------------------------------------------------

    The ninth column in Table VIII-3, with data only for construction, 
shows for each affected NAICS construction industry the number of full-
time-equivalent (FTE) affected workers that corresponds to the total 
number of affected construction workers in the previous column.\10\ 
This distinction is necessary because affected construction workers may 
spend large amounts of time working on tasks with no risk of silica 
exposure. As shown in Table VIII-3, the 1.8 million affected workers in 
construction converts to approximately 652,000 FTE affected workers. In 
contrast, OSHA based its analysis of the affected workers in general 
industry and maritime on the assumption that they were engaged full 
time in activities with some silica exposure.
---------------------------------------------------------------------------

    \10\ FTE affected workers becomes a relevant variable in the 
estimation of control costs in the construction industry. The reason 
is that, consistent with the costing methodology, control costs 
depend only on how many worker-days there are in which exposures are 
above the PEL. These are the worker-days in which controls are 
required. For the derivation of FTEs, see Tables IV-8 and IV-22 and 
the associated text in ERG (2007a).
---------------------------------------------------------------------------

    The last three columns in Table VIII-3 show combined total revenues 
for all entities (not just affected entities) in each affected 
industry, and the average revenue per entity and per establishment in 
each affected industry. Because OSHA did not have data to distinguish 
revenues for affected entities and establishments in any industry, 
average revenue per entity and average revenue per affected entity (as 
well as average revenue per establishment and average revenue per 
affected establishment) are estimated to be equal in value.
Silica Exposure Profile of At-Risk Workers
    The technological feasibility analyses presented in Chapter IV of 
the PEA contain data and discussion of worker exposures to silica 
throughout industry. Exposure profiles, by job category, were developed 
from individual exposure measurements that were judged to be 
substantive and to contain sufficient accompanying description to allow 
interpretation of the circumstance of each measurement. The resulting 
exposure profiles show the job categories with current overexposures to 
silica and, thus, the workers for whom silica controls would be 
implemented under the proposed rule.
    Chapter IV of the PEA includes a section with a detailed 
description of the methods used to develop the exposure profile and to 
assess the technological feasibility of the proposed standard. That 
section documents how OSHA selected and used the data to establish the 
exposure profiles for each operation in the affected industry sectors, 
and discusses sources of uncertainly including the following:
     Data Selection--OSHA discusses how exposure samples with 
sample durations of less than 480 minutes (an 8-hour shift) are used in 
the analysis.
     Use of IMIS data--OSHA discusses the limitations of data 
from its Integrated Management Information System.
     Use of analogous information--OSHA discusses how 
information from one industry or operation is used to describe 
exposures in other industries or operations with similar 
characteristics.
     Non-Detects--OSHA discusses how exposure data that is 
identified as ``less than the LOD (limit of detection)'' is used in the 
analysis.
    OSHA seeks comment on the assumptions and data selection criteria 
the Agency used to develop the exposure profiles shown in Chapter IV of 
the PEA.
    Table VIII-4 summarizes, from the exposure profiles, the total 
number of workers at risk from silica exposure at any level, and the 
distribution of 8-hour TWA respirable crystalline silica exposures by 
job category for general industry and maritime sectors and for 
construction activities. Exposures are grouped into the following 
ranges: less than 25 [mu]g/m\3\; >= 25 [mu]g/m\3\ and <= 50 [mu]g/m\3\; 
> 50 [mu]g/m\3\ and <= 100 [mu]g/m\3\; > 100 [mu]g/m\3\ and <= 250 
[mu]g/m\3\; and greater than 250 [mu]g/m\3\. These frequencies 
represent the percentages of production employees in each job category 
and sector currently exposed at levels within the indicated range.
    Table VIII-5 presents data by NAICS code--for each affected 
general, maritime, and construction industry--on the estimated number 
of workers currently at risk from silica exposure, as well as the 
estimated number of workers at risk of silica exposure at or above 25 
[mu]g/m\3\, above 50 [mu]g/m\3\, and above 100 [mu]g/m\3\. As shown, an 
estimated 1,026,000 workers (851,000 in construction; 176,000 in 
general industry and maritime) currently have silica exposures at or 
above the proposed action level of 25 [mu]g/m\3\; an estimated 770,000 
workers (648,000 in construction; 122,000 in general industry and 
maritime) currently have silica exposures above the proposed PEL of 50 
[mu]g/m\3\; and an estimated 501,000 workers (420,000 in construction; 
81,000 in general industry and maritime) currently have silica 
exposures above 100 [mu]g/m\3\--an alternative PEL investigated by OSHA 
for economic analysis purposes.
BILLING CODE 4510-26-P

[[Page 56348]]

[GRAPHIC] [TIFF OMITTED] TP12SE13.006


[[Page 56349]]


[GRAPHIC] [TIFF OMITTED] TP12SE13.007

BILLING CODE 4510-26-C

                        Table VIII-5--Numbers of Workers Exposed to Silica (by Affected Industry and Exposure Level ([mu]g/m\3\))
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                            Numbers exposed to Silica
             NAICS                      Industry            Number of       Number of   ----------------------------------------------------------------
                                                         establishments     employees        >=0          >=25         >=50        >=100        >=250
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      Construction
--------------------------------------------------------------------------------------------------------------------------------------------------------
236100.........................  Residential Building          198,912          966,198       55,338       32,260       24,445       14,652        7,502
                                  Construction.
236200.........................  Nonresidential                 44,702          741,978      173,939       83,003       63,198       39,632       20,504
                                  Building Construction.
237100.........................  Utility System                 21,232          496,628      217,070       76,687       53,073       28,667        9,783
                                  Construction.
237200.........................  Land Subdivision......         12,469           77,406        6,511        1,745        1,172          560          186

[[Page 56350]]

 
237300.........................  Highway, Street, and           11,860          325,182      204,899       58,441       39,273       19,347        7,441
                                  Bridge Construction.
237900.........................  Other Heavy and Civil           5,561           90,167       46,813       12,904        8,655        4,221        1,369
                                  Engineering
                                  Construction.
238100.........................  Foundation, Structure,        117,456        1,167,986      559,729      396,582      323,119      237,537      134,355
                                  and Building Exterior
                                  Contractors.
238200.........................  Building Equipment            182,368        1,940,281       20,358        6,752        4,947        2,876        1,222
                                  Contractors.
238300.........................  Building Finishing            133,343          975,335      120,012       49,202       37,952       24,662       14,762
                                  Contractors.
238900.........................  Other Specialty Trade          74,446          557,638      274,439       87,267       60,894       32,871       13,718
                                  Contractors.
999000.........................  State and local                    NA        5,762,939      170,068       45,847       31,080       15,254        5,161
                                  governments [d].
                                ------------------------------------------------------------------------------------------------------------------------
    Subtotals--Construction....  ......................        802,349       13,101,738    1,849,175      850,690      647,807      420,278      216,003
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              General Industry and Maritime
--------------------------------------------------------------------------------------------------------------------------------------------------------
324121.........................  Asphalt paving mixture          1,431           14,471        5,043           48           48            0            0
                                  and block
                                  manufacturing.
324122.........................  Asphalt shingle and               224           12,631        4,395        4,395        1,963          935            0
                                  roofing materials.
325510.........................  Paint and coating               1,344           46,209        3,285          404          404          404          404
                                  manufacturing.
327111.........................  Vitreous china                     41            5,854        2,802        2,128        1,319          853          227
                                  plumbing fixtures &
                                  bathroom accessories
                                  manufacturing.
327112.........................  Vitreous china, fine              731            9,178        4,394        3,336        2,068        1,337          356
                                  earthenware, & other
                                  pottery product
                                  manufacturing.
327113.........................  Porcelain electrical              125            6,168        2,953        2,242        1,390          898          239
                                  supply mfg.
327121.........................  Brick and structural              204           13,509        5,132        3,476        2,663        1,538          461
                                  clay mfg.
327122.........................  Ceramic wall and floor            193            7,094        2,695        1,826        1,398          808          242
                                  tile mfg.
327123.........................  Other structural clay              49            1,603          609          412          316          182           55
                                  product mfg.
327124.........................  Clay refractory                   129            4,475        1,646          722          364          191           13
                                  manufacturing.
327125.........................  Nonclay refractory                105            5,640        2,075          910          459          241           17
                                  manufacturing.
327211.........................  Flat glass                         83           11,003          271          164          154           64           45
                                  manufacturing.
327212.........................  Other pressed and                 499           20,625        1,034          631          593          248          172
                                  blown glass and
                                  glassware
                                  manufacturing.
327213.........................  Glass container                    72           14,392          722          440          414          173          120
                                  manufacturing.
327320.........................  Ready-mixed concrete            6,064          107,190       43,920       32,713       32,110       29,526       29,526
                                  manufacturing.
327331.........................  Concrete block and                951           22,738       10,962        5,489        3,866        2,329          929
                                  brick mfg.
327332.........................  Concrete pipe mfg.....            385           14,077        6,787        3,398        2,394        1,442          575
327390.........................  Other concrete product          2,281           66,095       31,865       15,957       11,239        6,769        2,700
                                  mfg.
327991.........................  Cut stone and stone             1,943           30,633       12,085       10,298        7,441        4,577        1,240
                                  product manufacturing.
327992.........................  Ground or treated                 271            6,629        5,051        5,051          891          297            0
                                  mineral and earth
                                  manufacturing.
327993.........................  Mineral wool                      321           19,241        1,090          675          632          268          182
                                  manufacturing.
327999.........................  All other misc.                   465           10,028        4,835        2,421        1,705        1,027          410
                                  nonmetallic mineral
                                  product mfg.
331111.........................  Iron and steel mills..            805          108,592          614          456          309          167           57
331112.........................  Electrometallurgical               22            2,198           12            9            6            3            1
                                  ferroalloy product
                                  manufacturing.
331210.........................  Iron and steel pipe               240           21,543          122           90           61           33           11
                                  and tube
                                  manufacturing from
                                  purchased steel.
331221.........................  Rolled steel shape                170           10,857           61           46           31           17            6
                                  manufacturing.
331222.........................  Steel wire drawing....            288           14,669           83           62           42           23            8
331314.........................  Secondary smelting and            150            7,381           42           31           21           11            4
                                  alloying of aluminum.
331423.........................  Secondary smelting,                31            1,278            7            5            4            2            1
                                  refining, and
                                  alloying of copper.
331492.........................  Secondary smelting,               217            9,383           53           39           27           14            5
                                  refining, and
                                  alloying of
                                  nonferrous metal
                                  (except cu & al).
331511.........................  Iron foundries........            527           59,209       22,111       16,417       11,140        6,005        2,071
331512.........................  Steel investment                  132           16,429        5,934        4,570        3,100        1,671          573
                                  foundries.
331513.........................  Steel foundries                   222           17,722        6,618        4,914        3,334        1,797          620
                                  (except investment).
331524.........................  Aluminum foundries                466           26,565        9,633        7,418        5,032        2,712          931
                                  (except die-casting).
331525.........................  Copper foundries                  256            6,120        2,219        1,709        1,159          625          214
                                  (except die-casting).
331528.........................  Other nonferrous                  124            4,710        1,708        1,315          892          481          165
                                  foundries (except die-
                                  casting).
332111.........................  Iron and steel forging            398           26,596          150          112           76           41           14
332112.........................  Nonferrous forging....             77            8,814           50           37           25           13            5
332115.........................  Crown and closure                  59            3,243           18           14            9            5            2
                                  manufacturing.
332116.........................  Metal stamping........          1,641           64,724          366          272          184           99           34
332117.........................  Powder metallurgy part            129            8,362           47           35           24           13            4
                                  manufacturing.
332211.........................  Cutlery and flatware              141            5,779           33           24           16            9            3
                                  (except precious)
                                  manufacturing.
332212.........................  Hand and edge tool              1,155           36,622          207          154          104           56           19
                                  manufacturing.
332213.........................  Saw blade and handsaw             136            7,304           41           31           21           11            4
                                  manufacturing.
332214.........................  Kitchen utensil, pot,              70            3,928           22           17           11            6            2
                                  and pan manufacturing.

[[Page 56351]]

 
332323.........................  Ornamental and                  2,450           39,947           54           26           19            7            7
                                  architectural metal
                                  work.
332439.........................  Other metal container             401           15,195           86           64           43           23            8
                                  manufacturing.
332510.........................  Hardware manufacturing            828           45,282          256          190          129           69           24
332611.........................  Spring (heavy gauge)              113            4,059           23           17           12            6            2
                                  manufacturing.
332612.........................  Spring (light gauge)              340           15,336           87           64           44           24            8
                                  manufacturing.
332618.........................  Other fabricated wire           1,198           36,364          205          153          104           56           19
                                  product manufacturing.
332710.........................  Machine shops.........         21,356          266,597        1,506        1,118          759          409          141
332812.........................  Metal coating and               2,599           56,978        4,695        2,255        1,632          606          606
                                  allied services.
332911.........................  Industrial valve                  488           38,330          216          161          109           59           20
                                  manufacturing.
332912.........................  Fluid power valve and             381           35,519          201          149          101           55           19
                                  hose fitting
                                  manufacturing.
332913.........................  Plumbing fixture                  144           11,513           65           48           33           18            6
                                  fitting and trim
                                  manufacturing.
332919.........................  Other metal valve and             268           18,112          102           76           51           28           10
                                  pipe fitting
                                  manufacturing.
332991.........................  Ball and roller                   180           27,197          154          114           77           42           14
                                  bearing manufacturing.
332996.........................  Fabricated pipe and               765           27,201          154          114           77           42           14
                                  pipe fitting
                                  manufacturing.
332997.........................  Industrial pattern                461            5,281           30           22           15            8            3
                                  manufacturing.
332998.........................  Enameled iron and                  76            5,655           96           56           38           16           11
                                  metal sanitary ware
                                  manufacturing.
332999.........................  All other                       3,123           72,201          408          303          205          111           38
                                  miscellaneous
                                  fabricated metal
                                  product manufacturing.
333319.........................  Other commercial and            1,349           53,012          299          222          151           81           28
                                  service industry
                                  machinery
                                  manufacturing.
333411.........................  Air purification                  351           14,883           84           62           42           23            8
                                  equipment
                                  manufacturing.
333412.........................  Industrial and                    163           10,506           59           44           30           16            6
                                  commercial fan and
                                  blower manufacturing.
333414.........................  Heating equipment                 407           20,577          116           86           59           32           11
                                  (except warm air
                                  furnaces)
                                  manufacturing.
333511.........................  Industrial mold                 2,126           39,917          226          168          114           61           21
                                  manufacturing.
333512.........................  Machine tool (metal               530           17,220           97           72           49           26            9
                                  cutting types)
                                  manufacturing.
333513.........................  Machine tool (metal               285            8,556           48           36           24           13            5
                                  forming types)
                                  manufacturing.
333514.........................  Special die and tool,           3,232           57,576          325          241          164           88           30
                                  die set, jig, and
                                  fixture manufacturing.
333515.........................  Cutting tool and                1,552           34,922          197          146           99           54           18
                                  machine tool
                                  accessory
                                  manufacturing.
333516.........................  Rolling mill machinery             73            3,020           17           13            9            5            2
                                  and equipment
                                  manufacturing.
333518.........................  Other metalworking                383           12,470           70           52           35           19            7
                                  machinery
                                  manufacturing.
333612.........................  Speed changer,                    226           12,374           70           52           35           19            7
                                  industrial high-speed
                                  drive, and gear
                                  manufacturing.
333613.........................  Mechanical power                  231           15,645           88           66           44           24            8
                                  transmission
                                  equipment
                                  manufacturing.
333911.........................  Pump and pumping                  490           30,764          174          129           88           47           16
                                  equipment
                                  manufacturing.
333912.........................  Air and gas compressor            318           21,417          121           90           61           33           11
                                  manufacturing.
333991.........................  Power-driven handtool             150            8,714           49           37           25           13            5
                                  manufacturing.
333992.........................  Welding and soldering             275           15,853           90           67           45           24            8
                                  equipment
                                  manufacturing.
333993.........................  Packaging machinery               619           21,179          120           89           60           32           11
                                  manufacturing.
333994.........................  Industrial process                335           10,720           61           45           31           16            6
                                  furnace and oven
                                  manufacturing.
333995.........................  Fluid power cylinder              319           19,887          112           83           57           31           11
                                  and actuator
                                  manufacturing.
333996.........................  Fluid power pump and              178           13,631           77           57           39           21            7
                                  motor manufacturing.
333997.........................  Scale and balance                 102            3,748           21           16           11            6            2
                                  (except laboratory)
                                  manufacturing.
333999.........................  All other                       1,725           52,454          296          220          149           80           28
                                  miscellaneous general
                                  purpose machinery
                                  manufacturing.
334518.........................  Watch, clock, and part            106            2,188           12            9            6            3            1
                                  manufacturing.
335211.........................  Electric housewares               105            7,425           22           10            8            3            3
                                  and household fans.
335221.........................  Household cooking                 125           16,033           47           22           16            6            6
                                  appliance
                                  manufacturing.
335222.........................  Household refrigerator             26           17,121           50           24           17            7            7
                                  and home freezer
                                  manufacturing.
335224.........................  Household laundry                  23           16,269           47           23           17            6            6
                                  equipment
                                  manufacturing.
335228.........................  Other major household              45           12,806           37           18           13            5            5
                                  appliance
                                  manufacturing.
336111.........................  Automobile                        181           75,225          425          316          214          115           40
                                  manufacturing.

[[Page 56352]]

 
336112.........................  Light truck and                    94          103,815          587          436          296          159           55
                                  utility vehicle
                                  manufacturing.
336120.........................  Heavy duty truck                   95           32,122          181          135           91           49           17
                                  manufacturing.
336211.........................  Motor vehicle body                820           47,566          269          200          135           73           25
                                  manufacturing.
336212.........................  Truck trailer                     394           32,260          182          135           92           50           17
                                  manufacturing.
336213.........................  Motor home                         91           21,533          122           90           61           33           11
                                  manufacturing.
336311.........................  Carburetor, piston,               116           10,537           60           44           30           16            6
                                  piston ring, and
                                  valve manufacturing.
336312.........................  Gasoline engine and               876           66,112          373          277          188          101           35
                                  engine parts
                                  manufacturing.
336322.........................  Other motor vehicle               697           62,016          350          260          176           95           33
                                  electrical and
                                  electronic equipment
                                  manufacturing.
336330.........................  Motor vehicle steering            257           39,390          223          165          112           60           21
                                  and suspension
                                  components (except
                                  spring) manufacturing.
336340.........................  Motor vehicle brake               241           33,782          191          142           96           52           18
                                  system manufacturing.
336350.........................  Motor vehicle                     535           83,756          473          351          238          128           44
                                  transmission and
                                  power train parts
                                  manufacturing.
336370.........................  Motor vehicle metal               781          110,578          624          464          315          170           58
                                  stamping.
336399.........................  All other motor                 1,458          149,251          843          626          425          229           79
                                  vehicle parts
                                  manufacturing.
336611.........................  Ship building and                 635           87,352        2,798        2,798        1,998        1,599        1,199
                                  repair.
336612.........................  Boat building.........          1,129           54,705        1,752        1,752        1,252        1,001          751
336992.........................  Military armored                   57            6,899           39           29           20           11            4
                                  vehicle, tank, and
                                  tank component
                                  manufacturing.
337215.........................  Showcase, partition,            1,733           59,080          334          248          168           91           31
                                  shelving, and locker
                                  manufacturing.
339114.........................  Dental equipment and              763           15,550          411          274          274          137            0
                                  supplies
                                  manufacturing.
339116.........................  Dental laboratories...          7,261           47,088       33,214        5,357        1,071            0            0
339911.........................  Jewelry (except                 1,777           25,280        7,813        4,883        3,418        2,442          977
                                  costume)
                                  manufacturing.
339913.........................  Jewelers' materials               264            5,199        1,607        1,004          703          502          201
                                  and lapidary work
                                  manufacturing.
339914.........................  Costume jewelry and               590            6,775        1,088          685          479          338          135
                                  novelty manufacturing.
339950.........................  Sign manufacturing....          6,415           89,360          496          249          172           57           57
423840.........................  Industrial supplies,           10,742          111,198          383          306          153           77            0
                                  wholesalers.
482110.........................  Rail transportation...             NA               NA       16,895       11,248        5,629        2,852        1,233
621210.........................  Dental offices........        124,553          817,396        7,980        1,287          257            0            0
                                ------------------------------------------------------------------------------------------------------------------------
    Subtotals--General Industry  ......................        238,942        4,406,990      294,886      175,801      122,472       80,731       48,956
     and Maritime.
                                ------------------------------------------------------------------------------------------------------------------------
        Totals.................  ......................      1,041,291       17,508,728    2,144,061    1,026,491      770,280      501,009      264,959
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on Table III-5 and the technological
  feasibility analysis presented in Chapter IV of the PEA.

D. Technological Feasibility Analysis of the Proposed Permissible 
Exposure Limit to Crystalline Silica Exposures

    Chapter IV of the Preliminary Economic Analysis (PEA) provides the 
technological feasibility analysis that guided OSHA's selection of the 
proposed PEL, consistent with the requirements of the Occupational 
Safety and Health Act (``OSH Act''), 29 U.S.C. 651 et seq. Section 
6(b)(5) of the OSH Act requires that OSHA ``set the standard which most 
adequately assures, to the extent feasible, on the basis of the best 
available evidence, that no employee will suffer material impairment of 
health or functional capacity.'' 29 U.S.C. 655(b)(5) (emphasis added). 
The Court of Appeals for the D.C. Circuit has clarified the Agency's 
obligation to demonstrate the technological feasibility of reducing 
occupational exposure to a hazardous substance:

    OSHA must prove a reasonable possibility that the typical firm 
will be able to develop and install engineering and work practice 
controls that can meet the PEL in most of its operations . . . The 
effect of such proof is to establish a presumption that industry can 
meet the PEL without relying on respirators . . . Insufficient proof 
of technological feasibility for a few isolated operations within an 
industry, or even OSHA's concession that respirators will be 
necessary in a few such operations, will not undermine this general 
presumption in favor of feasibility. Rather, in such operations 
firms will remain responsible for installing engineering and work 
practice controls to the extent feasible, and for using them to 
reduce . . . exposure as far as these controls can do so.

United Steelworkers of America, AFL-CIO-CIC v. Marshall, 647 F.2d 1189, 
1272 (D.C. Cir. 1980).
    Additionally, the D.C. Circuit has explained that ``[f]easibility 
of compliance turns on whether exposure levels at or below [the PEL] 
can be met in most operations most of the time. . . .'' American Iron & 
Steel Inst. v. OSHA, 939 F.2d 975, 990 (D.C. Cir. 1991).
    To demonstrate the limits of feasibility, OSHA's analysis examines 
the technological feasibility of the proposed PEL of 50 [mu]g/m\3\, as 
well as

[[Page 56353]]

the technological feasibility of an alternative PEL of 25 [mu]g/m\3\. 
In total, OSHA analyzed technological feasibility in 108 operations in 
general industry, maritime, and construction industries. This analysis 
addresses two different aspects of technological feasibility: (1) The 
extent to which engineering controls can reduce and maintain exposures; 
and (2) the capability of existing sampling and analytical methods to 
measure silica exposures. The discussion below summarizes the findings 
in Chapter IV of the PEA (see Docket No. OSHA-2010-0034).
Methodology
    The technological feasibility analysis relies on information from a 
wide variety of sources. These sources include published literature, 
OSHA inspection reports, NIOSH reports and engineering control 
feasibility studies, and information from other federal agencies, state 
agencies, labor organizations, industry associations, and other groups. 
OSHA has limited the analysis to job categories that are associated 
with substantial direct silica exposure. The technological feasibility 
analyses group the general industry and maritime workplaces into 23 
industry sectors.\11\ The Agency has divided each industry sector into 
specific job categories on the basis of common materials, work 
processes, equipment, and available exposure control methods. OSHA 
notes that these job categories are intended to represent job 
functions; actual job titles and responsibilities might differ 
depending on the facility.
---------------------------------------------------------------------------

    \11\ Note that OSHA's technological feasibility analysis 
contains 21 general industry sections. The number is expanded to 23 
in this summary because Table VIII.D-1 describes the foundry 
industry as three different sectors (ferrous, nonferrous, and non-
sand casting foundries) to provide a more detailed analysis of 
exposures.
---------------------------------------------------------------------------

    OSHA has organized the construction industry by grouping workers 
into 12 general construction activities. The Agency organized 
construction workers into general activities that create silica 
exposures rather than organizing them by job titles because 
construction workers often perform multiple activities and job titles 
do not always coincide with the sources of exposure. In organizing 
construction worker activity this way, OSHA was able to create a more 
accurate exposure profile and apply control methods to workers who 
perform these activities in any segment of the construction industry.
    The exposure profiles include silica exposure data only for workers 
in the United States. Information on international exposure levels is 
occasionally referenced for perspective or in discussions of control 
options. It is important to note that the vast majority of crystalline 
silica encountered by workers in the United States is in the quartz 
form, and the terms crystalline silica and quartz are often used 
interchangeably. Unless specifically indicated otherwise, all silica 
exposure data, samples, and results discussed in the technological 
feasibility analysis refer to measurements of personal breathing zone 
(PBZ) respirable crystalline silica.
    In general and maritime industries, the exposure profiles in the 
technological feasibility analysis consist mainly of full-shift 
samples, collected over periods of 360 minutes or more. By using full-
shift sampling results, OSHA minimizes the number of results that are 
less than the limit of detection (LOD) and eliminates the ambiguity 
associated with the LOD for low air volume samples. Thus, results that 
are reported in the original data source as below the LOD are included 
without contributing substantial uncertainty regarding their 
relationship to the proposed PEL. This is particularly important for 
general industry samples, which on average have lower silica levels 
than typical results for many tasks in the construction industry.
    In general and maritime industries, the exposure level for the 
period sampled is assumed to have continued over any unsampled portion 
of the worker's shift. OSHA has preliminarily determined that this 
sample criterion is valid because workers in these industries are 
likely to work at the same general task or same repeating set of tasks 
over most of their shift; thus, unsampled periods generally are likely 
to be similar to the sampled periods.
    In the construction industry, much of the data analyzed for the 
defined activities consisted of full-shift samples collected over 
periods of 360 minutes or more. Construction workers are likely to 
spend a shift working at multiple discrete tasks, independent of 
occupational titles, and do not normally engage in those discrete tasks 
for the entire duration of a shift. Therefore, the Agency occasionally 
included partial-shift samples (periods of less than 360 minutes), but 
has limited the use of partial-shift samples with results below the 
LOD, giving preference to data covering a greater part of the workers' 
shifts.
    OSHA believes that the partial-shift samples were collected for the 
entire duration of the task and that the exposure to silica ended when 
the task was completed. Therefore, OSHA assumes that the exposure to 
silica was zero for the remaining unsampled time. OSHA understands that 
this may not always be the case, and that there may be activities other 
than the sampled tasks that affect overall worker exposures, but the 
documentation regarding these factors is insufficient to use in 
calculating a time-weighted average. It is important to note, however, 
that the Agency has identified to the best of its ability the 
construction activities that create significant exposures to respirable 
crystalline silica.
    In cases where exposure information from a specific job category is 
not available, OSHA has based that portion of the exposure profile on 
surrogate data from one or more similar job categories in related 
industries. The surrogate data is selected based on strong similarities 
of raw materials, equipment, worker activities, and exposure duration 
between the job categories. When used, OSHA has clearly identified the 
surrogate data and the relationship between the industries or job 
categories.
1. Feasibility Determination of Sampling and Analytical Methods
    As part of its technological feasibility analysis, OSHA examined 
the capability of currently available sampling methods and sensitivity 
\12\ and precision of currently available analytical methods to measure 
respirable crystalline silica (please refer to the ``Feasibility of 
Measuring Respirable Crystalline Silica Exposures at The Proposed PEL'' 
section in Chapter IV of the PEA). The Agency understands that several 
commercially available personal sampling cyclones exist that can be 
operated at flow rates that conform to the ISO/CEN particle size 
selection criteria with an acceptable level of bias. Some of these 
sampling devices are the Dorr-Oliver, Higgens-Dowel, BGI GK 2.69, and 
the SKC G-3 cyclones. Bias against the ISO/CEN criteria will fall 
within 20 percent, and often is within 10 
percent.
---------------------------------------------------------------------------

    \12\ Note that sensitivity refers to the smallest quantity that 
can be measured with a specified level of accuracy, expressed either 
as the limit of detection or limit of quantification.
---------------------------------------------------------------------------

    Additionally, the Agency preliminarily concludes that all of the 
mentioned cyclones are capable of allowing a sufficient quantity of 
quartz to be collected from atmospheric concentrations as low as 25 
[mu]g/m\3\ to exceed the limit of quantification for the OSHA ID-142 
analytical method, provided that a sample duration is at least 4 hours. 
Furthermore, OSHA believes that these devices are also capable of 
collecting more than the minimum amount of cristobalite at the proposed 
PEL and action level

[[Page 56354]]

necessary for quantification with OSHA's method ID-142 for a full 
shift. One of these cyclones (GK 2.69) can also collect an amount of 
cristobalite exceeding OSHA's limit of quantification (LOQ) with a 4-
hour sample at the proposed PEL and action level.
    Regarding analytical methods to measure silica, OSHA investigated 
the sensitivity and precision of available methods. The Agency 
preliminarily concludes that the X-Ray Diffraction (XRD) and Infrared 
Spectroscopy (IR) methods of analysis are both sufficiently sensitive 
to quantify levels of quartz and cristobalite that would be collected 
on air samples taken from concentrations at the proposed PEL and action 
level. Available information shows that poor inter-laboratory agreement 
and lack of specificity render colorimetric spectrophotometry (another 
analytical method) inferior to XRD or IR techniques. As such, OSHA is 
proposing not to permit employers to rely on exposure monitoring 
results based on analytical methods that use colorimetric methods.
    For the OSHA XRD Method ID-142 (revised December 1996), precision 
is 23 percent at a working range of 50 to 160 [micro]g 
crystalline silica, and the SAE (sampling and analytical error) is 
19 percent. The NIOSH and MSHA XRD and IR methods report a 
similar degree of precision. OSHA's Salt Lake Technical Center (SLTC) 
evaluated the precision of ID-142 at lower filter loadings and has 
shown an acceptable level of precision is achieved at filter loadings 
of approximately 40 [micro]g and 20 [micro]g corresponding to the 
amounts collected from full-shift sampling at the proposed PEL and 
action level, respectively. This analysis showed that at filter 
loadings corresponding to the proposed PEL, the precision and SAE for 
quartz are 17 and 14 percent, respectively. For 
cristobalite, the precision and SAE are 19 and 16 percent, respectively. These results indicate that employers 
can have confidence in sampling results for the purpose of assessing 
compliance with the PEL and identifying when additional engineering and 
work practice controls and/or respiratory protection are needed.
    For example, given an SAE for quartz of 0.14 at a filter load of 40 
[micro]g, employers can be virtually certain that the PEL is not 
exceeded where exposures are less than 43 [micro]g/m\3\, which 
represents the lower 95-percent confidence limit (i.e., 50 [micro]g/
m\3\ minus 50*0.14). At 43 [micro]g/m\3\, a full-shift sample that 
collects 816 L of air will result in a filter load of 35 [micro]g of 
quartz, or more than twice the LOQ for Method ID-142. Thus, OSHA 
believes that the method is sufficiently sensitive and precise to allow 
employers to distinguish between operations that have sufficient dust 
control to comply with the PEL from those that do not. Finally, OSHA's 
analysis of PAT data indicates that most laboratories achieve good 
agreement in results for samples having filter loads just above 40 
[micro]g quartz (49-70 [micro]g).
    At the proposed action level, the study by SLTC found the precision 
and SAE of the method for quartz at 20 [micro]g to be 19 
and 16 percent, respectively. For cristobalite, the 
precision and SAE at 20 [micro]g were also 19 and 16 percent, respectively. OSHA believes that these results show 
that Method ID-142 can achieve a sufficient degree of precision for the 
purpose of identifying those operations where routine exposure 
monitoring should be conducted.
    However, OSHA also believes that limitations in the 
characterization of the precision of the analytical method in this 
range of filter load preclude the Agency from proposing a PEL of 25 
[micro]g/m\3\ at this time. First, the measurement error increases by 
about 4 to 5 percent for a full-shift sample taken at 25 [micro]g/m\3\ 
compared to one taken at 50 [micro]g/m\3\, and the error would be 
expected to increase further as filter loads approach the limit of 
detection. Second, for an employer to be virtually certain that an 
exposure to quartz did not exceed 25 [micro]g/m\3\ as an exposure 
limit, the exposure would have to be below 21 [micro]g/m\3\ given the 
SAE of 16 percent calculated from the SLTC study. For a 
full-shift sample of 0.816 L of air, only about 17 [micro]g of quartz 
would be collected at 21 [micro]g/m\3\, which is near the LOQ for 
Method ID-142 and at the maximum acceptable LOD that would be required 
by the proposed rule. Thus, given a sample result that is below a 
laboratory's reported LOD, employers might not be able to rule out 
whether a PEL of 25 [micro]g/m\3\ was exceeded.
    Finally, there are no available data that describe the total 
variability seen between laboratories at filter loadings in the range 
of 20 [micro]g crystalline silica since the lowest filter loading used 
in PAT samples is about 50 [micro]g. Given these considerations, OSHA 
believes that a PEL of 50 [micro]g/m\3\ is more appropriate in that 
employers will have more confidence that sampling results are properly 
informing them where additional dust controls and respiratory 
protection is needed.
    Based on the evaluation of the nationally recognized sampling and 
analytical methods for measuring respirable crystalline silica 
presented in the section titled ``Feasibility of Measuring Respirable 
Crystalline Silica Exposures at The Proposed PEL'' in Chapter IV of the 
PEA, OSHA preliminarily concludes that it is technologically feasible 
to reliably measure exposures of workers at the proposed PEL of 50 
[micro]g/m\3\ and action level of 25 [micro]g/m\3\. OSHA notes that the 
sampling and analytical error is larger at the proposed action level 
than that for the proposed PEL. In the ``Issues'' section of this 
preamble (see Provisions of the Standards--Exposure Assessment), OSHA 
solicits comments on whether measurements of exposures at the proposed 
action level and PEL are sufficiently precise to permit employers to 
adequately determine when additional exposure monitoring is necessary 
under the standard, when to provide workers with the required medical 
surveillance, and when to comply with all other requirements of the 
proposed standard. OSHA also solicits comments on the appropriateness 
of specific requirements in the proposed standard for laboratories that 
perform analyses of respirable crystalline silica samples to reduce the 
variability between laboratories.
2. Feasibility Determination of Control Technologies
    The Agency has conducted a feasibility analysis for each of the 
identified 23 general industry sectors and 12 construction industry 
activities that are potentially affected by the proposed silica 
standard. Additionally, the Agency identified 108 operations within 
those sectors/activities and developed exposure profiles for each 
operation, except for two industries, engineered stone products and 
landscape contracting industries. For these two industries, data 
satisfying OSHA's criteria for inclusion in the exposure profile were 
unavailable (refer to the Methodology section in Chapter 4 of the PEA 
for criteria). However, the Agency obtained sufficient information in 
both of these industries to make feasibility determinations (see 
Chapter IV Sections C.7 and C.11 of the PEA). Each feasibility analysis 
contains a description of the applicable operations, the baseline 
conditions for each operation (including the respirable silica samples 
collected), additional controls necessary to reduce exposures, and 
final feasibility determinations for each operation.
3. Feasibility Findings for the Proposed Permissible Exposure Limit of 
50 [mu]g/m\3\
    Tables VIII-6 and VIII-7 summarize all the industry sectors and 
construction

[[Page 56355]]

activities studied in the technological feasibility analysis and show 
how many operations within each can achieve levels of 50 [mu]g/m\3\ 
through the implementation of engineering and work practice controls. 
The tables also summarize the overall feasibility finding for each 
industry sector or construction activity based on the number of 
feasible versus not feasible operations. For the general industry 
sector, OSHA has preliminarily concluded that the proposed PEL of 50 
[mu]g/m\3\ is technologically feasible for all affected industries. For 
the construction activities, OSHA has determined that the proposed PEL 
of 50 [mu]g/m\3\ is feasible in 10 out of 12 of the affected 
activities. Thus, OSHA preliminarily concludes that engineering and 
work practices will be sufficient to reduce and maintain silica 
exposures to the proposed PEL of 50 [mu]g/m\3\ or below in most 
operations most of the time in the affected industries. For those few 
operations within an industry or activity where the proposed PEL is not 
technologically feasible even when workers use recommended engineering 
and work practice controls (seven out of 108 operations, see Tables 
VIII-6 and VIII-7), employers can supplement controls with respirators 
to achieve exposure levels at or below the proposed PEL.
4. Feasibility Findings for an Alternative Permissible Exposure Limit 
of 25 [mu]g/m\3\
    Based on the information presented in the technological feasibility 
analysis, OSHA believes that engineering and work practice controls 
identified to date will not be sufficient to consistently reduce 
exposures to PELs lower than 50 [mu]g/m\3\. The Agency believes that a 
proposed PEL of 25 [mu]g/m\3\, for example, would not be feasible for 
many industries, and to use respiratory protection would have to be 
required in most operations and most of the time to achieve compliance.
    However, OSHA has data indicating that an alternative PEL of 25 
[mu]g/m\3\ has already been achieved in several industries (e.g. 
asphalt paving products, dental laboratories, mineral processing, and 
paint and coatings manufacturing in general industry, and drywall 
finishers and heavy equipment operators in construction). In these 
industries, airborne respirable silica concentrations are inherently 
low because either small amounts of silica containing materials are 
handled or these materials are not subjected to high energy processes 
that generate large amounts of respirable dust.
    For many of the other industries, OSHA believes that engineering 
and work practice controls will not be able to reduce and maintain 
exposures to an alternative PEL of 25 [mu]g/m\3\ in most operations and 
most of the time. This is especially the case in industries that use 
silica containing material in substantial quantities and industries 
with high energy operations. For example, in general industry, the 
ferrous foundry industry would not be able to comply with an 
alternative PEL of 25 [mu]g/m\3\ without widespread respirator use. In 
this industry, silica containing sand is transported, used, and 
recycled in significant quantities to create castings, and as a result, 
workers can be exposed to high levels of silica in all steps of the 
production line. Additionally, some high energy operations in foundries 
create airborne dust that causes high worker exposures to silica. One 
of these operations is the shakeout process, where operators monitor 
equipment that separates castings from mold materials by mechanically 
vibrating or tumbling the casting. The dust generated from this process 
causes elevated silica exposures for shakeout operators and often 
contributes to exposures for other workers in a foundry. For small, 
medium, and large castings, exposure information with engineering 
controls in place show that exposures below 50 [mu]g/m\3\ can be 
consistently achieved, but exposures above an alternative PEL of 25 
[mu]g/m\3\ still occur. With engineering controls in place, exposure 
data for these operations range from 13 [mu]g/m\3\ to 53 [mu]g/m\3\, 
with many of the reported exposures above 25 [mu]g/m\3\.
    In the construction industry, OSHA estimates that an alternative 
PEL of 25 [mu]g/m\3\ would be infeasible in most operations because 
most of them are high energy operations that produce significant levels 
of dust, causing workers to have elevated exposures, and available 
engineering controls would not be able to maintain exposures at or 
below the alternative PEL most of the time. For example, jackhammering 
is a high energy operation that creates a large volume of silica 
containing dust, which disburses rapidly in highly disturbed air. OSHA 
estimates that the exposure levels of most workers operating 
jackhammers outdoors will be reduced to less that 100 [mu]g/m\3\ as an 
8-hour TWA, by using either wet methods or LEV paired with a suitable 
vacuum.
    OSHA believes that typically, the majority of jackhammering is 
performed for less than four hours of a worker's shift, and in these 
circumstances the Agency estimates that most workers will experience 
levels below 50 [mu]g/m\3\. Jackhammer operators who work indoors or 
with multiple jackhammers will achieve similar results granted that the 
same engineering controls are used and that fresh air circulation is 
provided to prevent accumulation of respirable dust in a worker's 
vicinity. OSHA does not have any data indicating that these control 
strategies would reduce exposures of most workers to levels of 25 
[mu]g/m\3\ or less.
5. Overall Feasibility Determination
    Based on the information presented in the technological feasibility 
analysis, the Agency believes that 50 [mu]g/m\3\ is the lowest feasible 
PEL. An alternative PEL of 25 [mu]g/m\3\ would not be feasible because 
the engineering and work practice controls identified to date will not 
be sufficient to consistently reduce exposures to levels below 25 
[mu]g/m\3\ in most operations most of the time. OSHA believes that an 
alternative PEL of 25 [mu]g/m\3\ would not be feasible for many 
industries, and that the use of respiratory protection would be 
necessary in most operations most of the time to achieve compliance. 
Additionally, the current methods of sampling analysis create higher 
errors and lower precision in measurement as concentrations of silica 
lower than the proposed PEL are analyzed. However, the Agency 
preliminarily concludes that these sampling and analytical methods are 
adequate to permit employers to comply with all applicable requirements 
triggered by the proposed action level and PEL.

[[Page 56356]]



  Table VIII-6--Summary of Technological Feasibility of Control Technologies in General and Maritime Industries
                                          Affected by Silica Exposures
----------------------------------------------------------------------------------------------------------------
                                                   Number of          Number of
                                                 operations for     operations for
                                                   which the          which the
                                Total number    proposed PEL is    proposed PEL is   Overall feasibility finding
       Industry sector           of affected    achievable with     NOT achievable       for industry sector
                                 operations       engineering      with engineering
                                               controls and work  controls and work
                                               practice controls  practice controls
----------------------------------------------------------------------------------------------------------------
Asphalt Paving Products......               3                  3                  0  Feasible.
Asphalt Roofing Materials....               2                  2                  0  Feasible.
Concrete Products............               6                  5                  1  Feasible.
Cut Stone....................               5                  5                  0  Feasible.
Dental Equipment and                        1                  1                  0  Feasible.
 Suppliers.
Dental Laboratories..........               1                  1                  0  Feasible.
Engineered Stone Products....               1                  1                  0  Feasible.
Foundries: Ferrous*..........              12                 12                  0  Feasible.
Foundries: Nonferrous*.......              12                 12                  0  Feasible.
Foundries: Non-Sand Casting*.              11                 11                  0  Feasible.
Glass........................               2                  2                  0  Feasible.
Jewelry......................               1                  1                  0  Feasible.
Landscape Contracting........               1                  1                  0  Feasible.
Mineral Processing...........               1                  1                  0  Feasible.
Paint and Coatings...........               2                  2                  0  Feasible.
Porcelain Enameling..........               2                  2                  0  Feasible.
Pottery......................               5                  5                  0  Feasible.
Railroads....................               5                  5                  0  Feasible.
Ready-Mix Concrete...........               5                  4                  1  Feasible.
Refractories.................               5                  5                  0  Feasible.
Refractory Repair............               1                  1                  0  Feasible.
Shipyards (Maritime Industry)               2                  1                  1  Feasible.
Structural Clay..............               3                  3                  0  Feasible.
                              =================
    Totals...................              89              96.6%               3.4%  ...........................
----------------------------------------------------------------------------------------------------------------
* Section 8 of the Technological Feasibility Analysis includes four subsectors of the foundry industry. Each
  subsector includes its own exposure profile and feasibility analysis in that section. This table lists three
  of those four subsectors individually based on the difference in casting processes used and subsequent
  potential for silica exposure. The table does not include captive foundries because the captive foundry
  operations are incorporated into the larger manufacturing process of the parent foundry.


