[Federal Register Volume 59, Number 34 (Friday, February 18, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-3591]
[[Page Unknown]]
[Federal Register: February 18, 1994]
_______________________________________________________________________
Part II
Department of Labor
_______________________________________________________________________
Mine Safety and Health Administration
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30 CFR Part 56, et al.
Air Quality: Health Standards for Abrasive Blasting and Drill Dust
Control;
Final Rule
DEPARTMENT OF LABOR
Mine Safety and Health Administration
30 CFR Parts 56, 57, 58, 70, and 72
RIN 1219-AA48
Air Quality: Health Standards for Abrasive Blasting and Drill
Dust Control
AGENCY: Mine Safety and Health Administration (MSHA), Labor.
ACTION: Final rule.
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SUMMARY: This final rule addresses abrasive blasting and drill dust
control at all metal and nonmetal and coal mines. The final rule
retains existing requirements for rock drilling operations at metal and
nonmetal mines and establishes new requirements for rock drilling
operations at surface coal mines and surface work areas of underground
coal mines. The final rule also revises existing requirements for rock
drilling operations at underground coal mines. In addition, it
establishes new specific standards for abrasive blasting operations at
coal mines and expands existing provisions at metal and nonmetal mines.
EFFECTIVE DATE: April 19, 1994.
FOR FURTHER INFORMATION CONTACT: Patricia W. Silvey; Director, Office
of Standards, Regulations and Variances; MSHA; (703) 235-1910.
SUPPLEMENTARY INFORMATION:
I. Background
On August 29, 1989 (54 FR 35760), MSHA published a notice in the
Federal Register inviting public comment on a proposed rule on air
quality, chemical substances, and respiratory protection in mining. The
proposed rule addressed means of controlling exposure to hazardous
substances, permissible exposure limits, exposure monitoring, dangerous
atmospheres, respiratory protection, carcinogens, asbestos construction
work, drill dust control, abrasive blasting, and prohibited areas for
food and beverages. This final rule addresses abrasive blasting and
drill dust control, which are the first of these sections to be
completed.
In comments on the proposal, the Agency received requests to hold
public hearings. In response, the Agency held three sets of public
hearings on the proposed rule. The first set of public hearings, which
specifically addressed abrasive blasting and drill dust control, was
held in Denver, Colorado, on June 4, 1990, and in Pittsburgh,
Pennsylvania, on June 7, 1990. Following the public hearings, the
record remained open until August 30, 1991, to allow interested persons
to submit supplementary statements and data.
During the rulemaking process, MSHA received written and oral
comments from all segments of the mining community. The Agency's final
rule addresses the comments received and is consistent with the goals
of the Federal Mine Safety and Health Act of 1977 (Mine Act), Executive
Order 12866, the Regulatory Flexibility Act, and the Paperwork
Reduction Act.
After analyzing the comments received, the public hearing
testimony, and technical and health data, the Agency is issuing this
final rule on abrasive blasting and drill dust control to address
immediate health concerns. The final rule makes no substantive changes
to existing regulations for drill dust control at metal and nonmetal
mines and at underground coal mines. However, the final rule
establishes new requirements for drill dust control at surface coal
mines. The final rule also expands existing requirements for abrasive
blasting at metal and nonmetal mines and establishes new requirements
for both surface and underground coal mines. The existing respirable
coal mine dust standards in parts 70, 71, and 90 are unaffected by this
final rule.
This final rule is consistent with section 101(a)(6)(A) of the Mine
Act, which mandates the development of standards dealing with toxic
substances to attain the highest degree of protection possible for
miners. Section 101(a)(6)(A) also requires MSHA to take into
consideration the latest available scientific data in the field, the
feasibility of the standards, and experience gained under the Mine Act
and other health and safety laws.
This rulemaking codifies health standards for abrasive blasting and
drill dust control in a new part 58 for metal and nonmetal mines and a
new part 72 for coal mines. In the following discussion, the
designation ``58/72'' indicates that a standard appears in both parts
58 and 72.
In an effort to fully explore the issues presented by this
rulemaking, MSHA has included in the rulemaking record several
scientific studies concerning abrasive blasting and drill dust control
that were published after the close of the comment period on August 30,
1991. These references are CDC/NIOSH Alert * * * Lead Poisoning in
Construction Workers, April 1992; CDC/NIOSH Alert * * * Silicosis and
Deaths in Rock Drillers, August 1992; CDC/NIOSH Alert * * * Silicosis
and Deaths From Sandblasting, August 1992; Goodman et al., 1992; and
Mickelsen and Froehlich, May 1993. None of these references are
entirely new data, but rather they further confirm the Agency's
rulemaking decision and address concerns raised by commenters. MSHA
reviewed these documents in order to attain its statutory obligation to
consider the latest available scientific data in the field.