 Table VIII-7--Summary of Technological Feasibility of Control Technologies in Construction Activities Affected
                                               by Silica Exposures
----------------------------------------------------------------------------------------------------------------
                                                   Number of          Number of
                                                 operations for     operations for
                                                   which the          which the
                                Total number    proposed PEL is    proposed PEL is   Overall feasibility finding
    Construction activity        of affected    achievable with     NOT achievable           for activity
                                 operations       engineering      with engineering
                                               controls and work  controls and work
                                               practice controls  practice controls
----------------------------------------------------------------------------------------------------------------
Abrasive Blasters............               2                  0                  2  Not Feasible.
Drywall Finishers............               1                  1                  0  Feasible.
Heavy Equipment Operators....               1                  1                  0  Feasible.
Hole Drillers Using Hand-Held               1                  1                  0  Feasible.
 Drills.
Jackhammer and Impact                       1                  1                  0  Feasible.
 Drillers.
Masonry Cutters Using                       3                  3                  0  Feasible.
 Portable Saws.
Masonry Cutters Using                       1                  1                  0  Feasible.
 Stationary Saws.
Millers Using Portable and                  3                  3                  0  Feasible.
 Mobile Machines.
Rock and Concrete Drillers...               1                  1                  0  Feasible.
Rock-Crushing Machine                       1                  1                  0  Feasible.
 Operators and Tenders.
Tuckpointers and Grinders....               3                  1                  2  Not Feasible.
Underground Construction                    1                  1                  0  Feasible.
 Workers.
                              ----------------------------------------------------------------------------------
    Totals...................              19              78.9%              21.1%
----------------------------------------------------------------------------------------------------------------

E. Costs of Compliance

    Chapter V of the PEA in support of the proposed silica rule 
provides a detailed assessment of the costs to establishments in all 
affected industry sectors of reducing worker exposures to silica to an 
eight-hour time-weighted average (TWA) permissible exposure limit (PEL) 
of 50 [mu]g/m\3\ and of complying with the proposed standard's 
ancillary requirements. The discussion below summarizes the findings in 
the PEA cost chapter. OSHA's preliminary cost assessment is based on 
the Agency's technological feasibility

[[Page 56357]]

analysis presented in Chapter IV of the PEA (2013); analyses of the 
costs of the proposed standard conducted by OSHA's contractor, Eastern 
Research Group (ERG, 2007a, 2007b, and 2013); and the comments 
submitted to the docket as part of the SBREFA panel process.
    OSHA estimates that the proposed rule will cost $657.9 million per 
year in 2009 dollars. Costs originally estimated for earlier years were 
adjusted to 2009 dollars using the appropriate price indices. All costs 
are annualized using a discount rate of 7 percent. (A sensitivity 
analysis using discount rates of 3 percent and 0 percent is presented 
in the discussion of net benefits.) One-time costs are annualized over 
10-year annualization period, and capital goods are annualized over the 
life of the equipment. OSHA has historically annualized one-time costs 
over at least a 10-year period, which approximately reflects the 
average life of a business in the United States. (The Agency has chosen 
a longer annualization period under special circumstances, such as when 
a rule involves longer and more complex phase-in periods. In general, a 
longer annualization period, in such cases, will tend to reduce 
annualized costs slightly.)
    The estimated costs for the proposed silica standard rule include 
the additional costs necessary for employers to achieve full 
compliance. They do not include costs associated with current 
compliance that has already been achieved with regard to the new 
requirements or costs necessary to achieve compliance with existing 
silica requirements, to the extent that some employers may currently 
not be fully complying with applicable regulatory requirements.
    Table VIII-8 provides the annualized costs of the proposed rule by 
cost category for general industry, maritime, and construction. As 
shown in Table VIII-8, of the total annualized costs of the proposed 
rule, $132.5 million would be incurred by general industry, $14.2 
million by maritime, and $511.2 million by construction.
    Table VIII-9 shows the annualized costs of the proposed rule by 
cost category and by industry for general industry and maritime, and 
Table VIII-10 shows the annualized costs similarly disaggregated for 
construction. These tables show that engineering control costs 
represent 69 percent of the costs of the proposed standard for general 
industry and maritime and 47 percent of the costs of the proposed 
standard for construction. Considering other leading cost categories, 
costs for exposure assessment and respirators represent, respectively, 
20 percent and 5 percent of the costs of the proposed standard for 
general industry and maritime; costs for respirators and medical 
surveillance represent, respectively, 16 percent and 15 percent of the 
costs of the proposed standard for construction.
    While the costs presented here represent the Agency's best estimate 
of the costs to industry of complying with the proposed rule under 
static conditions (that is, using existing technology and the current 
deployment of workers), OSHA recognizes that the actual costs could be 
somewhat higher or lower, depending on the Agency's possible 
overestimation or underestimation of various cost factors. In Chapter 
VII of the PEA, OSHA provides a sensitivity analysis of its cost 
estimates by modifying certain critical unit cost factors. Beyond the 
sensitivity analysis, however, OSHA believes its cost estimates may 
significantly overstate the actual costs of the proposed rule because, 
in response to the rule, industry may be able to take two types of 
actions to reduce compliance costs.
    First, in construction, 53 percent of the estimated costs of the 
proposed rule (all costs except engineering controls) vary directly 
with the number of workers exposed to silica. However, as shown in 
Table VIII-3 of this preamble, almost three times as many construction 
workers would be affected by the proposed rule as would the number of 
full-time-equivalent construction workers necessary to do the work. 
This is because most construction workers currently do work involving 
silica exposure for only a portion of their workday. In response to the 
proposed rule, many employers are likely to assign work so that fewer 
construction workers perform tasks involving silica exposure; 
correspondingly, construction work involving silica exposure will tend 
to become a full-time job for some construction workers.\13\ Were this 
approach fully implemented in construction, the actual cost of the 
proposed rule would decline by over 25 percent, or by $180 million 
annually, to under $480 million annually.\14\
---------------------------------------------------------------------------

    \13\ There are numerous instances of job reassignments and job 
specialties arising in response to OSHA regulation. For example, 
asbestos removal and confined space work in construction have become 
activities performed by well-trained specialized employees, not 
general laborers (whose only responsibility is to identify the 
presence of asbestos or a confined space situation and then to 
notify the appropriate specialist).
    \14\ OSHA expected that such a structural change in construction 
work assignments would not have a significant effect on the benefits 
of the proposed rule. As discussed in Chapter VII of the PEA, the 
benefits of the proposed rule are relatively insensitive to changes 
in average occupational tenure or how total silica exposure in an 
industry is distributed among individual workers.
---------------------------------------------------------------------------

    Second, the costs presented here do not take into account the 
likely development and dissemination of cost-reducing compliance 
technology in response to the proposed rule.\15\ One possible example 
is the development of safe substitutes for silica sand in abrasive 
blasting operations, repair and replacement of refractory materials, 
foundry operations, and the railroad transportation industry. Another 
is expanded uses of automated processes, which would allow workers to 
be isolated from the points of operation that involve silica exposure 
(such as tasks between the furnace and the pouring machine in foundries 
and at sand transfer stations in structural clay production 
facilities). Yet another example is the further development and use of 
bags with valves that seal effectively when filled, thereby preventing 
product leakage and worker exposure (for example, in mineral processing 
and concrete products industries). Probably the most pervasive and 
significant technological advances, however, will likely come from the 
integration of compliant control technology into production equipment 
as standard equipment. Such advances would both increase the 
effectiveness and reduce the costs of silica controls retrofitted to 
production equipment. Possible examples include local exhaust 
ventilation (LEV) systems attached to portable tools used by grinders 
and tuckpointers; enclosed operator cabs equipped with air filtration 
and air conditioning in industries that mechanically transfer silica or 
silica-containing materials; and machine-integrated wet dust 
suppression systems used, for example, in road milling operations. Of 
course, all the possible technological advances in response to the 
proposed rule and their effects on costs are difficult to predict.\16\
---------------------------------------------------------------------------

    \15\ Evidence of such technological responses to regulation is 
widespread (see for example Ashford, Ayers, and Stone (1985), OTA 
(1995), and OSHA's regulatory reviews of existing standards under 
Sec.  610 of the Regulatory Flexibility Act (``610 lookback 
reviews'')).
    \16\ A dramatic example from OSHA's 610 lookback review of its 
1984 ethylene oxide (EtO) standard is the use of EtO as a sterilant. 
OSHA estimated the costs of add-on controls for EtO sterilization, 
but in response to the standard, improved EtO sterilizers with 
built-in controls were developed and widely disseminated at about 
half the cost of the equipment with add-on controls. (See OSHA, 
2005.) Lower-cost EtO sterilizers with built-in controls did not 
exist, and their development had not been predicted by OSHA, at the 
time the final rule was published in 1984.
---------------------------------------------------------------------------

    OSHA has decided at this time not to create a more dynamic and 
predictive analysis of possible cost-reducing

[[Page 56358]]

technological advances or worker specialization because the 
technological and economic feasibility of the proposed rule can easily 
be demonstrated using existing technology and employment patterns. 
However, OSHA believes that actual costs, if future developments of 
this type were fully accounted for, would be lower than those estimated 
here.
    OSHA invites comment on this discussion concerning the costs of the 
proposed rule.

   Table VIII-8--Annualized Compliance Costs for Employers in General Industry, Maritime, and Construction Affected by OSHA's Proposed Silica Standard
                                                                     [2009 dollars]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Engineering
                                             controls                                                                        Regulated
                Industry                     (includes      Respirators      Exposure         Medical        Training        areas or          Total
                                             abrasive                       assessment     surveillance                   access control
                                             blasting)
--------------------------------------------------------------------------------------------------------------------------------------------------------
General Industry........................     $88,442,480      $6,914,225     $29,197,633      $2,410,253      $2,952,035      $2,580,728    $132,497,353
Maritime................................      12,797,027              NA         671,175         646,824          43,865          70,352      14,229,242
Construction............................     242,579,193      84,004,516      44,552,948      76,012,451      47,270,844      16,745,663     511,165,616
                                         ---------------------------------------------------------------------------------------------------------------
    Total...............................     343,818,700      90,918,741      74,421,757      79,069,527      50,266,744      19,396,743     657,892,211
--------------------------------------------------------------------------------------------------------------------------------------------------------
U.S. Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG (2007a, 2007b, and 2013).


         Table VIII-9--Annualized Compliance Costs for All General Industry and Maritime Establishments Affected by the Proposed Silica Standard
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Engineering
                                                          controls
          NAICS                      Industry             (includes    Respirators    Exposure       Medical      Training      Regulated       Total
                                                          abrasive                   assessment   surveillance                    areas
                                                          blasting)
--------------------------------------------------------------------------------------------------------------------------------------------------------
324121...................  Asphalt paving mixture and       $179,111        $2,784        $8,195          $962       $49,979        $1,038      $242,070
                            block manufacturing.
324122...................  Asphalt shingle and roofing     2,194,150       113,924       723,761        39,364        43,563        42,495     3,157,257
                            materials.
325510...................  Paint and coating                       0        23,445        70,423         8,179        33,482         8,752       144,281
                            manufacturing.
327111...................  Vitreous china plumbing         1,128,859        76,502       369,478        26,795        29,006        28,554     1,659,194
                            fixtures & bathroom
                            accessories manufacturing.
327112...................  Vitreous china, fine            1,769,953       119,948       579,309        42,012        45,479        44,770     2,601,471
                            earthenware, & other
                            pottery product
                            manufacturing.
327113...................  Porcelain electrical supply     1,189,482        80,610       389,320        28,234        30,564        30,087     1,748,297
                            mfg.
327121...................  Brick and structural clay       6,966,654       154,040       554,322        53,831        51,566        57,636     7,838,050
                            mfg.
327122...................  Ceramic wall and floor tile     3,658,389        80,982       306,500        28,371        27,599        30,266     4,132,107
                            mfg.
327123...................  Other structural clay             826,511        18,320        72,312         6,417         6,302         6,838       936,699
                            product mfg.
327124...................  Clay refractory                   304,625        21,108       124,390         7,393        17,043         7,878       482,438
                            manufacturing.
327125...................  Nonclay refractory                383,919        26,602       156,769         9,318        21,479         9,929       608,017
                            manufacturing.
327211...................  Flat glass manufacturing...       227,805         8,960        29,108         3,138         2,800         3,344       275,155
327212...................  Other pressed and blown           902,802        34,398       111,912        12,048        10,708        12,839     1,084,706
                            glass and glassware
                            manufacturing.
327213...................  Glass container                   629,986        24,003        78,093         8,374         7,472         8,959       756,888
                            manufacturing.
327320...................  Ready-mixed concrete            7,029,710     1,862,221     5,817,205       652,249       454,630       695,065    16,511,080
                            manufacturing.
327331...................  Concrete block and brick        2,979,495       224,227       958,517        78,536       113,473        83,692     4,437,939
                            mfg.
327332...................  Concrete pipe mfg..........     1,844,576       138,817       593,408        48,621        70,250        51,813     2,747,484
327390...................  Other concrete product mfg.     8,660,830       651,785     2,786,227       228,290       329,844       243,276    12,900,251
327991...................  Cut stone and stone product     5,894,506       431,758     1,835,498       151,392       126,064       161,080     8,600,298
                            manufacturing.
327992...................  Ground or treated mineral       3,585,439        51,718       867,728        18,134        52,692        19,295     4,595,006
                            and earth manufacturing.
327993...................  Mineral wool manufacturing.       897,980        36,654       122,015        12,852        11,376        13,675     1,094,552
327999...................  All other misc. nonmetallic     1,314,066        98,936       431,012        34,691        50,435        36,911     1,966,052
                            mineral product mfg.
331111...................  Iron and steel mills.......       315,559        17,939        72,403         6,129         5,836         6,691       424,557
331112...................  Electrometallurgical                6,375           362         1,463           124           118           135         8,577
                            ferroalloy product
                            manufacturing.
331210...................  Iron and steel pipe and            62,639         3,552        14,556         1,239         1,222         1,328        84,537
                            tube manufacturing from
                            purchased steel.
331221...................  Rolled steel shape                 31,618         1,793         7,348           625           617           670        42,672
                            manufacturing.
331222...................  Steel wire drawing.........        42,648         2,419         9,911           843           832           904        57,557
331314...................  Secondary smelting and             21,359         1,213         4,908           419           406           453        28,757
                            alloying of aluminum.
331423...................  Secondary smelting,                 3,655           207           857            72            71            78         4,940
                            refining, and alloying of
                            copper.
331492...................  Secondary smelting,                27,338         1,551         6,407           539           531           580        36,946
                            refining, and alloying of
                            nonferrous metal (except
                            cu & al).
331511...................  Iron foundries.............    11,372,127       645,546     2,612,775       223,005       216,228       241,133    15,310,815
331512...................  Steel investment foundries.     3,175,862       179,639       739,312        62,324        58,892        67,110     4,283,138
331513...................  Steel foundries (except         3,403,790       193,194       794,973        67,027        65,679        72,174     4,596,837
                            investment).
331524...................  Aluminum foundries (except      5,155,172       291,571     1,220,879       101,588        97,006       108,935     6,975,150
                            die-casting).
331525...................  Copper foundries (except        1,187,578        67,272       309,403        23,668        23,448        25,095     1,636,463
                            die-casting).

[[Page 56359]]

 
331528...................  Other nonferrous foundries        914,028        51,701       212,778        17,937        16,949        19,314     1,232,708
                            (except die-casting).
332111...................  Iron and steel forging.....        77,324         4,393        19,505         1,538         1,555         1,640       105,955
332112...................  Nonferrous forging.........        25,529         1,451         6,440           508           513           541        34,982
332115...................  Crown and closure                   9,381           532         2,236           186           186           199        12,720
                            manufacturing.
332116...................  Metal stamping.............       188,102        10,676        45,595         3,734         3,736         3,988       255,832
332117...................  Powder metallurgy part             24,250         1,375         5,727           481           479           514        32,828
                            manufacturing.
332211...................  Cutlery and flatware               16,763           952         4,229           333           337           355        22,970
                            (except precious)
                            manufacturing.
332212...................  Hand and edge tool                106,344         6,041        26,356         2,110         2,118         2,255       145,223
                            manufacturing.
332213...................  Saw blade and handsaw              21,272         1,209         5,090           418           411           451        28,851
                            manufacturing.
332214...................  Kitchen utensil, pot, and          11,442           650         2,886           228           230           243        15,678
                            pan manufacturing.
332323...................  Ornamental and                     28,010         1,089         4,808           383           572           406        35,267
                            architectural metal work.
332439...................  Other metal container              44,028         2,502        11,106           876           885           934        60,330
                            manufacturing.
332510...................  Hardware manufacturing.....       131,574         7,476        33,190         2,617         2,646         2,790       180,292
332611...................  Spring (heavy gauge)               11,792           670         2,974           235           237           250        16,158
                            manufacturing.
332612...................  Spring (light gauge)               44,511         2,529        11,228           885           895           944        60,992
                            manufacturing.
332618...................  Other fabricated wire             105,686         6,005        26,659         2,102         2,125         2,241       144,819
                            product manufacturing.
332710...................  Machine shops..............       774,529        44,074       211,043        15,533        16,157        16,423     1,077,759
332812...................  Metal coating and allied        2,431,996        94,689       395,206        33,145        48,563        35,337     3,038,935
                            services.
332911...................  Industrial valve                  111,334         6,316        25,894         2,197         2,159         2,361       150,261
                            manufacturing.
332912...................  Fluid power valve and hose        103,246         5,863        24,854         2,040         2,021         2,189       140,213
                            fitting manufacturing.
332913...................  Plumbing fixture fitting           33,484         1,901         8,060           661           655           710        45,472
                            and trim manufacturing.
332919...................  Other metal valve and pipe         52,542         2,984        12,648         1,038         1,028         1,114        71,354
                            fitting manufacturing.
332991...................  Ball and roller bearing            79,038         4,488        19,027         1,561         1,547         1,676       107,338
                            manufacturing.
332996...................  Fabricated pipe and pipe           78,951         4,483        19,006         1,560         1,545         1,674       107,219
                            fitting manufacturing.
332997...................  Industrial pattern                 15,383           874         3,703           304           301           326        20,891
                            manufacturing.
332998...................  Enameled iron and metal            46,581         2,225         9,304           774           969           831        60,684
                            sanitary ware
                            manufacturing.
332999...................  All other miscellaneous           209,692        11,915        53,603         4,181         4,256         4,446       288,093
                            fabricated metal product
                            manufacturing.
333319...................  Other commercial and              154,006         8,741        37,161         3,053         3,046         3,266       209,273
                            service industry machinery
                            manufacturing.
333411...................  Air purification equipment         43,190         2,453        10,037           847           823           916        58,265
                            manufacturing.
333412...................  Industrial and commercial          30,549         1,735         7,099           599           582           648        41,212
                            fan and blower
                            manufacturing.
333414...................  Heating equipment (except          59,860         3,399        13,911         1,174         1,141         1,269        80,754
                            warm air furnaces)
                            manufacturing.
333511...................  Industrial mold                   116,034         6,597        30,348         2,317         2,375         2,460       160,131
                            manufacturing.
333512...................  Machine tool (metal cutting        49,965         2,839        12,313           988           985         1,059        68,151
                            types) manufacturing.
333513...................  Machine tool (metal forming        24,850         1,411         6,157           495           500           527        33,940
                            types) manufacturing.
333514...................  Special die and tool, die         167,204         9,513        44,922         3,346         3,458         3,545       231,988
                            set, jig, and fixture
                            manufacturing.
333515...................  Cutting tool and machine          101,385         5,764        26,517         2,025         2,075         2,150       139,916
                            tool accessory
                            manufacturing.
333516...................  Rolling mill machinery and          8,897           506         2,327           178           182           189        12,279
                            equipment manufacturing.
333518...................  Other metalworking                 36,232         2,060         9,476           724           742           768        50,002
                            machinery manufacturing.
333612...................  Speed changer, industrial          35,962         2,043         8,308           702           674           763        48,452
                            high-speed drive, and gear
                            manufacturing.
333613...................  Mechanical power                   45,422         2,581        10,493           886           852           963        61,197
                            transmission equipment
                            manufacturing.
333911...................  Pump and pumping equipment         89,460         5,077        21,139         1,767         1,746         1,897       121,086
                            manufacturing.
333912...................  Air and gas compressor             62,241         3,534        14,975         1,230         1,219         1,320        84,518
                            manufacturing.
333991...................  Power-driven handtool              25,377         1,441         6,105           501           497           538        34,459
                            manufacturing.
333992...................  Welding and soldering              46,136         2,622        10,882           904           879           978        62,401
                            equipment manufacturing.
333993...................  Packaging machinery                61,479         3,491        15,004         1,219         1,218         1,304        83,714
                            manufacturing.
333994...................  Industrial process furnace         31,154         1,768         7,694           620           626           661        42,523
                            and oven manufacturing.
333995...................  Fluid power cylinder and           57,771         3,280        13,532         1,137         1,113         1,225        78,057
                            actuator manufacturing.
333996...................  Fluid power pump and motor         39,598         2,247         9,296           782           772           840        53,535
                            manufacturing.

[[Page 56360]]

 
333997...................  Scale and balance (except          10,853           616         2,688           216           218           230        14,822
                            laboratory) manufacturing.
333999...................  All other miscellaneous           152,444         8,657        36,677         3,012         2,985         3,232       207,006
                            general purpose machinery
                            manufacturing.
334518...................  Watch, clock, and part              6,389           363         1,596           127           129           135         8,740
                            manufacturing.
335211...................  Electric housewares and            11,336           437         1,641           149           203           163        13,928
                            household fans.
335221...................  Household cooking appliance        24,478           944         3,543           321           438           352        30,077
                            manufacturing.
335222...................  Household refrigerator and         26,139         1,009         3,784           343           468           376        32,118
                            home freezer manufacturing.
335224...................  Household laundry equipment        24,839           958         3,596           326           444           357        30,521
                            manufacturing.
335228...................  Other major household              19,551           754         2,830           256           350           281        24,023
                            appliance manufacturing.
336111...................  Automobile manufacturing...       218,635        12,444        49,525         4,203         3,914         4,636       293,357
336112...................  Light truck and utility           301,676        17,170        68,335         5,799         5,400         6,397       404,778
                            vehicle manufacturing.
336120...................  Heavy duty truck                   93,229         5,303        21,179         1,800         1,692         1,977       125,181
                            manufacturing.
336211...................  Motor vehicle body                138,218         7,849        32,738         2,722         2,674         2,931       187,131
                            manufacturing.
336212...................  Truck trailer manufacturing        93,781         5,325        21,786         1,841         1,791         1,989       126,512
336213...................  Motor home manufacturing...        62,548         3,557        14,284         1,212         1,147         1,326        84,073
336311...................  Carburetor, piston, piston         30,612         1,739         7,044           598           576           649        41,219
                            ring, and valve
                            manufacturing.
336312...................  Gasoline engine and engine        192,076        10,910        44,198         3,753         3,616         4,073       258,625
                            parts manufacturing.
336322...................  Other motor vehicle               180,164        10,233        41,457         3,520         3,392         3,820       242,586
                            electrical and electronic
                            equipment manufacturing.
336330...................  Motor vehicle steering and        114,457         6,504        26,216         2,228         2,128         2,427       153,960
                            suspension components
                            (except spring)
                            manufacturing.
336340...................  Motor vehicle brake system         98,118         5,573        22,578         1,917         1,847         2,080       132,114
                            manufacturing.
336350...................  Motor vehicle transmission        243,348        13,832        55,796         4,730         4,510         5,160       327,377
                            and power train parts
                            manufacturing.
336370...................  Motor vehicle metal               321,190        18,237        73,408         6,282         6,057         6,810       431,985
                            stamping.
336399...................  All other motor vehicle           433,579        24,628        99,769         8,472         8,162         9,194       583,803
                            parts manufacturing.
336611...................  Ship building and repair...     7,868,944            NA       412,708       397,735        26,973        43,259     8,749,619
336612...................  Boat building..............     4,928,083            NA       258,467       249,089        16,892        27,092     5,479,624
336992...................  Military armored vehicle,          20,097         1,142         4,786           394           383           426        27,227
                            tank, and tank component
                            manufacturing.
337215...................  Showcase, partition,              171,563         9,741        41,962         3,405         3,412         3,638       233,720
                            shelving, and locker
                            manufacturing.
339114...................  Dental equipment and              272,308        15,901        48,135         5,524         4,157         5,930       351,955
                            supplies manufacturing.
339116...................  Dental laboratories........       103,876        62,183       892,167        21,602       335,984        23,193     1,439,004
339911...................  Jewelry (except costume)          260,378       198,421       876,676        69,472        81,414        73,992     1,560,353
                            manufacturing.
339913...................  Jewelers' materials and            53,545        40,804       180,284        14,287        16,742        15,216       320,878
                            lapidary work
                            manufacturing.
339914...................  Costume jewelry and novelty        54,734        27,779       122,885         9,726        11,337        10,359       236,821
                            manufacturing.
339950...................  Sign manufacturing.........       227,905         9,972        44,660         3,491         5,173         3,718       294,919
423840...................  Industrial supplies,               97,304         8,910        60,422         3,149         4,199         3,315       177,299
                            wholesalers.
482110...................  Rail transportation........             0       327,176     1,738,398       110,229       154,412       121,858     2,452,073
621210...................  Dental offices.............        24,957        14,985       251,046         5,286        87,408         5,572       389,256
                                                       -------------------------------------------------------------------------------------------------
                           Total......................   101,239,507     6,914,225    29,868,808     3,057,076     2,995,900     2,651,079   146,726,595
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG (2013).


                    Table VIII-10--Annualized Compliance Costs for Construction Employers Affected by OSHA's Proposed Silica Standard
                                                                     [2009 dollars]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Engineering
                                                          controls                                                              Regulated
          NAICS                      Industry             (includes    Respirators    Exposure       Medical      Training      areas and       Total
                                                          abrasive                   assessment   surveillance                   access
                                                          blasting)                                                              control
--------------------------------------------------------------------------------------------------------------------------------------------------------
236100...................  Residential Building          $14,610,121    $2,356,507    $1,949,685    $2,031,866    $1,515,047      $825,654   $23,288,881
                            Construction.
236200...................  Nonresidential Building        16,597,147     7,339,394     4,153,899     6,202,842     4,349,517     1,022,115    39,664,913
                            Construction.
237100...................  Utility System Construction    30,877,799     2,808,570     4,458,900     2,386,139     5,245,721       941,034    46,718,162
237200...................  Land Subdivision...........       676,046        59,606       128,183        51,327       173,183        22,443     1,110,789
237300...................  Highway, Street, and Bridge    16,771,688     2,654,815     3,538,146     2,245,164     4,960,966       637,082    30,807,861
                            Construction.

[[Page 56361]]

 
237900...................  Other Heavy and Civil           4,247,372       430,127       825,247       367,517     1,162,105       131,843     7,164,210
                            Engineering Construction.
238100...................  Foundation, Structure, and     66,484,670    59,427,878    17,345,127    50,179,152    14,435,854     8,034,530   215,907,211
                            Building Exterior
                            Contractors.
238200...................  Building Equipment              3,165,237       366,310       394,270       316,655       526,555       133,113     4,902,138
                            Contractors.
238300...................  Building Finishing             34,628,392     2,874,918     2,623,763     5,950,757     3,156,004     1,025,405    50,259,239
                            Contractors.
238900...................  Other Specialty Trade          43,159,424     4,044,680     5,878,597     4,854,336     7,251,924     2,815,017    68,003,978
                            Contractors.
999000...................  State and Local Governments    11,361,299     1,641,712     3,257,131     1,426,696     4,493,968     1,157,427    23,338,234
                            [c].
                                                       -------------------------------------------------------------------------------------------------
                           Total--Construction........   242,579,193    84,004,516    44,552,948    76,012,451    47,270,844    16,745,663   511,165,616
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG (2013).

1. Unit Costs, Other Cost Parameters, and Methodological Assumptions by 
Major Provision
    Below, OSHA summarizes its methodology for estimating unit and 
total costs for the major provisions required under the proposed silica 
standard. For a full presentation of the cost analysis, see Chapter V 
of the PEA and ERG (2007a, 2007b, 2011, 2013). OSHA invites comment on 
all aspects of its preliminary cost analysis.
a. Engineering Controls
    Engineering controls include such measures as local exhaust 
ventilation, equipment hoods and enclosures, dust suppressants, spray 
booths and other forms of wet methods, high efficient particulate air 
(HEPA) vacuums, and control rooms.
    Following ERG's (2011) methodology, OSHA estimated silica control 
costs on a per-worker basis, allowing the costs to be related directly 
to the estimates of the number of overexposed workers. OSHA then 
multiplied the estimated control cost per worker by the numbers of 
overexposed workers for both the proposed PEL of 50 [mu]g/m\3\ and the 
alternative PEL of 100 [mu]g/m\3\, introduced for economic analysis 
purposes. The numbers of workers needing controls (i.e., workers 
overexposed) are based on the exposure profiles for at-risk occupations 
developed in the technological feasibility analysis in Chapter IV of 
the PEA and estimates of the number of workers employed in these 
occupations developed in the industry profile in Chapter III of the 
PEA. This worker-based method is necessary because, even though the 
Agency has data on the number of firms in each affected industry, on 
the occupations and industrial activities with worker exposure to 
silica, on exposure profiles of at-risk occupations, and on the costs 
of controlling silica exposure for specific industrial activities, OSHA 
does not have a way to match up these data at the firm level. Nor does 
OSHA have facility-specific data on worker exposure to silica or even 
facility-specific data on the level of activity involving worker 
exposure to silica. Thus, OSHA could not directly estimate per-
affected-facility costs, but instead, first had to estimate aggregate 
compliance costs and then calculate the average per-affected-facility 
costs by dividing aggregate costs by the number of affected facilities.
    In general, OSHA viewed the extent to which exposure controls are 
already in place to be reflected in the distribution of overexposures 
among the affected workers. Thus, for example, if 50 percent of workers 
in a given occupation are found to be overexposed relative to the 
proposed silica PEL, OSHA judged this equivalent to 50 percent of 
facilities lacking the relevant exposure controls. The remaining 50 
percent of facilities are expected either to have installed the 
relevant controls or to engage in activities that do not require that 
the exposure controls be in place. OSHA recognizes that some facilities 
might have the relevant controls in place but are still unable, for 
whatever reason, to achieve the PEL under consideration. ERG's review 
of the industrial hygiene literature and other source materials (as 
noted in ERG, 2007b), however, suggest that the large majority of 
overexposed workers lack relevant controls. Thus, OSHA has generally 
assumed that overexposures occur due to the absence of suitable 
controls. This assumption results in an overestimate of costs since, in 
some cases, employers may merely need to upgrade or better maintain 
existing controls or to improve work practices rather than to install 
and maintain new controls.
    There are two situations in which the proportionality assumption 
may oversimplify the estimation of the costs of the needed controls. 
First, some facilities may have the relevant controls in place but are 
still unable, for whatever reason, to achieve the PEL under 
consideration for all employees. ERG's review of the industrial hygiene 
literature and other source materials (as noted in ERG, 2007b, pg. 3-
4), however, suggest that the large majority of overexposed workers 
lack relevant controls. Thus, OSHA has generally assumed that 
overexposures occur due to the absence of suitable controls. This 
assumption could, in some cases, result in an overestimate of costs 
where employers merely need to upgrade or better maintain existing 
controls or to improve work practices rather than to install and 
maintain new controls. Second, there may be situations where facilities 
do not have the relevant controls in place but nevertheless have only a 
fraction of all affected employees above the PEL. If, in such 
situations, an employer would have to install all the controls 
necessary to meet the PEL, OSHA may have underestimated the control 
costs. However, OSHA believes that, in general, employers could come 
into compliance by such methods as checking the work practices of the 
employee who is above the PEL or installing smaller amounts of LEV at 
costs that would be more or less proportional to the costs for all 
employees. Nevertheless there may be situations in which a complete set 
of controls would be necessary if even one employee in a work area is 
above the PEL. OSHA welcomes comment on the extent to which this 
approach may yield underestimates or overestimates of costs.
    At many workstations, employers must improve ventilation to reduce 
silica exposures. Ventilation improvements will take a variety of

[[Page 56362]]

forms at different workstations and in different facilities and 
industries. The cost of ventilation enhancements generally reflects the 
expense of ductwork and other equipment for the immediate workstation 
or individual location and, potentially, the cost of incremental 
capacity system-wide enhancements and increased operation costs for the 
heating, ventilation, and air conditioning (HVAC) system for the 
facility.
    For a number of occupations, the technological feasibility analysis 
indicates that, in addition to ventilation, the use of wet methods, 
improved housekeeping practices, and enclosure of process equipment are 
needed to reduce silica exposures. The degree of incremental 
housekeeping depends upon how dusty the operations are and the 
applicability of HEPA vacuums or other equipment to the dust problem. 
The incremental costs for most such occupations arise due to the labor 
required for these additional housekeeping efforts. Because additional 
labor for housekeeping will be required on virtually every work shift 
by most of the affected occupations, the costs of housekeeping are 
substantial. Employers also need to purchase HEPA vacuums and must 
incur the ongoing costs of HEPA vacuum filters. To reduce silica 
exposures by enclosure of process equipment, such as in the use of 
conveyors near production workers in mineral processing, covers can be 
particularly effective where silica-containing materials are 
transferred (and notable quantities of dust become airborne), or, as 
another example, where dust is generated, such as in sawing or grinding 
operations.
    For construction, ERG (2007a) defined silica dust control measures 
for each representative job as specified in Table 1 of the proposed 
rule. Generally, these controls involve either a dust collection system 
or a water-spray approach (wet method) to capture and suppress the 
release of respirable silica dust. Wet-method controls require a water 
source (e.g., tank) and hoses. The size of the tank varies with the 
nature of the job and ranges from a small hand-pressurized tank to a 
large tank for earth drilling operations. Depending on the tool, dust 
collection methods entail vacuum equipment, including a vacuum unit and 
hoses, and either a dust shroud or an extractor. For example, concrete 
grinding operations using hand-held tools require dust shroud adapters 
for each tool and a vacuum. The capacity of the vacuum depends on the 
type and size of tool being used. Some equipment, such as concrete 
floor grinders, comes with a dust collection system and a port for a 
vacuum hose. The estimates of control costs for those jobs using dust 
collection methods assume that an HEPA filter will be required.
    For each job, ERG estimated the annual cost of the appropriate 
controls and translated this cost to a daily charge. The unit costs for 
control equipment were based on price information collected from 
manufacturers and vendors. In some cases, control equipment costs were 
based on data on equipment rental charges.
    As noted above, included among the engineering controls in OSHA's 
cost model are housekeeping and dust-suppression controls in general 
industry. For the maritime industry and for construction, abrasive 
blasting operations are expected to require the use of wet methods to 
control silica dust.
    Tables V-3, V-4, V-21, V-22, and V-31 in Chapter V of the PEA and 
Tables V-A-1 and V-A-2 in Appendix V-A provide details on the unit 
costs, other unit parameters, and methodological assumptions applied by 
OSHA to estimate engineering control costs.
b. Respiratory Protection
    OSHA's cost estimates assume that implementation of the recommended 
silica controls prevents workers in general industry and maritime from 
being exposed over the PEL in most cases. Specifically, based on its 
technological feasibility analysis, OSHA expects that the technical 
controls are adequate to keep silica exposures at or below the PEL for 
an alternative PEL of 100 [mu]g/m\3\ (introduced for economic analysis 
purposes).\17\ For the proposed 50 [mu]g/m\3\ PEL, OSHA's feasibility 
analysis suggests that the controls that employers use, either because 
of technical limitations or imperfect implementation, might not be 
adequate in all cases to ensure that worker exposures in all affected 
job categories are at or below 50 [mu]g/m\3\. For this preliminary cost 
analysis, OSHA estimates that ten percent of the at-risk workers in 
general industry would require respirators, at least occasionally, 
after the implementation of engineering controls to achieve compliance 
with the proposed PEL of 50 [mu]g/m\3\. For workers in maritime, the 
only activity with silica exposures above the proposed PEL of 50 [mu]g/
m\3\ is abrasive blasting, and maritime workers engaged in abrasive 
blasting are already required to use respirators under the existing 
OSHA ventilation standard (29 CFR 1910.94(a)). Therefore, OSHA has 
estimated no additional costs for maritime workers to use respirators 
as a result of the proposed silica rule.
---------------------------------------------------------------------------

    \17\ As a result, OSHA expects that establishments in general 
industry do not currently use respirators to comply with the current 
OSHA PEL for quartz of approximately 100 [micro]g/m\3\.
---------------------------------------------------------------------------

    For construction, employers whose workers receive exposures above 
the PEL are assumed to adopt the appropriate task-specific engineering 
controls and, where required, respirators prescribed in Table 1 and 
under paragraph (g)(1) in the proposed standard. Respirator costs in 
the construction industry have been adjusted to take into account 
OSHA's estimate (consistent with the findings from the NIOSH 
Respiratory Survey, 2003) that 56 percent of establishments in the 
construction industry are already using respirators that would be in 
compliance with the proposed silica rule.
    ERG (2013) used respirator cost information from a 2003 OSHA 
respirator study to estimate the annual cost of $570 (in 2009 dollars) 
for a half-mask, non-powered, air-purifying respirator and $638 per 
year (in 2009 dollars) for a full-face non-powered air-purifying 
respirator (ERG, 2003). These unit costs reflect the annualized cost of 
respirator use, including accessories (e.g., filters), training, fit 
testing, and cleaning.
    In addition to bearing the costs associated with the provision of 
respirators, employers will incur a cost burden to establish respirator 
programs. OSHA projects that this expense will involve an initial 8 
hours for establishments with 500 or more employees and 4 hours for all 
other firms. After the first year, OSHA estimates that 20 percent of 
establishments would revise their respirator program every year, with 
the largest establishments (500 or more employees) expending 4 hours 
for program revision, and all other employers expending two hours for 
program revision. Consistent with the findings from the NIOSH 
Respiratory Survey (2003), OSHA estimates that 56 percent of 
establishments in the construction industry that would require 
respirators to achieve compliance with the proposed PEL already have a 
respirator program.\18\ OSHA further estimates that 50 percent of firms 
in general industry and all maritime firms that would require

[[Page 56363]]

respirators to achieve compliance already have a respirator program.
---------------------------------------------------------------------------

    \18\ OSHA's derivation of the 56 percent current compliance rate 
in construction, in the context of the proposed silica rule, is 
described in Chapter V in the PEA.
---------------------------------------------------------------------------

c. Exposure Assessment
    Most establishments wishing to perform exposure monitoring will 
require the assistance of an outside consulting industrial hygienist 
(IH) to obtain accurate results. While some firms might already employ 
or train qualified staff, ERG (2007b) judged that the testing protocols 
are fairly challenging and that few firms have sufficiently skilled 
staff to eliminate the need for outside consultants.
    Table V-8 in the PEA shows the unit costs and associated 
assumptions used to estimate exposure assessment costs. Unit costs for 
exposure sampling include direct sampling costs, the costs of 
productivity losses, and recordkeeping costs, and, depending on 
establishment size, range from $225 to $412 per sample in general 
industry and maritime and from $228 to $415 per sample in construction.
    For costing purposes, based on ERG (2007b), OSHA estimated that 
there are four workers per work area. OSHA interpreted the initial 
exposure assessment as requiring first-year testing of at least one 
worker in each distinct job classification and work area who is, or may 
reasonably be expected to be, exposed to airborne concentrations of 
respirable crystalline silica at or above the action level. This may 
result in overestimated exposure assessment costs in construction 
because OSHA anticipates that many employers, aware that their 
operations currently expose their workers to silica levels above the 
PEL, will simply choose to comply with Table 1 and avoid the costs of 
conducting exposure assessments.
    For periodic monitoring, the proposed standard provides employers 
an option of assessing employee exposures either under a fixed schedule 
(paragraph (d)(3)(i)) or a performance-based schedule (paragraph 
(d)(3)(ii)). Under the fixed schedule, the proposed standard requires 
semi-annual sampling for exposures at or above the action level and 
quarterly sampling for exposures above the 50 [mu]g/m\3\ PEL. 
Monitoring must be continued until the employer can demonstrate that 
exposures are no longer at or above the action level. OSHA used the 
fixed schedule option under the frequency-of-monitoring requirements to 
estimate, for costing purposes, that exposure monitoring will be 
conducted (a) twice a year where initial or subsequent exposure 
monitoring reveals that employee exposures are at or above the action 
level but at or below the PEL, and (b) four times a year where initial 
or subsequent exposure monitoring reveals that employee exposures are 
above the PEL.
    As required under paragraph (d)(4) of the proposed rule, whenever 
there is a change in the production, process, control equipment, 
personnel, or work practices that may result in new or additional 
exposures at or above the action level or when the employer has any 
reason to suspect that a change may result in new or additional 
exposures at or above the action level, the employer must conduct 
additional monitoring. Based on ERG (2007a, 2007b), OSHA estimated that 
approximately 15 percent of workers whose initial exposure or 
subsequent monitoring was at or above the action level would undertake 
additional monitoring.
    A more detailed description of unit costs, other unit parameters, 
and methodological assumptions for exposure assessments is presented in 
Chapter V of the PEA.
d. Medical Surveillance
    Paragraph (h) of the proposed standard requires an initial health 
screening and then triennial periodic screenings for workers exposed 
above the proposed PEL of 50 [mu]g/m\3\ for 30 days or more per year. 
ERG (2013) assembled information on representative unit costs for 
initial and periodic medical surveillance. Separate costs were 
estimated for current employees and for new hires as a function of the 
employment size (i.e., 1-19, 20-499, or 500+ employees) of affected 
establishments. Table V-10 in the PEA presents ERG's unit cost data and 
modeling assumptions used by OSHA to estimate medical surveillance 
costs.
    In accordance with the paragraph (h)(2) of the proposed rule, the 
initial (baseline) medical examination would consist of (1) a medical 
and work history, (2) a physical examination with special emphasis on 
the respiratory system, (3) a chest X-ray that is interpreted according 
to guidelines of the International Labour Organization, (4) a pulmonary 
function test that meets certain criteria and is administered by 
spirometry technician with current certification from a NIOSH-approved 
spirometry course, (5) testing for latent tuberculosis (TB) infection, 
and (6) any other tests deemed appropriate by the physician or licensed 
health care professional (PLHCP).
    As shown in Table V-10 in the PEA, the estimated unit cost of the 
initial health screening for current employees in general industry and 
maritime ranges from approximately $378 to $397 and includes direct 
medical costs, the opportunity cost of worker time (i.e., lost work 
time, evaluated at the worker's 2009 hourly wage, including fringe 
benefits) for offsite travel and for the initial health screening 
itself, and recordkeeping costs. The variation in the unit cost of the 
initial health screening is due entirely to differences in the 
percentage of workers expected to travel offsite for the health 
screening. In OSHA's experience, the larger the establishment the more 
likely it is that the selected PLHCP would provide the health screening 
services at the establishment's worksite. OSHA estimates that 20 
percent of establishments with fewer than 20 employees, 75 percent of 
establishments with 20-499 employees, and 100 percent of establishments 
with 500 or more employees would have the initial health screening for 
current employees conducted onsite.
    The unit cost components of the initial health screening for new 
hires in general industry and maritime are identical to those for 
existing employees with the exception that the percentage of workers 
expected to travel offsite for the health screening would be somewhat 
larger (due to fewer workers being screened annually, in the case of 
new hires, and therefore yielding fewer economies of onsite screening). 
OSHA estimates that 10 percent of establishments with fewer than 20 
employees, 50 percent of establishments with 20-499 employees, and 90 
percent of establishments with 500 or more employees would have the 
initial health screening for new hires conducted onsite. As shown in 
Chapter V in the PEA, the estimated unit cost of the initial health 
screening for new hires in general industry and maritime ranges from 
approximately $380 to $399.
    The unit costs of medical surveillance in construction were derived 
using identical methods. As shown in Table V-39 of the PEA, the 
estimated unit costs of the initial health screening for current 
employees in construction range from approximately $389 to $425; the 
estimated unit costs of the initial health screening for new hires in 
construction range from approximately $394 to $429.
    In accordance with paragraph (h)(3) of the proposed rule, the 
periodic medical examination (every third year after the initial health 
screening) would consist of (1) a medical and work history review and 
update, (2) a physical examination with special emphasis on the 
respiratory system, (3) a chest X-ray that meets certain standards of 
the International Labour Organization, (4) a pulmonary function test 
that meets certain criteria and is administered by a spirometry 
technician with current certification

[[Page 56364]]

from a NIOSH-approved spirometry course, (5) testing for latent TB 
infection, if recommended by the PLHCP, and (6) any other tests deemed 
appropriate by the PLHCP.
    The estimated unit cost of periodic health screening also includes 
direct medical costs, the opportunity cost of worker time, and 
recordkeeping costs. As shown in Table V-10 in the PEA, these triennial 
unit costs in general industry and maritime vary from $378 to $397. For 
construction, as shown in Table V-39 in the PEA, the triennial unit 
costs for periodic health screening vary from roughly $389 to $425. The 
variation in the unit cost (with or without the chest X-ray and 
pulmonary function test) is due entirely to differences in the 
percentage of workers expected to travel offsite for the periodic 
health screening. OSHA estimated that the share of workers traveling 
offsite, as a function of establishment size, would be the same for the 
periodic health screening as for the initial health screening for 
existing employees.
    ERG (2013) estimated a turnover rate of 27.2 percent in general 
industry and maritime and 64.0 percent in construction, based on 
estimates of the separations rate (layoffs, quits, and retirements) 
provided by the Bureau of Labor Statistics (BLS, 2007). However, not 
all new hires would require initial medical testing. As specified in 
paragraph (h)(2) of the proposed rule, employees who had received a 
qualifying medical examination within the previous twelve months would 
be exempt from the initial medical examination. OSHA estimates that 25 
percent of new hires in general industry and maritime and 60 percent of 
new hires in construction would be exempt from the initial medical 
examination.
    Although OSHA believes that some affected establishments in general 
industry, maritime, and construction currently provide some medical 
testing to their silica-exposed employees, the Agency doubts that many 
provide the comprehensive health screening required under the proposed 
rule. Therefore for costing purposes for the proposed rule, OSHA has 
assumed no current compliance with the proposed health screening 
requirements. OSHA requests information from interested parties on the 
current levels and the comprehensiveness of health screening in general 
industry, maritime, and construction.
    Finally, OSHA estimated the unit cost of a medical examination by a 
pulmonary specialist for those employees found to have signs or 
symptoms of silica-related disease or are otherwise referred by the 
PLHCP. OSHA estimates that a medical examination by a pulmonary 
specialist costs approximately $307 for workers in general industry and 
maritime and $333 for workers in construction. This cost includes 
direct medical costs, the opportunity cost of worker time, and 
recordkeeping costs. In all cases, OSHA anticipates that the worker 
will travel offsite to receive the medical examination by a pulmonary 
specialist.
    See Chapter V in the PEA for a full discussion of OSHA's analysis 
of medical surveillance costs under the proposed standard.
e. Information and Training
    As specified in paragraph (i) of the proposed rule and 29 CFR 
1910.1200, training is required for all employees in jobs where there 
is potential exposure to respirable crystalline silica. In addition, 
new hires would require training before starting work. As previously 
noted, ERG (2013) provided an estimate of the new-hire rate in general 
industry and maritime, based on the BLS-estimated separations rate of 
27.2 percent in manufacturing, and an estimate of the new-hire rate in 
construction, based on the BLS-estimated separations rate in 
construction of 64.0 percent.
    OSHA estimated separate costs for initial training of current 
employees and for training new hires. Given that new-hire training 
might need to be performed frequently during the year, OSHA estimated a 
smaller class size for new hires. OSHA anticipates that training, in 
accordance with the requirements of the proposed rule, will be 
conducted by in-house safety or supervisory staff with the use of 
training modules or videos and will last, on average, one hour. ERG 
(2007b) judged that establishments could purchase sufficient training 
materials at an average cost of $2 per worker, encompassing the cost of 
handouts, video presentations, and training manuals and exercises. ERG 
(2013) included in the cost estimates for training the value of worker 
and trainer time as measured by 2009 hourly wage rates (to include 
fringe benefits). ERG also developed estimates of average class sizes 
as a function of establishment size. For initial training, ERG 
estimated an average class size of 5 workers for establishments with 
fewer than 20 employees, 10 workers for establishments with 20 to 499 
employees, and 20 workers for establishments with 500 or more 
employees. For new hire training, ERG estimated an average class size 
of 2 workers for establishments with fewer than 20 employees, 5 workers 
for establishments with 20 to 499 employees, and 10 workers for 
establishments with 500 or more employees.
    The unit costs of training are presented in Tables V-14 (for 
general industry/maritime) and V-43 (for construction) in the PEA. 
Based on ERG's work, OSHA estimated the annualized cost (annualized 
over 10 years) of initial training per current employee at between 
$3.02 and $3.57 and the annual cost of new-hire training at between 
$22.50 and $32.72 per employee in general industry and maritime, 
depending on establishment size. For construction, OSHA estimated the 
annualized cost of initial training per employee at between $3.68 and 
$4.37 and the annual cost of new hire training at between $27.46 and 
$40.39 per employee, depending on establishment size.
    OSHA recognizes that many affected establishments currently provide 
training on the hazards of respirable crystalline silica in the 
workplace. Consistent with some estimates developed by ERG (2007a and 
2007b), OSHA estimates that 50 percent of affected establishments 
already provide such training. However, some of the training specified 
in the proposed rule requires that workers be familiar with the 
training and medical surveillance provisions in the rule. OSHA expects 
that these training requirements in the proposed rule are not currently 
being provided. Therefore, for costing purposes for the proposed rule, 
OSHA has estimated that 50 percent of affected establishments currently 
provide their workers, and would provide new hires, with training that 
would comply with approximately 50 percent of the training 
requirements. In other words, OSHA estimates that those 50 percent of 
establishments currently providing training on workplace silica hazards 
would provide an additional 30 minutes of training to comply with the 
proposed rule; the remaining 50 percent of establishments would provide 
60 minutes of training to comply with the proposed rule. OSHA also 
recognizes that many new hires may have been previously employed in the 
same industry, and in some cases by the same establishment, so that 
they might have already received (partial) silica training. However, 
for purposes of cost estimation, OSHA estimates that all new hires will 
receive the full silica training from the new employer. OSHA requests 
comments from interested parties on the reasonableness of these 
assumptions.
f. Regulated Areas and Access Control
    Paragraph (e)(1) of the proposed standard requires that wherever an

[[Page 56365]]

employee's exposure to airborne concentrations of respirable 
crystalline silica is, or can reasonably be expected to be, in excess 
of the PEL, each employer shall establish and implement either a 
regulated area in accordance with paragraph (e)(2) or an access control 
plan in accordance with paragraph (e)(3). For costing purposes, OSHA 
estimated that employers in general industry and maritime would 
typically prefer and choose option (e)(2) and would therefore establish 
regulated areas when an employee's exposure to airborne concentrations 
of silica exceeds, or can reasonably be expected to exceed, the PEL. 
OSHA believes that general industry and maritime employers will prefer 
this option as it is expected to be the most practical alternative in 
fixed worksites. Requirements in the proposed rule for a regulated area 
include demarcating the boundaries of the regulated area (as separate 
from the rest of the workplace), limiting access to the regulated area, 
providing an appropriate respirator to each employee entering the 
regulated area, and providing protective clothing as needed in the 
regulated area.
    Based on ERG (2007b), OSHA derived unit cost estimates for 
establishing and maintaining regulated areas to comply with these 
requirements and estimated that one area would be necessary for every 
eight workers in general industry and maritime exposed above the PEL. 
Unit costs include planning time (estimated at eight hours of 
supervisor time annually); material costs for signs and boundary 
markers (annualized at $63.64 in 2009 dollars); and costs of $500 
annually for two disposable respirators per day to be used by 
authorized persons (other than those who regularly work in the 
regulated area) who might need to enter the area in the course of their 
job duties. In addition, for costing purposes, OSHA estimates that, in 
response to the protective work clothing requirements in regulated 
areas, ten percent of employees in regulated areas would wear 
disposable protective clothing daily, estimated at $5.50 per suit, for 
an annual clothing cost of $1,100 per regulated area. Tables V-16 in 
the PEA shows the cost assumptions and unit costs applied in OSHA's 
cost model for regulated areas in general industry and maritime. 
Overall, OSHA estimates that each regulated area would, on average, 
cost employers $1,732 annually in general industry and maritime.
    For construction, OSHA estimated that some employers would select 
the (e)(2) option concerning regulated areas while other employers 
would prefer the (e)(3) option concerning written access control plans 
whenever an employee's exposure to airborne concentrations of 
respirable crystalline silica exceeds, or can reasonably be expected to 
exceed, the PEL.
    Based on the respirator specifications developed by ERG (2007a) and 
shown in Table V-34 in the PEA, ERG derived the full-time-equivalent 
number of workers engaged in construction tasks where respirators are 
required and estimated the costs of establishing a regulated area for 
these workers.
    Under the second option for written access control plans, the 
employer must include the following elements in the plan: competent 
person provisions; notification and demarcation procedures; multi-
employer workplace procedures; provisions for limiting access; 
provisions for supplying respirators; and protective clothing 
procedures. OSHA anticipates that employers will incur costs for labor, 
materials, respiratory protection, and protective clothing to comply 
with the proposed access control plan requirements.
    Table V-45 in the PEA shows the unit costs and assumptions for 
developing costs for regulated areas and for access control plans in 
construction. ERG estimated separate development and implementation 
costs. ERG judged that developing either a regulated area or an access 
control plan would take approximately 4 hours of a supervisor's time. 
The time allowed to set up a regulated area or an access control plan 
is intended to allow for the communication of access restrictions and 
locations at multi-employer worksites. ERG estimated a cost of $116 per 
job based on job frequency and the costs for hazard tape and warning 
signs (which are reusable). ERG estimated a labor cost of $27 per job 
for implementing a written access control plan (covering the time 
expended for revision of the access control plan for individual jobs 
and communication of the plan). In addition, OSHA estimated that there 
would be annual disposable clothing costs of $333 per crew for 
employers who implement either regulated areas or the access control 
plan option. In addition, OSHA estimated that there would be annual 
respirator costs of $60 per crew for employers who implement either 
option.
    ERG aggregated costs by estimating an average crew size of four in 
construction and an average job length of ten days. ERG judged that 
employers would choose to establish regulated areas in 75 percent of 
the instances where either regulated areas or an access control plan is 
required, and that written access control plans would be established 
for the remaining 25 percent.
    See Chapter V in the PEA for a full discussion of OSHA's analysis 
of costs for regulated areas and written access control plans under the 
proposed standard.

F. Economic Feasibility Analysis and Regulatory Flexibility 
Determination

    Chapter VI of the PEA presents OSHA's analysis of the economic 
impacts of its proposed silica rule on affected employers in general 
industry, maritime, and construction. The discussion below summarizes 
the findings in that chapter.
    As a first step, the Agency explains its approach for achieving the 
two major objectives of its economic impact analysis: (1) To establish 
whether the proposed rule is economically feasible for all affected 
industries, and (2) to determine if the Agency can certify that the 
proposed rule will not have a significant economic impact on a 
substantial number of small entities. Next, this approach is applied to 
industries with affected employers in general industry and maritime and 
then to industries with affected employers in construction. Finally, 
OSHA directed Inforum--a not-for-profit corporation (based at the 
University of Maryland) specializing in the design and application of 
macroeconomic models of the United States (and other countries)--to 
estimate the industry and aggregate employment effects of the proposed 
silica rule. The Agency invites comment on any aspect of the methods 
and data presented here or in Chapter VI of the PEA.
1. Analytic Approach
a. Economic Feasibility
    The Court of Appeals for the D.C. Circuit has long held that OSHA 
standards are economically feasible so long as their costs do not 
threaten the existence of, or cause massive economic dislocations 
within, a particular industry or alter the competitive structure of 
that industry. American Iron and Steel Institute. v. OSHA, 939 F.2d 
975, 980 (D.C. Cir. 1991); United Steelworkers of America, AFL-CIO-CLC 
v. Marshall, 647 F.2d 1189, 1265 (D.C. Cir. 1980); Industrial Union 
Department v. Hodgson, 499 F.2d 467, 478 (D.C. Cir. 1974).
    In practice, the economic burden of an OSHA standard on an 
industry--and whether the standard is economically feasible for that 
industry--depends on the magnitude of compliance costs incurred by 
establishments in that industry and the extent to which they

[[Page 56366]]

are able to pass those costs on to their customers. That, in turn, 
depends, to a significant degree, on the price elasticity of demand for 
the products sold by establishments in that industry.
    The price elasticity of demand refers to the relationship between 
the price charged for a product and the demand for that product: the 
more elastic the relationship, the less an establishment's compliance 
costs can be passed through to customers in the form of a price 
increase and the more it has to absorb compliance costs in the form of 
reduced profits. When demand is inelastic, establishments can recover 
most of the costs of compliance by raising the prices they charge; 
under this scenario, profit rates are largely unchanged and the 
industry remains largely unaffected. Any impacts are primarily on those 
customers using the relevant product. On the other hand, when demand is 
elastic, establishments cannot recover all compliance costs simply by 
passing the cost increase through in the form of a price increase; 
instead, they must absorb some of the increase from their profits. 
Commonly, this will mean reductions both in the quantity of goods and 
services produced and in total profits, though the profit rate may 
remain unchanged. In general, ``[w]hen an industry is subjected to a 
higher cost, it does not simply swallow it; it raises its price and 
reduces its output, and in this way shifts a part of the cost to its 
consumers and a part to its suppliers,'' in the words of the court in 
American Dental Association v. Secretary of Labor (984 F.2d 823, 829 
(7th Cir. 1993)).
    The court's summary is in accord with microeconomic theory. In the 
long run, firms can remain in business only if their profits are 
adequate to provide a return on investment that ensures that investment 
in the industry will continue. Over time, because of rising real 
incomes and productivity increases, firms in most industries are able 
to ensure an adequate profit. As technology and costs change, however, 
the long-run demand for some products naturally increases and the long-
run demand for other products naturally decreases. In the face of 
additional compliance costs (or other external costs), firms that 
otherwise have a profitable line of business may have to increase 
prices to stay viable. Increases in prices typically result in reduced 
quantity demanded, but rarely eliminate all demand for the product. 
Whether this decrease in the total production of goods and services 
results in smaller output for each establishment within the industry or 
the closure of some plants within the industry, or a combination of the 
two, is dependent on the cost and profit structure of individual firms 
within the industry.
    If demand is perfectly inelastic (i.e., the price elasticity of 
demand is zero), then the impact of compliance costs that are 1 percent 
of revenues for each firm in the industry would result in a 1 percent 
increase in the price of the product, with no decline in quantity 
demanded. Such a situation represents an extreme case, but might be 
observed in situations in which there were few if any substitutes for 
the product in question, or if the products of the affected sector 
account for only a very small portion of the revenue or income of its 
customers.
    If the demand is perfectly elastic (i.e., the price elasticity of 
demand is infinitely large), then no increase in price is possible and 
before-tax profits would be reduced by an amount equal to the costs of 
compliance (net of any cost savings--such as reduced workers' 
compensation insurance premiums--resulting from the proposed standard) 
if the industry attempted to maintain production at the same level as 
previously. Under this scenario, if the costs of compliance are such a 
large percentage of profits that some or all plants in the industry 
could no longer operate in the industry with hope of an adequate return 
on investment, then some or all of the firms in the industry would 
close. This scenario is highly unlikely to occur, however, because it 
can only arise when there are other products--unaffected by the 
proposed rule--that are, in the eyes of their customers, perfect 
substitutes for the products the affected establishments make.
    A common intermediate case would be a price elasticity of demand of 
one (in absolute terms). In this situation, if the costs of compliance 
amount to 1 percent of revenues, then production would decline by 1 
percent and prices would rise by 1 percent. As a result, industry 
revenues would remain the same, with somewhat lower production, but 
with similar profit rates (in most situations where the marginal costs 
of production net of regulatory costs would fall as well). Customers 
would, however, receive less of the product for their (same) 
expenditures, and firms would have lower total profits; this, as the 
court described in American Dental Association v. Secretary of Labor, 
is the more typical case.
    A decline in output as a result of an increase in price may occur 
in a variety of ways: individual establishments could each reduce their 
levels of production; some marginal plants could close; or, in the case 
of an expanding industry, new entry may be delayed until demand equals 
supply. In many cases it will be a combination of all three kinds of 
reductions in output. Which possibility is most likely depends on the 
form that the costs of the regulation take. If the costs are variable 
costs (i.e., costs that vary with the level of production at a 
facility), then economic theory suggests that any reductions in output 
will take the form of reductions in output at each affected facility, 
with few if any plant closures. If, on the other hand, the costs of a 
regulation primarily take the form of fixed costs (i.e., costs that do 
not vary with the level of production at a facility), then reductions 
in output are more likely to take the form of plant closures or delays 
in new entry.
    Most of the costs of this regulation, as estimated in Chapter V of 
the PEA, are variable costs. Almost all of the major costs of program 
elements, such as medical surveillance and training, will vary in 
proportion to the number of employees (which is a rough proxy for the 
amount of production). Exposure monitoring costs will vary with the 
number of employees, but do have some economies of scale to the extent 
that a larger firm need only conduct representative sampling rather 
than sample every employee. The costs of engineering controls in 
construction also vary by level of production because almost all 
necessary equipment can readily be rented and the productivity costs of 
using some of these controls vary proportionally to the level of 
production. Finally, the costs of operating engineering controls in 
general industry (the majority of the annualized costs of engineering 
controls in general industry) vary by the number of hours the 
establishment works, and thus vary by the level of production and are 
not fixed costs in the strictest sense.
    This leaves two kinds of costs that are, in some sense, fixed 
costs--capital costs of engineering controls in general industry and 
certain initial costs that new entries to the industry will not have to 
bear.
    Capital costs of engineering controls in general industry due to 
this standard are relatively small as compared to the total costs, 
representing less than 8 percent of total annualized costs and 
approximately $362 per year per affected establishment in general 
industry.
    Some initial costs are fixed in the sense that they will only be 
borne by firms in the industry today--these include initial costs for 
general training not currently required and initial costs of medical 
surveillance. Both of these costs will disappear after the initial year 
of the standard and thus would be

[[Page 56367]]

difficult to pass on. These costs, however, represent less than 4 
percent of total costs and less than $55 per affected establishment.
    As a result of these considerations, OSHA expects that it is 
somewhat more likely that reductions in industry output will be met by 
reductions in output at each affected facility rather than as a result 
of plant closures. However, closures of some marginal plants or poorly 
performing facilities are always possible.
    To determine whether a rule is economically feasible, OSHA begins 
with two screening tests to consider minimum threshold effects of the 
rule under two extreme cases: (1) all costs are passed through to 
customers in the form of higher prices (consistent with a price 
elasticity of demand of zero), and (2) all costs are absorbed by the 
firm in the form of reduced profits (consistent with an infinite price 
elasticity of demand).
    In the former case, the immediate impact of the rule would be 
observed in increased industry revenues. While there is no hard and 
fast rule, in the absence of evidence to the contrary, OSHA generally 
considers a standard to be economically feasible for an industry when 
the annualized costs of compliance are less than a threshold level of 
one percent of annual revenues. Retrospective studies of previous OSHA 
regulations have shown that potential impacts of such a small magnitude 
are unlikely to eliminate an industry or significantly alter its 
competitive structure,\19\ particularly since most industries have at 
least some ability to raise prices to reflect increased costs and, as 
shown in the PEA, normal price variations for products typically exceed 
three percent a year. Of course, OSHA recognizes that even when costs 
are within this range, there could be unusual circumstances requiring 
further analysis.
---------------------------------------------------------------------------

    \19\ See OSHA's Web page, http://www.osha.gov/dea/lookback.html#Completed, for a link to all completed OSHA lookback 
reviews.
---------------------------------------------------------------------------

    In the latter case, the immediate impact of the rule would be 
observed in reduced industry profits. OSHA uses the ratio of annualized 
costs to annual profits as a second check on economic feasibility. 
Again, while there is no hard and fast rule, in the absence of evidence 
to the contrary, OSHA has historically considered a standard to be 
economically feasible for an industry when the annualized costs of 
compliance are less than a threshold level of ten percent of annual 
profits. In the context of economic feasibility, the Agency believes 
this threshold level to be fairly modest, given that--as shown in the 
PEA--normal year-to-year variations in profit rates in an industry can 
exceed 40 percent or more. OSHA's choice of a threshold level of ten 
percent of annual profits is low enough that even if, in a hypothetical 
worst case, all compliance costs were upfront costs, then upfront costs 
would still equal seventy-one percent of profits and thus would be 
affordable from profits without resort to credit markets. If the 
threshold level were first-year costs of ten percent of annual profits, 
firms could even more easily expect to cover first-year costs at the 
threshold level out of current profits without having to access capital 
markets and otherwise being threatened with short-term insolvency.
    In general, because it is usually the case that firms would able to 
pass on some or all of the costs of the proposed rule, OSHA will tend 
to give much more weight to the ratio of industry costs to industry 
revenues than to the ratio of industry costs to industry profits. 
However, if costs exceed either the threshold percentage of revenue or 
the threshold percentage of profits for an industry, or if there is 
other evidence of a threat to the viability of an industry because of 
the standard, OSHA will examine the effect of the rule on that industry 
more closely. Such an examination would include market factors specific 
to the industry, such as normal variations in prices and profits, 
international trade and foreign competition, and any special 
circumstances, such as close domestic substitutes of equal cost, which 
might make the industry particularly vulnerable to a regulatory cost 
increase.
    The preceding discussion focused on the economic viability of the 
affected industries in their entirety. However, even if OSHA found that 
a proposed standard did not threaten the survival of affected 
industries, there is still the question of whether the industries' 
competitive structure would be significantly altered. For this reason, 
OSHA also examines the differential costs by size of firm.
b. Regulatory Flexibility Screening Analysis
    The Regulatory Flexibility Act (RFA), Pub. L. No. 96-354, 94 Stat. 
1164 (codified at 5 U.S.C. 601), requires Federal agencies to consider 
the economic impact that a proposed rulemaking will have on small 
entities. The RFA states that whenever a Federal agency is required to 
publish general notice of proposed rulemaking for any proposed rule, 
the agency must prepare and make available for public comment an 
initial regulatory flexibility analysis (IRFA). 5 U.S.C. 603(a). 
Pursuant to section 605(b), in lieu of an IRFA, the head of an agency 
may certify that the proposed rule will not have a significant economic 
impact on a substantial number of small entities. A certification must 
be supported by a factual basis. If the head of an agency makes a 
certification, the agency shall publish such certification in the 
Federal Register at the time of publication of general notice of 
proposed rulemaking or at the time of publication of the final rule. 5 
U.S.C. 605(b).
    To determine if the Assistant Secretary of Labor for OSHA can 
certify that the proposed silica rule will not have a significant 
economic impact on a substantial number of small entities, the Agency 
has developed screening tests to consider minimum threshold effects of 
the proposed rule on small entities. These screening tests are similar 
in concept to those OSHA developed above to identify minimum threshold 
effects for purposes of demonstrating economic feasibility.
    There are, however, two differences. First, for each affected 
industry, the screening tests are applied, not to all establishments, 
but to small entities (defined as ``small business concerns'' by SBA) 
and also to very small entities (defined by OSHA as entities with fewer 
than 20 employees). Second, although OSHA's regulatory flexibility 
screening test for revenues also uses a minimum threshold level of 
annualized costs equal to one percent of annual revenues, OSHA has 
established a minimum threshold level of annualized costs equal to five 
percent of annual profits for the average small entity or very small 
entity. The Agency has chosen a lower minimum threshold level for the 
profitability screening analysis and has applied its screening tests to 
both small entities and very small entities in order to ensure that 
certification will be made, and an IRFA will not be prepared, only if 
OSHA can be highly confident that a proposed rule will not have a 
significant economic impact on a substantial number of small entities 
in any affected industry.
2. Impacts in General Industry and Maritime
a. Economic Feasibility Screening Analysis: All Establishments
    To determine whether the proposed rule's projected costs of 
compliance would threaten the economic viability of affected 
industries, OSHA first compared, for each affected industry, annualized 
compliance costs to annual revenues and profits per (average)

[[Page 56368]]

affected establishment. The results for all affected establishments in 
all affected industries in general industry and maritime are presented 
in Table VIII-11, using annualized costs per establishment for the 
proposed 50 [mu]g/m\3\ PEL. Shown in the table for each affected 
industry are total annualized costs, the total number of affected 
establishments, annualized costs per affected establishment, annual 
revenues per establishment, the profit rate, annual profits per 
establishment, annualized compliance costs as a percentage of annual 
revenues, and annualized compliance costs as a percentage of annual 
profits.
    The annualized costs per affected establishment for each affected 
industry were calculated by distributing the industry-level 
(incremental) annualized compliance costs among all affected 
establishments in the industry, where costs were annualized using a 7 
percent discount rate. The annualized cost of the proposed rule for the 
average establishment in all of general industry and maritime is 
estimated at $2,571 in 2009 dollars. It is clear from Table VIII-11 
that the estimates of the annualized costs per affected establishment 
in general industry and maritime vary widely from industry to industry. 
These estimates range from $40,468 for NAICS 327111 (Vitreous china 
plumbing fixtures and bathroom accessories manufacturing) and $38,422 
for NAICS 327121 (Brick and structural clay manufacturing) to $107 for 
NAICS 325510 (Paint and coating manufacturing) and $49 for NAICS 621210 
(Dental offices).
    Table VIII-11 also shows that, within the general industry and 
maritime sectors, there are no industries in which the annualized costs 
of the proposed rule exceed 1 percent of annual revenues or 10 percent 
of annual profits. NAICS 327123 (Other structural clay product 
manufacturing) has both the highest cost impact as a percentage of 
revenues, of 0.39 percent, and the highest cost impact as a percentage 
of profits, of 8.78 percent. Based on these results, even if the costs 
of the proposed rule were 50 percent higher than OSHA has estimated, 
the highest cost impact as a percentage of revenues in any affected 
industry in general industry or maritime would be less than 0.6 
percent. Furthermore, the costs of the proposed rule would have to be 
more than 150 percent higher than OSHA has estimated for the cost 
impact as a percentage of revenues to equal 1 percent in any affected 
industry. For all affected establishments in general industry and 
maritime, the estimated annualized cost of the proposed rule is, on 
average, equal to 0.02 percent of annual revenue and 0.5 percent of 
annual profit.

[[Page 56369]]



                                Table VIII-11--Screening Analysis for Establishments in General Industry and Maritime Affected by OSHA's Proposed Silica Standard
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                               Annualized
                                                               Total          Number of        costs per       Revenues per   Profit rate \a\    Profits per       Costs as a       Costs as a
           NAICS                      Industry               annualized        affected         affected      establishment       (percent)     establishment    percentage of    percentage of
                                                               costs        establishments   establishment                                                          revenues         profits
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
324121....................  Asphalt paving mixture and           $242,070            1,431             $169       $6,617,887             7.50         $496,420             0.00             0.03
                             block manufacturing.
324122....................  Asphalt shingle and roofing         3,157,257              224           14,095       34,018,437             7.50        2,551,788             0.04             0.55
                             materials.
325510....................  Paint and coating                     144,281            1,344              107       19,071,850             5.38        1,026,902             0.00             0.01
                             manufacturing.
327111....................  Vitreous china plumbing             1,659,194               41           40,468       21,226,709             4.41          937,141             0.19             4.32
                             fixtures & bathroom
                             accessories manufacturing.
327112....................  Vitreous china, fine                2,601,471              731            3,559        1,203,017             4.41           53,112             0.30             6.70
                             earthenware, & other
                             pottery product
                             manufacturing.
327113....................  Porcelain electrical supply         1,748,297              125           13,986        8,091,258             4.41          357,222             0.17             3.92
                             mfg.
327121....................  Brick and structural clay           7,838,050              204           38,422       11,440,887             4.41          505,105             0.34             7.61
                             mfg.
327122....................  Ceramic wall and floor tile         4,132,107              193           21,410        6,706,175             4.41          296,072             0.32             7.23
                             mfg.
327123....................  Other structural clay                 936,699               49           19,116        4,933,258             4.41          217,799             0.39             8.78
                             product mfg.
327124....................  Clay refractory                       482,438              129            3,740        7,872,516             4.41          347,565             0.05             1.08
                             manufacturing.
327125....................  Nonclay refractory                    608,017              105            5,791       14,718,533             4.41          649,810             0.04             0.89
                             manufacturing.
327211....................  Flat glass manufacturing....          275,155               83            3,315       43,821,692             3.42        1,499,102             0.01             0.22
327212....................  Other pressed and blown             1,084,706              499            2,174        7,233,509             3.42          247,452             0.03             0.88
                             glass and glassware
                             manufacturing.
327213....................  Glass container                       756,888               72           10,512       64,453,615             3.42        2,204,903             0.02             0.48
                             manufacturing.
327320....................  Ready-mixed concrete               16,511,080            6,064            2,723        4,891,554             6.64          324,706             0.06             0.84
                             manufacturing.
327331....................  Concrete block and brick mfg        4,437,939              951            4,667        5,731,328             6.64          380,451             0.08             1.23
327332....................  Concrete pipe mfg...........        2,747,484              385            7,136        7,899,352             6.64          524,366             0.09             1.36
327390....................  Other concrete product mfg..       12,900,251            2,281            5,656        4,816,851             6.64          319,747             0.12             1.77
327991....................  Cut stone and stone product         8,600,298            1,943            4,426        1,918,745             5.49          105,320             0.23             4.20
                             manufacturing.
327992....................  Ground or treated mineral           4,595,006              271           16,956        8,652,610             5.49          474,944             0.20             3.57
                             and earth manufacturing.
327993....................  Mineral wool manufacturing..        1,094,552              321            3,410       18,988,835             5.49        1,042,303             0.02             0.33
327999....................  All other misc. nonmetallic         1,966,052              465            4,228        5,803,139             5.49          318,536             0.07             1.33
                             mineral product mfg.
331111....................  Iron and steel mills........          424,557              614              692       70,641,523             4.49        3,173,209             0.00             0.02
331112....................  Electrometallurgical                    8,577               12              692       49,659,392             4.49        2,230,694             0.00             0.03
                             ferroalloy product
                             manufacturing.
331210....................  Iron and steel pipe and tube           84,537              122              694       31,069,797             4.49        1,395,652             0.00             0.05
                             manufacturing from
                             purchased steel.
331221....................  Rolled steel shape                     42,672               61              694       28,102,003             4.49        1,262,339             0.00             0.05
                             manufacturing.
331222....................  Steel wire drawing..........           57,557               83              694       12,904,028             4.49          579,647             0.01             0.12
331314....................  Secondary smelting and                 28,757               42              692       29,333,260             4.46        1,309,709             0.00             0.05
                             alloying of aluminum.
331423....................  Secondary smelting,                     4,940                7              695       26,238,546             4.42        1,158,438             0.00             0.06
                             refining, and alloying of
                             copper.
331492....................  Secondary smelting,                    36,946               53              695       14,759,299             4.42          651,626             0.00             0.11
                             refining, and alloying of
                             nonferrous metal (except cu
                             & al).
331511....................  Iron foundries..............       15,310,815              527           29,053       19,672,534             4.11          809,290             0.15             3.59
331512....................  Steel investment foundries..        4,283,138              132           32,448       18,445,040             4.11          758,794             0.18             4.28
331513....................  Steel foundries (except             4,596,837              222           20,706       17,431,292             4.11          717,090             0.12             2.89
                             investment).
331524....................  Aluminum foundries (except          6,975,150              466           14,968        8,244,396             4.11          339,159             0.18             4.41
                             die-casting).
331525....................  Copper foundries (except die-       1,636,463              256            6,392        3,103,580             4.11          127,675             0.21             5.01
                             casting).
331528....................  Other nonferrous foundries          1,232,708              124            9,941        7,040,818             4.11          289,646             0.14             3.43
                             (except die-casting).
332111....................  Iron and steel forging......          105,955              150              705       15,231,376             4.71          716,646             0.00             0.10
332112....................  Nonferrous forging..........           34,982               50              705       28,714,500             4.71        1,351,035             0.00             0.05
332115....................  Crown and closure                      12,720               18              697       16,308,872             4.71          767,343             0.00             0.09
                             manufacturing.
332116....................  Metal stamping..............          255,832              366              700        6,748,606             4.71          317,526             0.01             0.22
332117....................  Powder metallurgy part                 32,828               47              696        9,712,731             4.71          456,990             0.01             0.15
                             manufacturing.
332211....................  Cutlery and flatware (except           22,970               33              705        9,036,720             5.22          472,045             0.01             0.15
                             precious) manufacturing.
332212....................  Hand and edge tool                    145,223              207              702        5,874,133             5.22          306,843             0.01             0.23
                             manufacturing.
332213....................  Saw blade and handsaw                  28,851               41              698       11,339,439             5.22          592,331             0.01             0.12
                             manufacturing.
332214....................  Kitchen utensil, pot, and              15,678               22              705       18,620,983             5.22          972,693             0.00             0.07
                             pan manufacturing.
332323....................  Ornamental and architectural           35,267               54              654        2,777,899             4.70          130,669             0.02             0.50
                             metal work.
332439....................  Other metal container                  60,330               86              705        7,467,745             3.58          267,613             0.01             0.26
                             manufacturing.
332510....................  Hardware manufacturing......          180,292              256              705       11,899,309             5.22          621,577             0.01             0.11
332611....................  Spring (heavy gauge)                   16,158               23              705        7,764,934             5.22          405,612             0.01             0.17
                             manufacturing.
332612....................  Spring (light gauge)                   60,992               87              705        8,185,896             5.22          427,602             0.01             0.16
                             manufacturing.
332618....................  Other fabricated wire                 144,819              205              705        5,120,358             5.22          267,469             0.01             0.26
                             product manufacturing.
332710....................  Machine shops...............        1,077,759            1,506              716        1,624,814             5.80           94,209             0.04             0.76
332812....................  Metal coating and allied            3,038,935            2,599            1,169        4,503,334             4.85          218,618             0.03             0.53
                             services.
332911....................  Industrial valve                      150,261              216              694       18,399,215             6.81        1,252,418             0.00             0.06
                             manufacturing.

[[Page 56370]]

 
332912....................  Fluid power valve and hose            140,213              201              698       22,442,750             6.81        1,527,658             0.00             0.05
                             fitting manufacturing.
332913....................  Plumbing fixture fitting and           45,472               65              698       24,186,039             6.81        1,646,322             0.00             0.04
                             trim manufacturing.
332919....................  Other metal valve and pipe             71,354              102              698       15,023,143             6.81        1,022,612             0.00             0.07
                             fitting manufacturing.
332991....................  Ball and roller bearing               107,338              154              698       36,607,380             6.81        2,491,832             0.00             0.03
                             manufacturing.
332996....................  Fabricated pipe and pipe              107,219              154              698        6,779,536             6.81          461,477             0.01             0.15
                             fitting manufacturing.
332997....................  Industrial pattern                     20,891               30              698        1,122,819             6.81           76,429             0.06             0.91
                             manufacturing.
332998....................  Enameled iron and metal                60,684               76              798       14,497,312             6.81          986,819             0.01             0.08
                             sanitary ware manufacturing.
332999....................  All other miscellaneous               288,093              408              707        4,405,921             6.81          299,907             0.02             0.24
                             fabricated metal product
                             manufacturing.
333319....................  Other commercial and service          209,273              299              699       10,042,625             4.86          487,919             0.01             0.14
                             industry machinery
                             manufacturing.
333411....................  Air purification equipment             58,265               84              694        7,353,577             4.55          334,804             0.01             0.21
                             manufacturing.
333412....................  Industrial and commercial              41,212               59              694       12,795,249             4.55          582,559             0.01             0.12
                             fan and blower
                             manufacturing.
333414....................  Heating equipment (except              80,754              116              694       11,143,189             4.55          507,342             0.01             0.14
                             warm air furnaces)
                             manufacturing.
333511....................  Industrial mold                       160,131              226              710        2,481,931             5.29          131,278             0.03             0.54
                             manufacturing.
333512....................  Machine tool (metal cutting            68,151               97              702        7,371,252             5.29          389,890             0.01             0.18
                             types) manufacturing.
333513....................  Machine tool (metal forming            33,940               48              702        5,217,940             5.29          275,994             0.01             0.25
                             types) manufacturing.
333514....................  Special die and tool, die             231,988              325              714        2,378,801             5.29          125,823             0.03             0.57
                             set, jig, and fixture
                             manufacturing.
333515....................  Cutting tool and machine              139,916              197              710        3,384,805             5.29          179,034             0.02             0.40
                             tool accessory
                             manufacturing.
333516....................  Rolling mill machinery and             12,279               17              710        9,496,141             5.29          502,283             0.01             0.14
                             equipment manufacturing.
333518....................  Other metalworking machinery           50,002               70              710        7,231,602             5.29          382,504             0.01             0.19
                             manufacturing.
333612....................  Speed changer, industrial              48,452               70              693       10,727,834             2.63          281,813             0.01             0.25
                             high-speed drive, and gear
                             manufacturing.
333613....................  Mechanical power                       61,197               88              693       14,983,120             2.63          393,597             0.00             0.18
                             transmission equipment
                             manufacturing.
333911....................  Pump and pumping equipment            121,086              174              696       17,078,357             4.58          781,566             0.00             0.09
                             manufacturing.
333912....................  Air and gas compressor                 84,518              121              698       21,079,073             4.58          964,653             0.00             0.07
                             manufacturing.
333991....................  Power-driven handtool                  34,459               49              698       22,078,371             4.58        1,010,384             0.00             0.07
                             manufacturing.
333992....................  Welding and soldering                  62,401               90              696       16,457,683             4.58          753,162             0.00             0.09
                             equipment manufacturing.
333993....................  Packaging machinery                    83,714              120              700        7,374,940             4.58          337,503             0.01             0.21
                             manufacturing.
333994....................  Industrial process furnace             42,523               61              702        5,584,460             4.58          255,565             0.01             0.27
                             and oven manufacturing.
333995....................  Fluid power cylinder and               78,057              112              695       13,301,790             4.58          608,737             0.01             0.11
                             actuator manufacturing.
333996....................  Fluid power pump and motor             53,535               77              695       18,030,122             4.58          825,122             0.00             0.08
                             manufacturing.
333997....................  Scale and balance (except              14,822               21              702        7,236,854             4.58          331,184             0.01             0.21
                             laboratory) manufacturing.
333999....................  All other miscellaneous               207,006              296              698        6,033,776             4.58          276,127             0.01             0.25
                             general purpose machinery
                             manufacturing.
334518....................  Watch, clock, and part                  8,740               12              703        4,924,986             5.94          292,667             0.01             0.24
                             manufacturing.
335211....................  Electric housewares and                13,928               22              643       22,023,076             4.21          927,874             0.00             0.07
                             household fans.
335221....................  Household cooking appliance            30,077               47              643       37,936,003             4.21        1,598,316             0.00             0.04
                             manufacturing.
335222....................  Household refrigerator and             32,118               26            1,235      188,132,355             4.21        7,926,376             0.00             0.02
                             home freezer manufacturing.
335224....................  Household laundry equipment            30,521               23            1,327      221,491,837             4.21        9,331,875             0.00             0.01
                             manufacturing.
335228....................  Other major household                  24,023               37              643      107,476,620             4.21        4,528,196             0.00             0.01
                             appliance manufacturing.
336111....................  Automobile manufacturing....          293,357              181            1,621      512,748,675             2.04       10,462,470             0.00             0.02
336112....................  Light truck and utility               404,778               94            4,306    1,581,224,101             2.04       32,264,364             0.00             0.01
                             vehicle manufacturing.
336120....................  Heavy duty truck                      125,181               95            1,318      194,549,998             2.04        3,969,729             0.00             0.03
                             manufacturing.
336211....................  Motor vehicle body                    187,131              269              696       15,012,805             2.04          306,331             0.00             0.23
                             manufacturing.
336212....................  Truck trailer manufacturing.          126,512              182              694       17,032,455             2.04          347,542             0.00             0.20
336213....................  Motor home manufacturing....           84,073               91              924       65,421,325             2.04        1,334,901             0.00             0.07
336311....................  Carburetor, piston, piston             41,219               60              693       21,325,990             2.04          435,150             0.00             0.16
                             ring, and valve
                             manufacturing.
336312....................  Gasoline engine and engine            258,625              373              693       36,938,061             2.04          753,709             0.00             0.09
                             parts manufacturing.

[[Page 56371]]

 
336322....................  Other motor vehicle                   242,586              350              693       33,890,776             2.04          691,530             0.00             0.10
                             electrical and electronic
                             equipment manufacturing.
336330....................  Motor vehicle steering and            153,960              223              692       42,374,501             2.04          864,638             0.00             0.08
                             suspension components
                             (except spring)
                             manufacturing.
336340....................  Motor vehicle brake system            132,114              191              693       51,498,927             2.04        1,050,819             0.00             0.07
                             manufacturing.
336350....................  Motor vehicle transmission            327,377              473              692       63,004,961             2.04        1,285,596             0.00             0.05
                             and power train parts
                             manufacturing.
336370....................  Motor vehicle metal stamping          431,985              624              692       33,294,026             2.04          679,354             0.00             0.10
336399....................  All other motor vehicle               583,803              843              693       31,304,202             2.04          638,752             0.00             0.11
                             parts manufacturing.
336611....................  Ship building and repair....        8,749,619              635           13,779       24,524,381             5.86        1,437,564             0.06             0.96
336612....................  Boat building...............        5,479,624            1,129            4,854        9,474,540             5.86          555,376             0.05             0.87
336992....................  Military armored vehicle,              27,227               39              697       44,887,321             6.31        2,832,073             0.00             0.02
                             tank, and tank component
                             manufacturing.
337215....................  Showcase, partition,                  233,720              334              701        4,943,560             4.54          224,593             0.01             0.31
                             shelving, and locker
                             manufacturing.
339114....................  Dental equipment and                  351,955              411              856        4,732,949            10.77          509,695             0.02             0.17
                             supplies manufacturing.
339116....................  Dental laboratories.........        1,439,004            7,261              198          563,964            10.77           60,734             0.04             0.33
339911....................  Jewelry (except costume)            1,560,353            1,777              878        3,685,009             5.80          213,566             0.02             0.41
                             manufacturing.
339913....................  Jewelers' materials and               320,878              264            1,215        3,762,284             5.80          218,045             0.03             0.56
                             lapidary work manufacturing.
339914....................  Costume jewelry and novelty           236,821              590              401        1,353,403             5.80           78,437             0.03             0.51
                             manufacturing.
339950....................  Sign manufacturing..........          294,919              496              594        1,872,356             5.80          108,513             0.03             0.55
423840....................  Industrial supplies,                  177,299              383              463        1,913,371             3.44           65,736             0.02             0.70
                             wholesalers.
482110....................  Rail transportation.........        2,452,073              N/A              N/A              N/A              N/A              N/A              N/A              N/A
621210....................  Dental offices..............          389,256            7,980               49          755,073             7.34           55,429             0.01             0.09
                                                         ---------------------------------------------------------------------------------------------------------------------------------------
                            Total.......................      146,726,595           56,121            2,571  ...............  ...............  ...............  ...............  ...............
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
[\a\] Profit rates were calculated by ERG (2013) as the average of profit rates for 2000 through 2006, based on balance sheet data reported in the Internal Revenue Service's Corporation Source
  Book (IRS, 2007).
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, based on ERG (2013).