II. General Introduction
Whenever miners conduct abrasive blasting or drilling they are
exposed to serious health hazards that require implementation of
specific dust controls before engaging in the activity. Enforcement by
using the permissible exposure limits alone would provide inadequate
protection for miners in these activities. During abrasive blasting and
drilling, there is the potential for extremely high exposures in short
periods of time to both the miners doing the abrasive blasting or
drilling and to other miners in the immediate area. Relying on samples
could allow miners to receive extremely hazardous doses of contaminants
before sampling results could be analyzed. In addition, miners could
face rapidly changing environments, all having potential for high
exposure. In addition, during abrasive blasting, although the type of
abrasive material may remain constant, the coatings of the base
material and the accumulated contaminants in the recycled abrasive
material may cause exposure to vary widely (Rekus, 1988; Mickelsen and
Froehlich, 1993).
Administrative controls, which control exposures by limiting the
amount of time a miner is in a contaminated atmosphere, are not
appropriate for abrasive blasting and drilling operations. Inherent in
the effective use of administrative controls is the assumption that the
environmental exposure will remain constant or predictable. This is not
characteristic of these two operations.
Due to the nature of the work being performed, the location of
these activities can change rapidly. The frequent change of location
also can make it extremely difficult to get sampling results quickly
enough to effectively evaluate a miner's current exposure. This is
particularly true in the case of independent contractors who, by the
time sampling results are evaluated, may have moved to another location
or mine. There also exists the problem of maintaining sample integrity
during abrasive blasting operations. When sampling is done outside of
an abrasive blasting hood, high velocity rebounding or ricocheting
abrasive material from the blasted surface can destroy the sample.
Because of these factors, the final rule specifies engineering
controls for drill dust control at all mines and requires a totally
enclosed system or an abrasive blasting respirator during abrasive
blasting operations.
Exposure to silica is a significant health hazard in abrasive
blasting and in drilling. When workers inhale silica, the lungs react
by developing fibrotic nodules and scarring around the trapped silica
particles. This condition is known as silicosis and can result in
respiratory difficulty and eventually death. Symptoms associated with
silicosis include shortness of breath, fever, and cyanosis. Severe
fungal or mycobacterial infections, such as tuberculosis, often cause
complications and may be fatal. Dust-impaired macrophages can no longer
function effectively in fighting disease by killing mycobacteria and
other organisms.
It is generally believed that the silica dust overwhelms
macrophages in the lungs (Craighead et al., 1988). This can be due to
silica toxicity or to a combination of toxicity and dust overload
(Morrow, 1988; Claypool, 1988; Berkow, 1987). When a person is exposed
to respirable dust containing crystalline silica, three types of
silicosis may occur, depending on the dust concentration. Chronic
silicosis usually occurs following relatively low exposures over 10 or
more years. Accelerated silicosis results from exposure to high
concentrations over 5 to 10 years. Acute silicosis or silico-
proteinosis occurs from exposure to the highest concentrations, with
symptoms developing within a few weeks to 4 or 5 years from initial
exposure (Merchant, 1986). Acute silicosis is characterized by the
accumulation of an amorphous granular lipoprotein released into the air
spaces and rapid development of respiratory disability in a few years
(Vallyathan, 1988). Silico-proteinosis results from dust overload as
well as silica toxicity (Claypool, 1988; Morrow, 1988; Heppleston et
al., 1970; Rubin et al., 1980).
When particles impact a surface during abrasive blasting, they
typically fracture into finer particles and become airborne. Inhalation
of freshly fractured silica particles appears to produce a more severe
lung reaction. Vallyathan (1988) studied freshly fractured silica dust
and found it exhibited more toxic characteristics than silica that had
aged at least 30 hours. Freshly fractured silica can react with water
to release short-lived oxygenated free radicals. Alveolar macrophages
are stimulated to a greater extent by freshly fractured free silica
than silica that has been aged. Vallyathan theorizes that this freshly
fractured silica and macrophage interaction may contribute to
development of acute silicosis, which is associated with sandblasting,
rock drilling, tunnelling, and silica flour mill operations.
III. Abrasive Blasting
A. Introduction
Abrasive blasting is the technique of projecting particles to
remove paint or other unwanted substances from a surface for the
purpose of preparing it for painting, welding, or other activities. In
mining, the location and type of equipment being cleaned by abrasive
blasting may change during every operation. The abrasive material can
be composed of a single substance, such as silica, or a composite
material, such as slag. The abrasive material, as well as anything
removed from the object or surface, can become airborne. In some
instances, the abrasive material can be collected and reused. This
process has the potential for accumulation of various toxic substances,
such as lead from paint (Rekus, 1988; CDC/NIOSH Alert, April 1992;
Mickelsen and Froehlich, 1993). The exposure hazard associated with
abrasive blasting is dependent on the type of abrasive blasting
conducted, the type of abrasive material used, and the substance being
abraded. Abrasive blasting represents a unique situation in mining that
is difficult to control by using traditional means.