[[Page 56372]]

b. Normal Year-to-Year Variations in Prices and Profit Rates
    The United States has a dynamic and constantly changing economy in 
which an annual percentage increase in industry revenues or prices of 
one percent or more are common. Examples of year-to-year changes in an 
industry that could cause such an increase in revenues or prices 
include increases in fuel, material, real estate, or other costs; tax 
increases; and shifts in demand.
    To demonstrate the normal year-to-year variation in prices for all 
the manufacturers in general industry and maritime affected by the 
proposed rule, OSHA developed in the PEA year-to-year producer price 
indices and year-to-year percentage changes in producer prices, by 
industry, for the years 1998-2009. For the combined affected 
manufacturing industries in general industry and maritime over the 12-
year period, the average change in producer prices was 3.8 percent a 
year. For the three industries in general industry and maritime with 
the largest estimated potential annual cost impact as a percentage of 
revenue (of approximately 0.35 percent, on average), the average annual 
changes in producer prices in these industries over the 12-year period 
averaged 3.5 percent.
    Based on these data, it is clear that the potential price impacts 
of the proposed rule in general industry and maritime are all well 
within normal year-to-year variations in prices in those industries. 
Thus, OSHA preliminarily concludes that the potential price impacts of 
the proposed would not threaten the economic viability of any 
industries in general industry and maritime.
    Changes in profit rates are also subject to the dynamics of the 
U.S. economy. A recession, a downturn in a particular industry, foreign 
competition, or the increased competitiveness of producers of close 
domestic substitutes are all easily capable of causing a decline in 
profit rates in an industry of well in excess of ten percent in one 
year or for several years in succession.
    To demonstrate the normal year-to-year variation in profit rates 
for all the manufacturers in general industry and maritime affected by 
the proposed rule, OSHA presented data in the PEA on year-to-year 
profit rates and year-to-year percentage changes in profit rates, by 
industry, for the years 2000-2006. For the combined affected 
manufacturing industries in general industry and maritime over the 7-
year period, the average change in profit rates was 38.9 percent a 
year. For the 7 industries in general industry and maritime with the 
largest estimated potential annual cost impacts as a percentage of 
profit--ranging from 4 percent to 9 percent--the average annual changes 
in profit rates in these industries over the 7-year period averaged 35 
percent.
    Nevertheless, a longer-term reduction in profit rates in excess of 
10 percent a year could be problematic for some affected industries and 
might conceivably, under sufficiently adverse circumstances, threaten 
an industry's economic viability. In OSHA's view, however, affected 
industries would generally be able to pass on most or all of the costs 
of the proposed rule in the form of higher prices rather than to bear 
the costs of the proposed rule in reduced profits. After all, it defies 
common sense to suggest that the demanded quantities of brick and 
structural clay, vitreous china, ceramic wall and floor tile, other 
structural clay products (such as clay sewer pipe), and the various 
other products manufactured by affected industries would significantly 
contract in response to a 0.4 percent (or lower) price increase for 
these products. It is of course possible that such price changes will 
result in some reduction in output, and the reduction in output might 
be met through the closure of a small percentage of the plants in the 
industry. However, the only realistic circumstance such that an entire 
industry would be significantly affected by small potential price 
increases would be the availability in the market of a very close or 
perfect substitute product not subject to OSHA regulation. The classic 
example, in theory, would be foreign competition. Below, OSHA examines 
the threat of foreign competition for affected U.S. establishments in 
general industry and maritime.
c. International Trade Effects
    The magnitude and strength of foreign competition is a critical 
factor in determining the ability of firms in the U.S. to pass on (part 
or all of) the costs of the proposed rule. If firms are unable to do 
so, they would likely absorb the costs of the proposed rule out of 
profits, possibly resulting in the business failure of individual firms 
or even, if the cost impacts are sufficiently large and pervasive, 
causing significant dislocations within an affected industry.
    In the PEA, OSHA examined how likely such an outcome is. The 
analysis there included a review of trade theory and empirical evidence 
and the estimation of impacts. Throughout, the Agency drew on ERG 
(2007c), which was prepared specifically to help analyze the 
international trade impacts of OSHA's proposed silica rule. A summary 
of the PEA results is presented below.
    ERG (2007c) focused its analysis on eight of the industries likely 
to be most affected by the proposed silica rule and for which import 
and export data were available. ERG combined econometric estimates of 
the elasticity of substitution between foreign and domestic products, 
Annual Survey of Manufactures data, and assumptions concerning the 
values for key parameters to estimate the effect of a range of 
hypothetical price increases on total domestic production. In 
particular, ERG estimated the domestic production that would be 
replaced by imported products and the decrease in exported products 
that would result from a 1 percent increase in prices--under the 
assumption that firms would attempt to pass on all of a 1 percent 
increase in costs arising from the proposed rule. The sum of the 
increase in imports and decrease in exports represents the total loss 
to industry attributable to the rule. These projected losses are 
presented as a percentage of baseline domestic production to provide 
some context for evaluating the relative size of these impacts.
    The effect of a 1 percent increase in the price of a domestic 
product is derived from the baseline level of U.S. domestic production 
and the baseline level of imports. The baseline ratio of import values 
to domestic production for the eight affected industries ranges from 
0.04 for iron foundries to 0.547 for ceramic wall and floor tile 
manufacturing--that is, baseline import values range from 4 percent to 
more than 50 percent of domestic production in these eight industries. 
ERG's estimates of the percentage reduction in U.S. production for the 
eight affected industries due to increased domestic imports (arising 
from a 1 percent increase in the price of domestic products) range from 
0.013 percent for iron foundries to 0.237 percent for cut stone and 
stone product manufacturing.
    ERG also estimated baseline ratio of U.S. exports to consumption in 
the rest of the world for the sample of eight affected industries. The 
ratios range from 0.001 for other concrete manufacturing to 0.035 
percent for nonclay refractory manufacturing. The estimated percentage 
reductions in U.S. production due to reduced U.S. exports (arising from 
a 1 percent increase in the price of domestic products) range from 
0.014 percent for ceramic wall and floor tile manufacturing to 0.201 
percent for nonclay refractory manufacturing.
    The total percentage change in U.S. production for the eight 
affected industries is the sum of the loss of

[[Page 56373]]

increased imports and the loss of exports. The total percentage 
reduction in U.S. production arising from a 1 percent increase in the 
price of domestic products range from a low of 0.085 percent for other 
concrete product manufacturing to a high of 0.299 percent for porcelain 
electrical supply manufacturing.
    These estimates suggest that the proposed rule would have only 
modest international trade effects. It was previously hypothesized that 
if price increases resulted in a substantial loss of revenue to foreign 
competition, then the increased costs of the proposed rule would have 
to come out of profits. That possibility has been contradicted by the 
results reported in this section. The maximum loss to foreign 
competition in any affected industry due to a 1 percent price increase 
was estimated at approximately 0.3 percent of industry revenue. 
Because, as reported earlier in this section, the maximum cost impact 
of the proposed rule for any affected industry would be 0.39 percent of 
revenue, this means that the maximum loss to foreign competition in any 
affected industry as a result of the proposed rule would be 0.12 
percent of industry revenue--which, even for the most affected 
industry, would hardly qualify as a substantial loss to foreign 
competition. This analysis cannot tell us whether the resulting change 
in revenues will lead to a small decline in the number of 
establishments in the industry or slightly less revenue for each 
establishment. However it can reasonably be concluded that revenue 
changes of this magnitude will not lead to the elimination of 
industries or significantly alter their competitive structure.
    Based on the Agency's preceding analysis of economic impacts on 
revenues, profits, and international trade, OSHA preliminarily 
concludes that the annualized costs of the proposed rule are below the 
threshold level that could threaten the economic viability of any 
industry in general industry or maritime. OSHA further notes that while 
there would be additional costs (not attributable to the proposed rule) 
for some employers in general industry and maritime to come into 
compliance with the current silica standard, these costs would not 
affect the Agency's preliminary determination of the economic 
feasibility of the proposed rule.
d. Economic Feasibility Screening Analysis: Small and Very Small 
Businesses
    The preceding discussion focused on the economic viability of the 
affected industries in their entirety and found that the proposed 
standard did not threaten the survival of these industries. Now OSHA 
wishes to demonstrate that the competitive structure of these 
industries would not be significantly altered.
    To address this issue, OSHA examined the annualized costs per 
affected small entity and per very small entity for each affected 
industry in general industry and maritime. Again, OSHA used a minimum 
threshold level of annualized costs equal to one percent of annual 
revenues--and, secondarily, annualized costs equal to ten percent of 
annual profits--below which the Agency has concluded that the costs are 
unlikely to threaten the survival of small entities or very small 
entities or, consequently, to alter the competitive structure of the 
affected industries.
    As shown in Table VIII-12 and Table VIII-13, the annualized cost of 
the proposed rule is estimated to be $2,103 for the average small 
entity in general industry and maritime and $616 for the average very 
small entity in general industry and maritime. These tables also show 
that there are no industries in general industry and maritime in which 
the annualized costs of the proposed rule for small entities or very 
small entities exceed one percent of annual revenues. NAICS 327111 
(Vitreous china plumbing fixtures & bathroom accessories manufacturing) 
has the highest potential cost impact as a percentage of revenues, of 
0.61 percent, for small entities, and NAICS 327112 (Vitreous china, 
fine earthenware, & other pottery product manufacturing) has the 
highest potential cost impact as a percentage of revenues, of 0.75 
percent, for very small entities. Small entities in two industries in 
general industry and maritime--NAICS 327111 and NAICS 327123 (Other 
structural clay product mfg.)--have annualized costs in excess of 10 
percent of annual profits (13.91 percent and 10.63 percent, 
respectively). NAICS 327112 is the only industry in general industry 
and maritime in which the annualized costs of the proposed rule for 
very small entities exceed ten percent of annual profits (16.92 
percent).
    In general, cost impacts for affected small entities or very small 
entities will tend to be somewhat higher, on average, than the cost 
impacts for the average business in those affected industries. That is 
to be expected. After all, smaller businesses typically suffer from 
diseconomies of scale in many aspects of their business, leading to 
less revenue per dollar of cost and higher unit costs. Small businesses 
are able to overcome these obstacles by providing specialized products 
and services, offering local service and better service, or otherwise 
creating a market niche for themselves. The higher cost impacts for 
smaller businesses estimated for this rule generally fall within the 
range observed in other OSHA regulations and, as verified by OSHA's 
lookback reviews, have not been of such a magnitude to lead to their 
economic failure.

[[Page 56374]]



                                Table VIII-12--Screening Analysis for Small Entities in General Industry and Maritime Affected by OSHA's Proposed Silica Standard
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               Total          Number of     Annualized cost                                                        Costs as a       Costs as a
           NAICS                      Industry               annualized     affected small    per affected     Revenues per   Profit rate [a]    Profits per     percentage  of   percentage  of
                                                               costs           entities          entity           entity         (percent)          entity          revenues         profits
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
324121....................  Asphalt paving mixture and           $140,305              431             $326      $10,428,583             7.50         $782,268             0.00             0.04
                             block manufacturing.
324122....................  Asphalt shingle and roofing           872,614              106            8,232       14,067,491             7.50        1,055,229             0.06             0.78
                             materials.
325510....................  Paint and coating                      71,718            1,042               69        6,392,803             5.38          344,213             0.00             0.02
                             manufacturing.
327111....................  Vitreous china plumbing               231,845               25            9,274        1,509,677             4.41           66,651             0.61            13.91
                             fixtures & bathroom
                             accessories manufacturing.
327112....................  Vitreous china, fine                1,854,472              717            2,586          693,637             4.41           30,623             0.37             8.45
                             earthenware, & other
                             pottery product
                             manufacturing.
327113....................  Porcelain electrical supply         1,004,480               97           10,355        4,574,464             4.41          201,959             0.23             5.13
                             mfg.
327121....................  Brick and structural clay           3,062,272               93           32,928        9,265,846             4.41          409,079             0.36             8.05
                             mfg.
327122....................  Ceramic wall and floor tile         2,189,278              173           12,655        3,236,635             4.41          142,895             0.39             8.86
                             mfg.
327123....................  Other structural clay                 510,811               42           12,162        2,592,114             4.41          114,440             0.47            10.63
                             product mfg.
327124....................  Clay refractory                       212,965               96            2,218        6,026,297             4.41          266,056             0.04             0.83
                             manufacturing.
327125....................  Nonclay refractory                    211,512               68            3,110        7,346,739             4.41          324,352             0.04             0.96
                             manufacturing.
327211....................  Flat glass manufacturing....          275,155               56            4,913       64,950,007             3.42        2,221,884             0.01             0.22
327212....................  Other pressed and blown               243,132              228            1,068          935,353             3.42           31,998             0.11             3.34
                             glass and glassware
                             manufacturing.
327213....................  Glass container                        57,797               24            2,408       10,181,980             3.42          348,317             0.02             0.69
                             manufacturing.
327320....................  Ready-mixed concrete               10,490,561            2,401            4,369        7,245,974             6.64          480,994             0.06             0.91
                             manufacturing.
327331....................  Concrete block and brick mfg        2,862,910              567            5,049        6,318,185             6.64          419,407             0.08             1.20
327332....................  Concrete pipe mfg...........        1,441,766              181            7,966        7,852,099             6.64          521,229             0.10             1.53
327390....................  Other concrete product mfg..        8,826,516            1,876            4,705        3,521,965             6.64          233,791             0.13             2.01
327991....................  Cut stone and stone product         8,028,431            1,874            4,284        1,730,741             5.49           95,001             0.25             4.51
                             manufacturing.
327992....................  Ground or treated mineral           2,108,649              132           15,975        6,288,188             5.49          345,160             0.25             4.63
                             and earth manufacturing.
327993....................  Mineral wool manufacturing..          291,145              175            1,664        6,181,590             5.49          339,309             0.03             0.49
327999....................  All other misc. nonmetallic         1,130,230              326            3,467        4,299,551             5.49          236,004             0.08             1.47
                             mineral product mfg.
331111....................  Iron and steel mills........          424,557              523              812       82,895,665             4.49        3,723,664             0.00             0.02
331112....................  Electrometallurgical                    4,987                7              692       24,121,503             4.49        1,083,535             0.00             0.06
                             ferroalloy product
                             manufacturing.
331210....................  Iron and steel pipe and tube           84,537               94              896       40,090,061             4.49        1,800,841             0.00             0.05
                             manufacturing from
                             purchased steel.
331221....................  Rolled steel shape                     42,672               54              787       31,848,937             4.49        1,430,651             0.00             0.05
                             manufacturing.
331222....................  Steel wire drawing..........           57,557               67              862       16,018,794             4.49          719,562             0.01             0.12
331314....................  Secondary smelting and                 15,277               20              777       18,496,524             4.46          825,857             0.00             0.09
                             alloying of aluminum.
331423....................  Secondary smelting,                     4,206                6              722       20,561,614             4.42          907,800             0.00             0.08
                             refining, and alloying of
                             copper.
331492....................  Secondary smelting,                    18,357               25              741        9,513,728             4.42          420,033             0.01             0.18
                             refining, and alloying of
                             nonferrous metal (except cu
                             & al).
331511....................  Iron foundries..............        5,312,382              408           13,021        5,865,357             4.11          241,290             0.22             5.40
331512....................  Steel investment foundries..        1,705,373              101           16,885        8,489,826             4.11          349,255             0.20             4.83
331513....................  Steel foundries (except             2,521,998              192           13,135       11,977,647             4.11          492,738             0.11             2.67
                             investment).
331524....................  Aluminum foundries (except          4,316,135              412           10,476        4,039,244             4.11          166,167             0.26             6.30
                             die-casting).
331525....................  Copper foundries (except die-       1,596,288              246            6,489        2,847,376             4.11          117,136             0.23             5.54
                             casting).
331528....................  Other nonferrous foundries            620,344              112            5,539        2,640,180             4.11          108,612             0.21             5.10
                             (except die-casting).
332111....................  Iron and steel forging......           47,376               63              756        8,310,925             4.71          391,034             0.01             0.19
332112....................  Nonferrous forging..........           13,056               17              760       21,892,338             4.71        1,030,048             0.00             0.07
332115....................  Crown and closure                       5,080                7              732        6,697,995             4.71          315,145             0.01             0.23
                             manufacturing.
332116....................  Metal stamping..............          212,110              279              759        5,360,428             4.71          252,211             0.01             0.30
332117....................  Powder metallurgy part                 17,537               23              762        6,328,522             4.71          297,761             0.01             0.26
                             manufacturing.
332211....................  Cutlery and flatware (except           10,419               14              738        2,852,835             5.22          149,022             0.03             0.50
                             precious) manufacturing.
332212....................  Hand and edge tool                     87,599              113              772        3,399,782             5.22          177,592             0.02             0.43
                             manufacturing.
332213....................  Saw blade and handsaw                   9,221               12              752        5,385,465             5.22          281,317             0.01             0.27
                             manufacturing.
332214....................  Kitchen utensil, pot, and              10,475               13              798       10,355,293             5.22          540,923             0.01             0.15
                             pan manufacturing.
332323....................  Ornamental and architectural           28,608               42              673        2,069,492             4.70           97,346             0.03             0.69
                             metal work.
332439....................  Other metal container                  43,857               56              784        5,260,693             3.58          188,521             0.01             0.42
                             manufacturing.
332510....................  Hardware manufacturing......           78,538              104              756        4,442,699             5.22          232,070             0.02             0.33
332611....................  Spring (heavy gauge)                   14,071               19              754        6,621,896             5.22          345,904             0.01             0.22
                             manufacturing.
332612....................  Spring (light gauge)                   36,826               44              834        4,500,760             5.22          235,103             0.02             0.35
                             manufacturing.
332618....................  Other fabricated wire                 113,603              148              765        3,440,489             5.22          179,719             0.02             0.43
                             product manufacturing.
332710....................  Machine shops...............        1,032,483            1,399              738        1,464,380             5.80           84,907             0.05             0.87
332812....................  Metal coating and allied            2,492,357            2,301            1,083        2,904,851             4.85          141,018             0.04             0.77
                             services.
332911....................  Industrial valve                       53,520               71              752        5,841,019             6.81          397,593             0.01             0.19
                             manufacturing.
332912....................  Fluid power valve and hose             41,712               55              757        6,486,405             6.81          441,524             0.01             0.17
                             fitting manufacturing.

[[Page 56375]]

 
332913....................  Plumbing fixture fitting and           19,037               25              752        9,183,477             6.81          625,111             0.01             0.12
                             trim manufacturing.
332919....................  Other metal valve and pipe             30,618               40              764        9,432,914             6.81          642,090             0.01             0.12
                             fitting manufacturing.
332991....................  Ball and roller bearing                13,624               18              741        5,892,239             6.81          401,079             0.01             0.18
                             manufacturing.
332996....................  Fabricated pipe and pipe               74,633               99              754        4,377,576             6.81          297,978             0.02             0.25
                             fitting manufacturing.
332997....................  Industrial pattern                     20,767               28              736        1,127,301             6.81           76,734             0.07             0.96
                             manufacturing.
332998....................  Enameled iron and metal                13,779               22              630        3,195,173             6.81          217,493             0.02             0.29
                             sanitary ware manufacturing.
332999....................  All other miscellaneous               230,825              311              742        2,904,500             6.81          197,707             0.03             0.38
                             fabricated metal product
                             manufacturing.
333319....................  Other commercial and service          123,816              165              750        4,960,861             4.86          241,023             0.02             0.31
                             industry machinery
                             manufacturing.
333411....................  Air purification equipment             27,021               36              748        4,449,669             4.55          202,591             0.02             0.37
                             manufacturing.
333412....................  Industrial and commercial              27,149               34              791        7,928,953             4.55          361,000             0.01             0.22
                             fan and blower
                             manufacturing.
333414....................  Heating equipment (except              45,308               61              741        5,667,272             4.55          258,027             0.01             0.29
                             warm air furnaces)
                             manufacturing.
333511....................  Industrial mold                       143,216              193              743        2,121,298             5.29          112,203             0.04             0.66
                             manufacturing.
333512....................  Machine tool (metal cutting            44,845               60              746        4,136,962             5.29          218,818             0.02             0.34
                             types) manufacturing.
333513....................  Machine tool (metal forming            30,365               40              758        4,358,035             5.29          230,511             0.02             0.33
                             types) manufacturing.
333514....................  Special die and tool, die             203,742              274              743        2,083,166             5.29          110,186             0.04             0.67
                             set, jig, and fixture
                             manufacturing.
333515....................  Cutting tool and machine              104,313              140              746        2,082,357             5.29          110,143             0.04             0.68
                             tool accessory
                             manufacturing.
333516....................  Rolling mill machinery and              9,604               13              744        8,330,543             5.29          440,630             0.01             0.17
                             equipment manufacturing.
333518....................  Other metalworking machinery           38,359               50              765        5,680,062             5.29          300,438             0.01             0.25
                             manufacturing.
333612....................  Speed changer, industrial              25,087               32              777        6,028,137             2.63          158,355             0.01             0.49
                             high-speed drive, and gear
                             manufacturing.
333613....................  Mechanical power                       26,182               35              754        9,094,798             2.63          238,915             0.01             0.32
                             transmission equipment
                             manufacturing.
333911....................  Pump and pumping equipment             41,360               54              762        6,220,799             4.58          284,686             0.01             0.27
                             manufacturing.
333912....................  Air and gas compressor                 23,948               32              758        6,290,845             4.58          287,891             0.01             0.26
                             manufacturing.
333991....................  Power-driven handtool                   9,867               13              732        3,816,319             4.58          174,648             0.02             0.42
                             manufacturing.
333992....................  Welding and soldering                  23,144               31              745        5,635,771             4.58          257,913             0.01             0.29
                             equipment manufacturing.
333993....................  Packaging machinery                    54,872               74              742        4,240,165             4.58          194,045             0.02             0.38
                             manufacturing.
333994....................  Industrial process furnace             34,418               45              757        4,470,378             4.58          204,580             0.02             0.37
                             and oven manufacturing.
333995....................  Fluid power cylinder and               32,249               43              756        5,830,077             4.58          266,805             0.01             0.28
                             actuator manufacturing.
333996....................  Fluid power pump and motor             15,258               20              772        4,401,836             4.58          201,444             0.02             0.38
                             manufacturing.
333997....................  Scale and balance (except              12,129               16              764        4,987,858             4.58          228,262             0.02             0.33
                             laboratory) manufacturing.
333999....................  All other miscellaneous               123,384              166              745        3,262,128             4.58          149,287             0.02             0.50
                             general purpose machinery
                             manufacturing.
334518....................  Watch, clock, and part                  6,646                9              732        2,878,581             5.94          171,059             0.03             0.43
                             manufacturing.
335211....................  Electric housewares and                 3,326                5              643        6,088,365             4.21          256,514             0.01             0.25
                             household fans.
335221....................  Household cooking appliance             6,521               10              649       10,460,359             4.21          440,715             0.01             0.15
                             manufacturing.
335222....................  Household refrigerator and             32,118               18            1,784      271,746,735             4.21       11,449,210             0.00             0.02
                             home freezer manufacturing.
335224....................  Household laundry equipment            30,521               17            1,795      299,665,426             4.21       12,625,478             0.00             0.01
                             manufacturing.
335228....................  Other major household                   1,917                3              671        8,269,046             4.21          348,391             0.01             0.19
                             appliance manufacturing.
336111....................  Automobile manufacturing....          293,357              167            1,757      555,733,594             2.04       11,339,563             0.00             0.02
336112....................  Light truck and utility               404,778               63            6,425    2,359,286,755             2.04       48,140,479             0.00             0.01
                             vehicle manufacturing.
336120....................  Heavy duty truck                      125,181               77            1,626      240,029,218             2.04        4,897,718             0.00             0.03
                             manufacturing.
336211....................  Motor vehicle body                    187,131              239              784       16,910,028             2.04          345,044             0.00             0.23
                             manufacturing.
336212....................  Truck trailer manufacturing.           54,137               72              748        9,018,164             2.04          184,013             0.01             0.41
336213....................  Motor home manufacturing....           84,073               79            1,064       75,358,742             2.04        1,537,671             0.00             0.07
336311....................  Carburetor, piston, piston             10,269               14              748        2,242,044             2.04           45,748             0.03             1.64
                             ring, and valve
                             manufacturing.
336312....................  Gasoline engine and engine             65,767               94              703        4,245,230             2.04           86,623             0.02             0.81
                             parts manufacturing.
336322....................  Other motor vehicle                    71,423              101              706        6,746,386             2.04          137,658             0.01             0.51
                             electrical and electronic
                             equipment manufacturing.
336330....................  Motor vehicle steering and             25,492               36              708        7,742,773             2.04          157,989             0.01             0.45
                             suspension components
                             (except spring)
                             manufacturing.
336340....................  Motor vehicle brake system             32,886               46              710        6,554,128             2.04          133,735             0.01             0.53
                             manufacturing.
336350....................  Motor vehicle transmission             46,869               66              710        6,058,947             2.04          123,631             0.01             0.57
                             and power train parts
                             manufacturing.
336370....................  Motor vehicle metal stamping          159,156              201              792       11,477,248             2.04          234,190             0.01             0.34
336399....................  All other motor vehicle               169,401              235              721        6,985,145             2.04          142,530             0.01             0.51
                             parts manufacturing.
336611....................  Ship building and repair....        8,749,619              575           15,217       27,083,446             5.86        1,587,570             0.06             0.96

[[Page 56376]]

 
336612....................  Boat building...............        2,612,088              814            3,209        5,304,212             5.86          310,921             0.06             1.03
336992....................  Military armored vehicle,              27,227               32              845       54,437,815             6.31        3,434,642             0.00             0.02
                             tank, and tank component
                             manufacturing.
337215....................  Showcase, partition,                  176,800              235              751        3,637,716             4.54          165,266             0.02             0.45
                             shelving, and locker
                             manufacturing.
339114....................  Dental equipment and                  261,393              292              895        2,619,222            10.77          282,066             0.03             0.32
                             supplies manufacturing.
339116....................  Dental laboratories.........        1,397,271            7,011              199          532,828            10.77           57,381             0.04             0.35
339911....................  Jewelry (except costume)            1,392,054            1,751              795        2,615,940             5.80          151,608             0.03             0.52
                             manufacturing.
339913....................  Jewelers' materials and               257,285              258              997        2,775,717             5.80          160,868             0.04             0.62
                             lapidary work manufacturing.
339914....................  Costume jewelry and novelty           242,158              588              412          971,681             5.80           56,314             0.04             0.73
                             manufacturing.
339950....................  Sign manufacturing..........          264,810              428              618        1,642,826             5.80           95,211             0.04             0.65
423840....................  Industrial supplies,                  143,614              226              636        5,001,467             3.44          171,830             0.01             0.37
                             wholesalers.
482110....................  Rail transportation.........              N/A              N/A              N/A              N/A              N/A              N/A              N/A              N/A
621210....................  Dental offices..............          370,174            7,423               50          663,948             7.34           48,739             0.01             0.10
                                                         ---------------------------------------------------------------------------------------------------------------------------------------
                            Total.......................       86,520,059           41,136            2,103
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
[a] Profit rates were calculated by ERG, 2013, as the average of profit rates for 2000 through 2006, based on balance sheet data reported in the Internal Revenue Service's Corporation Source
  Book (IRS, 2007).
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, based on ERG (2013).


                Table VIII-13--Screening Analysis for Very Small Entities (fewer than 20 employees) in General Industry and Maritime Affected by OSHA's Proposed Silica Standard
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Number of        Annualized
                                                               Total           affected        costs per       Revenues per   Profit rate [a]    Profits per       Costs as a       Costs as a
           NAICS                      Industry               annualized     entities with       affected          entity         (percent)          entity       percentage of    percentage of
                                                               costs        <20 employees       entities                                                            revenues         profits
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
324121....................  Asphalt paving mixture and            $27,770              260             $107       $4,335,678             7.50         $325,227             0.00             0.03
                             block manufacturing.
324122....................  Asphalt shingle and roofing            85,253               57            1,496        4,013,780             7.50          301,081             0.04             0.50
                             materials.
325510....................  Paint and coating                      18,910              324               58        1,871,296             5.38          100,758             0.00             0.06
                             manufacturing.
327111....................  Vitreous china plumbing                26,606               19            1,400          327,368             4.41           14,453             0.43             9.69
                             fixtures & bathroom
                             accessories manufacturing.
327112....................  Vitreous china, fine                  747,902              645            1,160          155,258             4.41            6,855             0.75            16.92
                             earthenware, & other
                             pottery product
                             manufacturing.
327113....................  Porcelain electrical supply            79,824               57            1,400          601,316             4.41           26,548             0.23             5.28
                             mfg.
327121....................  Brick and structural clay              76,696               31            2,474          715,098             4.41           31,571             0.35             7.84
                             mfg.
327122....................  Ceramic wall and floor tile           382,871              136            2,815          807,291             4.41           35,641             0.35             7.90
                             mfg.
327123....................  Other structural clay                  67,176               25            2,687          782,505             4.41           34,547             0.34             7.78
                             product mfg.
327124....................  Clay refractory                        29,861               55              543        1,521,469             4.41           67,172             0.04             0.81
                             manufacturing.
327125....................  Nonclay refractory                     34,061               40              852        1,506,151             4.41           66,495             0.06             1.28
                             manufacturing.
327211....................  Flat glass manufacturing....            4,450                4            1,075          905,562             3.42           30,978             0.12             3.47
327212....................  Other pressed and blown                87,895               79            1,107          370,782             3.42           12,684             0.30             8.73
                             glass and glassware
                             manufacturing.
327213....................  Glass container                         4,798                4            1,107        2,690,032             3.42           92,024             0.04             1.20
                             manufacturing.
327320....................  Ready-mixed concrete                1,897,131            1,429            1,328        1,922,659             6.64          127,628             0.07             1.04
                             manufacturing.
327331....................  Concrete block and brick mfg          544,975              339            1,608        1,995,833             6.64          132,485             0.08             1.21
327332....................  Concrete pipe mfg...........          116,670               67            1,741        2,375,117             6.64          157,662             0.07             1.10
327390....................  Other concrete product mfg..        1,885,496            1,326            1,422          974,563             6.64           64,692             0.15             2.20
327991....................  Cut stone and stone product         2,753,051            1,471            1,872          946,566             5.49           51,957             0.20             3.60
                             manufacturing.
327992....................  Ground or treated mineral             389,745               78            4,997        1,635,092             5.49           89,751             0.31             5.57
                             and earth manufacturing.
327993....................  Mineral wool manufacturing..           48,575               46            1,061        1,398,274             5.49           76,752             0.08             1.38
327999....................  All other misc. nonmetallic           311,859              235            1,327        1,457,181             5.49           79,985             0.09             1.66
                             mineral product mfg.
331111....................  Iron and steel mills........            9,342               12              777        4,177,841             4.49          187,668             0.02             0.41
331112....................  Electrometallurgical                        0                0              N/A        1,202,610             4.49           54,021              N/A              N/A
                             ferroalloy product
                             manufacturing.
331210....................  Iron and steel pipe and tube            1,706                2              774        2,113,379             4.49           94,933             0.04             0.82
                             manufacturing from
                             purchased steel.
331221....................  Rolled steel shape                      1,612                2              774        2,108,498             4.49           94,713             0.04             0.82
                             manufacturing.

[[Page 56377]]

 
331222....................  Steel wire drawing..........            2,939                4              774          835,444             4.49           37,528             0.09             2.06
331314....................  Secondary smelting and                  1,254                2              774        2,039,338             4.46           91,055             0.04             0.85
                             alloying of aluminum.
331423....................  Secondary smelting,                         0                0              N/A        2,729,146             4.42          120,492              N/A              N/A
                             refining, and alloying of
                             copper.
331492....................  Secondary smelting,                     2,897                4              774        1,546,332             4.42           68,271             0.05             1.13
                             refining, and alloying of
                             nonferrous metal (except cu
                             & al).
331511....................  Iron foundries..............          330,543              201            1,644        1,031,210             4.11           42,422             0.16             3.88
331512....................  Steel investment foundries..           47,902               27            1,774        1,831,394             4.11           75,340             0.10             2.35
331513....................  Steel foundries (except               162,670              102            1,595        1,577,667             4.11           64,902             0.10             2.46
                             investment).
331524....................  Aluminum foundries (except            503,027              235            2,141          874,058             4.11           35,957             0.24             5.95
                             die-casting).
331525....................  Copper foundries (except die-         370,110              164            2,257          814,575             4.11           33,510             0.28             6.73
                             casting).
331528....................  Other nonferrous foundries            162,043               77            2,104          837,457             4.11           34,451             0.25             6.11
                             (except die-casting).
332111....................  Iron and steel forging......            4,089                5              774        1,175,666             4.71           55,316             0.07             1.40
332112....................  Nonferrous forging..........              784                1              774        1,431,874             4.71           67,371             0.05             1.15
332115....................  Crown and closure                         992                1              774        1,715,882             4.71           80,733             0.05             0.96
                             manufacturing.
332116....................  Metal stamping..............           27,154               35              775        1,146,408             4.71           53,939             0.07             1.44
332117....................  Powder metallurgy part                  2,072                3              774        1,580,975             4.71           74,386             0.05             1.04
                             manufacturing.
332211....................  Cutlery and flatware (except            2,217                3              774          391,981             5.22           20,476             0.20             3.78
                             precious) manufacturing.
332212....................  Hand and edge tool                     19,535               25              774          770,858             5.22           40,267             0.10             1.92
                             manufacturing.
332213....................  Saw blade and handsaw                   2,296                3              774          975,698             5.22           50,967             0.08             1.52
                             manufacturing.
332214....................  Kitchen utensil, pot, and                   0                0              N/A          826,410             5.22           43,169              N/A              N/A
                             pan manufacturing.
332323....................  Ornamental and architectural            9,527               14              694          695,970             4.70           32,737             0.10             2.12
                             metal work.
332439....................  Other metal container                   5,279                7              788        1,027,511             3.58           36,822             0.08             2.14
                             manufacturing.
332510....................  Hardware manufacturing......           11,863               15              777          776,986             5.22           40,587             0.10             1.92
332611....................  Spring (heavy gauge)                    1,927                2              786        1,774,584             5.22           92,698             0.04             0.85
                             manufacturing.
332612....................  Spring (light gauge)                    4,960                6              774        1,085,302             5.22           56,692             0.07             1.36
                             manufacturing.
332618....................  Other fabricated wire                  19,946               26              774          778,870             5.22           40,685             0.10             1.90
                             product manufacturing.
332710....................  Machine shops...............          416,115              537              774          649,804             5.80           37,677             0.12             2.06
332812....................  Metal coating and allied              613,903              885              694          602,598             4.85           29,254             0.12             2.37
                             services.
332911....................  Industrial valve                        5,886                8              774        1,294,943             6.81           88,146             0.06             0.88
                             manufacturing.
332912....................  Fluid power valve and hose              4,491                6              774        1,350,501             6.81           91,927             0.06             0.84
                             fitting manufacturing.
332913....................  Plumbing fixture fitting and            1,505                2              774          811,318             6.81           55,226             0.10             1.40
                             trim manufacturing.
332919....................  Other metal valve and pipe              2,710                3              781        2,164,960             6.81          147,367             0.04             0.53
                             fitting manufacturing.
332991....................  Ball and roller bearing                 1,132                1              774        1,808,246             6.81          123,086             0.04             0.63
                             manufacturing.
332996....................  Fabricated pipe and pipe               12,453               16              774        1,237,265             6.81           84,220             0.06             0.92
                             fitting manufacturing.
332997....................  Industrial pattern                      8,917               12              774          503,294             6.81           34,259             0.15             2.26
                             manufacturing.
332998....................  Enameled iron and metal                 3,287                5              690          725,491             6.81           49,384             0.10             1.40
                             sanitary ware manufacturing.
332999....................  All other miscellaneous                55,981               72              774          933,734             6.81           63,558             0.08             1.22
                             fabricated metal product
                             manufacturing.
333319....................  Other commercial and service           19,776               26              774        1,127,993             4.86           54,803             0.07             1.41
                             industry machinery
                             manufacturing.
333411....................  Air purification equipment              4,745                6              774        1,152,661             4.55           52,480             0.07             1.47
                             manufacturing.
333412....................  Industrial and commercial               1,675                2              774        1,454,305             4.55           66,214             0.05             1.17
                             fan and blower
                             manufacturing.
333414....................  Heating equipment (except               6,087                8              777          901,560             4.55           41,047             0.09             1.89
                             warm air furnaces)
                             manufacturing.
333511....................  Industrial mold                        43,738               56              774          716,506             5.29           37,898             0.11             2.04
                             manufacturing.
333512....................  Machine tool (metal cutting             8,756               11              776          911,891             5.29           48,233             0.09             1.61
                             types) manufacturing.
333513....................  Machine tool (metal forming             4,666                6              774        1,308,768             5.29           69,225             0.06             1.12
                             types) manufacturing.
333514....................  Special die and tool, die              65,867               85              774          816,990             5.29           43,213             0.09             1.79
                             set, jig, and fixture
                             manufacturing.
333515....................  Cutting tool and machine               31,406               41              775          771,162             5.29           40,789             0.10             1.90
                             tool accessory
                             manufacturing.
333516....................  Rolling mill machinery and              1,361                2              774        2,243,812             5.29          118,683             0.03             0.65
                             equipment manufacturing.
333518....................  Other metalworking machinery            6,766                9              774          965,694             5.29           51,079             0.08             1.51
                             manufacturing.
333612....................  Speed changer, industrial               3,318                4              774        1,393,898             2.63           36,617             0.06             2.11
                             high-speed drive, and gear
                             manufacturing.
333613....................  Mechanical power                        3,114                4              774        2,113,156             2.63           55,511             0.04             1.39
                             transmission equipment
                             manufacturing.
333911....................  Pump and pumping equipment              7,209                9              774        1,343,868             4.58           61,500             0.06             1.26
                             manufacturing.
333912....................  Air and gas compressor                  4,228                5              774        1,644,664             4.58           75,266             0.05             1.03
                             manufacturing.
333991....................  Power-driven handtool                   2,212                3              774        2,158,268             4.58           98,770             0.04             0.78
                             manufacturing.
333992....................  Welding and soldering                   3,835                5              774        1,331,521             4.58           60,935             0.06             1.27
                             equipment manufacturing.
333993....................  Packaging machinery                     9,742               13              774          809,474             4.58           37,044             0.10             2.09
                             manufacturing.
333994....................  Industrial process furnace              5,631                7              774        1,324,790             4.58           60,627             0.06             1.28
                             and oven manufacturing.
333995....................  Fluid power cylinder and                3,955                5              774          916,613             4.58           41,947             0.08             1.84
                             actuator manufacturing.

[[Page 56378]]

 
333996....................  Fluid power pump and motor              2,670                3              774        1,417,549             4.58           64,872             0.05             1.19
                             manufacturing.
333997....................  Scale and balance (except               1,947                3              774        1,527,651             4.58           69,911             0.05             1.11
                             laboratory) manufacturing.
333999....................  All other miscellaneous                32,637               42              774          871,700             4.58           39,892             0.09             1.94
                             general purpose machinery
                             manufacturing.
334518....................  Watch, clock, and part                  1,322                2              774          586,350             5.94           34,844             0.13             2.22
                             manufacturing.
335211....................  Electric housewares and                     0                0              N/A          847,408             4.21           35,703              N/A              N/A
                             household fans.
335221....................  Household cooking appliance               722                1              698        2,228,319             4.21           93,883             0.03             0.74
                             manufacturing.
335222....................  Household refrigerator and                  0                0              N/A        4,917,513             4.21          207,184              N/A              N/A
                             home freezer manufacturing.
335224....................  Household laundry equipment                 0                0              N/A        1,767,776             4.21           74,480              N/A              N/A
                             manufacturing.
335228....................  Other major household                       0                0              N/A        1,706,991             4.21           71,919              N/A              N/A
                             appliance manufacturing.
336111....................  Automobile manufacturing....            2,147                3              774        1,507,110             2.04           30,752             0.05             2.52
336112....................  Light truck and utility                   795                1              774        1,089,801             2.04           22,237             0.07             3.48
                             vehicle manufacturing.
336120....................  Heavy duty truck                          943                1              774        4,371,350             2.04           89,196             0.02             0.87
                             manufacturing.
336211....................  Motor vehicle body                     12,371               16              774        1,720,545             2.04           35,107             0.04             2.20
                             manufacturing.
336212....................  Truck trailer manufacturing.            5,147                7              774        2,706,375             2.04           55,223             0.03             1.40
336213....................  Motor home manufacturing....            1,193                2              774        2,184,388             2.04           44,572             0.04             1.74
336311....................  Carburetor, piston, piston              1,329                2              774          870,496             2.04           17,762             0.09             4.36
                             ring, and valve
                             manufacturing.
336312....................  Gasoline engine and engine             11,683               15              774          867,703             2.04           17,705             0.09             4.37
                             parts manufacturing.
336322....................  Other motor vehicle                     8,618               11              774        1,383,831             2.04           28,237             0.06             2.74
                             electrical and electronic
                             equipment manufacturing.
336330....................  Motor vehicle steering and              2,876                4              774        1,543,436             2.04           31,493             0.05             2.46
                             suspension components
                             (except spring)
                             manufacturing.
336340....................  Motor vehicle brake system              2,386                3              774        1,378,684             2.04           28,132             0.06             2.75
                             manufacturing.
336350....................  Motor vehicle transmission              6,390                8              774          864,746             2.04           17,645             0.09             4.38
                             and power train parts
                             manufacturing.
336370....................  Motor vehicle metal stamping            5,759                7              778        1,519,875             2.04           31,013             0.05             2.51
336399....................  All other motor vehicle                16,021               21              774        1,369,097             2.04           27,936             0.06             2.77
                             parts manufacturing.
336611....................  Ship building and repair....          212,021               65            3,252          770,896             5.86           45,188             0.42             7.20
336612....................  Boat building...............          391,950              121            3,247        1,101,324             5.86           64,557             0.29             5.03
336992....................  Military armored vehicle,                   0                0              N/A        1,145,870             6.31           72,296              N/A              N/A
                             tank, and tank component
                             manufacturing.
337215....................  Showcase, partition,                   28,216               36              774          866,964             4.54           39,387             0.09             1.96
                             shelving, and locker
                             manufacturing.
339114....................  Dental equipment and                   79,876               87              922          657,192            10.77           70,773             0.14             1.30
                             supplies manufacturing.
339116....................  Dental laboratories.........        1,040,112            6,664              156          326,740            10.77           35,187             0.05             0.44
339911....................  Jewelry (except costume)              533,353            1,532              348          673,857             5.80           39,054             0.05             0.89
                             manufacturing.
339913....................  Jewelers' materials and                86,465              218              397          919,422             5.80           53,285             0.04             0.74
                             lapidary work manufacturing.
339914....................  Costume jewelry and novelty           100,556              368              274          454,292             5.80           26,329             0.06             1.04
                             manufacturing.
339950....................  Sign manufacturing..........           89,586              140              639          521,518             5.80           30,225             0.12             2.12
423840....................  Industrial supplies,                   50,612               95              531        2,432,392             3.44           83,567             0.02             0.64
                             wholesalers.
482110....................  Rail transportation.........              N/A              N/A              N/A              N/A              N/A              N/A              N/A              N/A
621210....................  Dental offices..............          320,986            6,506               49          562,983             7.34           41,328             0.01             0.12
                                                         ---------------------------------------------------------------------------------------------------------------------------------------
                            Total.......................       15,745,425           25,544              616
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Profit rates were calculated by ERG, 2013, as the average of profit rates for 2000 through 2006, based on balance sheet data reported in the Internal Revenue Service's Corporation Source
  Book (IRS, 2007).
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, based on ERG (2013).