There are several different methods of abrasive blasting. Air
pressure blasting is the most commonly used technique in mining. In
this process, air pressure is used to propel abrasive material at a
high velocity against an object to abrade unwanted substances from its
surface. This type of abrasive blasting has the greatest potential to
cause overexposure to toxic substances resulting from the abrasive
material itself or the substances removed.
Another abrasive blasting method uses abrasive material entrained
in water or other liquid media. The abrasive material is propelled by
either liquid pressure or a combination of liquid and air pressure. The
abrasive material entrained in the liquid media is forced to strike an
object at a high velocity, which causes unwanted substances to be
abraded. Though the potential for overexposure is reduced by the water
used in this method, a health hazard still exists due to small
fractured particles found in the mist that is generated. After
blasting, cleanup of dried materials also can be a potential exposure
problem (Craighead et al., 1988).
In mining, abrasive blasting is a commonly used method of cleaning
surfaces in preparation for painting or welding. It is generally done
on a periodic basis, most commonly during maintenance procedures and
plant overhaul. For these activities, the hazards of abrasive blasting
in mining are the same as those in general industry. The references
cited in this preamble generally relate to studies conducted on non-
miners. Documentation of similar disease prevalence in miners
performing abrasive blasting is limited because miners who perform
abrasive blasting are grouped into maintenance or general laborer job
categories and, thus, are often difficult to identify. Also, many mine
operators employ independent contractors to perform these activities,
and disease prevalence among such contractors is difficult to track.
Because the process and materials are essentially the same in mining as
in general industry, MSHA believes that miners performing abrasive
blasting experience risks similar to those described in the scientific
studies cited in this preamble that address industries other than
mining.
B. Background
1. Metal and Nonmetal Mining
Existing metal and nonmetal standards at 30 CFR 56/57.5010 prohibit
the use of silica sand or other materials containing more than 1
percent free silica as an abrasive material in abrasive blasting at all
surface mines and at the surface areas of underground mines, unless all
exposed persons are protected by a full-flow respirator or equivalent.
Existing Sec. 57.5016 prohibits the use of silica sand or other
materials containing more than 1 percent free silica as an abrasive
substance in abrasive blasting operations underground.
The majority of abrasive blasting performed at metal and nonmetal
mines is conducted on the surface and most of these operations are
carried out by hand-held dry blasting methods. In almost all of these
operations, abrasive blasting hoods with supplied air are used to
protect the worker. These hoods are approved by the National Institute
for Occupational Safety and Health (NIOSH). Also, small abrasive
blasting work boxes are used in some maintenance shops.
2. Coal Mining
Currently, MSHA does not specifically regulate abrasive blasting at
surface and underground coal mines. However, 30 CFR 75.1720 and 77.1710
require protective clothing for protection against the impact of
particles from such operations at coal mines. Abrasive blasting occurs
at a small number of surface and underground coal mines and then only
on an infrequent basis. These operations may be performed by either the
mine operator or an independent contractor. MSHA has observed abrasive
blasting at coal mines where adequate respiratory protection was not
being worn. Due to the serious health risk of overexposure to
crystalline silica and other materials being used, the final rule
requires the use of engineering controls or personal protective
equipment at all abrasive blasting operations.
C. Abrasive Blasting--Toxicity
For many years, abrasive blasters have been considered to be at
high risk of developing silicosis (Craighead et al., 1988). The use of
sandblasting for the purpose of cleaning metal surfaces before painting
has been prohibited by law in the United Kingdom since 1949 and in the
European Economic Community since 1966 (Ziskind, 1976). The increased
use of sand as an abrasive in the United States since World War II was
noted to have produced a resurgence of accelerated silicosis in
sandblasters (Ziskind, 1976). In 1974, NIOSH recommended that silica
(or other substances containing more than 1 percent free silica) be
prohibited as an abrasive blasting material (NIOSH, 1974).
Early reports of acute silicosis among sandblasters include
Buechner and Ansari (1969), who reported evidence of an alveolar
proteinosis-like response of pulmonary tissue to occupational silica
exposure. Autopsy examination of four sandblasters revealed silica
crystals and a protein material in the lungs. The workers had
sandblasted for an average period of 4 years.