[[Page 56379]]

    As a point of clarification, OSHA would like to draw attention to 
industries with captive foundries. There are three industries with 
captive foundries whose annualized costs for very small entities 
approach five percent of annual profits: NAICS 336311 (Carburetor, 
piston ring, and valve manufacturing); NAICS 336312 (Gasoline engine 
and engine parts manufacturing); and NAICS 336350 (Motor vehicle 
transmission and power train parts manufacturing). For very small 
entities in all three of these industries, the annualized costs as a 
percentage of annual profits are approximately 4.4 percent. OSHA 
believes, however, that very small entities in industries with captive 
foundries are unlikely to actually have captive foundries and that the 
captive foundries allocated to very small entities in fact belong in 
larger entities. This would have the result that the costs as 
percentage of profits for these larger entities would be lower than the 
4.4 percent reported above. Instead, OSHA assumed that the affected 
employees would be distributed among entities of different size 
according to each entity size class's share of total employment. In 
other words, if 15 percent of employees in an industry worked in very 
small entities (those with fewer than 20 employees), then OSHA assumed 
that 15 percent of affected employees in the industry would work in 
very small entities. However, in reality, OSHA anticipates that in 
industries with captive foundries, none of the entities with fewer than 
20 employees have captive foundries or, if they do, that the impacts 
are much smaller than estimated here. OSHA invites comment about 
whether and to what extent very small entities have captive foundries 
(in industries with captive foundries).
    Regardless of whether the cost estimates have been inflated for 
very small entities in the three industries with captive foundries 
listed above, there are two reasons why OSHA is confident that the 
competitive structure of these industries would not be threatened by 
adverse competitive conditions for very small entities. First, as shown 
in Appendix VI-B of the PEA, very small entities in NAICS 336311, NAICS 
336312, and NAICS 336350 account for 3 percent, 2 percent, and 3 
percent, respectively, of the total number of establishments in the 
industry. Although it is possible that some of these very small 
entities could exit the industry in response to the proposed rule, 
courts interpreting the OSH Act have historically taken the view that 
losing at most 3 percent of the establishments in an industry would 
alter the competitive structure of that industry. Second, very small 
entities in industries with captive foundries, when confronted with 
higher foundry costs as a result of the proposed rule, have the option 
of dropping foundry activities, purchasing foundry products and 
services from businesses directly in the foundry industry, and focusing 
on the main goods and services produced in the industry. This, after 
all, is precisely what the rest of the establishments in these 
industries do.
e. Regulatory Flexibility Screening Analysis
    To determine if the Assistant Secretary of Labor for OSHA can 
certify that the proposed silica rule will not have a significant 
economic impact on a substantial number of small entities, the Agency 
has developed screening tests to consider minimum threshold effects of 
the proposed rule on small entities. The minimum threshold effects for 
this purpose are annualized costs equal to one percent of annual 
revenues and annualized costs equal to five percent of annual profits 
applied to each affected industry. OSHA has applied these screening 
tests both to small entities and to very small entities. For purposes 
of certification, the threshold level cannot be exceeded for affected 
small entities or very small entities in any affected industry.
    Table VIII-12 and Table VIII-13 show that, in general industry and 
maritime, the annualized costs of the proposed rule do not exceed one 
percent of annual revenues for small entities or for very small 
entities in any industry. These tables also show that the annualized 
costs of the proposed rule exceed five percent of annual profits for 
small entities in 10 industries and for very small entities in 13 
industries. OSHA is therefore unable to certify that the proposed rule 
will not have a significant economic impact on a substantial number of 
small entities in general industry and maritime and must prepare an 
Initial Regulatory Flexibility Analysis (IRFA). The IRFA is presented 
in Section VIII.I of this preamble.
3. Impacts in Construction
a. Economic Feasibility Screening Analysis: All Establishments
    To determine whether the proposed rule's projected costs of 
compliance would threaten the economic viability of affected 
construction industries, OSHA used the same data sources and 
methodological approach that were used earlier in this chapter for 
general industry and maritime. OSHA first compared, for each affected 
construction industry, annualized compliance costs to annual revenues 
and profits per (average) affected establishment. The results for all 
affected establishments in all affected construction industries are 
presented in Table VIII-14, using annualized costs per establishment 
for the proposed 50 [mu]g/m\3\ PEL. The annualized cost of the proposed 
rule for the average establishment in construction, encompassing all 
construction industries, is estimated at $1,022 in 2009 dollars. It is 
clear from Table VIII-14 that the estimates of the annualized costs per 
affected establishment in the 10 construction industries vary widely. 
These estimates range from $2,598 for NAICS 237300 (Highway, street, 
and bridge construction) and $2,200 for NAICS 237100 (Utility system 
construction) to $241 for NAICS 238200 (Building finishing contractors) 
and $171 for NAICS 237200 (Land subdivision).
    Table VIII-14 shows that in no construction industry do the 
annualized costs of the proposed rule exceed one percent of annual 
revenues or ten percent of annual profits. NAICS 238100 (Foundation, 
structure, and building exterior contractors) has both the highest cost 
impact as a percentage of revenues, of 0.13 percent, and the highest 
cost impact as a percentage of profits, of 2.97 percent. Based on these 
results, even if the costs of the proposed rule were 50 percent higher 
than OSHA has estimated, the highest cost impact as a percentage of 
revenues in any affected construction industry would be less than 0.2 
percent. Furthermore, the costs of the proposed rule would have to be 
more than 650 percent higher than OSHA has estimated for the cost 
impact as a percentage of revenues to equal 1 percent in any affected 
construction industry. For all affected establishments in construction, 
the estimated annualized cost of the proposed rule is, on average, 
equal to 0.05 percent of annual revenue and 1.0 percent of annual 
profit.
    Therefore, even though the annualized costs of the proposed rule 
incurred by the construction industry as a whole are almost four times 
the combined annualized costs incurred by general industry and 
maritime, OSHA preliminarily concludes, based on its screening 
analysis, that the annualized costs as a percentage of annual revenues 
and as a percentage of annual profits are below the threshold level 
that could threaten the economic viability of any of the construction 
industries. OSHA further notes that while there would be

[[Page 56380]]

additional costs (not attributable to the proposed rule) for some 
employers in construction industries to come into compliance with the 
current silica standard, these costs would not affect the Agency's 
preliminary determination of the economic feasibility of the proposed 
rule.
    Below, OSHA provides additional information to further support the 
Agency's conclusion that the proposed rule would not threaten the 
economic viability of any construction industry.

                    Table VIII-14--Screening Analysis for Establishments in Construction Affected by OSHA's Proposed Silica Standard
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                     Annualized
                                         Total        Affected       costs per     Revenues per   Profit rate   Profits per    Costs as a    Costs as a
     NAICS            Industry        annualized   establishments     affected    establishment       \a\      establishment   percentage    percentage
                                         costs                     establishment                   (percent)                   of revenues   of profits
--------------------------------------------------------------------------------------------------------------------------------------------------------
236100.........  Residential          $23,288,881         55,338            $421     $2,002,532          4.87        $97,456          0.02          0.43
                  Building
                  Construction.
236200.........  Nonresidential        39,664,913         44,702             887      7,457,045          4.87        362,908          0.01          0.24
                  Building
                  Construction.
237100.........  Utility System        46,718,162         21,232           2,200      4,912,884          5.36        263,227          0.04          0.84
                  Construction.
237200.........  Land Subdivision..     1,110,789          6,511             171      2,084,334         11.04        230,214          0.01          0.07
237300.........  Highway, Street,      30,807,861         11,860           2,598      8,663,019          5.36        464,156          0.03          0.56
                  and Bridge
                  Construction.
237900.........  Other Heavy and        7,164,210          5,561           1,288      3,719,070          5.36        199,264          0.03          0.65
                  Civil Engineering
                  Construction.
238100.........  Foundation,          215,907,211        117,456           1,838      1,425,510          4.34         61,832          0.13          2.97
                  Structure, and
                  Building Exterior
                  Contractors.
238200.........  Building Equipment     4,902,138         20,358             241      1,559,425          4.34         67,640          0.02          0.36
                  Contractors.
238300.........  Building Finishing    50,259,239        120,012             419        892,888          4.34         38,729          0.05          1.08
                  Contractors.
238900.........  Other Specialty       68,003,978         74,446             913      1,202,048          4.48         53,826          0.08          1.70
                  Trade Contractors.
999000.........  State and local       23,338,234            N/A             N/A            N/A           N/A            N/A           N/A           N/A
                  governments \d\.
                                    --------------------------------------------------------------------------------------------------------------------
                 Total.............   511,165,616        477,476           1,022  .............  ............  .............  ............  ............
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Profit rates were calculated by ERG, 2013, as the average of profit rates for 2000 through 2006, based on balance sheet data reported in the
  Internal Revenue Service's Corporation Source Book (IRS, 2007).
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, based on ERG (2013).

b. Normal Year-to-Year Variations in Profit Rates
    As previously noted, the United States has a dynamic and constantly 
changing economy in which large year-to-year changes in industry profit 
rates are commonplace. A recession, a downturn in a particular 
industry, foreign competition, or the increased competitiveness of 
producers of close domestic substitutes are all easily capable of 
causing a decline in profit rates in an industry of well in excess of 
ten percent in one year or for several years in succession.
    To demonstrate the normal year-to-year variation in profit rates 
for all the manufacturers in construction affected by the proposed 
rule, OSHA presented data in the PEA on year-to-year profit rates and 
year-to-year percentage changes in profit rates, by industry, for the 
years 2000--2006. For the combined affected manufacturing industries in 
general industry and maritime over the 7-year period, the average 
change in profit rates was 15.4 percent a year.
    What these data indicate is that, even if, theoretically, the 
annualized costs of the proposed rule for the most significantly 
affected construction industries were completely absorbed in reduced 
annual profits, the magnitude of reduced annual profit rates are well 
within normal year-to-year variations in profit rates in those 
industries and do not threaten their economic viability. Of course, a 
permanent loss of profits would present a greater problem than a 
temporary loss, but it is unlikely that all costs of the proposed rule 
would be absorbed in lost profits. Given that, as discussed in Chapter 
VI of the PEA, the overall price elasticity of demand for the outputs 
of the construction industry is fairly low and that almost all of the 
costs estimated in Chapter V of the PEA are variable costs, there is a 
reasonable chance that most firms will see small declines in output 
rather than that any but the most extremely marginal firms would close.
    Considering the costs of the proposed rule relative to the size of 
construction activity in the United States, OSHA preliminarily 
concludes that the price and profit impacts of the proposed rule on 
construction industries would, in practice, be quite limited. Based on 
ERG (2007a), on an annual basis, the cost of the proposed rule would be 
equal to approximately 2 percent of the value of affected, silica-
generating construction activity, and silica-generating construction 
activity accounts for approximately 4.8 percent of all construction 
spending in the U.S. Thus, the annualized cost of the proposed rule 
would be equal to approximately 0.1 percent of the value of annual 
construction activity in the U.S. On top of that, construction activity 
in the U.S. is not subject to any meaningful foreign competition, and 
any foreign firms performing construction activities in the United 
States would be subject to OSHA regulations.
c. Impacts by Type of Construction Demand
    The demand for construction services originates in three 
independent sectors: residential building construction, nonresidential 
building construction, and nonbuilding construction.
    Residential Building Construction: Residential housing demand is 
derived from the household demand for housing services. These services 
are provided by the stock of single and multi-unit residential housing 
units. Residential housing construction represents changes to the 
housing stock and includes construction of new units and

[[Page 56381]]

modifications, renovations, and repairs to existing units. A number of 
studies have examined the price sensitivity of the demand for housing 
services. Depending on the data source and estimation methodologies, 
these studies have estimated the demand for housing services at price 
elasticity values ranging from -0.40 to -1.0, with the smaller (in 
absolute value) less elastic values estimated for short-run periods. In 
the long run, it is reasonable to expect the demand for the stock of 
housing to reflect similar levels of price sensitivity. Since housing 
investments include changes in the existing stock (renovations, 
depreciation, etc.) as well as new construction, it is likely that the 
price elasticity of demand for new residential construction will be 
lower than that for residential construction as a whole.
    OSHA judges that many of the silica-generating construction 
activities affected by the proposed rule are not widely used in single-
family construction. This assessment is consistent with the cost 
estimates that show relatively low impacts for residential building 
contractors. Multi-family residential construction might have more 
substantial impacts, but, based on census data, this type of 
construction represents a relatively small share of net investment in 
residential buildings.
    Nonresidential Building Construction: Nonresidential building 
construction consists of industrial, commercial, and other 
nonresidential structures. As such, construction demand is derived from 
the demand for the output of the industries that use the buildings. For 
example, the demand for commercial office space is derived from the 
demand for the output produced by the users of the office space. The 
price elasticity of demand for this construction category will depend, 
among other things, on the price elasticity of demand for the final 
products produced, the importance of the costs of construction in the 
total cost of the final product, and the elasticity of substitution of 
other inputs that could substitute for nonresidential building 
construction. ERG (2007c) found no studies that attempted to quantify 
these relationships. But given the costs of the proposed rule relative 
to the size of construction spending in the United States, the 
resultant price or revenue effects are likely to be so small as to be 
barely detectable.
    Nonbuilding Construction: Nonbuilding construction includes roads, 
bridges, and other infrastructure projects. Utility construction (power 
lines, sewers, water mains, etc.) and a variety of other construction 
types are also included. A large share of this construction (63.8 
percent) is publicly financed (ERG, 2007a). For this reason, a large 
percentage of the decisions regarding the appropriate level of such 
investments is not made in a private market setting. The relationship 
between the costs and price of such investments and the level of demand 
might depend more on political considerations than the factors that 
determine the demand for privately produced goods and services.
    While a number of studies have examined the factors that determine 
the demand for publicly financed construction projects, these studies 
have focused on the ability to finance such projects (e.g., tax 
receipts) and socio-demographic factors (e.g., population growth) to 
the exclusion of cost or price factors. In the absence of budgetary 
constraints, OSHA believes, therefore, that the price elasticity of 
demand for public investment is probably quite low. On the other hand, 
budget-imposed limits might constrain public construction spending. If 
the dollar value of public investments were fixed, a price elasticity 
of demand of 1 (in absolute terms) would be implied. Any percentage 
increase in construction costs would be offset with an equal percentage 
reduction in investment (measured in physical units), keeping public 
construction expenditures constant.
    Public utility construction comprises the remainder of nonbuilding 
construction. This type of construction is subject to the same derived-
demand considerations discussed for nonresidential building 
construction, and for the same reasons, OSHA expects the price and 
profit impacts to be quite small.
d. Economic Feasibility Screening Analysis: Small and Very Small 
Businesses
    The preceding discussion focused on the economic viability of the 
affected construction industries in their entirety and found that the 
proposed standard did not threaten the survival of these construction 
industries. Now OSHA wishes to demonstrate that the competitive 
structure of these industries would not be significantly altered.
    To address this issue, OSHA examined the annualized costs per 
affected small and very small entity for each affected construction 
industry. Table VIII-15 and Table VIII-16 show that in no construction 
industries do the annualized costs of the proposed rule exceed one 
percent of annual revenues or ten percent of annual profits either for 
small entities or for very small entities. Therefore, OSHA 
preliminarily concludes, based on its screening analysis, that the 
annualized costs as a percentage of annual revenues and as a percentage 
of annual profits are below the threshold level that could threaten the 
competitive structure of any of the construction industries.

                    Table VIII-15--Screening Analysis for Small Entities in Construction Affected by OSHA's Proposed Silica Standard
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                       Annualized
                                              Total       Affected      costs per   Revenues per   Profit rate   Profits per   Costs as a    Costs as a
       NAICS              Industry         annualized       small       affected      entities         \a\        entities     percentage    percentage
                                              costs       entities      entities                    (percent)                  of revenues   of profits
--------------------------------------------------------------------------------------------------------------------------------------------------------
236100............  Residential Building   $18,527,934        44,212          $419    $1,303,262          4.87       $67,420          0.03          0.62
                     Construction.
236200............  Nonresidential          24,443,185        42,536           575     4,117,755          4.87       200,396          0.01          0.29
                     Building
                     Construction.
237100............  Utility System          30,733,201        20,069         1,531     3,248,053          5.36       174,027          0.05          0.88
                     Construction.
237200............  Land Subdivision....       546,331         3,036           180     1,215,688         11.04       134,272          0.01          0.13
237300............  Highway, Street, and    13,756,992        10,350         1,329     3,851,971          5.36       206,385          0.03          0.64
                     Bridge Construction.
237900............  Other Heavy and          5,427,484         5,260         1,032     2,585,858          5.36       138,548          0.04          0.74
                     Civil Engineering
                     Construction.
238100............  Foundation,            152,160,159       115,345         1,319       991,258          4.34        42,996          0.13          3.07
                     Structure, and
                     Building Exterior
                     Contractors.

[[Page 56382]]

 
238200............  Building Equipment       3,399,252        13,933           244     1,092,405          4.34        47,383          0.02          0.51
                     Contractors.
238300............  Building Finishing      36,777,673        87,362           421       737,930          4.34        32,008          0.06          1.32
                     Contractors.
238900............  Other Specialty         53,432,213        73,291           729     1,006,640          4.48        45,076          0.07          1.62
                     Trade Contractors.
999000............  State and local          2,995,955        13,482           222           N/A           N/A           N/A           N/A           N/A
                     governments [d].
                                         ---------------------------------------------------------------------------------------------------------------
                    Total...............   342,200,381       428,876           798  ............  ............  ............  ............  ............
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Profit rates were calculated by ERG, 2013, as the average of profit rates for 2000 through 2006, based on balance sheet data reported in the
  Internal Revenue Service's Corporation Source Book (IRS, 2007).
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, based on ERG (2013).


     Table VIII-16--Screening Analysis for Very Small Entities (Fewer Than 20 Employees) in Construction Affected by OSHA's Proposed Silica Standard
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          Affected     Annualized
                                              Total       entities      costs per   Revenues per   Profit rate   Profits per   Costs as a    Costs as a
       NAICS              Industry         annualized     with <20      affected      entities         [a]        entities     percentage    percentage
                                              costs       employees     entities                    (percent)                  of revenues   of profits
--------------------------------------------------------------------------------------------------------------------------------------------------------
236100............  Residential Building   $13,837,293        32,042          $432      $922,275          4.87       $44,884          0.05          0.96
                     Construction.
236200............  Nonresidential          10,777,269        35,746           301     1,902,892          4.87        92,607          0.02          0.33
                     Building
                     Construction.
237100............  Utility System           8,578,771        16,113           532       991,776          5.36        53,138          0.05          1.00
                     Construction.
237200............  Land Subdivision....       546,331         3,036           180     1,215,688         11.04       134,272          0.01          0.13
237300............  Highway, Street, and     4,518,038         8,080           559     1,649,324          5.36        88,369          0.03          0.63
                     Bridge Construction.
237900............  Other Heavy and          1,650,007         4,436           372       834,051          5.36        44,688          0.04          0.83
                     Civil Engineering
                     Construction.
238100............  Foundation,             81,822,550       105,227           778       596,296          4.34        25,864          0.13          3.01
                     Structure, and
                     Building Exterior
                     Contractors.
238200............  Building Equipment       1,839,588         7,283           253       579,724          4.34        25,146          0.04          1.00
                     Contractors.
238300............  Building Finishing      21,884,973        50,749           431       429,154          4.34        18,615          0.10          2.32
                     Contractors.
238900............  Other Specialty         30,936,078        68,075           454       600,658          4.48        26,897          0.08          1.69
                     Trade Contractors.
999000............  State and local                N/A           N/A           N/A           N/A           N/A           N/A           N/A           N/A
                     governments [d].
                                         ---------------------------------------------------------------------------------------------------------------
                    Total...............   176,390,899       330,786           533  ............  ............  ............  ............  ............
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Profit rates were calculated by ERG, 2013, as the average of profit rates for 2000 through 2006, based on balance sheet data reported in the
  Internal Revenue Service's Corporation Source Book (IRS, 2007).
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, based on ERG (2013).

e. Differential Impacts on Small Entities and Very Small Entities
    Below, OSHA provides some additional information about differential 
compliance costs for small and very small entities that might influence 
the magnitude of differential impacts for these smaller businesses.
    The distribution of impacts by size of business is affected by the 
characteristics of the compliance measures. For silica controls in 
construction, the dust control measures consist primarily of equipment 
modifications and additions made to individual tools, rather than 
large, discrete investments, such as might be applied in a 
manufacturing setting. As a result, compliance advantages for large 
firms through economies of scale are limited. It is possible that some 
large construction firms might derive purchasing power by buying dust 
control measures in bulk. Given the simplicity of many control 
measures, however, such as the use of wet methods on machines already 
manufactured to accommodate them, such differential purchasing power 
appears to be of limited consequence.
    The greater capital resources of large firms will give them some 
advantage in making the relatively large investments for some control 
measures. For example, cab enclosures on heavy construction equipment 
or foam-based dust control systems on rock crushers might be 
particularly expensive for some small entities with an unusual number 
of heavy equipment pieces. Nevertheless, where differential investment 
capabilities might exist, small construction firms might also have the 
capability to achieve compliance with lower-cost measures, such as by 
modifying work practices. In the case of rock crushing, for example, 
simple water spray systems can be arranged without large-scale 
investments in the best commercially available systems.
    In the program area, large firms might have a slight advantage in 
the delivery of training or in arranging for health screenings. Given 
the likelihood that small firms can, under most circumstances, call 
upon independent

[[Page 56383]]

training specialists at competitive prices, and the widespread 
availability of medical services for health screenings, the advantage 
for large firms is, again, expected to be fairly modest.
f. Regulatory Flexibility Screening Analysis
    To determine if the Assistant Secretary of Labor for OSHA can 
certify that the proposed silica rule will not have a significant 
economic impact on a substantial number of small entities, the Agency 
has developed screening tests to consider minimum threshold effects of 
the proposed rule on small entities. The minimum threshold effects for 
this purpose are annualized costs equal to one percent of annual 
revenues and annualized costs equal to five percent of annual profits 
applied to each affected industry. OSHA has applied these screening 
tests both to small entities and to very small entities. For purposes 
of certification, the threshold levels cannot be exceeded for affected 
small or very small entities in any affected industry.
    Table VIII-15 and Table VIII-16 show that in no construction 
industries do the annualized costs of the proposed rule exceed one 
percent of annual revenues or five percent of annual profits either for 
small entities or for very small entities. However, as previously noted 
in this section, OSHA is unable to certify that the proposed rule will 
not have a significant economic impact on a substantial number of small 
entities in general industry and maritime and must prepare an Initial 
Regulatory Flexibility Analysis (IRFA). The IRFA is presented in 
Section VIII.I of this preamble.
4. Employment Impacts on the U.S. Economy
    In October 2011, OSHA directed Inforum--a not-for-profit Maryland 
corporation (based at the University of Maryland)--to run its 
macroeconomic model to estimate the employment impacts of the costs of 
the proposed silica rule.\20\ The specific model of the U.S. economy 
that Inforum used--called the LIFT model--is particularly suitable for 
this work because it combines the industry detail of a pure input-
output model (which shows, in matrix form, how the output of each 
industry serves as inputs in other industries) with macroeconomic 
modeling of demand, investment, and other macroeconomic parameters.\21\ 
The Inforum model can thus both trace changes in particular industries 
through their effect on other industries and also examine the effects 
of these changes on aggregate demand, imports, exports, and investment, 
and in turn determine net changes to GDP, employment, prices, etc.
---------------------------------------------------------------------------

    \20\ Inforum has over 40 years experience designing and using 
macroeconomic models of the United States (and other countries).
    \21\ LIFT stands for Long-Term Interindustry Forecasting Tool. 
This model combines a dynamic input-output core for 97 productive 
sectors with a full macroeconomic model with more than 800 
macroeconomic variables. LIFT employs a ``bottoms-up'' regression 
approach to macroeconomic modeling (so that aggregate investment, 
employment, and exports, for example, are the sum of investment and 
employment by industry and exports by commodity). Unlike some 
simpler forecasting models, price effects are embedded in the model 
and the results are time-dependent (that is, they are not static or 
steady-state, but present year-by-year estimates of impacts 
consistent with economic conditions at the time).
---------------------------------------------------------------------------

    In order to estimate the possible macroeconomic impacts of the 
proposed rule, Inforum had to run its model twice: once to establish a 
baseline and then again with changes in industry expenditures to 
reflect the year-by-year costs of the proposed silica rule as estimated 
by OSHA in its Preliminary Economic Analysis (PEA).\22\ The difference 
in employment, GDP, etc. between the two runs of the model revealed the 
estimated economic impacts of the proposed rule.\23\
---------------------------------------------------------------------------

    \22\ OSHA worked with Inforum to disaggregate compliance costs 
into categories that mapped into specific LIFT production sectors. 
Inforum also established a mapping between OSHA's NAICS-based 
industries and the LIFT production sectors. OSHA's compliance cost 
estimates were based on production and employment levels in affected 
industries in 2006 (although the costs were then inflated to 2009 
dollars). Therefore, Inforum benchmarked compliance cost estimates 
in future years to production and employment conditions in 2006 
(that is, compliance costs in a future year were proportionately 
adjusted to production and employment changes from 2006 to that 
future year). See Inforum (2011) for a discussion of these and other 
transformations of OSHA's cost estimates to conform to the 
specifications of the LIFT model.
    \23\ Because OSHA's analysis of the hydraulic fracturing 
industry for the proposed silica rule was not conducted until after 
the draft PEA had been completed, OSHA's estimates of the compliance 
costs for this industry were not included in Inforum's analysis of 
the rule's employment and other macroeconomic impacts on the U.S. 
economy. It should be noted that, according to the Agency's 
estimates, compliance costs for the hydraulic fracturing industry 
represent only about 4 percent of the total compliance costs for all 
affected industries.
---------------------------------------------------------------------------

    OSHA selected 2014 as the starting year for running the Inforum 
model under the assumption that that would be the earliest that a final 
silica rule could take effect. Inforum ran the model through the year 
2023 and reported its annual and cumulative results for the ten-year 
period 2014-2023. The most important Inforum result is that the 
proposed silica rule cumulatively generates an additional 8,625 job-
years over the period 2014-2023, or an additional 862.5 job-years 
annually, on average, over the period (Inforum, 2011).\24\
---------------------------------------------------------------------------

    \24\ A ``job-year'' is the term of art used to reflect the fact 
that an additional person is employed for a year, not that a new job 
has necessarily been permanently created.
---------------------------------------------------------------------------

    For a fuller discussion of the employment and other macroeconomic 
impacts of the silica rule, see Inforum (2011) and Chapter VI of the 
PEA for the proposed rule.

G. Benefits and Net Benefits

    In this section, OSHA presents a summary of the estimated benefits, 
net benefits, and incremental benefits of the proposed silica rule. 
This section also contains a sensitivity analysis to show how robust 
the estimates of net benefits are to changes in various cost and 
benefit parameters. A full explanation of the derivation of the 
estimates presented here is provided in Chapter VII of the PEA for the 
proposed rule. OSHA invites comments on any aspect of its estimation of 
the benefits and net benefits of the proposed rule.
1. Estimation of the Number of Silica-Related Diseases Avoided
    OSHA estimated the benefits associated with the proposed PEL of 50 
[mu]g/m\3\ and, for economic analysis purposes, with an alternative PEL 
of 100 [mu]g/m\3\ for respirable crystalline silica by applying the 
dose-response relationship developed in the Agency's quantitative risk 
assessment (QRA)--summarized in Section VI of this preamble--to 
exposures at or below the current PELs. OSHA determined exposures at or 
below the current PELs by first developing an exposure profile 
(presented in Chapter IV of the PEA) for industries with workers 
exposed to respirable crystalline silica, using OSHA inspection and 
site-visit data, and then applying this exposure profile to the total 
current worker population. The industry-by-industry exposure profile 
was previously presented in Section VIII.C of this preamble.
    By applying the dose-response relationship to estimates of 
exposures at or below the current PELs across industries, it is 
possible to project the number of cases of the following diseases 
expected to occur in the worker population given exposures at or below 
the current PELs (the ``baseline''):
     Fatal cases of lung cancer,
     fatal cases of non-malignant respiratory disease 
(including silicosis),
     fatal cases of end-stage renal disease, and
     cases of silicosis morbidity.
    In addition, it is possible to project the number of these cases 
that would be avoided under alternative, lower PELs.

[[Page 56384]]

As a simplified example, suppose that the risk per worker of a given 
health endpoint is 2 in 1,000 at 100 [mu]g/m\3\ and 1 in 1,000 at 50 
[mu]g/m\3\ and that there are 100,000 workers currently exposed at 100 
[mu]g/m\3\. In this example, the proposed PEL would lower exposures to 
50 [mu]g/m\3\, thereby cutting the risk in half and lowering the number 
of expected cases in the future from 200 to 100.
    The estimated benefits for the proposed silica rule represent the 
additional benefits derived from employers achieving full compliance 
with the proposed PEL relative to the current PELs. They do not include 
benefits associated with current compliance that has already been 
achieved with regard to the new requirements or benefits obtained from 
future compliance with existing silica requirements, to the extent that 
some employers may currently not be fully complying with applicable 
regulatory requirements.
    The technological feasibility analysis, described earlier in this 
section of the preamble, demonstrated the effectiveness of controls in 
meeting or exceeding the proposed OSHA PEL. For purposes of estimating 
the benefit of reducing the PEL, OSHA has made some simplifying 
assumptions. On the one hand, given the lack of background information 
on respirator use related to existing exposure data, OSHA used existing 
personal exposure measurement information, unadjusted for potential 
respirator use.\25\ On the other hand, OSHA assumed that compliance 
with the existing and proposed rule would result in reductions in 
exposure levels to exactly the existing standard and proposed PEL, 
respectively. However, in many cases, indivisibilities in the 
application of respirators, as well as certain types of engineering 
controls, may cause employers to reduce exposures to some point below 
the existing standard or the proposed PEL. This is particularly true in 
the construction sector for employers who opt to follow Table 1, which 
specifies particular controls.
---------------------------------------------------------------------------

    \25\ Based on available data, the Agency estimated the weighted 
average for the relevant exposure groups to match up with the 
quantitative risk assessment. For the 50-100 [mu]g/m\3\ exposure 
range, the Agency estimated an average exposure of 62.5 [mu]g/m\3\. 
For the 100-250 [mu]g/m\3\ range, the Agency estimated an average 
exposure of 125 [mu]g/m\3\.
---------------------------------------------------------------------------

    In order to examine the effect of simply changing the PEL, OSHA 
compared the number of various kinds of cases that would occur if a 
worker were exposed for an entire working life to PELs of 50 [mu]g/m\3\ 
or 100 [mu]g/m\3\ to the number of cases that would occur at levels of 
exposure at or below the current PELs. The number of avoided cases over 
a hypothetical working life of exposure for the current population at a 
lower PEL is then equal to the difference between the number of cases 
at levels of exposure at or below the current PEL for that population 
minus the number of cases at the lower PEL. This approach represents a 
steady-state comparison based on what would hypothetically happen to 
workers who received a specific average level of occupational exposure 
to silica during an entire working life. (In order to incorporate the 
element of timing to assess the economic value of the health benefits, 
OSHA presents a modified approach later in this section.)
    Based on OSHA's application of the Steenland et al. (2001) log-
linear and the Attfield and Costello (2004) models, Table VIII-17 shows 
the estimated number of avoided fatal lung cancers for PELs of 50 
[mu]g/m\3\ and 100 [mu]g/m\3\. At the proposed PEL of 50 [mu]g/m\3\, an 
estimated 2,404 to 12,173 lung cancers would be prevented over the 
lifetime of the current worker population, with a midpoint estimate of 
7,289 fatal cancers prevented. This is the equivalent of between 53 and 
271 cases avoided annually, with a midpoint estimate of 162 cases 
avoided annually, given a 45-year working life of exposure.
    Following Park (2002), as discussed in summary of the Agency's QRA 
in Section VI of this preamble, OSHA also estimates that the proposed 
PEL of 50 [mu]g/m\3\ would prevent an estimated 16,878 fatalities over 
a lifetime from non-malignant respiratory diseases arising from silica 
exposure. This is equivalent to 375 fatal cases prevented annually. 
Some of these fatalities would be classified as silicosis, but most 
would be classified as other pneumoconioses and chronic obstructive 
pulmonary disease (COPD), which includes chronic bronchitis and 
emphysema.
    As also discussed in the summary of the Agency's QRA in Section VI 
of this preamble, OSHA finds that workers with large exposures to 
silica are at elevated risk of end-stage renal disease (ESRD). Based on 
Steenland, Attfield, and Mannetje (2002), OSHA estimates that the 
proposed PEL of 50 [mu]g/m\3\ would prevent 6,774 cases of end-stage 
renal disease over a working life of exposure, or about 151 cases 
annually.
    Combining the three major fatal health endpoints--for lung cancer, 
non-malignant respiratory diseases, and end-stage renal disease--OSHA 
estimates that the proposed PEL would prevent between 26,055 and 35,825 
premature fatalities over a lifetime, with a midpoint estimate of 
30,940 fatalities prevented. This is the equivalent of between 579 and 
796 premature fatalities avoided annually, with a midpoint estimate of 
688 premature fatalities avoided annually, given a 45-year working life 
of exposure.
    In addition, the rule would prevent a large number of cases of 
silicosis morbidity. Based on Rosenman et al. (2003), the Agency 
estimates that between 2,700 and 5,475 new cases of silicosis, at an 
ILO X-ray rating of 1/0 or higher, occur annually at the present PELs 
as a result of silica exposure at establishments within OSHA's 
jurisdiction. Based on the studies summarized in OSHA's QRA, OSHA 
expects that the proposed rule will eliminate the large majority of 
these cases.
    The Agency has not included the elimination of the less severe 
silicosis cases in its estimates of the monetized benefits and net 
benefits of the proposed rule. Instead, OSHA separately estimated the 
number of silicosis cases reaching the more severe levels of 2/1 and 
above. Based on a study by Buchannan et al. (2003) of a cohort of coal 
miners (as discussed in the Agency's QRA), OSHA estimates that the 
proposed PEL of 50 [mu]g/m\3\ would prevent 71,307 cases of moderate-
to-severe silicosis (registering 2/1 or more, using the ILO method for 
assessing severity) over a working life, or about 1,585 cases of 
moderate-to-severe silicosis prevented annually.
    Note that the Agency based its estimates of reductions in the 
number of silica-related diseases over a working life of constant 
exposure for workers who are employed in a respirable crystalline 
silica-exposed occupation for their entire working lives, from ages 20 
to 65. While the Agency is legally obligated to examine the effect of 
exposures from a working lifetime of exposure,\26\ in an alternative 
analysis purely for informational purposes, the Agency examined, in 
Chapter VII of the PEA, the effect of assuming that workers are exposed 
for only 25 working years, as opposed to the 45 years assumed in the 
main analysis. While all workers are assumed to have less cumulative 
exposure under the 25-years-of-

[[Page 56385]]

exposure assumption, the effective exposed population over time is 
proportionately increased. Estimated prevented cases of end-stage renal 
disease and silicosis morbidity are lower in the 25-year model, whereas 
cases of fatal non-malignant lung disease are higher. In the case of 
lung cancer, the effect varies by model, with a lower high-end estimate 
(Attfield & Costello, 2004) and a higher low-end estimate (Steenland 
et. al., 2001 log-linear model). Overall, however, the 45-year-working-
life assumption yields larger estimates of the number of cases of 
avoided fatalities and illnesses than does the 25-years-of-exposure 
assumption. For example, the midpoint estimates of the number of 
avoided fatalities and illnesses under the proposed PEL of 50 [mu]g/
m\3\ would decline from 688 and 1,585, respectively, under the 45-year-
working-life assumption to 683 and 642, respectively, under the 25-
year-working-life assumption. Note the effect, in this case, of going 
from a 45-year-working-life assumption to a 25-year-working-life 
assumption would be a 1 percent reduction in the number of avoided 
fatalities and a 59 percent reduction in the number of avoided 
illnesses. The divergence reflects differences in the mathematical 
structure of the risk assessment models that are the basis for these 
estimates.\27\
---------------------------------------------------------------------------

    \26\ Section (6)(b)(5) of the OSH Act states: ``The Secretary, 
in promulgating standards dealing with toxic materials or harmful 
physical agents under this subsection, shall set the standard which 
most adequately assures, to the extent feasible, on the basis of the 
best available evidence, that no employee will suffer material 
impairment of health or functional capacity even if such employee 
has regular exposure to the hazard dealt with by such standard for 
the period of his working life.'' Given that it is necessary for 
OSHA to reach a determination of significant risk over a working 
life, it is a logical extension to estimate what this translates 
into in terms of estimated benefits for the affected population over 
the same period.
    \27\ Technically, this analysis assumes that workers receive 25 
years worth of silica exposure, but that they receive it over 45 
working years, as is assumed by the risk models in the QRA. It also 
accounts for the turnover implied by 25, as opposed to 45, years of 
work. However, it is possible that an alternate analysis, which 
accounts for the larger number of post-exposure worker-years implied 
by workers departing their jobs before the end of their working 
lifetime, might find larger health effects for workers receiving 25 
years worth of silica exposure.
---------------------------------------------------------------------------

    OSHA believes that 25 years of worker exposure to respirable 
crystalline silica may be a reasonable alternative estimate for 
informational purposes. However, to accommodate the possibility that 
average worker exposure to silica over a working life may be shorter, 
at least in certain industries (see the following paragraph), the 
Agency also examined the effect of assuming only 13 years of exposure 
for the average worker. The results were broadly similar to the 25 
years of exposure--annual fatalities prevented were higher (788), but 
illnesses prevented lower (399), with the lower average cumulative 
exposure being offset to a substantial degree by a larger exposed 
population. The same effect is seen if one assumes only 6.6 years of 
cumulative exposure to silica for the average worker: estimated 
fatalities rise to 832 cases annually, with 385 cases of silicosis 
morbidity. In short, the aggregate estimated benefits of the rule 
appear to be relatively insensitive to implicit assumptions of average 
occupational tenure. Nonetheless, the Agency is confident that the 
typical affected worker sustains an extended period of exposure to 
silica.
    Even in the construction industry, which has an extremely high rate 
of job turnover, the mean job tenure with one's current employer is 6.6 
years (BLS, 2010a), and the median age of construction workers in the 
U.S. is 41.6 years (BLS, 2010b). OSHA is unaware of any data on job 
tenure within an industry, but the Agency would expect job tenure in 
the construction industry would be at least twice the job tenure with 
one's current employer. Furthermore, many workers may return to the 
construction industry after unemployment or work in another industry. 
Of course, job tenure is longer in the other industries affected by the 
proposed rule.
    The proposed rule also contains specific provisions for diagnosing 
latent tuberculosis (TB) in the silica-exposed population and thereby 
reducing the risk of TB being spread to the population at large. The 
Agency currently lacks good methods for quantifying these benefits. Nor 
has the Agency attempted to assess benefits directly stemming from 
enhanced medical surveillance in terms of reducing the severity of 
symptoms from the illnesses that do result from present or future 
exposure to silica. However, the Agency welcomes comment on the likely 
magnitude of these currently non-quantified health benefits arising 
from the proposed rule and on methods for better measuring these 
effects.
    OSHA's risk estimates are based on application of exposure-response 
models derived from several individual epidemiological studies as well 
as the pooled cohort studies of Steenland et al. (2001) and Mannetje et 
al. (2002). OSHA recognizes that there is uncertainty around any of the 
point estimates of risk derived from any single study. In its 
preliminary risk assessment (summarized in Section VI of this 
preamble), OSHA has made efforts to characterize some of the more 
important sources of uncertainty to the extent that available data 
permit. This specifically includes characterizing statistical 
uncertainty by reporting the confidence intervals around each of the 
risk estimates; by quantitatively evaluating the impact of 
uncertainties in underlying exposure data used in the cohort studies; 
and by exploring the use of alternative exposure-response model forms. 
OSHA believes that these efforts reflect much, but not necessarily all, 
of the uncertainties associated with the approaches taken by 
investigators in their respective risk analyses. However, OSHA believes 
that characterizing the risks and benefits as a range of estimates 
derived from the full set of available studies, rather than relying on 
any single study as the basis for its estimates, better reflects the 
uncertainties in the estimates and more fairly captures the range of 
risks likely to exist across a wide range of industries and exposure 
situations.
    Another source of uncertainty involves the degree to which OSHA's 
risk estimates reflect the risk of disease among workers with widely 
varying exposure patterns. Some workers are exposed to fairly high 
concentrations of crystalline silica only intermittently, while others 
experience more regular and constant exposure. Risk models employed in 
the quantitative assessment are based on a cumulative exposure metric, 
which is the product of average daily silica concentration and duration 
of worker exposure for a specific job. Consequently, these models 
predict the same risk for a given cumulative exposure regardless of the 
pattern of exposure, reflecting a worker's long-term average exposure 
without regard to intermittencies or other variances in exposure, and 
are therefore generally applicable to all workers who are exposed to 
silica in the various industries. Section VI of this preamble provides 
evidence supporting the use of cumulative exposure as the preferred 
dose metric. Although the Agency believes that the results of its risk 
assessment are broadly relevant to all occupational exposure situations 
involving crystalline silica, OSHA acknowledges that differences exist 
in the relative toxicity of crystalline silica particles present in 
different work settings due to factors such as the presence of mineral 
or metal impurities on quartz particle surfaces, whether the particles 
have been freshly fractured or are aged, and size distribution of 
particles. However, in its preliminary risk assessment, OSHA 
preliminarily concludes that the estimates from the studies and 
analyses relied upon are fairly representative of a wide range of 
workplaces reflecting differences in silica polymorphism, surface 
properties, and impurities.
    Thus, OSHA has a high degree of confidence in the risk estimates 
associated with exposure to the current and proposed PELs. OSHA 
acknowledges there is greater uncertainty in the risk estimates for the 
proposed action level of 0.025 mg/m\3\ than exists at the current (0.1 
mg/m\3\)

[[Page 56386]]

and proposed (0.05 mg/m\3\) PELs, particularly given some evidence of a 
threshold for silicosis between the proposed PEL and action level. 
Given the Agency's findings that controlling exposures below the 
proposed PEL would not be technologically feasible for employers, OSHA 
believes that a precise estimate of the risk for exposures below the 
proposed action level is not necessary to further inform the Agency's 
regulatory action. OSHA requests comment on remaining sources of 
uncertainties in its risk and benefits estimates that have not been 
specifically characterized by OSHA in its analysis.

[[Page 56387]]

[GRAPHIC] [TIFF OMITTED] TP12SE13.008


[[Page 56388]]


2. Estimating the Stream of Benefits Over Time
    Risk assessments in the occupational environment are generally 
designed to estimate the risk of an occupationally related illness over 
the course of an individual worker's lifetime. As previously discussed, 
the current occupational exposure profile for a particular substance 
for the current cohort of workers can be matched up against the 
expected profile after the proposed standard takes effect, creating a 
``steady state'' estimate of benefits. However, in order to annualize 
the benefits for the period of time after the silica rule takes effect, 
it is necessary to create a timeline of benefits for an entire active 
workforce over that period.
    In order to characterize the magnitude of benefits before the 
steady state is reached, OSHA created a linear phase-in model to 
reflect the potential timing of benefits. Specifically, OSHA estimated 
that, for all non-cancer cases, while the number of cases would 
gradually decline as a result of the proposed rule, they would not 
reach the steady-state level until 45 years had passed. The reduction 
in cases estimated to occur in any given year in the future was 
estimated to be equal to the steady-state reduction (the number of 
cases in the baseline minus the number of cases in the new steady 
state) times the ratio of the number of years since the standard was 
implemented and a working life of 45 years. Expressed mathematically:

Nt=(C--S) x (t/45),

where Nt is the number of non-malignant silica-related 
diseases avoided in year t; C is the current annual number of non-
malignant silica-related diseases; S is the steady-state annual number 
of non-malignant silica-related diseases; and t represents the number 
of years after the proposed standard takes effect, with t<=45.
    In the case of lung cancer, the function representing the decline 
in the number of cases as a result of the proposed rule is similar, but 
there would be a 15-year lag before any reduction in cancer cases would 
be achieved. Expressed mathematically, for lung cancer:

Lt=(Cm--Sm) x ((t-15)/45)),

where 15 <= t <= 60 and Lt is the number of lung cancer 
cases avoided in year t as a result of the proposed rule; Cm 
is the current annual number of silica-related lung cancers; and 
Sm is the steady-state annual number of silica-related lung 
cancers.
    A more complete discussion of the functioning and results of this 
model is presented in Chapter VII of the PEA.
    This model was extended to 60 years for all the health effects 
previously discussed in order to incorporate the 15-year lag, in the 
case of lung cancer, and a 45-year working life. As a practical matter, 
however, there is no overriding reason for stopping the benefits 
analysis at 60 years. An internal analysis by OSHA indicated that, both 
in terms of cases prevented, and even with regard to monetized 
benefits, particularly when lower discount rates are used, the 
estimated benefits of the standard are noticeably larger on an 
annualized basis if the analysis extends further into the future. The 
Agency welcomes comment on the merit of extending the benefits analysis 
beyond the 60 years analyzed in the PEA.
    In order to compare costs to benefits, OSHA assumes that economic 
conditions remain constant and that annualized costs--and the 
underlying costs--will repeat for the entire 60-year time horizon used 
for the benefits analysis (as discussed in Chapter V of the PEA). OSHA 
welcomes comments on the assumption for both the benefit and cost 
analysis that economic conditions remain constant for sixty years. OSHA 
is particularly interested in what assumptions and time horizon should 
be used instead and why.
3. Monetizing the Benefits
    To estimate the monetary value of the reductions in the number of 
silica-related fatalities, OSHA relied, as OMB recommends, on estimates 
developed from the willingness of affected individuals to pay to avoid 
a marginal increase in the risk of fatality. While a willingness-to-pay 
(WTP) approach clearly has theoretical merit, it should be noted that 
an individual's willingness to pay to reduce the risk of fatality would 
tend to underestimate the total willingness to pay, which would include 
the willingness of others--particularly the immediate family--to pay to 
reduce that individual's risk of fatality.\28\
---------------------------------------------------------------------------

    \28\ See, for example, Thaler and Rosen (1976), pp. 265-266. In 
addition, see Sunstein (2004), p. 433. ``This point demonstrates a 
general and badly neglected problem for WTP as it is currently used: 
agencies consider people's WTP to eliminate statistical risks, 
without taking account of the fact that others--especially family 
members and close friends--would also be willing to pay something to 
eliminate those risks.''
---------------------------------------------------------------------------

    For estimates using the willingness-to-pay concept, OSHA relied on 
existing studies of the imputed value of fatalities avoided based on 
the theory of compensating wage differentials in the labor market. 
These studies rely on certain critical assumptions for their accuracy, 
particularly that workers understand the risks to which they are 
exposed and that workers have legitimate choices between high- and low-
risk jobs. These assumptions are far from obviously met in actual labor 
markets.\29\ A number of academic studies, as summarized in Viscusi & 
Aldy (2003), have shown a correlation between higher job risk and 
higher wages, suggesting that employees demand monetary compensation in 
return for a greater risk of injury or fatality. The estimated trade-
off between lower wages and marginal reductions in fatal occupational 
risk--that is, workers' willingness to pay for marginal reductions in 
such risk--yields an imputed value of an avoided fatality: the 
willingness-to-pay amount for a reduction in risk divided by the 
reduction in risk.\30\ OSHA has used this approach in many recent 
proposed and final rules. Although this approach has been found to 
yield results that are less than statistically robust (see, for 
example, Hintermann, Alberini and Markandya, 2010), OSHA views these 
estimates as the best available, and will use them for its basic 
estimates. OSHA welcomes comments on the use of willingness-to-pay 
measures and estimates based on compensating wage differentials.
---------------------------------------------------------------------------

    \29\ On the former assumption, see the discussion in Chapter II 
of the PEA on imperfect information. On the latter, see, for 
example, the discussion of wage compensation for risk for union 
versus nonunion workers in Dorman and Hagstrom (1998).
    \30\ For example, if workers are willing to pay $50 each for a 
1/100,000 reduction in the probability of dying on the job, then the 
imputed value of an avoided fatality would be $50 divided by 1/
100,000, or $5,000,000. Another way to consider this result would be 
to assume that 100,000 workers made this trade-off. On average, one 
life would be saved at a cost of $5,000,000.
---------------------------------------------------------------------------

    Viscusi & Aldy (2003) conducted a meta-analysis of studies in the 
economics literature that use a willingness-to-pay methodology to 
estimate the imputed value of life-saving programs and found that each 
fatality avoided was valued at approximately $7 million in 2000 
dollars. This $7 million base number in 2000 dollars yields an estimate 
of $8.7 million in 2009 dollars for each fatality avoided.\31\
---------------------------------------------------------------------------

    \31\ An alternative approach to valuing an avoided fatality is 
to monetize, for each year that a life is extended, an estimate from 
the economics literature of the value of that statistical life-year 
(VSLY). See, for instance, Aldy and Viscusi (2007) for discussion of 
VSLY theory and FDA (2003), pp. 41488-9, for an application of VSLY 
in rulemaking. OSHA has not investigated this approach, but welcomes 
comment on the issue.
---------------------------------------------------------------------------

    In addition to the benefits that are based on the implicit value of 
fatalities avoided, workers also place an implicit value on 
occupational injuries or illnesses avoided, which reflect their

[[Page 56389]]

willingness to pay to avoid monetary costs (for medical expenses and 
lost wages) and quality-of-life losses as a result of occupational 
illness. Silicosis, lung cancer, and renal disease can adversely affect 
individuals for years or even decades in non-fatal cases, or before 
ultimately proving fatal. Because measures of the benefits of avoiding 
these illnesses are rare and difficult to find, OSHA has included a 
range based on a variety of estimation methods.
    Consistent with Buchannan et al. (2003), OSHA estimated the total 
number of moderate to severe silicosis cases prevented by the proposed 
rule, as measured by 2/1 or more severe X-rays (based on the ILO rating 
system). However, while radiological evidence of moderate to severe 
silicosis is evidence of significant material impairment of health, 
placing a precise monetary value on this condition is difficult, in 
part because the severity of symptoms may vary significantly among 
individuals. For that reason, for this preliminary analysis, the Agency 
employed a broad range of valuation, which should encompass the range 
of severity these individuals may encounter. Using the willingness-to-
pay approach, discussed in the context of the imputed value of 
fatalities avoided, OSHA has estimated a range in valuations (updated 
and reported in 2009 dollars) that runs from approximately $62,000 per 
case--which reflects estimates developed by Viscusi and Aldy (2003), 
based on a series of studies primarily describing simple accidents--to 
upwards of $5.1 million per case--which reflects work developed by 
Magat, Viscusi & Huber (1996) for non-fatal cancer. The latter number 
is based on an approach that places a willingness-to-pay value to avoid 
serious illness that is calibrated relative to the value of an avoided 
fatality. OSHA (2006) previously used this approach in the Final 
Economic Analysis (FEA) supporting its hexavalent chromium final rule, 
and EPA (2003) used this approach in its Stage 2 Disinfection and 
Disinfection Byproducts Rule concerning regulation of primary drinking 
water. Based on Magat, Viscusi & Huber (1996), EPA used studies on the 
willingness-to-pay to avoid nonfatal lymphoma and chronic bronchitis as 
a basis for valuing a case of nonfatal cancer at 58.3 percent of the 
value of a fatal cancer. OSHA's estimate of $5.1 million for an avoided 
case of non-fatal cancer is based on this 58.3 percent figure.
    The Agency believes this range of estimates is descriptive of the 
value of preventing morbidity associated with moderate to severe 
silicosis, as well as the morbidity preceding mortality due to other 
causes enumerated here--lung cancer, lung diseases other than cancer, 
and renal disease.\32\ OSHA therefore is applying these values to those 
situations as well.
---------------------------------------------------------------------------

    \32\ There are several benchmarks for valuation of health 
impairment due to silica exposure, using a variety of techniques, 
which provide a number of mid-range estimates between OSHA's high 
and low estimates. For a fuller discussion of these estimates, see 
Chapter VII of the PEA.
---------------------------------------------------------------------------

    The Agency is interested in public input on the issue of valuing 
the cost to society of non-fatal cases of moderate to severe silicosis, 
as well as the morbidity associated with other related diseases of the 
lung, and with renal disease.
a. The Monetized Benefits of the Proposed Rule
    Table VIII-18 presents the estimated annualized (over 60 years, 
using a 0 percent discount rate) benefits from each of these components 
of the valuation, and the range of estimates, based on risk model 
uncertainty (notably in the case of lung cancer), and the range of 
uncertainty regarding valuation of morbidity. (Mid-point estimates of 
the undiscounted benefits for each of the first 60 years are provided 
in the middle columns of Table VII-A-1 in Appendix VII-A in the PEA. 
The estimates by year reach a peak of $11.9 billion in the 60th year.)
    As shown, the full range of monetized benefits, undiscounted, for 
the proposed PEL of 50 [mu]g/m\3\ runs from $3.2 billion annually, in 
the case of the lowest estimate of lung cancer risk and the lowest 
valuation for morbidity, up to $10.9 billion annually, for the highest 
of both. Note that the value of total benefits is more sensitive to the 
valuation of morbidity (ranging from $3.5 billion to $10.3 billion, 
given estimates at the midpoint of the lung cancer models) than to the 
lung cancer model used (ranging from $6.4 to $7.4 billion, given 
estimates at the midpoint of the morbidity valuation).\33\
---------------------------------------------------------------------------

    \33\ As previously indicated, these valuations include all the 
various estimated health endpoints. In the case of mortality this 
includes lung cancer, non-malignant respiratory disease and end-
stage renal disease. The Agency highlighted lung cancers in this 
discussion due to the model uncertainty. In calculating the 
monetized benefits, the Agency is typically referring to the 
midpoint of the high and low ends of potential valuation--in this 
case, the undiscounted midpoint of $3.2 billion and $10.9 billion..
---------------------------------------------------------------------------

    This comports with the very wide range of valuation for morbidity. 
At the low end of the valuation range, the total value of benefits is 
dominated by mortality ($3.4 billion out of $3.5 billion at the case 
frequency midpoint), whereas at the high end the majority of the 
benefits are related to morbidity ($6.9 billion out of $10.3 billion at 
the case frequency midpoint). Also, the analysis illustrates that most 
of the morbidity benefits are related to silicosis cases that are not 
ultimately fatal. At the valuation and case frequency midpoint, $3.4 
billion in benefits are related to mortality, $1.0 billion are related 
to morbidity preceding mortality, and $2.4 billion are related to 
morbidity not preceding mortality.

[[Page 56390]]

[GRAPHIC] [TIFF OMITTED] TP12SE13.009

b. A Suggested Adjustment to Monetized Benefits
    OSHA's estimates of the monetized benefits of the proposed rule are 
based on the imputed value of each avoided fatality and each avoided 
silica-related disease. To this point, these imputed values have been 
assumed to remain constant over time.
    OSHA now would like to suggest that an adjustment be made to 
monetized benefits to reflect the fact that the imputed value of 
avoided fatalities and avoided diseases will tend to increase over 
time. Two related factors suggest such an increase in value over time.
    First, economic theory suggests that the value of reducing life-
threatening

[[Page 56391]]

and health-threatening risks will increase as real per capita income 
increases. With increased income, an individual's health and life 
become more valuable relative to other goods because, unlike other 
goods, they are without close substitutes and in relatively fixed or 
limited supply. Expressed differently, as income increases, consumption 
will increase but the marginal utility of consumption will decrease. In 
contrast, added years of life (in good health) is not subject to the 
same type of diminishing returns--implying that an effective way to 
increase lifetime utility is by extending one's life and maintaining 
one's good health (Hall and Jones, 2007).
    Second, real per capita income has broadly been increasing 
throughout U.S. history, including recent periods. For example, for the 
period 1950 through 2000, real per capita income grew at an average 
rate of 2.31 percent a year (Hall and Jones, 2007) \34\ although real 
per capita income for the recent 25 year period 1983 through 2008 grew 
at an average rate of only 1.3 percent a year (U.S. Census Bureau, 
2010). More important is the fact that real U.S. per capita income is 
projected to grow significantly in future years. For example, the 
Annual Energy Outlook (AEO) projections, prepared by the Energy 
Information Administration (EIA) in the Department of Energy (DOE), 
show an average annual growth rate of per capita income in the United 
States of 2.7 percent for the period 2011-2035.\35\ The U.S. 
Environmental Protection Agency prepared its economic analysis of the 
Clean Air Act using the AEO projections. Although these estimates may 
turn out to be somewhat higher or lower than predicted, OSHA believes 
that it is reasonable to use the same AEO projections employed by DOE 
and EPA, and correspondingly projects that per capita income in the 
United States will increase by 2.7 percent a year.
---------------------------------------------------------------------------

    \34\ The results are similar if the historical period includes a 
major economic downturn (such as the United States has recently 
experienced). From 1929 through 2003, a period in U.S. history that 
includes the Great Depression, real per capita income still grew at 
an average rate of 2.22 percent a year (Gomme and Rupert, 2004).
    \35\ The EIA used DOE's National Energy Modeling System (NEMS) 
to produce the Annual Energy Outlook (AEO) projections (EIA, 2011). 
Future per capita GDP was calculated by dividing the projected real 
gross domestic product each year by the projected U.S. population 
for that year.
---------------------------------------------------------------------------

    On the basis of the predicted increase in real per capita income in 
the United States over time and the expected resulting increase in the 
value of avoided fatalities and diseases, OSHA is considering adjusting 
its estimates of the benefits of the proposed rule to reflect the 
anticipated increase in their value over time. This type of adjustment 
has been recognized by OMB (2003), supported by EPA's Science Advisory 
Board (EPA, 2000), and applied by EPA.\36\ OSHA proposes to accomplish 
this adjustment by modifying benefits in year i from [Bi] to 
[Bi * (1 + [eta])\i\], where ``[eta]'' is the estimated 
annual increase in the magnitude of the benefits of the proposed rule.
---------------------------------------------------------------------------

    \36\ See, for example, EPA (2003, 2008).
---------------------------------------------------------------------------

    What remains is to estimate a value for ``[eta]'' with which to 
increase benefits annually in response to annual increases in real per 
capita income. Probably the most direct evidence of the value of 
``[eta]'' comes from the work of Costa and Kahn (2003, 2004). They 
estimate repeated labor market compensating wage differentials from 
cross-sectional hedonic regressions using census and fatality data from 
the Bureau of Labor Statistics for 1940, 1950, 1960, 1970, and 1980. In 
addition, with the imputed income elasticity of the value of life on 
per capita GNP of 1.7 derived from the 1940-1980 data, they then 
predict the value of an avoided fatality in 1900, 1920, and 2000. Given 
the change in the value of an avoided fatality over time, it is 
possible to estimate a value of ``[eta]'' of 3.4 percent a year from 
1900-2000; of 4.3 percent a year from 1940-1980; and of 2.5 percent a 
year from 1980-2000. Other, more indirect evidence comes from estimates 
in the economics literature on the income elasticity for the value of a 
statistical life. Viscusi and Aldy (2003) performed a meta-analysis on 
50 wage-risk studies and concluded that the point estimates across a 
variety of model specifications ranged between 0.5 and 0.6. Applied to 
a long-term increase in per capita income of about 2.7 percent a year, 
this would suggest a value of ``[eta]'' of about 1.5 percent a year. 
More recently, Kniesner, Viscusi, and Ziliak (2010), using panel data 
quintile regressions, developed an estimate of the overall income 
elasticity of the value of a statistical life of 1.44. Applied to a 
long-term increase in per capita income of about 2.7 percent a year, 
this would suggest a value of ``[eta]'' of about 3.9 percent a year.
    Based on the preceding discussion of these two approaches for 
estimating the annual increase in the value of the benefits of the 
proposed rule and the fact that, as previously noted, the projected 
increase in real per capita income in the United States has flattened 
in the most recent 25 year period, OSHA suggests a value of ``[eta]'' 
of approximately 2 percent a year. The Agency invites comment on this 
estimate and on estimates of the income elasticity of the value of a 
statistical life.
    While the Agency believes that the rising value, over time, of 
health benefits is a real phenomenon that should be taken into account 
in estimating the annualized benefits of the proposed rule, OSHA is at 
this time only offering these adjusted monetized benefits as analytic 
alternatives for consideration. Table VIII-19, which follows the 
discussion on discounting monetized benefits, shows estimates of the 
monetized benefits of the proposed rule (under alternative discount 
rates) both with and without this suggested increase in monetized 
benefits over time. The Agency invites comment on this suggested 
adjustment to monetized benefits.
4. Discounting of Monetized Benefits
    As previously noted, the estimated stream of benefits arising from 
the proposed silica rule is not constant from year to year, both 
because of the 45-year delay after the rule takes effect until all 
active workers obtain reduced silica exposure over their entire working 
lives and because of, in the case of lung cancer, a 15-year latency 
period between reduced exposure and a reduction in the probability of 
disease. An appropriate discount rate \37\ is needed to reflect the 
timing of benefits over the 60-year period after the rule takes effect 
and to allow conversion to an equivalent steady stream of annualized 
benefits.
---------------------------------------------------------------------------

    \37\ Here and elsewhere throughout this section, unless 
otherwise noted, the term ``discount rate'' always refers to the 
real discount rate--that is, the discount rate net of any 
inflationary effects.
---------------------------------------------------------------------------

a. Alternative Discount Rates for Annualizing Benefits
    Following OMB (2003) guidelines, OSHA has estimated the annualized 
benefits of the proposed rule using separate discount rates of 3 
percent and 7 percent. Consistent with the Agency's own practices in 
recent proposed and final rules, OSHA has also estimated, for 
benchmarking purposes, undiscounted benefits--that is, benefits using a 
zero percent discount rate.
    The question remains, what is the ``appropriate'' or ``preferred'' 
discount rate to use to monetize health benefits? The choice of 
discount rate is a controversial topic, one that has been the source of 
scholarly economic debate for several decades. However, in simplest 
terms, the basic choices involve a social opportunity cost of capital 
approach or social rate of time preference approach.

[[Page 56392]]

    The social opportunity cost of capital approach reflects the fact 
that private funds spent to comply with government regulations have an 
opportunity cost in terms of foregone private investments that could 
otherwise have been made. The relevant discount rate in this case is 
the pre-tax rate of return on the foregone investments (Lind, 1982b, 
pp. 24-32). The rate of time preference approach is intended to measure 
the tradeoff between current consumption and future consumption, or in 
the context of the proposed rule, between current benefits and future 
benefits. The individual rate of time preference is influenced by 
uncertainty about the availability of the benefits at a future date and 
whether the individual will be alive to enjoy the delayed benefits. By 
comparison, the social rate of time preference takes a broader view 
over a longer time horizon--ignoring individual mortality and the 
riskiness of individual investments (which can be accounted for 
separately) .
    The usual method for estimating the social rate of time preference 
is to calculate the post-tax real rate of return on long-term, risk-
free assets, such as U.S. Treasury securities (OMB, 2003). A variety of 
studies have estimated these rates of return over time and reported 
them to be in the range of approximately 1-4 percent.
    In accordance with OMB Circular A-4 (2003), OSHA presents benefits 
and net benefits estimates using discount rates of 3 percent 
(representing the social rate of time preference) and 7 percent (a rate 
estimated using the social cost of capital approach). The Agency is 
interested in any evidence, theoretical or applied, that would inform 
the application of discount rates to the costs and benefits of a 
regulation.
b. Summary of Annualized Benefits Under Alternative Discount Rates
    Table VIII-19 presents OSHA's estimates of the sum of the 
annualized benefits of the proposed rule, using alternative discount 
rates at 0, 3, and 7 percent, with a breakout between construction and 
general industry, and including the possible alternative of increasing 
monetized benefits in response to annual increases in per capita income 
over time.
    Given that the stream of benefits extends out 60 years, the value 
of future benefits is sensitive to the choice of discount rate. As 
previously established in Table VIII-18, the undiscounted benefits 
range from $3.2 billion to $10.9 billion annually. Using a 7 percent 
discount rate, the annualized benefits range from $1.6 billion to $5.4 
billion. As can be seen, going from undiscounted benefits to a 7 
percent discount rate has the effect of cutting the annualized benefits 
of the proposed rule approximately in half.
    The Agency's best estimate of the total annualized benefits of the 
proposed rule--using a 3 percent discount rate with no adjustment for 
the increasing value of health benefits over time-- is between $2.4 and 
$8.1 billion, with a mid-point value of $5.3 billion.
    As previously mentioned, OSHA has not attempted to estimate the 
monetary value of less severe silicosis cases, measured at 1/0 to 1/2 
on the ILO scale. The Agency believes the economic loss to individuals 
with less severe cases of silicosis could be substantial, insofar as 
they may be accompanied by a lifetime of medical surveillance and lung 
damage, and potentially may require a change in career. However, many 
of these effects can be difficult to isolate and measure in economic 
terms, particularly in those cases where there is no obvious effect yet 
on physiological function or performance. The Agency invites public 
comment on this issue.

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[[Page 56394]]


5. Net Benefits of the Proposed Rule
    OSHA has estimated, in Table VIII-20, the net benefits of the 
proposed rule (with a PEL of 50 [mu]g/m\3\), based on the benefits and 
costs previously presented. Table VIII-20 also provides estimates of 
annualized net benefits for an alternative PEL of 100 [mu]g/m\3\. Both 
the proposed rule and the alternative rule have the same ancillary 
provisions and an action level equal to half of the PEL in both cases.
    Table VIII-20 is being provided for informational purposes only. As 
previously noted, the OSH Act requires the Agency to set standards 
based on eliminating significant risk to the extent feasible. An 
alternative criterion of maximizing net (monetized) benefits may result 
in very different regulatory outcomes. Thus, this analysis of net 
benefits has not been used by OSHA as the basis for its decision 
concerning the choice of a PEL or of other ancillary requirements for 
this proposed silica rule.
    Table VIII-20 shows net benefits using alternative discount rates 
of 0, 3, and 7 percent for benefits and costs and includes a possible 
adjustment to monetized benefits to reflect increases in real per 
capita income over time. (An expanded version of Tables VIII-20, with a 
breakout of net benefits between construction and general industry/
maritime, is provided in Table VII-B-1 in Appendix B, of the PEA.) OSHA 
has relied on a uniform discount rate applied to both costs and 
benefits. The Agency is interested in any evidence, theoretical or 
applied, that would support or refute the application of differential 
discount rates to the costs and benefits of a regulation.
    As previously noted, the choice of discount rate for annualizing 
benefits has a significant effect on annualized benefits. The same is 
true for net benefits. For example, the net benefits using a 7 percent 
discount rate for benefits are considerably smaller than the net 
benefits using a 0 percent discount rate, declining by more than half 
under all scenarios. (Conversely, as noted in Chapter V of the PEA, the 
choice of discount rate for annualizing costs has only a very minor 
effect on annualized costs.)
    Based on the results presented in Table VIII-20, OSHA finds:
     While the net benefits of the proposed rule vary 
considerably--depending on the choice of discount rate used to 
annualize benefits and on whether the benefits being used are in the 
high, midpoint, or low range-- benefits exceed costs for the proposed 
50 [mu]g/m\3\ PEL in all cases that OSHA considered.
     The Agency's best estimate of the net annualized benefits 
of the proposed rule--using a uniform discount rate for both benefits 
and costs of 3 percent--is between $1.8 billion and $7.5 billion, with 
a midpoint value of $4.6 billion.
     The alternative of a 100 [mu]g/m\3\ PEL was found to have 
lower net benefits under all assumptions, relative to the proposed 50 
[mu]g/m\3\ PEL. However, for this alternative PEL, benefits were found 
to exceed costs in all cases that OSHA considered.
6. Incremental Benefits of the Proposed Rule
    Incremental costs and benefits are those that are associated with 
increasing the stringency of the standard. A comparison of incremental 
benefits and costs provides an indication of the relative efficiency of 
the proposed PEL and the alternative PEL. Again, OSHA has conducted 
these calculations for informational purposes only and has not used 
this information as the basis for selecting the PEL for the proposed 
rule.
    OSHA provided, in Table VIII-20, estimates of the net benefits of 
an alternative 100 [mu]g/m\3\ PEL. The incremental costs, benefits, and 
net benefits of going from a 100 [mu]g/m\3\ PEL to a 50 [mu]g/m\3\ PEL 
(as well as meeting a 50 [mu]g/m\3\ PEL and then going to a 25 [mu]g/
m\3\ PEL--which the Agency has determined is not feasible), for 
alternative discount rates of 3 and 7 percent, are presented in Tables 
VIII-21 and VIII-22. Table VIII-21 breaks out costs by provision and 
benefits by type of disease and by morbidity/mortality, while Table 
VIII-22 breaks out costs and benefits by major industry sector. As 
Table VIII-21 shows, at a discount rate of 3 percent, a PEL of 50 
[mu]g/m\3\, relative to a PEL of 100 [mu]g/m\3\, imposes additional 
costs of $339 million per year; additional benefits of $2.5 billion per 
year, and additional net benefits of $2.16 billion per year. The 
proposed PEL of 50 [mu]g/m\3\ also has higher net benefits using either 
a 3 percent or 7 percent discount rate.
    Table VIII-22 continues this incremental analysis but with 
breakdowns between construction and general industry/maritime. This 
table shows that construction provides most of the incremental costs, 
but the incremental benefits are more evenly divided between the two 
sectors. Nevertheless, both sectors show strong positive net benefits, 
which are greater for the proposed PEL of 50 [mu]g/m\3\ than the 
alternative of 100 [mu]g/m\3\.
    Tables VIII-21 and VIII-22 demonstrate that, across all discount 
rates, there are net benefits to be achieved by lowering exposures to 
100 [mu]g/m\3\ and then, in turn, lowering them further to 50 [mu]g/
m\3\. However, the majority of the benefits and costs attributable to 
the proposed rule are from the initial effort to lower exposures to 100 
[mu]g/m\3\. Consistent with the previous analysis, net benefits decline 
across all increments as the discount rate for annualizing benefits 
increases.
    In addition to examining alternative PELs, OSHA also examined 
alternatives to other provisions of the standard. These alternatives 
are discussed in Section VIII.H of this preamble.

Table VIII-20--Annual Monetized net Benefits Resulting From a Reduction in Exposure to Crystalline Silica due to
                       Proposed PEL of 50 [mu]g/m\3\ and Alternative PEL of 100 [mu]g/m\3\
                                                   [$Billions]
----------------------------------------------------------------------------------------------------------------
                                     PEL
-----------------------------------------------------------------------------        50                100
                Discount rate                              Range
----------------------------------------------------------------------------------------------------------------
Undiscounted (0%)...........................  Low...........................              $2.5              $1.2
                                              Midpoint......................               6.4               3.4
                                              High..........................              10.2               5.6
Discounted at 3%, with a suggested increased  Low...........................               2.3               1.1
 in monetized benefits over time.             Midpoint......................               5.8               3.1
                                              High..........................               9.3               5.1
3%..........................................  Low...........................               1.8               0.8
                                              Midpoint......................               4.6               2.5
                                              High..........................               7.5               4.1

[[Page 56395]]

 
Discounted at 7%, with a suggested increased  Low...........................               1.3               0.6
 in monetized benefits over time.             Midpoint......................               3.6               1.9
                                              High..........................               5.9               3.3
7%..........................................  Low...........................               1.0               0.5
                                              Midpoint......................               2.8               1.5
                                              High..........................               4.7               2.6
----------------------------------------------------------------------------------------------------------------
Source: U.S. Department of Labor, Occupational Safety and Health Administration, Directorate of Standards and
  Guidance, Office of Regulatory Analysis.


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[[Page 56398]]

7. Sensitivity Analysis
    In this section, OSHA presents the results of two different types 
of sensitivity analysis to demonstrate how robust the estimates of net 
benefits are to changes in various cost and benefit parameters. In the 
first type of sensitivity analysis, OSHA made a series of isolated 
changes to individual cost and benefit input parameters in order to 
determine their effects on the Agency's estimates of annualized costs, 
annualized benefits, and annualized net benefits. In the second type of 
sensitivity analysis--a so-called ``break-even'' analysis--OSHA also 
investigated isolated changes to individual cost and benefit input 
parameters, but with the objective of determining how much they would 
have to change for annualized costs to equal annualized benefits.
    Again, the Agency has conducted these calculations for 
informational purposes only and has not used these results as the basis 
for selecting the PEL for the proposed rule.
Analysis of Isolated Changes to Inputs
    The methodology and calculations underlying the estimation of the 
costs and benefits associated with this rulemaking are generally linear 
and additive in nature. Thus, the sensitivity of the results and 
conclusions of the analysis will generally be proportional to isolated 
variations a particular input parameter. For example, if the estimated 
time that employees need to travel to (and from) medical screenings 
were doubled, the corresponding labor costs would double as well.
    OSHA evaluated a series of such changes in input parameters to test 
whether and to what extent the general conclusions of the economic 
analysis held up. OSHA first considered changes to input parameters 
that affected only costs and then changes to input parameters that 
affected only benefits. Each of the sensitivity tests on cost 
parameters had only a very minor effect on total costs or net costs. 
Much larger effects were observed when the benefits parameters were 
modified; however, in all cases, net benefits remained significantly 
positive. On the whole, OSHA found that the conclusions of the analysis 
are reasonably robust, as changes in any of the cost or benefit input 
parameters still show significant net benefits for the proposed rule. 
The results of the individual sensitivity tests are summarized in Table 
VIII-23 and are described in more detail below.
    In the first of these sensitivity test where OSHA doubled the 
estimated portion of employees in regulated areas requiring disposable 
clothing, from 10 to 20 percent, and estimates of other input 
parameters remained unchanged, Table VIII-23 shows that the estimated 
total costs of compliance would increase by $3.6 million annually, or 
by about 0.54 percent, while net benefits would also decline by $3.6 
million, from $4,582 million to $4,528 million annually.
    In a second sensitivity test, OSHA decreased the estimated current 
prevalence of baseline silica training by half, from 50 percent to 25 
percent. As shown in Table VIII-23, if OSHA's estimates of other input 
parameters remained unchanged, the total estimated costs of compliance 
would increase by $7.9 million annually, or by about 1.19 percent, 
while net benefits would also decline by $7.9 million annually, from 
$4,532 million to $4,524 million annually.

[[Page 56399]]

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    In a third sensitivity test, OSHA doubled the estimated travel time 
for employees to and from medical exams from 60 to 120 minutes. As 
shown in Table VIII-23, if OSHA's estimates of other input parameters 
remained unchanged, the total estimated costs of compliance would 
increase by $1.4 million annually, or by about 0.22 percent, while net 
benefits would also decline by $1.4 million annually, from $4,532 
million to $4,530 million annually.
    In a fourth sensitivity test, OSHA reduced its estimate of the 
number of workers who could be represented by an exposure monitoring 
sample from four to three. This would have the effect of increasing 
such costs by one-third. As shown in Table VIII-23, if OSHA's estimates 
of other input parameters remained unchanged, the total estimated costs 
of compliance would increase by $24.8 million annually, or by about 
3.77 percent, while net benefits would also decline by $24.8 million 
annually, from $4,532 million to $4,507 million annually.
    In a fifth sensitivity test, OSHA increased by 50 percent the size 
of the productivity penalty arising from the use of engineering 
controls in construction. As shown in Table VIII-

[[Page 56400]]

23, if OSHA's estimates of other input parameters remained unchanged, 
the total estimated costs of compliance would increase by $35.8 million 
annually, or by about 5.44 percent (and by 7.0 percent in 
construction), while net benefits would also decline by $35.8 million 
annually, from $4,532 million to $4,496 million annually.
    In a sixth sensitivity test, based on the discussion in Chapter V 
of this PEA, OSHA reduced the costs of respirator cartridges to reflect 
possible reductions in costs since the original costs per filter were 
developed in 2003, and inflated to current dollars. For this purpose, 
OSHA reduced respirator filter costs by 40 percent to reflect the 
recent lower-quartile estimates of costs relative to the costs used in 
OSHA's primary analysis. As shown in Table VIII-23, the total estimated 
costs of compliance would be reduced by $21.2 million annually, or by 
about 3.23 percent, while net benefits would also increase by $21.2 
million annually, from $4,532 million to $4,553 million annually.
    In a seventh sensitivity test, OSHA reduced the average crew size 
in general industry and maritime subject to a ``unit'' of engineering 
controls from 4 to 3. This would have the effect of increasing such 
costs by one-third. As shown in Table VIII-23, if OSHA's estimates of 
other input parameters remained unchanged, the total estimated costs of 
compliance would increase by $20.8 million annually, or by about 3.16 
percent (and by 14.2 percent in general industry and maritime), while 
net benefits would also decline by $20.8 million annually, from $4,532 
million to $4,511 million annually.
    In an eighth sensitivity test, OSHA considered the effect on 
annualized net benefits of varying the discount rate for costs and the 
discount rate for benefits separately. In particular, the Agency 
examined the effect of reducing the discount rate for costs from 7 
percent to 3 percent. As indicated in Table VIII-23, this parameter 
change lowers the estimated annualized cost by $20.6 million, or 3.13 
percent. Total annualized net benefits would increase from $4,532 
million annually to $4,552 million annually.
    The Agency also performed sensitivity tests on several input 
parameters used to estimate the benefits of the proposed rule. In the 
first two tests, in an extension of results previously presented in 
Table VIII-21, the Agency examined the effect on annualized net 
benefits of employing the high-end estimate of the benefits, as well as 
the low-end estimate. As discussed previously, the Agency examined the 
sensitivity of the benefits to both the number of different fatal lung 
cancer cases prevented, as well as the valuation of individual 
morbidity cases. Table VIII-23 presents the effect on annualized net 
benefits of using the extreme values of these ranges, the high 
mortality count and high morbidity valuation case, and the low 
mortality count and low morbidity valuation case. As indicated, using 
the high estimate of mortality cases prevented and morbidity valuation, 
the benefits rise by 56% to $8.1 billion, yielding net benefits of $7.5 
billion. For the low estimate of both cases and valuation, the benefits 
decline by 54 percent, to $2.4 billion, yielding net benefits of $1.7 
billion.
    In the third sensitivity test of benefits, the Agency examined the 
effect of raising the discount rate for benefits to 7 percent. The 
fourth sensitivity test of benefits examines the effect of adjusting 
monetized benefits to reflect increases in real per capita income over 
time. The results of these two sensitivity tests were previously shown 
in Table VIII-20 and are repeated in Table VIII-23. Raising the 
interest rate to 7 percent lowers the estimated benefits by 33 percent, 
to $3.5 billion, yielding annualized net benefits of $2.8 billion. 
Adjusting monetized benefits to reflect increases in real per capita 
income over time raises the benefits by 22 percent, to $6.3 billion, 
yielding net benefits of $5.7 billion.
``Break-Even'' Analysis
    OSHA also performed sensitivity tests on several other parameters 
used to estimate the net costs and benefits of the proposed rule. 
However, for these, the Agency performed a ``break-even'' analysis, 
asking how much the various cost and benefits inputs would have to vary 
in order for the costs to equal, or break even with, the benefits. The 
results are shown in Table VIII-24.

[[Page 56401]]

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    In one break-even test on cost estimates, OSHA examined how much 
costs would have to increase in order for costs to equal benefits. As 
shown in Table VIII-24, this point would be reached if costs increased 
by $4.5 billion, or 689 percent.
    In a second test, looking specifically at the estimated engineering 
control costs, the Agency found that these costs would need to increase 
by $4.5 billion, or 1,318 percent, for costs to equal benefits.
    In a third sensitivity test, on benefits, OSHA examined how much 
its estimated monetary valuation of an avoided illness or an avoided 
fatality would need to be reduced in order for the costs to equal the 
benefits. Since the total valuation of prevented mortality and 
morbidity are each estimated to exceed $1.9 billion, while the 
estimated costs are $0.6 billion, an independent break-even point for 
each is impossible. In other words, for example, if no value is 
attached to an avoided illness associated with the rule, but the 
estimated value of an avoided fatality is held constant, the rule still 
has substantial net benefits. Only through a

[[Page 56402]]

reduction in the estimated net value of both components is a break-even 
point possible.
    The Agency, therefore, examined how large an across-the-board 
reduction in the monetized value of all avoided illnesses and 
fatalities would be necessary for the benefits to equal the costs. As 
shown in Table VIII-24, an 87 percent reduction in the monetized value 
of all avoided illnesses and fatalities would be necessary for costs to 
equal benefits, reducing the estimated value to $1.1 million per life 
saved, and an equivalent percentage reduction to about $0.3 million per 
illness prevented.
    In a fourth break-even sensitivity test, OSHA estimated how many 
fewer silica-related fatalities and illnesses would be required for 
benefits to equal costs. Paralleling the previous discussion, 
eliminating either the prevented mortality or morbidity cases alone 
would be insufficient to lower benefits to the break-even point. The 
Agency therefore examined them as a group. As shown in Table VIII-24, a 
reduction of 87 percent, for both simultaneously, is required to reach 
the break-even point--600 fewer mortality cases prevented annually, and 
1,384 fewer morbidity cases prevented annually.
    Taking into account both types of sensitivity analysis the Agency 
performed on its point estimates of the annualized costs and annualized 
benefits of the proposed rule, the results demonstrate that net 
benefits would be positive in all plausible cases tested. In 
particular, this finding would hold even with relatively large 
variations in individual input parameters. Alternately, one would have 
to imagine extremely large changes in costs or benefits for the rule to 
fail to produce net benefits. OSHA concludes that its finding of 
significant net benefits resulting from the proposed rule is a robust 
one.
    OSHA welcomes input from the public regarding all aspects of this 
sensitivity analysis, including any data or information regarding the 
accuracy of the preliminary estimates of compliance costs and benefits 
and how the estimates of costs and benefits may be affected by varying 
assumptions and methodological approaches.

H. Regulatory Alternatives

    This section discusses various regulatory alternatives to the 
proposed OSHA silica standard. OSHA believes that this presentation of 
regulatory alternatives serves two important functions. The first is to 
explore the possibility of less costly ways (than the proposed rule) to 
provide an adequate level of worker protection from exposure to 
respirable crystalline silica. The second is tied to the Agency's 
statutory requirement, which underlies the proposed rule, to reduce 
significant risk to the extent feasible. If, based on evidence 
presented during notice and comment, OSHA is unable to justify its 
preliminary findings of significant risk and feasibility as presented 
in this preamble to the proposed rule, the Agency must then consider 
regulatory alternatives that do satisfy its statutory obligations.
    Each regulatory alternative presented here is described and 
analyzed relative to the proposed rule. Where appropriate, the Agency 
notes whether the regulatory alternative, to be a legitimate candidate 
for OSHA consideration, requires evidence contrary to the Agency's 
findings of significant risk and feasibility. To facilitate comment, 
the regulatory alternatives have been organized into four categories: 
(1) Alternative PELs to the proposed PEL of 50 [mu]g/m\3\; (2) 
regulatory alternatives that affect proposed ancillary provisions; (3) 
a regulatory alternative that would modify the proposed methods of 
compliance; and (4) regulatory alternatives concerning when different 
provisions of the proposed rule would take effect.
Alternative PELs
    OSHA is proposing a new PEL for respirable crystalline silica of 50 
[mu]g/m\3\ for all industry sectors covered by the rule. OSHA's 
proposal is based on the requirements of the Occupational Safety and 
Health Act (OSH Act) and court interpretations of the Act. For health 
standards issued under section 6(b)(5) of the OSH Act, OSHA is required 
to promulgate a standard that reduces significant risk to the extent 
that it is technologically and economically feasible to do so. See 
Section II of this preamble, Pertinent Legal Authority, for a full 
discussion of OSHA legal requirements.
    OSHA has conducted an extensive review of the literature on adverse 
health effects associated with exposure to respirable crystalline 
silica. The Agency has also developed estimates of the risk of silica-
related diseases assuming exposure over a working lifetime at the 
proposed PEL and action level, as well as at OSHA's current PELs. These 
analyses are presented in a background document entitled ``Respirable 
Crystalline Silica--Health Effects Literature Review and Preliminary 
Quantitative Risk Assessment'' and are summarized in this preamble in 
Section V, Health Effects Summary, and Section VI, Summary of OSHA's 
Preliminary Quantitative Risk Assessment, respectively. The available 
evidence indicates that employees exposed to respirable crystalline 
silica well below the current PELs are at increased risk of lung cancer 
mortality and silicosis mortality and morbidity. Occupational exposures 
to respirable crystalline silica also may result in the development of 
kidney and autoimmune diseases and in death from other nonmalignant 
respiratory diseases. As discussed in Section VII, Significance of 
Risk, in this preamble, OSHA preliminarily finds that worker exposure 
to respirable crystalline silica constitutes a significant risk and 
that the proposed standard will substantially reduce this risk.
    Section 6(b) of the OSH Act (29 U.S.C. 655(b)) requires OSHA to 
determine that its standards are technologically and economically 
feasible. OSHA's examination of the technological and economic 
feasibility of the proposed rule is presented in the Preliminary 
Economic Analysis and Initial Regulatory Flexibility Analysis (PEA), 
and is summarized in this section (Section VIII) of this preamble. For 
general industry and maritime, OSHA has preliminarily concluded that 
the proposed PEL of 50 [mu]g/m\3\ is technologically feasible for all 
affected industries. For construction, OSHA has preliminarily 
determined that the proposed PEL of 50 [mu]g/m\3\ is feasible in 10 out 
of 12 of the affected activities. Thus, OSHA preliminarily concludes 
that engineering and work practices will be sufficient to reduce and 
maintain silica exposures to the proposed PEL of 50 [mu]g/m\3\ or below 
in most operations most of the time in the affected industries. For 
those few operations within an industry or activity where the proposed 
PEL is not technologically feasible even when workers use recommended 
engineering and work practice controls, employers can supplement 
controls with respirators to achieve exposure levels at or below the 
proposed PEL.
    OSHA developed quantitative estimates of the compliance costs of 
the proposed rule for each of the affected industry sectors. The 
estimated compliance costs were compared with industry revenues and 
profits to provide a screening analysis of the economic feasibility of 
complying with the revised standard and an evaluation of the potential 
economic impacts. Industries with unusually high costs as a percentage 
of revenues or profits were further analyzed for possible economic 
feasibility issues. After performing these analyses, OSHA has 
preliminarily concluded that compliance with the

[[Page 56403]]

requirements of the proposed rule would be economically feasible in 
every affected industry sector.
    OSHA has examined two regulatory alternatives (named Regulatory 
Alternatives 1 and 2) that would modify the PEL for 
the proposed rule. Under Regulatory Alternative 1, the 
proposed PEL would be changed from 50 [mu]g/m\3\ to 100 [mu]g/m\3\ for 
all industry sectors covered by the rule, and the action level would be 
changed from 25 [mu]g/m\3\ to 50 [mu]g/m\3\ (thereby keeping the action 
level at one-half of the PEL). Under Regulatory Alternative 2, 
the proposed PEL would be lowered from 50 [mu]g/m\3\ to 25 [mu]g/m\3\ 
for all industry sectors covered by the rule, while the action level 
would remain at 25 [mu]g/m\3\ (because of difficulties in accurately 
measuring exposure levels below 25 [mu]g/m\3\).
    Tables VIII-25 and VIII-26 present, for informational purposes, the 
estimated costs, benefits, and net benefits of the proposed rule under 
the proposed PEL of 50 [mu]g/m\3\ and for the regulatory alternatives 
of a PEL of 100 [mu]g/m\3\ and a PEL of 25 [mu]g/m\3\ (Regulatory 
Alternatives  1 and 2), using alternative discount 
rates of 3 and 7 percent. These two tables also present the incremental 
costs, the incremental benefits, and the incremental net benefits of 
going from a PEL of 100 [mu]g/m\3\ to the proposed PEL of 50 [mu]g/m\3\ 
and then of going from the proposed PEL of 50 [mu]g/m\3\ to a PEL of 25 
[mu]g/m\3\. Table VIII-25 breaks out costs by provision and benefits by 
type of disease and by morbidity/mortality, while Table VIII-26 breaks 
out costs and benefits by major industry sector.

[[Page 56404]]

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[[Page 56405]]


[GRAPHIC] [TIFF OMITTED] TP12SE13.016

    As Tables VIII-25 and VIII-26 show, going from a PEL of 100 [mu]g/
m\3\ to a PEL of 50 [mu]g/m\3\ would prevent, annually, an additional 
357 silica-related fatalities and an additional 632 cases of silicosis. 
Based on its preliminary findings that

[[Page 56406]]

the proposed PEL of 50 [mu]g/m\3\ significantly reduces worker risk 
from silica exposure (as demonstrated by the number of silica-related 
fatalities and silicosis cases avoided) and is both technologically and 
economically feasible, OSHA cannot propose a PEL of 100 [mu]g/m\3\ 
(Regulatory Alternative 1) without violating its statutory 
obligations under the OSH Act. However, the Agency will consider 
evidence that challenges its preliminary findings.
    As previously noted, Tables VIII-25 and VIII-26 also show the costs 
and benefits of a PEL of 25 [mu]g/m\3\ (Regulatory Alternative 
2), as well as the incremental costs and benefits of going 
from the proposed PEL of 50 [mu]g/m\3\ to a PEL of 25 [mu]g/m\3\. 
Because OSHA determined that a PEL of 25 [mu]g/m\3\ would not be 
feasible (that is, engineering and work practices would not be 
sufficient to reduce and maintain silica exposures to a PEL of 25 
[mu]g/m\3\ or below in most operations most of the time in the affected 
industries), the Agency did not attempt to identify engineering 
controls or their costs for affected industries to meet this PEL. 
Instead, for purposes of estimating the costs of going from a PEL of 50 
[mu]g/m\3\ to a PEL of 25 [mu]g/m\3\, OSHA assumed that all workers 
exposed between 50 [mu]g/m\3\ and 25 [mu]g/m\3\ would have to wear 
respirators to achieve compliance with the 25 [mu]g/m\3\ PEL. OSHA then 
estimated the associated additional costs for respirators, exposure 
assessments, medical surveillance, and regulated areas (the latter 
three for ancillary requirements specified in the proposed rule).
    As shown in Tables VIII-25 and VIII-26, going from a PEL of 50 
[mu]g/m\3\ to a PEL of 25 [mu]g/m\3\ would prevent, annually, an 
additional 335 silica-related fatalities and an additional 186 cases of 
silicosis. These estimates support OSHA's preliminarily finding that 
there is significant risk remaining at the proposed PEL of 50 [mu]g/
m\3\. However, the Agency has preliminarily determined that a PEL of 25 
[mu]g/m\3\ (Regulatory Alternative 2) is not technologically 
feasible, and for that reason, cannot propose it without violating its 
statutory obligations under the OSH Act.
Regulatory Alternatives That Affect Ancillary Provisions
    The proposed rule contains several ancillary provisions (provisions 
other the PEL), including requirements for exposure assessment, medical 
surveillance, silica training, and regulated areas or access control. 
As shown in Table VIII-25, these ancillary provisions represent 
approximately $223 million (or about 34 percent) of the total 
annualized costs of the rule of $658 million (using a 7 percent 
discount rate). The two most expensive of the ancillary provisions are 
the requirements for medical surveillance, with annualized costs of $79 
million, and the requirements for exposure monitoring, with annualized 
costs of $74 million.
    As proposed, the requirements for exposure assessment are triggered 
by the action level. As described in this preamble, OSHA has defined 
the action level for the proposed standard as an airborne concentration 
of respirable crystalline silica of 25 [mu]g/m\3\ calculated as an 
eight-hour time-weighted average. In this proposal, as in other 
standards, the action level has been set at one-half of the PEL.
    Because of the variable nature of employee exposures to airborne 
concentrations of respirable crystalline silica, maintaining exposures 
below the action level provides reasonable assurance that employees 
will not be exposed to respirable crystalline silica at levels above 
the PEL on days when no exposure measurements are made. Even when all 
measurements on a given day may fall below the PEL (but are above the 
action level), there is some chance that on another day, when exposures 
are not measured, the employee's actual exposure may exceed the PEL. 
When exposure measurements are above the action level, the employer 
cannot be reasonably confident that employees have not been exposed to 
respirable crystalline silica concentrations in excess of the PEL 
during at least some part of the work week. Therefore, requiring 
periodic exposure measurements when the action level is exceeded 
provides the employer with a reasonable degree of confidence in the 
results of the exposure monitoring.
    The action level is also intended to encourage employers to lower 
exposure levels in order to avoid the costs associated with the 
exposure assessment provisions. Some employers would be able to reduce 
exposures below the action level in all work areas, and other employers 
in some work areas. As exposures are lowered, the risk of adverse 
health effects among workers decreases.
    OSHA's preliminary risk assessment indicates that significant risk 
remains at the proposed PEL of 50 [mu]g/m\3\. Where there is continuing 
significant risk, the decision in the Asbestos case (Bldg. and 
Constr.Trades Dep't, AFL-CIO v. Brock, 838 F.2d 1258, 1274 (DC Cir. 
1988)) indicated that OSHA should use its legal authority to impose 
additional requirements on employers to further reduce risk when those 
requirements will result in a greater than de minimis incremental 
benefit to workers' health. OSHA's preliminary conclusion is that the 
requirements triggered by the action level will result in a very real 
and necessary, but non-quantifiable, further reduction in risk beyond 
that provided by the PEL alone. OSHA's choice of proposing an action 
level for exposure monitoring of one-half of the PEL is based on the 
Agency's successful experience with other standards, including those 
for inorganic arsenic (29 CFR 1910.1018), ethylene oxide (29 CFR 
1910.1047), benzene (29 CFR 1910.1028), and methylene chloride (29 CFR 
1910.1052).
    As specified in the proposed rule, all workers exposed to 
respirable crystalline silica above the PEL of 50 [mu]g/m\3\ are 
subject to the medical surveillance requirements. This means that the 
medical surveillance requirements would apply to 15,172 workers in 
general industry and 336,244 workers in construction. OSHA estimates 
that 457 possible silicosis cases will be referred to pulmonary 
specialists annually as a result of this medical surveillance.
    OSHA has preliminarily determined that these ancillary provisions 
will: (1) help to ensure the PEL is not exceeded, and (2) minimize risk 
to workers given the very high level of risk remaining at the PEL. OSHA 
did not estimate, and the benefits analysis does not include, monetary 
benefits resulting from early discovery of illness.
    Because medical surveillance and exposure assessment are the two 
most costly ancillary provisions in the proposed rule, the Agency has 
examined four regulatory alternatives (named Regulatory Alternatives 
3, 4, 5, and 6) involving changes 
to one or the other of these ancillary provisions. These four 
regulatory alternatives are defined below and the incremental cost 
impact of each is summarized in Table VIII-27. In addition, OSHA is 
including a regulatory alternative (named Regulatory Alternative 
7) that would remove all ancillary provisions.

[[Page 56407]]

[GRAPHIC] [TIFF OMITTED] TP12SE13.017

    Under Regulatory Alternative 3, the action level would be 
raised from 25 [micro]g/m\3\ to 50 [micro]g/m\3\ while keeping the PEL 
at 50 [micro]g/m\3\. As a result, exposure monitoring requirements 
would be triggered only if workers were exposed

[[Page 56408]]

above the proposed PEL of 50 [micro]g/m\3\. As shown in Table VIII-27, 
Regulatory Option 3 would reduce the annualized cost of the 
proposed rule by about $62 million, using a discount rate of either 3 
percent or 7 percent.
    Under Regulatory Alternative 4, the action level would 
remain at 25 [micro]g/m\3\ but medical surveillance would now be 
triggered by the action level, not the PEL. As a result, medical 
surveillance requirements would be triggered only if workers were 
exposed at or above the proposed action level of 25 [micro]g/m\3\. As 
shown in Table VIII-27, Regulatory Option 4 would increase the 
annualized cost of the proposed rule by about $143 million, using a 
discount rate of 3 percent (and by about $169 million, using a discount 
rate of 7 percent).
    Under Regulatory Alternative 5, the only change to the 
proposed rule would be to the medical surveillance requirements. 
Instead of requiring workers exposed above the PEL to have a medical 
check-up every three years, those workers would be required to have a 
medical check-up annually. As shown in Table VIII-27, Regulatory Option 
5 would increase the annualized cost of the proposed rule by 
about $69 million, using a discount rate of 3 percent (and by about $66 
million, using a discount rate of 7 percent).
    Regulatory Alternative 6 would essentially combine the 
modified requirements in Regulatory Alternatives 4 and 
5. Under Regulatory Alternative 6, medical 
surveillance would be triggered by the action level, not the PEL, and 
workers exposed at or above the action level would be required to have 
a medical check-up annually rather than triennially. The exposure 
monitoring requirements in the proposed rule would not be affected. As 
shown in Table VIII-27, Regulatory Option 6 would increase the 
annualized cost of the proposed rule by about $342 million, using a 
discount rate of either 3 percent or 7 percent.
    OSHA is not able to quantify the effects of these preceding four 
regulatory alternatives on protecting workers exposed to respirable 
crystalline silica at levels at or below the proposed PEL of 50 
[micro]g/m\3\--where significant risk remains. The Agency solicits 
comment on the extent to which these regulatory options may improve or 
reduce the effectiveness of the proposed rule.
    The final regulatory alternative affecting ancillary provisions, 
Regulatory Alternative 7, would eliminate all of the ancillary 
provisions of the proposed rule, including exposure assessment, medical 
surveillance, training, and regulated areas or access control. However, 
it should be carefully noted that elimination of the ancillary 
provisions does not mean that all costs for ancillary provisions would 
disappear. In order to meet the PEL, employers would still commonly 
need to do monitoring, train workers on the use of controls, and set up 
some kind of regulated areas to indicate where respirator use would be 
required. It is also likely that employers would increasingly follow 
the many recommendations to provide medical surveillance for employees. 
OSHA has not attempted to estimate the extent to which the costs of 
these activities would be reduced if they were not formally required, 
but OSHA welcomes comment on the issue.
    As indicated previously, OSHA preliminarily finds that there is 
significant risk remaining at the proposed PEL of 50 [mu]g/m\3\. 
However, the Agency has also preliminarily determined that 50 [mu]g/
m\3\ is the lowest feasible PEL. Therefore, the Agency believes that it 
is necessary to include ancillary provisions in the proposed rule to 
further reduce the remaining risk. OSHA anticipates that these 
ancillary provisions will reduce the risk beyond the reduction that 
will be achieved by a new PEL alone.
    OSHA's reasons for including each of the proposed ancillary 
provisions are detailed in Section XVI of this preamble, Summary and 
Explanation of the Standards. In particular, OSHA believes that 
requirements for exposure assessment (or alternately, using specified 
exposure control methods for selected construction operations) would 
provide a basis for ensuring that appropriate measures are in place to 
limit worker exposures. Medical surveillance is particularly important 
because individuals exposed above the PEL (which triggers medical 
surveillance in the proposed rule) are at significant risk of death and 
illness. Medical surveillance would allow for identification of 
respirable crystalline silica-related adverse health effects at an 
early stage so that appropriate intervention measures can be taken. 
OSHA believes that regulated areas and access control are important 
because they serve to limit exposure to respirable crystalline silica 
to as few employees as possible. Finally, OSHA believes that worker 
training is necessary to inform employees of the hazards to which they 
are exposed, along with associated protective measures, so that 
employees understand how they can minimize potential health hazards. 
Worker training on silica-related work practices is particularly 
important in controlling silica exposures because engineering controls 
frequently require action on the part of workers to function 
effectively.
    OSHA expects that the benefits estimated under the proposed rule 
will not be fully achieved if employers do not implement the ancillary 
provisions of the proposed rule. For example, OSHA believes that the 
effectiveness of the proposed rule depends on regulated areas or access 
control to further limit exposures and on medical surveillance to 
identify disease cases when they do occur.
    Both industry and worker groups have recognized that a 
comprehensive standard is needed to protect workers exposed to 
respirable crystalline silica. For example, the industry consensus 
standards for crystalline silica, ASTM E 1132-06, Standard Practice for 
Health Requirements Relating to Occupational Exposure to Respirable 
Crystalline Silica, and ASTM E 2626-09, Standard Practice for 
Controlling Occupational Exposure to Respirable Crystalline Silica for 
Construction and Demolition Activities, as well as the draft proposed 
silica standard for construction developed by the Building and 
Construction Trades Department, AFL-CIO, have each included 
comprehensive programs. These recommended standards include provisions 
for methods of compliance, exposure monitoring, training, and medical 
surveillance (ASTM, 2006; 2009; BCTD 2001). Moreover, as mentioned 
previously, where there is continuing significant risk, the decision in 
the Asbestos case (Bldg. and Constr. Trades Dep't, AFL-CIO v. Brock, 
838 F.2d 1258, 1274 (DC Cir. 1988)) indicated that OSHA should use its 
legal authority to impose additional requirements on employers to 
further reduce risk when those requirements will result in a greater 
than de minimis incremental benefit to workers' health. OSHA 
preliminarily concludes that the additional requirements in the 
ancillary provisions of the proposed standard clearly exceed this 
threshold.
A Regulatory Alternative That Modifies the Methods of Compliance
    The proposed standard in general industry and maritime would 
require employers to implement engineering and work practice controls 
to reduce employees' exposures to or below the PEL. Where engineering 
and/or work practice controls are insufficient, employers would still 
be required to implement them to reduce exposure as much as possible, 
and to supplement them with a respiratory protection program. Under the 
proposed

[[Page 56409]]

construction standard, employers would be given two options for 
compliance. The first option largely follows requirements for the 
general industry and maritime proposed standard, while the second 
option outlines, in Table 1 (Exposure Control Methods for Selected 
Construction Operations) of the proposed rule, specific construction 
exposure control methods. Employers choosing to follow OSHA's proposed 
control methods would be considered to be in compliance with the 
engineering and work practice control requirements of the proposed 
standard, and would not be required to conduct certain exposure 
monitoring activities.
    One regulatory alternative (Regulatory Alternative 8) 
involving methods of compliance would be to eliminate Table 1 as a 
compliance option in the construction sector. Under this regulatory 
alternative, OSHA estimates that there would be no effect on estimated 
benefits but that the annualized costs of complying with the proposed 
rule (without the benefit of the Table 1 option in construction) would 
increase by $175 million, totally in exposure monitoring costs, using a 
3 percent discount rate (and by $178 million using a 7 percent discount 
rate), so that the total annualized compliance costs for all affected 
establishments in construction would increase from $495 to $670 million 
using a 3 percent discount rate (and from $511 to $689 million using a 
7 percent discount rate).
Regulatory Alternatives That Affect the Timing of the Standard
    The proposed rule would become effective 60 days following 
publication of the final rule in the Federal Register. Provisions 
outlined in the proposed standard would become enforceable 180 days 
following the effective date, with the exceptions of engineering 
controls and laboratory requirements. The proposed rule would require 
engineering controls to be implemented no later than one year after the 
effective date, and laboratory requirements would be required to begin 
two years after the effective date.
    One regulatory alternative (Regulatory Alternative 9) 
involving the timing of the standard would arise if, contrary to OSHA's 
preliminary findings, a PEL of 50 [micro]g/m\3\ with an action level of 
25 [micro]g/m\3\ were found to be technologically and economically 
feasible some time in the future (say, in five years), but not feasible 
immediately. In that case, OSHA might issue a final rule with a PEL of 
50 [micro]g/m\3\ and an action level of 25 [micro]g/m\3\ to take effect 
in five years, but at the same time issue an interim PEL of 100 
[micro]g/m\3\ and an action level of 50 [micro]g/m\3\ to be in effect 
until the final rule becomes feasible. Under this regulatory 
alternative, and consistent with the public participation and ``look 
back'' provisions of Executive Order 13563, the Agency could monitor 
compliance with the interim standard, review progress toward meeting 
the feasibility requirements of the final rule, and evaluate whether 
any adjustments to the timing of the final rule would be needed. Under 
Regulatory Alternative 9, the estimated costs and benefits 
would be somewhere between those estimated for a PEL of 100 [micro]g/
m\3\ with an action level of 50 [micro]g/m\3\ and those estimated for a 
PEL of 50 [micro]g/m\3\ with an action level of 25 [micro]g/m\3\, the 
exact estimates depending on the length of time until the final rule is 
phased in. OSHA emphasizes that this regulatory alternative is contrary 
to the Agency's preliminary findings of economic feasibility and, for 
the Agency to consider it, would require specific evidence introduced 
on the record to show that the proposed rule is not now feasible but 
would be feasible in the future.
    Although OSHA did not explicitly develop or quantitatively analyze 
any other regulatory alternatives involving longer-term or more complex 
phase-ins of the standard (possibly involving more delayed 
implementation dates for small businesses), OSHA is soliciting comments 
on this issue. Such a particularized, multi-year phase-in would have 
several advantages, especially from the viewpoint of impacts on small 
businesses. First, it would reduce the one-time initial costs of the 
standard by spreading them out over time, a particularly useful 
mechanism for small businesses that have trouble borrowing large 
amounts of capital in a single year. A differential phase-in for 
smaller firms would also aid very small firms by allowing them to gain 
from the control experience of larger firms. A phase-in would also be 
useful in certain industries--such as foundries, for example--by 
allowing employers to coordinate their environmental and occupational 
safety and health control strategies to minimize potential costs. 
However a phase-in would also postpone the benefits of the standard, 
recognizing, as described in Chapter VII of the PEA, that the full 
benefits of the proposal would take a number of years to fully 
materialize even in the absence of a phase-in.
    As previously discussed in the Introduction to this preamble, OSHA 
requests comments on these regulatory alternatives, including the 
Agency's choice of regulatory alternatives (and whether there are other 
regulatory alternatives the Agency should consider) and the Agency's 
analysis of them.

I. Initial Regulatory Flexibility Analysis

    The Regulatory Flexibility Act, as amended in 1996, requires the 
preparation of an Initial Regulatory Flexibility Analysis (IRFA) for 
proposed rules where there would be a significant economic impact on a 
substantial number of small entities. (5 U.S.C. 601-612). Under the 
provisions of the law, each such analysis shall contain:
    1. A description of the impact of the proposed rule on small 
entities;
    2. A description of the reasons why action by the agency is being 
considered;
    3. A succinct statement of the objectives of, and legal basis for, 
the proposed rule;
    4. A description of and, where feasible, an estimate of the number 
of small entities to which the proposed rule will apply;
    5. A description of the projected reporting, recordkeeping, and 
other compliance requirements of the proposed rule, including an 
estimate of the classes of small entities which will be subject to the 
requirements and the type of professional skills necessary for 
preparation of the report or record;
    6. An identification, to the extent practicable, of all relevant 
Federal rules which may duplicate, overlap, or conflict with the 
proposed rule; and
    7. A description and discussion of any significant alternatives to 
the proposed rule which accomplish the stated objectives of applicable 
statutes and which minimize any significant economic impact of the 
proposed rule on small entities, such as
    (a) The establishment of differing compliance or reporting 
requirements or timetables that take into account the resources 
available to small entities;
    (b) The clarification, consolidation, or simplification of 
compliance and reporting requirements under the rule for such small 
entities;
    (c) The use of performance rather than design standards; and
    (d) An exemption from coverage of the rule, or any part thereof, 
for such small entities.

5 U.S.C. 603, 607.

    The Regulatory Flexibility Act further states that the required 
elements of the IRFA may be performed in conjunction with or as part of 
any other agenda or analysis required by any other law if such other 
analysis satisfies the provisions of the IRFA. 5 U.S.C. 605.
    While a full understanding of OSHA's analysis and conclusions with 
respect to

[[Page 56410]]

costs and economic impacts on small entities requires a reading of the 
complete PEA and its supporting materials, this IRFA will summarize the 
key aspects of OSHA's analysis as they affect small entities.
A Description of the Impact of the Proposed Rule on Small Entities
    Section VIII.F of this preamble summarized the impacts of the 
proposed rule on small entities. Tables VIII-12 and VIII-15 showed 
costs as a percentage of profits and revenues for small entities in 
general industry and maritime and in construction, respectively, 
classified as small by the Small Business Administration, and Tables 
VIII-13 and VIII-16 showed costs as a percentage of revenues and 
profits for business entities with fewer than 20 employees in general 
industry and maritime and in construction, respectively. (The costs in 
these tables were annualized using a discount rate of 7 percent.)
A Description of the Reasons Why Action by the Agency Is Being 
Considered
    Exposure to crystalline silica has been shown to increase the risk 
of several serious diseases. Crystalline silica is the only known cause 
of silicosis, which is a progressive respiratory disease in which 
respirable crystalline silica particles cause an inflammatory reaction 
in the lung, leading to lung damage and scarring, and, in some cases, 
to complications resulting in disability and death. In addition, many 
well-conducted investigations of exposed workers have shown that 
exposure increases the risk of mortality from lung cancer, chronic 
obstructive pulmonary disease (COPD), and renal disease. OSHA's 
detailed analysis of the scientific literature and silica-related 
health risks are presented in the background document entitled 
``Respirable Crystalline Silica--Health Effects Literature Review and 
Preliminary Quantitative Risk Assessment'' (placed in Docket OSHA-2010-
0034).
    Based on a review of over 60 epidemiological studies covering more 
than 30 occupational groups, OSHA preliminarily concludes that 
crystalline silica is a human carcinogen. Most of these studies 
documented that exposed workers experience higher lung cancer mortality 
rates than do unexposed workers or the general population, and that the 
increase in lung cancer mortality is related to cumulative exposure to 
crystalline silica. These exposure-related trends strongly implicate 
crystalline silica as a likely causative agent. This is consistent with 
the conclusions of other government and public health organizations, 
including the International Agency for Research on Cancer (IARC), the 
Agency for Toxic Substance and Disease Registry (ATSDR), the World 
Health Organization (WHO), the U.S. Environmental Protection Agency 
(EPA), the National Toxicology Program (NTP), the National Academies of 
Science (NAS), the National Institute for Occupational Safety and 
Health (NIOSH), and the American Conference of Governmental Industrial 
Hygienists (ACGIH).
    OSHA believes that the strongest evidence for carcinogenicity comes 
from studies in five industry sectors (diatomaceous earth, pottery, 
granite, industrial sand, and coal mining) as well as a study by 
Steenland et al. (2001) that analyzed pooled data from 10 occupational 
cohort studies; each of these studies found a positive relationship 
between exposure to crystalline silica and lung cancer mortality. Based 
on a variety of relative risk models fit to these data sets, OSHA 
estimates that the excess lifetime risk to workers exposed over a 
working life of 45 years at the current general industry permissible 
exposure limit (PEL) (approximately 100 [mu]g/m\3\ respirable 
crystalline silica) is between 13 and 60 deaths per 1,000 workers. For 
exposure over a working life at the current construction and shipyard 
employment PELs (estimated to range between 250 and 500 [mu]g/m\3\), 
the estimated risk lies between 37 and 653 deaths per 1,000. Reducing 
these PELs to the proposed PEL of 50 [mu]g/m\3\ respirable crystalline 
silica results in a substantial reduction of these risks, to a range 
estimated to be between 6 and 26 deaths per 1,000 workers.
    OSHA has also quantitatively evaluated the mortality risk from non-
malignant respiratory disease, including silicosis and COPD. Risk 
estimates for silicosis mortality are based on a study by Mannetje et 
al. (2002), which pooled data from six worker cohort studies to derive 
a quantitative relationship between exposure and death rate for 
silicosis. For non-malignant respiratory disease, risk estimates are 
based on an epidemiologic study of diatomaceous earth workers, which 
included a quantitative exposure-response analysis (Park et al., 2002). 
For 45 years of exposure to the current general industry PEL, OSHA's 
estimates of excess lifetime risk are 11 deaths per 1,000 workers for 
the pooled analysis and 83 deaths per 1,000 workers based on Park et 
al.'s (2002) estimates. At the proposed PEL, estimates of silicosis and 
non-malignant respiratory disease mortality are 7 and 43 deaths per 
1,000, respectively. As noted by Park et al. (2002), it is likely that 
silicosis as a cause of death is often misclassified as emphysema or 
chronic bronchitis; thus, Mannetje et al.'s selection of deaths may 
tend to underestimate the true risk of silicosis mortality, while Park 
et al.'s (2002) analysis would more fairly capture the total 
respiratory mortality risk from all non-malignant causes, including 
silicosis and COPD.
    OSHA also identified seven studies that quantitatively described 
relationships between exposure to respirable crystalline silica and 
silicosis morbidity, as diagnosed from chest radiography (i.e., chest 
x-rays or computerized tomography). Estimates of silicosis morbidity 
derived from these cohort studies range from 60 to 773 cases per 1,000 
workers for a 45-year exposure to the current general industry PEL, and 
approach unity for a 45-year exposure to the current construction/
shipyard PEL. Estimated risks of silicosis morbidity range from 20 to 
170 cases per 1,000 workers for a 45-year exposure to the proposed PEL, 
reflecting a substantial reduction in the risk associated with exposure 
to the current PELs.
    OSHA's estimates of crystalline silica-related renal disease 
mortality risk are derived from an analysis by Steenland et al. (2002), 
in which data from three cohort studies were pooled to derive a 
quantitative relationship between exposure to silica and the relative 
risk of end-stage renal disease mortality. The cohorts included workers 
in the U.S. gold mining, industrial sand, and granite industries. From 
this study, OSHA estimates that exposure to the current general 
industry and proposed PELs over a working life would result in a 
lifetime excess renal disease risk of 39 and 32 deaths per 1,000 
workers, respectively. For exposure to the current construction/
shipyard PEL, OSHA estimates the excess lifetime risk to range from 52 
to 63 deaths per 1,000 workers.
A Statement of the Objectives of, and Legal Basis for, the Proposed 
Rule
    The objective of the proposed rule is to reduce the numbers of 
fatalities and illnesses occurring among employees exposed to 
respirable crystalline silica in general industry, maritime, and 
construction sectors. This objective will be achieved by requiring 
employers to install engineering controls where appropriate and to 
provide employees with the equipment, respirators, training, exposure 
monitoring, medical surveillance, and other protective

[[Page 56411]]

measures to perform their jobs safely. The legal basis for the rule is 
the responsibility given the U.S. Department of Labor through the 
Occupational Safety and Health Act of 1970 (OSH Act). The OSH Act 
provides that, in promulgating health standards dealing with toxic 
materials or harmful physical agents, the Secretary ``shall set the 
standard which most adequately assures, to the extent feasible, on the 
basis of the best available evidence that no employee will suffer 
material impairment of health or functional capacity even if such 
employee has regular exposure to the hazard dealt with by such standard 
for the period of his working life.'' 29 U.S.C. Sec. 655(b)(5). See 
Section II of this preamble for a more detailed discussion of the 
Secretary's legal authority to promulgate standards.
A Description of and Estimate of the Number of Small Entities To Which 
the Proposed Rule Will Apply
    OSHA has completed a preliminary analysis of the impacts associated 
with this proposal, including an analysis of the type and number of 
small entities to which the proposed rule would apply, as described 
above. In order to determine the number of small entities potentially 
affected by this rulemaking, OSHA used the definitions of small 
entities developed by the Small Business Administration (SBA) for each 
industry.
    OSHA estimates that approximately 470,000 small business or 
government entities would be affected by the proposed standard. Within 
these small entities, roughly 1.3 million workers are exposed to 
crystalline silica and would be protected by the proposed standard. A 
breakdown, by industry, of the number of affected small entities is 
provided in Table III-3 in Chapter III of the PEA.
    OSHA estimates that approximately 356,000 very small entities would 
be affected by the proposed standard. Within these very small entities, 
roughly 580,000 workers are exposed to crystalline silica and would be 
protected by the proposed standard. A breakdown, by industry, of the 
number of affected very small entities is provided in Table III-4 in 
Chapter III of the PEA.
A Description of the Projected Reporting, Recordkeeping, and Other 
Compliance Requirements of the Proposed Rule
    Tables VIII-28 and VIII-29 show the average costs of the proposed 
standard by NAICS code and by compliance requirement for, respectively, 
small entities (classified as small by SBA) and very small entities 
(fewer than 20 employees). For the average small entity in general 
industry and maritime, the estimated cost of the proposed rule would be 
about $2,103 annually, with engineering controls accounting for 67 
percent of the costs and exposure monitoring accounting for 23 percent 
of the costs. For the average small entity in construction, the 
estimate cost of the proposed rule would be about $798 annually, with 
engineering controls accounting for 47 percent of the costs, exposure 
monitoring accounting for 17 percent of the costs, and medical 
surveillance accounting for 15 percent of the costs.
    For the average very small entity in general industry and maritime, 
the estimate cost of the proposed rule would be about $616 annually, 
with engineering controls accounting for 55 percent of the costs and 
exposure monitoring accounting for 33 percent of the costs. For the 
average very small entity in construction, the estimate cost of the 
proposed rule would be about $533 annually, with engineering controls 
accounting for 45 percent of the costs, exposure monitoring accounting 
for 16 percent of the costs, and medical surveillance accounting for 16 
percent of the costs.
    Table VIII-30 shows the unit costs which form the basis for these 
cost estimates for the average small entity and very small entity.

        Table VIII-28--Average Costs for Small Entities Affected by the Proposed Silica Standard for General Industry, Maritime, and Construction
                                                                     [2009 dollars]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Engineering
                                                          controls                                                              Regulated
          NAICS                      Industry             (includes    Respirators    Exposure       Medical      Training      areas or        Total
                                                          abrasive                   monitoring   surveillance                   access
                                                          blasting)                                                              control
--------------------------------------------------------------------------------------------------------------------------------------------------------
324121...................  Asphalt paving mixture and           $232            $4           $13            $1           $74            $1          $326
                            block manufacturing.
324122...................  Asphalt shingle and roofing         5,721           297         1,887           103           114           111         8,232
                            materials.
325510...................  Paint and coating                       0            10            36             3            15             4            69
                            manufacturing.
327111...................  Vitreous china plumbing             6,310           428         2,065           150           162           160         9,274
                            fixtures & bathroom
                            accessories manufacturing.
327112...................  Vitreous china, fine                1,679           114           663            41            47            42         2,586
                            earthenware, & other
                            pottery product
                            manufacturing.
327113...................  Porcelain electrical supply         6,722           458         2,656           162           188           170        10,355
                            mfg.
327121...................  Brick and structural clay          28,574           636         3,018           226           237           236        32,928
                            mfg.
327122...................  Ceramic wall and floor tile        10,982           245         1,160            87            91            91        12,655
                            mfg.
327123...................  Other structural clay              10,554           235         1,115            83            87            87        12,162
                            product mfg.
327124...................  Clay refractory                     1,325            92           653            33            81            34         2,218
                            manufacturing.
327125...................  Nonclay refractory                  1,964           136           802            48           110            51         3,110
                            manufacturing.
327211...................  Flat glass manufacturing...         4,068           160           520            56            50            60         4,913
327212...................  Other pressed and blown               889            34           110            12            11            13         1,068
                            glass and glassware
                            manufacturing.
327213...................  Glass container                     2,004            76           248            27            24            29         2,408
                            manufacturing.
327320...................  Ready-mixed concrete                1,728           460         1,726           163           121           171         4,369
                            manufacturing.
327331...................  Concrete block and brick            3,236           245         1,257            87           134            91         5,049
                            mfg.
327332...................  Concrete pipe mfg..........         5,105           386         1,983           137           211           143         7,966
327390...................  Other concrete product mfg.         3,016           228         1,171            81           125            85         4,705
327991...................  Cut stone and stone product         2,821           207         1,040            74            65            77         4,284
                            manufacturing.
327992...................  Ground or treated mineral          12,034           174         3,449            62           191            65        15,975
                            and earth manufacturing.
327993...................  Mineral wool manufacturing.         1,365            56           185            20            17            21         1,664
327999...................  All other misc. nonmetallic         2,222           168           863            60            92            62         3,467
                            mineral product mfg.
331111...................  Iron and steel mills.......           604            34           138            12            11            13           812

[[Page 56412]]

 
331112...................  Electrometallurgical                  514            29           118            10            10            11           692
                            ferroalloy product
                            manufacturing.
331210...................  Iron and steel pipe and               664            38           154            13            13            14           896
                            tube manufacturing from
                            purchased steel.
331221...................  Rolled steel shape                    583            33           135            12            11            12           787
                            manufacturing.
331222...................  Steel wire drawing.........           638            36           148            13            12            14           862
331314...................  Secondary smelting and                577            33           133            11            11            12           777
                            alloying of aluminum.
331423...................  Secondary smelting,                   534            30           125            11            10            11           722
                            refining, and alloying of
                            copper.
331492...................  Secondary smelting,                   548            31           128            11            11            12           741
                            refining, and alloying of
                            nonferrous metal (except
                            cu & al).
331511...................  Iron foundries.............         9,143           522         2,777           185           200           194        13,021
331512...................  Steel investment foundries.        11,874           675         3,596           240           249           251        16,885
331513...................  Steel foundries (except             9,223           526         2,802           187           202           196        13,135
                            investment).
331524...................  Aluminum foundries (except          7,367           419         2,231           149           155           156        10,476
                            die-casting).
331525...................  Copper foundries (except            4,563           260         1,382            92            96            96         6,489
                            die-casting).
331528...................  Other nonferrous foundries          3,895           222         1,179            79            82            82         5,539
                            (except die-casting).
332111...................  Iron and steel forging.....           531            30           161            11            12            11           756
332112...................  Nonferrous forging.........           533            30           162            11            12            11           760
332115...................  Crown and closure                     514            29           156            10            11            11           732
                            manufacturing.
332116...................  Metal stamping.............           533            30           162            11            12            11           759
332117...................  Powder metallurgy part                535            31           163            11            12            11           762
                            manufacturing.
332211...................  Cutlery and flatware                  518            30           157            10            11            11           738
                            (except precious)
                            manufacturing.
332212...................  Hand and edge tool                    542            31           165            11            12            12           772
                            manufacturing.
332213...................  Saw blade and handsaw                 528            30           160            11            12            11           752
                            manufacturing.
332214...................  Kitchen utensil, pot, and             560            32           170            11            12            12           798
                            pan manufacturing.
332323...................  Ornamental and                        524            20           102             7            11             8           673
                            architectural metal work.
332439...................  Other metal container                 550            31           167            11            12            12           784
                            manufacturing.
332510...................  Hardware manufacturing.....           531            30           161            11            12            11           756
332611...................  Spring (heavy gauge)                  529            30           161            11            12            11           754
                            manufacturing.
332612...................  Spring (light gauge)                  585            33           178            12            13            12           834
                            manufacturing.
332618...................  Other fabricated wire                 537            31           163            11            12            11           765
                            product manufacturing.
332710...................  Machine shops..............           518            30           157            10            11            11           738
332812...................  Metal coating and allied              843            33           165            12            18            12         1,083
                            services.
332911...................  Industrial valve                      528            30           160            11            12            11           752
                            manufacturing.
332912...................  Fluid power valve and hose            532            30           162            11            12            11           757
                            fitting manufacturing.
332913...................  Plumbing fixture fitting              528            30           160            11            12            11           752
                            and trim manufacturing.
332919...................  Other metal valve and pipe            536            31           163            11            12            11           764
                            fitting manufacturing.
332991...................  Ball and roller bearing               545            31           131            11            11            12           741
                            manufacturing.
332996...................  Fabricated pipe and pipe              529            30           161            11            12            11           754
                            fitting manufacturing.
332997...................  Industrial pattern                    517            29           157            10            11            11           736
                            manufacturing.
332998...................  Enameled iron and metal               484            23            97             8            10             9           630
                            sanitary ware
                            manufacturing.
332999...................  All other miscellaneous               521            30           158            11            11            11           742
                            fabricated metal product
                            manufacturing.
333319...................  Other commercial and                  526            30           160            11            12            11           750
                            service industry machinery
                            manufacturing.
333411...................  Air purification equipment            525            30           160            11            11            11           748
                            manufacturing.
333412...................  Industrial and commercial             555            32           169            11            12            12           791
                            fan and blower
                            manufacturing.
333414...................  Heating equipment (except             520            30           158            11            11            11           741
                            warm air furnaces)
                            manufacturing.
333511...................  Industrial mold                       522            30           159            11            11            11           743
                            manufacturing.
333512...................  Machine tool (metal cutting           524            30           159            11            11            11           746
                            types) manufacturing.
333513...................  Machine tool (metal forming           532            30           162            11            12            11           758
                            types) manufacturing.
333514...................  Special die and tool, die             522            30           158            11            11            11           743
                            set, jig, and fixture
                            manufacturing.
333515...................  Cutting tool and machine              524            30           159            11            11            11           746
                            tool accessory
                            manufacturing.

[[Page 56413]]

 
333516...................  Rolling mill machinery and            522            30           159            11            11            11           744
                            equipment manufacturing.
333518...................  Other metalworking                    537            31           163            11            12            11           765
                            machinery manufacturing.
333612...................  Speed changer, industrial             546            31           166            11            12            12           777
                            high-speed drive, and gear
                            manufacturing.
333613...................  Mechanical power                      529            30           161            11            12            11           754
                            transmission equipment
                            manufacturing.
333911...................  Pump and pumping equipment            535            31           163            11            12            11           762
                            manufacturing.
333912...................  Air and gas compressor                532            30           162            11            12            11           758
                            manufacturing.
333991...................  Power-driven handtool                 514            29           156            10            11            11           732
                            manufacturing.
333992...................  Welding and soldering                 523            30           159            11            11            11           745
                            equipment manufacturing.
333993...................  Packaging machinery                   521            30           158            11            11            11           742
                            manufacturing.
333994...................  Industrial process furnace            531            30           161            11            12            11           757
                            and oven manufacturing.
333995...................  Fluid power cylinder and              531            30           161            11            12            11           756
                            actuator manufacturing.
333996...................  Fluid power pump and motor            542            31           165            11            12            11           772
                            manufacturing.
333997...................  Scale and balance (except             537            31           163            11            12            11           764
                            laboratory) manufacturing.
333999...................  All other miscellaneous               523            30           159            11            11            11           745
                            general purpose machinery
                            manufacturing.
334518...................  Watch, clock, and part                514            29           156            10            11            11           732
                            manufacturing.
335211...................  Electric housewares and               523            20            76             7             9             8           643
                            household fans.
335221...................  Household cooking appliance           529            20            77             7             9             8           649
                            manufacturing.
335222...................  Household refrigerator and          1,452            56           210            19            26            21         1,784
                            home freezer manufacturing.
335224...................  Household laundry equipment         1,461            56           212            19            26            21         1,795
                            manufacturing.
335228...................  Other major household                 523            20           101             7            11             8           671
                            appliance manufacturing.
336111...................  Automobile manufacturing...         1,309            75           297            25            23            28         1,757
336112...................  Light truck and utility             4,789           273         1,085            92            86           102         6,425
                            vehicle manufacturing.
336120...................  Heavy duty truck                    1,211            69           275            23            22            26         1,626
                            manufacturing.
336211...................  Motor vehicle body                    579            33           137            11            11            12           784
                            manufacturing.
336212...................  Truck trailer manufacturing           525            30           160            11            11            11           748
336213...................  Motor home manufacturing...           792            45           181            15            15            17         1,064
336311...................  Carburetor, piston, piston            525            30           160            11            11            11           748
                            ring, and valve
                            manufacturing.
336312...................  Gasoline engine and engine            522            30           120            10            10            11           703
                            parts manufacturing.
336322...................  Other motor vehicle                   524            30           121            10            10            11           706
                            electrical and electronic
                            equipment manufacturing.
336330...................  Motor vehicle steering and            526            30           120            10            10            11           708
                            suspension components
                            (except spring)
                            manufacturing.
336340...................  Motor vehicle brake system            527            30           121            10            10            11           710
                            manufacturing.
336350...................  Motor vehicle transmission            528            30           121            10            10            11           710
                            and power train parts
                            manufacturing.
336370...................  Motor vehicle metal                   556            32           169            11            12            12           792
                            stamping.
336399...................  All other motor vehicle               535            30           123            10            10            11           721
                            parts manufacturing.
336611...................  Ship building and repair...        13,685             0           718           692            47            75        15,217
336612...................  Boat building..............         2,831             0           202           149            11            16         3,209
336992...................  Military armored vehicle,             624            35           149            12            12            13           845
                            tank, and tank component
                            manufacturing.
337215...................  Showcase, partition,                  527            30           160            11            12            11           751
                            shelving, and locker
                            manufacturing.
339114...................  Dental equipment and                  671            39           145            14            11            15           895
                            supplies manufacturing.
339116...................  Dental laboratories........            12             7           130             3            44             3           199
339911...................  Jewelry (except costume)              120            92           475            33            41            34           795
                            manufacturing.
339913...................  Jewelers' materials and               151           115           596            41            51            43           997
                            lapidary work
                            manufacturing.
339914...................  Costume jewelry and novelty            87            44           229            16            19            16           412
                            manufacturing.
339950...................  Sign manufacturing.........           465            20           107             7            11             8           618
423840...................  Industrial supplies,                  313            29           257            10            15            11           636
                            wholesalers.

[[Page 56414]]

 
482110...................  Rail transportation........  ............  ............  ............  ............  ............  ............  ............
621210...................  Dental offices.............             3             2            32             1            11             1            50
                           Total--General Industry and         1,399            93           483            46            46            36         2,103
                            Maritime.
236100...................  Residential Building                  264            43            34            37            27            15           419
                            Construction.
236200...................  Nonresidential Building               234           104            67            89            66            14           575
                            Construction.
237100...................  Utility System Construction           978            89           172            78           185            30         1,531
237200...................  Land Subdivision...........           104             9            25             8            30             3           180
237300...................  Highway, Street, and Bridge           692           109           179            95           227            26         1,329
                            Construction.
237900...................  Other Heavy and Civil                 592            60           134            52           175            18         1,032
                            Engineering Construction.
238100...................  Foundation, Structure, and            401           359           113           307            91            49         1,319
                            Building Exterior
                            Contractors.
238200...................  Building Equipment                    156            18            21            16            27             7           244
                            Contractors.
238300...................  Building Finishing                    289            24            23            50            27             9           421
                            Contractors.
238900...................  Other Specialty Trade                 460            43            65            52            79            30           729
                            Contractors.
999000...................  State and Local Governments           108            16            31            14            43            11           222
                            [c].
                           Total--Construction........           375           132            72           122            71            26           798
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG (2013).


    Table VIII-29--Average Costs for Very Small Entities (<20 Employees) Affected by the Proposed Silica Standard for General Industry, Maritime, and
                                                                      Construction
                                                                     [2009 dollars]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Engineering
                                                          controls                                                              Regulated
          NAICS                      Industry             (includes    Respirators    Exposure       Medical      Training      areas or        Total
                                                          abrasive                   monitoring   surveillance                   access
                                                          blasting)                                                              control
--------------------------------------------------------------------------------------------------------------------------------------------------------
324121...................  Asphalt paving mixture and            $74            $1            $5            $0           $26            $0          $107
                            block manufacturing.
324122...................  Asphalt shingle and roofing           914            48           476            17            23            18         1,496
                            materials.
325510...................  Paint and coating                       0             7            33             3            13             3            58
                            manufacturing.
327111...................  Vitreous china plumbing               851            58           422            21            26            22         1,400
                            fixtures & bathroom
                            accessories manufacturing.
327112...................  Vitreous china, fine                  705            48           349            17            22            18         1,160
                            earthenware, & other
                            pottery product
                            manufacturing.
327113...................  Porcelain electrical supply           851            58           422            21            26            22         1,400
                            mfg.
327121...................  Brick and structural clay           2,096            47           277            17            19            17         2,474
                            mfg.
327122...................  Ceramic wall and floor tile         2,385            53           316            19            22            20         2,815
                            mfg.
327123...................  Other structural clay               2,277            51           301            18            21            19         2,687
                            product mfg.
327124...................  Clay refractory                       301            21           186             8            20             8           543
                            manufacturing.
327125...................  Nonclay refractory                    471            33           291            12            32            12           852
                            manufacturing.
327211...................  Flat glass manufacturing...           842            34           163            12            12            12         1,075
327212...................  Other pressed and blown               873            34           164            12            12            12         1,107
                            glass and glassware
                            manufacturing.
327213...................  Glass container                       873            34           164            12            12            12         1,107
                            manufacturing.
327320...................  Ready-mixed concrete                  475           127           595            46            37            47         1,328
                            manufacturing.
327331...................  Concrete block and brick              966            74           470            27            44            27         1,608
                            mfg.
327332...................  Concrete pipe mfg..........         1,046            80           509            29            48            29         1,741
327390...................  Other concrete product mfg.           854            65           416            23            39            24         1,422
327991...................  Cut stone and stone product         1,158            86           535            31            30            32         1,872
                            manufacturing.
327992...................  Ground or treated mineral           3,564            52         1,280            19            63            19         4,997
                            and earth manufacturing.
327993...................  Mineral wool manufacturing.           823            34           166            12            12            13         1,061
327999...................  All other misc. nonmetallic           797            61           388            22            37            22         1,327
                            mineral product mfg.
331111...................  Iron and steel mills.......           517            30           197            11            13            11           777
331112...................  Electrometallurgical                    0             0             0             0             0             0             0
                            ferroalloy product
                            manufacturing.
331210...................  Iron and steel pipe and               514            30           196            11            12            11           774
                            tube manufacturing from
                            purchased steel.
331221...................  Rolled steel shape                    514            30           196            11            12            11           774
                            manufacturing.
331222...................  Steel wire drawing.........           514            30           196            11            12            11           774
331314...................  Secondary smelting and                514            30           196            11            12            11           774
                            alloying of aluminum.
331423...................  Secondary smelting,                     0             0             0             0             0             0             0
                            refining, and alloying of
                            copper.
331492...................  Secondary smelting,                   514            30           196            11            12            11           774
                            refining, and alloying of
                            nonferrous metal (except
                            cu & al).
331511...................  Iron foundries.............         1,093            63           416            23            26            23         1,644
331512...................  Steel investment foundries.         1,181            68           448            24            28            25         1,774
331513...................  Steel foundries (except             1,060            61           404            22            26            22         1,595
                            investment).

[[Page 56415]]

 
331524...................  Aluminum foundries (except          1,425            82           541            29            33            30         2,141
                            die-casting).
331525...................  Copper foundries (except            1,503            86           570            31            35            32         2,257
                            die-casting).
331528...................  Other nonferrous foundries          1,401            80           532            29            33            30         2,104
                            (except die-casting).
332111...................  Iron and steel forging.....           514            30           196            11            12            11           774
332112...................  Nonferrous forging.........           514            30           196            11            12            11           774
332115...................  Crown and closure                     514            30           196            11            12            11           774
                            manufacturing.
332116...................  Metal stamping.............           515            30           196            11            12            11           775
332117...................  Powder metallurgy part                514            30           196            11            12            11           774
                            manufacturing.
332211...................  Cutlery and flatware                  514            30           196            11            12            11           774
                            (except precious)
                            manufacturing.
332212...................  Hand and edge tool                    514            30           196            11            12            11           774
                            manufacturing.
332213...................  Saw blade and handsaw                 514            30           196            11            12            11           774
                            manufacturing.
332214...................  Kitchen utensil, pot, and               0             0             0             0             0             0             0
                            pan manufacturing.
332323...................  Ornamental and                        520            20           127             7            12             8           694
                            architectural metal work.
332439...................  Other metal container                 524            30           199            11            13            11           788
                            manufacturing.
332510...................  Hardware manufacturing.....           517            30           197            11            13            11           777
332611...................  Spring (heavy gauge)                  523            30           199            11            13            11           786
                            manufacturing.
332612...................  Spring (light gauge)                  514            30           196            11            12            11           774
                            manufacturing.
332618...................  Other fabricated wire                 514            30           196            11            12            11           774
                            product manufacturing.
332710...................  Machine shops..............           515            30           196            11            12            11           774
332812...................  Metal coating and allied              519            20           127             7            12             8           694
                            services.
332911...................  Industrial valve                      514            30           196            11            12            11           774
                            manufacturing.
332912...................  Fluid power valve and hose            514            30           196            11            12            11           774
                            fitting manufacturing.
332913...................  Plumbing fixture fitting              514            30           196            11            12            11           774
                            and trim manufacturing.
332919...................  Other metal valve and pipe            519            30           198            11            13            11           781
                            fitting manufacturing.
332991...................  Ball and roller bearing               514            30           196            11            12            11           774
                            manufacturing.
332996...................  Fabricated pipe and pipe              514            30           196            11            12            11           774
                            fitting manufacturing.
332997...................  Industrial pattern                    514            30           196            11            12            11           774
                            manufacturing.
332998...................  Enameled iron and metal               484            23           153             8            12             9           690
                            sanitary ware
                            manufacturing.
332999...................  All other miscellaneous               514            30           196            11            12            11           774
                            fabricated metal product
                            manufacturing.
333319...................  Other commercial and                  514            30           196            11            12            11           774
                            service industry machinery
                            manufacturing.
333411...................  Air purification equipment            514            30           196            11            12            11           774
                            manufacturing.
333412...................  Industrial and commercial             514            30           196            11            12            11           774
                            fan and blower
                            manufacturing.
333414...................  Heating equipment (except             517            30           197            11            13            11           777
                            warm air furnaces)
                            manufacturing.
333511...................  Industrial mold                       515            30           196            11            12            11           774
                            manufacturing.
333512...................  Machine tool (metal cutting           516            30           196            11            13            11           776
                            types) manufacturing.
333513...................  Machine tool (metal forming           514            30           196            11            12            11           774
                            types) manufacturing.
333514...................  Special die and tool, die             515            30           196            11            12            11           774
                            set, jig, and fixture
                            manufacturing.
333515...................  Cutting tool and machine              515            30           196            11            12            11           775
                            tool accessory
                            manufacturing.
333516...................  Rolling mill machinery and            514            30           196            11            12            11           774
                            equipment manufacturing.
333518...................  Other metalworking                    514            30           196            11            12            11           774
                            machinery manufacturing.
333612...................  Speed changer, industrial             514            30           196            11            12            11           774
                            high-speed drive, and gear
                            manufacturing.
333613...................  Mechanical power                      514            30           196            11            12            11           774
                            transmission equipment
                            manufacturing.
333911...................  Pump and pumping equipment            514            30           196            11            12            11           774
                            manufacturing.
333912...................  Air and gas compressor                514            30           196            11            12            11           774
                            manufacturing.
333991...................  Power-driven handtool                 514            30           196            11            12            11           774
                            manufacturing.
333992...................  Welding and soldering                 514            30           196            11            12            11           774
                            equipment manufacturing.
333993...................  Packaging machinery                   514            30           196            11            12            11           774
                            manufacturing.
333994...................  Industrial process furnace            514            30           196            11            12            11           774
                            and oven manufacturing.

[[Page 56416]]

 
333995...................  Fluid power cylinder and              514            30           196            11            12            11           774
                            actuator manufacturing.
333996...................  Fluid power pump and motor            514            30           196            11            12            11           774
                            manufacturing.
333997...................  Scale and balance (except             514            30           196            11            12            11           774
                            laboratory) manufacturing.
333999...................  All other miscellaneous               514            30           196            11            12            11           774
                            general purpose machinery
                            manufacturing.
334518...................  Watch, clock, and part                514            30           196            11            12            11           774
                            manufacturing.
335211...................  Electric housewares and                 0             0             0             0             0             0             0
                            household fans.
335221...................  Household cooking appliance           523            20           127             7            12             8           698
                            manufacturing.
335222...................  Household refrigerator and              0             0             0             0             0             0             0
                            home freezer manufacturing.
335224...................  Household laundry equipment             0             0             0             0             0             0             0
                            manufacturing.
335228...................  Other major household                   0             0             0             0             0             0             0
                            appliance manufacturing.
336111...................  Automobile manufacturing...           514            30           196            11            12            11           774
336112...................  Light truck and utility               514            30           196            11            12            11           774
                            vehicle manufacturing.
336120...................  Heavy duty truck                      514            30           196            11            12            11           774
                            manufacturing.
336211...................  Motor vehicle body                    514            30           196            11            12            11           774
                            manufacturing.
336212...................  Truck trailer manufacturing           514            30           196            11            12            11           774
336213...................  Motor home manufacturing...           514            30           196            11            12            11           774
336311...................  Carburetor, piston, piston            514            30           196            11            12            11           774
                            ring, and valve
                            manufacturing.
336312...................  Gasoline engine and engine            514            30           196            11            12            11           774
                            parts manufacturing.
336322...................  Other motor vehicle                   514            30           196            11            12            11           774
                            electrical and electronic
                            equipment manufacturing.
336330...................  Motor vehicle steering and            514            30           196            11            12            11           774
                            suspension components
                            (except spring)
                            manufacturing.
336340...................  Motor vehicle brake system            514            30           196            11            12            11           774
                            manufacturing.
336350...................  Motor vehicle transmission            514            30           196            11            12            11           774
                            and power train parts
                            manufacturing.
336370...................  Motor vehicle metal                   517            30           197            11            13            11           778
                            stamping.
336399...................  All other motor vehicle               514            30           196            11            12            11           774
                            parts manufacturing.
336611...................  Ship building and repair...         2,820             0           253           151            13            16         3,252
336612...................  Boat building..............         2,816             0           252           151            12            15         3,247
336992...................  Military armored vehicle,               0             0             0             0             0             0             0
                            tank, and tank component
                            manufacturing.
337215...................  Showcase, partition,                  514            30           196            11            12            11           774
                            shelving, and locker
                            manufacturing.
339114...................  Dental equipment and                  663            39           180            14            12            14           922
                            supplies manufacturing.
339116...................  Dental laboratories........             8             5           107             2            32             2           156
339911...................  Jewelry (except costume)               45            35           225            13            17            13           348
                            manufacturing.
339913...................  Jewelers' materials and                52            40           256            14            19            15           397
                            lapidary work
                            manufacturing.
339914...................  Costume jewelry and novelty            50            26           166             9            12            10           274
                            manufacturing.
339950...................  Sign manufacturing.........           459            20           132             7            12             7           639
423840...................  Industrial supplies,                  262            24           215             9            13             9           531
                            wholesalers.
482110...................  Rail transportation........
621210...................  Dental offices.............             3             2            32             1            11             1            49
                           Total--General Industry and           337            29           205            12            23            11           616
                            Maritime.
236100...................  Residential Building                  264            43            42            38            30            15           432
                            Construction.
236200...................  Nonresidential Building               117            52            42            46            37             7           301
                            Construction.
237100...................  Utility System Construction           326            30            71            27            69            10           532
237200...................  Land Subdivision...........           104             9            25             8            30             3           180
237300...................  Highway, Street, and Bridge           275            44            89            39           102            10           559
                            Construction.
237900...................  Other Heavy and Civil                 202            20            57            18            67             6           372
                            Engineering Construction.
238100...................  Foundation, Structure, and            228           204            80           180            58            28           778
                            Building Exterior
                            Contractors.
238200...................  Building Equipment                    156            18            26            16            30             7           253
                            Contractors.
238300...................  Building Finishing                    289            24            28            51            30             9           431
                            Contractors.
238900...................  Other Specialty Trade                 276            26            49            32            53            18           454
                            Contractors.
999000...................  State and Local Governments           N/A           N/A           N/A           N/A           N/A           N/A           N/A
                            [c].

[[Page 56417]]

 
                           Total--Construction........           242            87            56            83            49            17           533
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG (2013).


 Table VIII-30--Source Information for the Unit Cost Estimates Used in OSHA's Preliminary Cost Analysis for General Industry, Maritime, and Construction
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Ventilation    Capital cost                     Annualized
            Control \[a]\                     Description         airflow (cfm)       \[b]\      Operating cost   capital cost      Comment or source
--------------------------------------------------------------------------------------------------------------------------------------------------------
Saw enclosure........................  8' x 8' x 8' wood/                   N/A         $487.70          $48.77         $118.95  Fabrication costs
                                        plastic.                                                                                  estimated by ERG,
                                                                                                                                  assuming in-plant
                                                                                                                                  work. Five-year life.
Cab enclosures.......................  Enclosed cabs...........             N/A       15,164.82        5,307.69        3,698.56  ERG estimate based on
                                                                                                                                  vendor interviews.
LEV for hand held grinders...........  Shrouds + vacuum........             N/A        1,671.63          585.07          407.70  Vacuum plus shroud
                                                                                                                                  adapter (http://www.proventilation.com/products/productDetail.asp?id=15 5); 35% for
                                                                                                                                  maintenance and
                                                                                                                                  operating costs.
Upgraded abrasive blast cabinet......  Improved maintenance and             N/A        4,666.10        1,000.00          664.35  Assumes add.
                                        purchases for some.                                                                       maintenance (of up to
                                                                                                                                  $2,000) or new
                                                                                                                                  cabinets ($8,000)
                                                                                                                                  (Norton, 2003).
Improved spray booth for pottery.....  Maintenance time &                   N/A          116.65          114.68          231.33  Annual: $100 materials
                                        materials.                                                                                plus 4 hours
                                                                                                                                  maintenance time.
Improved LEV for ceramics spray booth  Increased air flow; per              N/A            3.21            0.88            3.21  25% of installed CFM
                                        cfm.                                                                                      price.
Exhaust for saw, cut stone industry..  Based on saw LEV (e.g.,              450        5,774.30        1,577.35          822.13  ERG based on typical
                                        pg. 10-158, 159, 160,                                                                     saw cfm requirements.
                                        ACGIH, 2001).
LEV for hand chipping in cut stone...  Granite cutting and                  600        7,699.06        2,103.14        1,096.17  ERG estimate of cfm
                                        finishing; (pg. 10-94,                                                                    requirements.
                                        ACGIH, 2001).
Exhaust trimming machine.............  Based on abrasive cut-               500        6,415.89        1,752.61          913.48  Opening of 2 sq ft
                                        off saw; (pg. 10-134)                                                                     assumed, with 250 cfm/
                                        (ACGIH, 2001).                                                                            sq.ft.
Bag opening..........................  Bag opening station;               1,513       19,414.48        5,303.41        2,764.18  3.5' x 1.5' opening;
                                        (pg. 10-19, ACGIH,                                                                        with ventilated bag
                                        2001).                                                                                    crusher (200 cfm).
Conveyor ventilation.................  Conveyor belt                        700        8,982.24        2,453.66        1,278.87  Per take-off point, 2'
                                        ventilation; (pg. 10-                                                                     wide belt.
                                        70, ACGIH, 2001).
Bucket elevator ventilation..........  Bucket elevator                    1,600       20,530.84        5,608.36        2,923.13  2' x 3' x 30' casing; 4
                                        ventilation (pg. 10-68;                                                                   take-offs @250 cfm;
                                        ACGIH, 2001).                                                                             100 cfm per sq ft of
                                                                                                                                  cross section.
Bin and hopper ventilation...........  Bin and hopper                     1,050       13,473.36        3,680.49        1,918.30  350 cfm per ft2; 3'
                                        ventilation (pg. 10-69;                                                                   belt width.
                                        ACGIH, 2001).
Screen ventilation...................  Ventilated screen (pg.             1,200       15,398.13        4,206.27        2,192.35  4' x 6' screen; 50 cfm
                                        10-173, ACGIH, 2001).                                                                     per ft\2\.
Batch operator workstation...........  Bin & hopper ventilation           1,050       13,473.36        3,680.49        1,918.30  ERG estimate of cfm
                                        for unvented mixers                                                                       requirements.
                                        (pg. 10-69, ACGIH,
                                        2001).
LEV for hand grinding operator         Hand grinding bench (pg.           3,750       48,119.16       13,144.60        6,851.09  ERG estimate of cfm
 (pottery).                             10-135, ACGIH, 2001).                                                                     requirements.

[[Page 56418]]

 
LEV, mixer and muller hood...........  Mixer & muller hood (pg.           1,050       13,473.36        3,680.49        1,918.30  ERG estimate of cfm
                                        10-87, ACGIH, 2001).                                                                      requirements.
LEV for bag filling stations.........  Bag filling station (pg.           1,500       19,247.66        5,257.84        2,740.43  Includes costs for air
                                        10-15, ACGIH, 2001).                                                                      shower.
Installed manual spray mister........  Manual controls, system              N/A       10,207.09        1,020.71        1,453.26  National Environmental
                                        covers 100 ft of                                                                          Services Company
                                        conveyor.                                                                                 (Kestner, 2003).
Install cleaning hoses, reslope        Plumbing for hose                    N/A       36,412.40        3,258.87        5,184.31  ERG estimate. Includes
 floor, drainage.                       installations, floor                                                                      cost of water and
                                        resloping and troughs.                                                                    labor time.
Shakeout conveyor enclosure..........  Ventilated shakeout               10,000      128,317.75       35,052.26       18,269.56  ERG estimate.
                                        conveyor enclosure.
Shakeout side-draft ventilation......  Shakeout double side-             28,800      369,555.11      100,950.52       52,616.33  ERG estimate of cfm
                                        draft table (pg. 10-23,                                                                   requirements.
                                        ACGIH, 2001).
Shakeout enclosing hood..............  Ventilated enclosing               7,040       90,335.69       24,676.79       12,861.77  ERG estimate of opening
                                        hood (pg. 10-23, ACGIH,                                                                   size required.
                                        2001); 4' x 4' openings.
Small knockout table.................  Portable grinding table            1,350       17,322.90        4,732.06        2,466.39  ERG estimate of opening
                                        pg. 10-136), ACGIH,                                                                       size required.
                                        2001), 3' x 3' opening.
Large knockout table.................  Hand grinding table pg.            4,800       61,592.52       16,825.09        8,769.39  ERG estimate of bench
                                        10-135), ACGIH, 2001),                                                                    surface area.
                                        4' x 6' surface.
Ventilated abrasive cutoff saw.......  Ventilated cut-off saw             1,500       19,247.66        5,257.84        2,740.43  ERG estimate of opening
                                        (pg. 10-134, ACGIH,                                                                       size required.
                                        2001, 2' x 3' opening.
Hand grinding bench (foundry)........  Bench with LEV (pg. 10-            3,750       48,119.16       13,144.60        6,851.09  ERG estimate of cfm
                                        135, ACGIH, 2001); 3' x                                                                   requirements; 250 cfm/
                                        5'.                                                                                       sq. ft.
Forming operator bench (pottery).....  Bench with LEV (pg. 10-            1,400       17,964.48        4,907.32        2,557.74  ERG estimate of cfm
                                        149, ACGIH, 2001), 3' x                                                                   requirements; 125 cfm
                                        4'.                                                                                       per linear foot.
Hand grinding bench (pottery)........  Bench with LEV (pg. 10-            2,400       30,796.26        8,412.54        4,384.69  ERG estimate of cfm
                                        135, ACGIH, 2001); 3' x                                                                   requirements; 200 cfm/
                                        4'.                                                                                       sq. ft.
Hand tool hardware...................  Retrofit suction                     200          464.21          701.05           66.09  ERG estimate of cfm
                                        attachment.                                                                               requirements.
Clean air island.....................  Clean air supplied                 2,500       32,079.44        8,763.07        4,567.39  ERG estimate of cfm
                                        directly to worker.                                                                       requirements; 125 cfm/
                                                                                                                                  sq. ft. for 20 square
                                                                                                                                  feet.
Water fed chipping equipment drum      Shop-built water feed                N/A          116.65            0.00          116.65  ERG estimate. $100 in
 cleaning.                              equipment.                                                                                annual costs.
Ventilation for drum cleaning........  Ventilation blower and               N/A          792.74          198.18          193.34  Electric blower (1,277
                                        ducting.                                                                                  cfm) and 25 ft. of
                                                                                                                                  duct. Northern Safety
                                                                                                                                  Co. (p. 193).
Control room.........................  10' x 10' ventilated                 200       19,556.79          701.05        2,784.45  ERG estimate based on
                                        control room with HEPA                                                                    RSMeans (2003), ACGIH
                                        filter.                                                                                   (2001).
Control room improvement.............  Repair and improve                   N/A        2,240.00          N/A             318.93  ERG estimate. Assumes
                                        control room enclosure.                                                                   repairs are 20% of new
                                                                                                                                  control room cost.
Improved bag valves..................  Bags with extended                   N/A            0.01          N/A                N/A  Cecala et. al., (1986).
                                        polyethylene valve,
                                        incremental cost per
                                        bag.

[[Page 56419]]

 
Dust suppressants....................  Kleen Products 50 lb                 N/A          N/A             634.54            0.00  0.28/lb, 2 lbs/day; 5
                                        poly bag green sweeping                                                                   minutes/day
                                        compound.                                                                                 (www.fastenal.com).
HEPA vacuum for housekeeping.........  NILFISK VT60 wet/dry                 N/A        3,494.85          511.20          852.36  Nilfisk, HEPA vacuum
                                        hepa vac, 15 gal.                                                                         (http://www.sylvane.com/nilfisk.html).
HEPA vacuum for housekeeping.........  NILFISK, large capacity.             N/A        7,699.06          988.90        1,877.73  Nilfisk, HEPA vacuum
                                                                                                                                  (McCarthy, 2003).
Yard dust suppression................  100 ft, 1'' contractor               N/A          204.14            0.00          112.91  Contactor hose and
                                        hose and nozzle.                                                                          nozzle; 2 year life;
                                                                                                                                  (www.pwmall.com).
Wet methods to clean concrete mixing   10 mins per day per                  N/A            0.00          916.82            0.00  10 mins per day per
 equip..                                operator.                                                                                 mixer operator.
HEPA vacuum substitute for compressed  Incremental time to                  N/A          N/A             494.54            0.00  5 min per day per
 air.                                   remove dust by vacuum.                                                                    affected worker.
Spray system for wet concrete          Shop-built sprayer                   N/A          204.67           20.47          113.20  Assumes $100 in
 finishing.                             system.                                                                                   materials and 4 hours
                                                                                                                                  to fabricate. Also 10%
                                                                                                                                  for maintenance.
Substitute alt., non-silica, blasting  Alternative media                    N/A            0.00       33,646.00            0.00  Based on 212,000 square
 media.                                 estimated to cost 22                                                                      feet of coverage per
                                        percent more.                                                                             year per crew.
Abrasive blasting cost per square      125 blasting days per                N/A          N/A               2.00             N/A  ERG estimate based on
 foot (dry blasting).                   year.                                                                                     RSMeans (2009).
Half-mask, non-powered, air-purifying  Unit cost includes                   N/A          N/A             570.13             N/A
 respirator.                            expenses for
                                        accessories, training,
                                        fit testing, and
                                        cleaning.
Full-face nonpowered air-purifying     Unit cost includes                   N/A          N/A             637.94             N/A
 respirator.                            expenses for
                                        accessories, training,
                                        fit testing, and
                                        cleaning.
Half-face respirator (construction)..  Unit cost includes                   N/A          N/A             468.74             N/A
                                        expenses for
                                        accessories, training,
                                        fit testing, and
                                        cleaning.
Industrial Hygiene Fees/personal       Consulting IH                        N/A          N/A             500                N/A
 breathing zone.                        technician--rate per
                                        sample. Assumes IH rate
                                        of $500 per day and
                                        samples per day of 2,
                                        6, and 8 for small,
                                        medium, and large
                                        establishments,
                                        respectively.
Exposure assessment lab fees and       ........................             N/A          N/A             133.38             N/A  Lab fees (EMSL
 shipping cost.                                                                                                                   Laboratory, 2000) and
                                                                                                                                  OSHA estimates.
                                                                                                                                  Inflated to 2009
                                                                                                                                  values.
Physical examination by knowledgeable  Evaluation and office                N/A          N/A             100.00             N/A  ERG, 2013.
 Health Care Practitioner.              consultation including
                                        detailed examination.
Chest X-ray..........................  Tri-annual radiologic                N/A          N/A              79.61             N/A
                                        examination, chest;
                                        stereo, frontal. Costs
                                        include consultation
                                        and written report.

[[Page 56420]]

 
Pulmonary function test..............  Tri-annual spirometry,               N/A          N/A              54.69             N/A
                                        including graphic
                                        record, total and timed
                                        vital capacity,
                                        expiratory flow rate
                                        measurements(s), and/or
                                        maximal voluntary
                                        ventilation.
Examination by a pulmonary specialist  Office consultation and              N/A          N/A             190.28             N/A
 \[c]\.                                 evaluation by a
                                        pulmonary specialist.
Training instructor cost per hour....  ........................             N/A          N/A              34.09             N/A  Based on supervisor
                                                                                                                                  wage, adjusted for
                                                                                                                                  fringe benefits (BLS,
                                                                                                                                  2008, updated to 2009
                                                                                                                                  dollars).
Training materials for class per       Estimated cost of $2 per             N/A          N/A               2.00             N/A
 attendee.                              worker for the training/
                                        reading materials.
Value of worker time spent in class..  ........................             N/A          N/A              17.94             N/A  Based on worker wage,
                                                                                                                                  adjusted for fringe
                                                                                                                                  benefits (BLS, 2008,
                                                                                                                                  updated to 2009
                                                                                                                                  dollars).
Cost--disposable particulate           1.00 per respirator per              N/A          N/A               1.00             N/A  Lab Safety Supply,
 respirator (N95).                      day, typical cost for                                                                     2010.
                                        N95 disposable
                                        respirator.
Disposable clothing..................  Per suit, daily clothing             N/A          N/A               5.50             N/A  Lab Safety Supply,
                                        costs for 10% of                                                                          2010.
                                        workers.
Hazard tape..........................  Per regulated area for               N/A          N/A               5.80             N/A  Lab Safety Supply,
                                        annual set-up (300 ft).                                                                   2010.
Warning signs (6 per regulated area).  25.30 per sign..........             N/A          N/A             151.80             N/A  Lab Safety Supply,
                                                                                                                                  2010.
Wet kit, with water tank.............  ........................             N/A          226.73      \[d]\ 0.18          125.40  Contractors Direct
                                                                                                                                  (2009); Berland House
                                                                                                                                  of Tools (2009);
                                                                                                                                  mytoolstore (2009).
Dust shrouds: grinder................  ........................             N/A           97.33      \[d]\ 0.14           97.33  Contractors Direct
                                                                                                                                  (2009); Berland House
                                                                                                                                  of Tools (2009); Dust-
                                                                                                                                  Buddy (2009); Martin
                                                                                                                                  (2008).
Water tank, portable (unspecified      ........................             N/A          N/A        \[e]\ 15.50             N/A  RSMeans--based on
 capacity).                                                                                                                       monthly rental cost.
Water tank, small capacity (hand       ........................             N/A           73.87      \[d]\ 0.11           79.04  Contractors Direct
 pressurized).                                                                                                                    (2009); mytoolstore
                                                                                                                                  (2009).
Hose (water), 20', 2'' diameter......  ........................             N/A          N/A         \[e]\ 1.65             N/A  RSMeans--based on
                                                                                                                                  monthly cost.
Custom water spray nozzle and          ........................             N/A          363         \[d]\ 0.54          388.68  New Jersey Laborers'
 attachments.                                                                                                                     Health and Safety Fund
                                                                                                                                  (2007).
Hose (water), 200', 2'' diameter.....  ........................             N/A          N/A        \[e]\ 16.45             N/A  RSMeans--based on
                                                                                                                                  monthly rental cost.
Vacuum, 10-15 gal with HEPA..........  ........................             N/A          725         \[d]\ 0.56          400.99  ICS (2009); Dust
                                                                                                                                  Collection (2009);
                                                                                                                                  EDCO (2009); CS Unitec
                                                                                                                                  (2009).
Vacuum, large capacity with HEPA.....  ........................             N/A        2,108         \[d]\ 1.63        1,165.92  ICS (2009); EDCO
                                                                                                                                  (2009); Aramsco
                                                                                                                                  (2009).

[[Page 56421]]

 
Dust extraction kit (rotary hammers).  ........................             N/A          215         \[d]\ 0.30          214.81  Grainger (2009);
                                                                                                                                  mytoolstore (2009);
                                                                                                                                  Toolmart (2009).
Dust control/quarry drill............  ........................             N/A          N/A        \[e]\ 17.33             N/A  RSMeans Heavy
                                                                                                                                  Construction Cost Data
                                                                                                                                  (2008).
Dustless drywall sander..............  ........................             N/A          133         \[d]\ 0.19          133.33  Home Depot (2009); LSS
                                                                                                                                  (2009); Dustless Tech
                                                                                                                                  (2009).
Cab enclosure/w ventilation and air    ........................             N/A       13,000         \[d]\ 2.59        1,850.91  Estimates from
 conditioning.                                                                                                                    equipment suppliers
                                                                                                                                  and retrofitters.
Foam dust suppression system.........  ........................             N/A       14,550       \[e]\ 162.07        2,071.59  Midyette (2003).
Water tank, engine driven discharge,   ........................             N/A          N/A       \[d]\ 121.50             N/A  RSMeans (2008)--based
 5000 gal..                                                                                                                       on monthly rental
                                                                                                                                  cost.
Tunnel dust suppression system         ........................             N/A        7,928         \[e]\ 2.71        1,933.47  Raring (2003).
 supplement.
Training instructor cost per hour      ........................             N/A          N/A              43.12             N/A  Based on supervisor
 (Construction).                                                                                                                  wage, adjusted for
                                                                                                                                  fringe benefits (BLS,
                                                                                                                                  2008, updated to 2009
                                                                                                                                  dollars).
Value of worker time spent in class    ........................             N/A          N/A              22.22             N/A  Based on worker wage,
 (Construction).                                                                                                                  adjusted for fringe
                                                                                                                                  benefits (BLS, 2008,
                                                                                                                                  updated to 2009
                                                                                                                                  dollars).
Warning signs (3 per regulated area)   25.30 per sign..........             N/A          N/A              75.90             N/A  Lab Safety Supply,
 (Construction).                                                                                                                  2010.
Per-worker costs for written access    Weighted average annual                                           175.56
 control plan or regulated area setup   cost per worker;
 implementation (Construction).         Applies to workers with
                                        exposures above the PEL.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\[a]\ For local exhaust ventilation (LEV), maintenance, and conveyor covers, OSHA applied the following estimates:
LEV: capital cost = $12.83 per cfm; operating cost = $3.51 per cfm; annualized capital cost = $1.83 per cfm; based on current energy prices and the
  estimates of consultants to ERG (2013).
Maintenance: estimated as 10% of capital cost.
Conveyor Covers: estimated as $17.10 per linear foot for 100 ft. (Landola, 2003); capital cost = $19.95 per linear ft., including all hardware;
  annualized capital cost = $2.84 per linear ft.
\[b]\ Adjusted from 2003 price levels using an inflation factor of 1.166, calculated as the ratio of average annual GDP Implicit Price Deflator for 2009
  and 2003.
\[c]\ Mean expense per office-based physician visit to a pulmonary specialist for diagnosis and treatment, based on data from the 2004 Medical
  Expenditure Panel Survey. Inflated to 2009 dollars using the consumer price inflator for medical services.
Costs for physical exams and tests, chest X-ray, and pulmonary tests are direct medical costs used in bundling services under Medicare (Intellimed
  International, 2003). Costs are inflated by 30% to eliminate the effect of Medicare discounts that are unlikely to apply to occupational medicine
  environments.
\[d]\ Daily maintenance and operating cost.
\[e]\ Daily equipment costs derived from RS Means (2008) monthly rental rates, which include maintenance and operating costs.
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG (2013).

Federal Rules Which May Duplicate, Overlap, or Conflict With the 
Proposed Rule.
    OSHA has not identified any other Federal rules which may 
duplicate, overlap, or conflict with the proposal, and requests 
comments from the public regarding this issue.
1. Alternatives to the Proposed Rule which Accomplish the Stated 
Objectives of Applicable Statutes and which Minimize any Significant 
Economic Impact of the Proposed Rule on Small Entities
    This section first discusses several provisions in the proposed 
standard that OSHA has adopted or modified based on comments from small 
entity representatives (SERs) during the SBREFA Panel process or on 
recommendations made by the SBREFA Panel as potentially alleviating 
impacts on small entities. Then, the Agency presents various regulatory 
alternatives to the proposed OSHA silica standard.
a. Elements of Proposed Rule To Reduce Impacts on Small Entities
    The SBREFA Panel was concerned that changing work conditions in the 
construction industry would make it

[[Page 56422]]

difficult to apply some of the provisions that OSHA suggested at the 
time of the Panel. OSHA has preliminarily decided to change its 
approach in this sector. OSHA is proposing two separate standards, one 
for general industry and maritime and one for construction. As 
described earlier in this preamble, in construction, OSHA has provided 
a table--labeled Table 1, Exposure Control Methods for Selected 
Construction Operations--that for special operations enables the 
employer to implement engineering controls, work practices, and 
respiratory protection without the need for exposure assessment. Table 
1 in the proposed construction standard presents engineering and work 
practice controls and respiratory protection options for special 
operations. Where employees perform the special operations listed in 
the table and the employer has fully implemented the engineering 
controls, work practices, and respiratory protection specified in the 
table, the employer is not required to assess the exposure of employees 
performing such operations.
    As an alternative to the regulated area provision, OSHA is 
proposing that employers be permitted the option of establishing 
written access control plans that must contain provisions for a 
competent person; procedures for notifying employees of the presence of 
exposure to respirable crystalline silica and demarcating such areas 
from the rest of the workplace; in multi-employer workplaces, the 
methods for informing other employers of the presence and location of 
areas where silica exposures may exceed the PEL; provisions for 
limiting access to areas where silica exposures are likely; and 
procedures for providing respiratory protection to employees entering 
areas with controlled access. Further discussion on this alternative is 
found in the Summary and Explanation for paragraph (e) Regulated Areas 
and Access Control.
    OSHA believes that, although the estimated per-worker cost for 
written access control plans averages somewhat higher than the per-
worker cost for regulated areas ($199.29 per worker for the control 
plans vs. $167.65 per worker for the regulated area), access control 
plans may be significantly less costly and more protective than 
regulated areas in certain work situations.
    Some SERs were already applying many of the protective controls and 
practices that would be required by the ancillary provisions of the 
standard. However, many SERs objected to the provisions regarding 
housekeeping, protective clothing, and hygiene facilities. For this 
proposed rule, OSHA removed the requirement for hygiene facilities, 
which has resulted in the elimination of compliance costs for change 
rooms, shower facilities, lunch rooms, and hygiene-specific 
housekeeping requirements. OSHA also restricted the provision for 
protective clothing (or, alternatively, any other means to remove 
excessive silica dust from work clothing) to situations where there is 
the potential for employees' work clothing to become grossly 
contaminated with finely divided material containing crystalline 
silica.
b. Regulatory Alternatives
    For the convenience of those persons interested only in OSHA's 
regulatory flexibility analysis, this section repeats the discussion of 
the various regulatory alternatives to the proposed OSHA silica 
standard presented in the Introduction and in Section VIII.H of this 
preamble.
    Each regulatory alternative presented here is described and 
analyzed relative to the proposed rule. Where appropriate, the Agency 
notes whether the regulatory alternative, to be a legitimate candidate 
for OSHA consideration, requires evidence contrary to the Agency's 
findings of significant risk and feasibility. To facilitate comment, 
the regulatory alternatives have been organized into four categories: 
(1) Alternative PELs to the proposed PEL of 50 [mu]g/m\3\; (2) 
regulatory alternatives that affect proposed ancillary provisions; (3) 
a regulatory alternative that would modify the proposed methods of 
compliance; and (4) regulatory alternatives concerning when different 
provisions of the proposed rule would take effect.
Alternative PELs
    OSHA is proposing a new PEL for respirable crystalline silica of 50 
[mu]g/m\3\ for all industry sectors covered by the rule. OSHA's 
proposal is based on the requirements of the Occupational Safety and 
Health Act (OSH Act) and court interpretations of the Act. For health 
standards issued under section 6(b)(5) of the OSH Act, OSHA is required 
to promulgate a standard that reduces significant risk to the extent 
that it is technologically and economically feasible to do so. See 
Section II of this preamble, Pertinent Legal Authority, for a full 
discussion of OSHA legal requirements.
    OSHA has conducted an extensive review of the literature on adverse 
health effects associated with exposure to respirable crystalline 
silica. The Agency has also developed estimates of the risk of silica-
related diseases assuming exposure over a working lifetime at the 
proposed PEL and action level, as well as at OSHA's current PELs. These 
analyses are presented in a background document entitled ``Respirable 
Crystalline Silica--Health Effects Literature Review and Preliminary 
Quantitative Risk Assessment'' and are summarized in this preamble in 
Section V, Health Effects Summary, and Section VI, Summary of OSHA's 
Preliminary Quantitative Risk Assessment, respectively. The available 
evidence indicates that employees exposed to respirable crystalline 
silica well below the current PELs are at increased risk of lung cancer 
mortality and silicosis mortality and morbidity. Occupational exposures 
to respirable crystalline silica also may result in the development of 
kidney and autoimmune diseases and in death from other nonmalignant 
respiratory diseases. As discussed in Section VII, Significance of 
Risk, in this preamble, OSHA preliminarily finds that worker exposure 
to respirable crystalline silica constitutes a significant risk and 
that the proposed standard will substantially reduce this risk.
    Section 6(b) of the OSH Act (29 U.S.C. 655(b)) requires OSHA to 
determine that its standards are technologically and economically 
feasible. OSHA's examination of the technological and economic 
feasibility of the proposed rule is presented in the Preliminary 
Economic Analysis and Initial Regulatory Flexibility Analysis (PEA), 
and is summarized in this section (Section VIII) of this preamble. For 
general industry and maritime, OSHA has preliminarily concluded that 
the proposed PEL of 50 [mu]g/m\3\ is technologically feasible for all 
affected industries. For construction, OSHA has preliminarily 
determined that the proposed PEL of 50 [mu]g/m\3\ is feasible in 10 out 
of 12 of the affected activities. Thus, OSHA preliminarily concludes 
that engineering and work practices will be sufficient to reduce and 
maintain silica exposures to the proposed PEL of 50 [mu]g/m\3\ or below 
in most operations most of the time in the affected industries. For 
those few operations within an industry or activity where the proposed 
PEL is not technologically feasible even when workers use recommended 
engineering and work practice controls, employers can supplement 
controls with respirators to achieve exposure levels at or below the 
proposed PEL.
    OSHA developed quantitative estimates of the compliance costs of 
the proposed rule for each of the affected industry sectors. The 
estimated compliance costs were compared with

[[Page 56423]]

industry revenues and profits to provide a screening analysis of the 
economic feasibility of complying with the revised standard and an 
evaluation of the potential economic impacts. Industries with unusually 
high costs as a percentage of revenues or profits were further analyzed 
for possible economic feasibility issues. After performing these 
analyses, OSHA has preliminarily concluded that compliance with the 
requirements of the proposed rule would be economically feasible in 
every affected industry sector.
    OSHA has examined two regulatory alternatives (named Regulatory 
Alternatives 1 and 2) that would modify the PEL for 
the proposed rule. Under Regulatory Alternative 1, the 
proposed PEL would be changed from 50 [mu]g/m\3\ to 100 [mu]g/m\3\ for 
all industry sectors covered by the rule, and the action level would be 
changed from 25 [mu]g/m\3\ to 50 [mu]g/m\3\ (thereby keeping the action 
level at one-half of the PEL). Under Regulatory Alternative 2, 
the proposed PEL would be lowered from 50 [mu]g/m\3\ to 25 [mu]g/m\3\ 
for all industry sectors covered by the rule, while the action level 
would remain at 25 [mu]g/m\3\ (because of difficulties in accurately 
measuring exposure levels below 25 [mu]g/m\3\).
    Tables VIII-31A and VIII-31B present, for informational purposes, 
the estimated costs, benefits, and net benefits of the proposed rule 
under the proposed PEL of 50 [mu]g/m\3\ and for the regulatory 
alternatives of a PEL of 100 [mu]g/m\3\ and a PEL of 25 [mu]g/m\3\ 
(Regulatory Alternatives  1 and 2), using alternative 
discount rates of 3 and 7 percent. These two tables also present the 
incremental costs, the incremental benefits, and the incremental net 
benefits of going from a PEL of 100 [mu]g/m\3\ to the proposed PEL of 
50 [mu]g/m\3\ and then of going from the proposed PEL of 50 [mu]g/m\3\ 
to a PEL of 25 [mu]g/m\3\. Table VIII-31A breaks out costs by provision 
and benefits by type of disease and by morbidity/mortality, while Table 
VIII-31B breaks out costs and benefits by major industry sector.

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[[Page 56425]]


[GRAPHIC] [TIFF OMITTED] TP12SE13.019

    As Tables VIII-31A and VIII-31B show, going from a PEL of 100 
[mu]g/m\3\ to a PEL of 50 [mu]g/m\3\ would prevent, annually, an 
additional 357 silica-related fatalities and an additional 632 cases of 
silicosis. Based on its

[[Page 56426]]

preliminary findings that the proposed PEL of 50 [mu]g/m\3\ 
significantly reduces worker risk from silica exposure (as demonstrated 
by the number of silica-related fatalities and silicosis cases avoided) 
and is both technologically and economically feasible, OSHA cannot 
propose a PEL of 100 [mu]g/m\3\ (Regulatory Alternative 1) 
without violating its statutory obligations under the OSH Act. However, 
the Agency will consider evidence that challenges its preliminary 
findings.
    As previously noted, Tables VIII-31A and VIII-31B also show the 
costs and benefits of a PEL of 25 [mu]g/m\3\ (Regulatory Alternative 
2), as well as the incremental costs and benefits of going 
from the proposed PEL of 50 [mu]g/m\3\ to a PEL of 25 [mu]g/m\3\. 
Because OSHA determined that a PEL of 25 [mu]g/m\3\ would not be 
feasible (that is, engineering and work practices would not be 
sufficient to reduce and maintain silica exposures to a PEL of 25 
[mu]g/m\3\ or below in most operations most of the time in the affected 
industries), the Agency did not attempt to identify engineering 
controls or their costs for affected industries to meet this PEL. 
Instead, for purposes of estimating the costs of going from a PEL of 50 
[mu]g/m\3\ to a PEL of 25 [mu]g/m\3\, OSHA assumed that all workers 
exposed between 50 [mu]g/m\3\ and 25 [mu]g/m\3\ would have to wear 
respirators to achieve compliance with the 25 [mu]g/m\3\ PEL. OSHA then 
estimated the associated additional costs for respirators, exposure 
assessments, medical surveillance, and regulated areas (the latter 
three for ancillary requirements specified in the proposed rule).
    As shown in Tables VIII-31A and VIII-31B, going from a PEL of 50 
[mu]g/m\3\ to a PEL of 25 [mu]g/m\3\ would prevent, annually, an 
additional 335 silica-related fatalities and an additional 186 cases of 
silicosis. These estimates support OSHA's preliminarily finding that 
there is significant risk remaining at the proposed PEL of 50 [mu]g/
m\3\. However, the Agency has preliminarily determined that a PEL of 25 
[mu]g/m\3\ (Regulatory Alternative 2) is not technologically 
feasible, and for that reason, cannot propose it without violating its 
statutory obligations under the OSH Act.
Regulatory Alternatives That Affect Ancillary Provisions
    The proposed rule contains several ancillary provisions (provisions 
other the PEL), including requirements for exposure assessment, medical 
surveillance, silica training, and regulated areas or access control. 
As shown in Table VIII-31A, these ancillary provisions represent 
approximately $223 million (or about 34 percent) of the total 
annualized costs of the rule of $658 million (using a 7 percent 
discount rate). The two most expensive of the ancillary provisions are 
the requirements for medical surveillance, with annualized costs of $79 
million, and the requirements for exposure monitoring, with annualized 
costs of $74 million.
    As proposed, the requirements for exposure assessment are triggered 
by the action level. As described in the preamble, OSHA has defined the 
action level for the proposed standard as an airborne concentration of 
respirable crystalline silica of 25 [mu]g/m\3\ calculated as an eight-
hour time-weighted average. In this proposal, as in other standards, 
the action level has been set at one-half of the PEL.
    Because of the variable nature of employee exposures to airborne 
concentrations of respirable crystalline silica, maintaining exposures 
below the action level provides reasonable assurance that employees 
will not be exposed to respirable crystalline silica at levels above 
the PEL on days when no exposure measurements are made. Even when all 
measurements on a given day may fall below the PEL (but are above the 
action level), there is some chance that on another day, when exposures 
are not measured, the employee's actual exposure may exceed the PEL. 
When exposure measurements are above the action level, the employer 
cannot be reasonably confident that employees have not been exposed to 
respirable crystalline silica concentrations in excess of the PEL 
during at least some part of the work week. Therefore, requiring 
periodic exposure measurements when the action level is exceeded 
provides the employer with a reasonable degree of confidence in the 
results of the exposure monitoring.
    The action level is also intended to encourage employers to lower 
exposure levels in order to avoid the costs associated with the 
exposure assessment provisions. Some employers would be able to reduce 
exposures below the action level in all work areas, and other employers 
in some work areas. As exposures are lowered, the risk of adverse 
health effects among workers decreases.
    OSHA's preliminary risk assessment indicates that significant risk 
remains at the proposed PEL of 50 [mu]g/m\3\. Where there is continuing 
significant risk, the decision in the Asbestos case (Bldg. and 
Constr.Trades Dep't, AFL-CIO v. Brock, 838 F.2d 1258, 1274 (D.C. Cir. 
1988)) indicated that OSHA should use its legal authority to impose 
additional requirements on employers to further reduce risk when those 
requirements will result in a greater than de minimis incremental 
benefit to workers' health. OSHA's preliminary conclusion is that the 
requirements triggered by the action level will result in a very real 
and necessary, but non-quantifiable, further reduction in risk beyond 
that provided by the PEL alone. OSHA's choice of proposing an action 
level for exposure monitoring of one-half of the PEL is based on the 
Agency's successful experience with other standards, including those 
for inorganic arsenic (29 CFR 1910.1018), ethylene oxide (29 CFR 
1910.1047), benzene (29 CFR 1910.1028), and methylene chloride (29 CFR 
1910.1052).
    As specified in the proposed rule, all workers exposed to 
respirable crystalline silica above the PEL of 50 [mu]g/m\3\ are 
subject to the medical surveillance requirements. This means that the 
medical surveillance requirements would apply to 15,172 workers in 
general industry and 336,244 workers in construction. OSHA estimates 
that 457 possible silicosis cases will be referred to pulmonary 
specialists annually as a result of this medical surveillance.
    OSHA has preliminarily determined that these ancillary provisions 
will: (1) Help to ensure the PEL is not exceeded, and (2) minimize risk 
to workers given the very high level of risk remaining at the PEL. OSHA 
did not estimate, and the benefits analysis does not include, monetary 
benefits resulting from early discovery of illness.
    Because medical surveillance and exposure assessment are the two 
most costly ancillary provisions in the proposed rule, the Agency has 
examined four regulatory alternatives (named Regulatory Alternatives