Abrasive blasters are also at high risk of developing active
tuberculosis (Bailey et al., 1974). Merewether (1936) found that the
average duration of employment at the time of death was 8.3 years for
abrasive blasters with silico-tuberculosis, compared to 32 years for
this fatal combination in other occupations. Bailey et al. (1974) also
found similar results. Merewether (1936) reported that 5.4 percent (24
of 441) of the sandblasters in his study in Great Britain died from
silicosis or silicosis with tuberculosis in a 3.5-year period.
In 1988, a physician reported three cases of silicosis in
sandblasters (CDC MMWR, 1990). One of these individuals, a 34-year-old
man, died with acute silicotic alveolar proteinosis. Later
investigations revealed an additional seven sandblasters who had
silicosis. All worked at one facility that used a mixture of flint and
garnet to sandblast oil pipe. The mean duration of exposure was 4.5
years, with one case as short as 18 months. Blast cabinets and
protective booths were poorly designed and not maintained. Workers wore
only disposable respirators and none had been fit tested.
In another case, a 49-year-old nonsmoker with a 6-year history as a
sandblaster was admitted to a hospital complaining of difficulty in
breathing, cough, lack of appetite, fever and a 20-lb weight loss
(Owens et al., 1988). He was diagnosed with chronic silicosis and
bacterial pneumonia and died on the twentieth day of his hospital stay.
Four sandblasters in a tombstone factory developed acute silicosis
after an average of 3-years' exposure at ages 23, 37, 38, and 47
(Suratt et al., 1977). Three of the four are known to have died from
silicosis. It was determined that the blasting agent used during
sandblasting contained 98 percent crystalline free silica. The
employees worked inside enclosed but vented blasting chambers and wore
negative pressure half-mask respirators with disposable filters.
Bailey et al. (1974) examined the records of 88 sandblaster-
painters who were admitted to Charity Hospital in New Orleans. Of
these, 83 had silicosis and 22 were confirmed as having tuberculosis.
The mean age of these 22 individuals was 44, with an average exposure
of 10 years. At the time of the study, 27 percent (8 of 22) had died.
Three of these individuals died of ``acute'' silicosis, which had
characteristics of pulmonary alveolar proteinosis. The average age at
the time of death was 44.2 years, with an average exposure of 8.3
years. The authors note that in almost all of the 22 cases, the
sandblaster hoods were not attached to an external air supply.
Samimi et al. (1974) studied sandblasting and associated workers on
steel fabrication yards. They sampled sandblasters and workers
physically located near the abrasive blasting operations. Personal
exposure of helpers, pot handlers, painters, and welders indicated an
average exposure from 1.9 to 7.4 times the permissible threshold limit
value (TLV), with the helper having the highest exposure among the
secondary occupations. Environmental samples on the outside of abrasive
blasting hoods were as high as 37.25 mg/m\3\, which was 318 times the
TLV. Samples taken inside non-supplied-air abrasive blasting hoods
exceeded the TLV in all cases, with the highest exposure being 80 times
the TLV. Although sampling data indicated that overexposures occurred
with supplied-air respirators being used, the authors noted that this
may have been due to sampling during times when the respirator was not
continually worn, as well as to poorly maintained equipment. Samples
taken under modern and well-maintained hoods indicate exposures would
be only one-third of the TLV.
In studies, other abrasives used instead of silica also have been
demonstrated to be fibrogenic. MacKay et al. (1980) found that
commercial coal-slag derived grit produced pulmonary fibrosis in rats.
The copper slag tested did not produce fibrosis, but did produce
granulomas.
Stettler et al. (1988) studied the fibrogenic and carcinogenic
potential of copper and nickel smelter slags that have been used as a
substitute for sand in abrasive blasting. The copper slags not only
produced some fibrosis, but also produced lung tumors in the rats. The
authors were unable to determine the exact causative agent because many
trace elements, such as arsenic and beryllium, were present in the
slags.
D. Control Technology
Abrasive blasting creates high particulate concentrations within
open or enclosed spaces where the work is performed. The force of the
abrasive stream (60 to 120 pounds per square inch (psi)) produces fine
fragments of respirable size (less than 10 micrometers (m) in
diameter). A high percentage of the particles are in the 1 to 3
m range in which alveolar deposition is significant (Bailey et
al., 1974).
MSHA recognizes that there are limitations in the engineering
controls for abrasive blasting in mining. Abrasive blasting, by its
nature, is used to prepare equipment for maintenance. Because the
equipment to be prepared can vary considerably in size and location at
the mine, it would be extremely costly and technically very difficult
to build temporary enclosures around the equipment with properly
designed ventilation and dust filtration equipment to prevent exposure
to miners. Some small equipment can be easily moved, which allows for
abrasive blasting of that equipment to be performed in commercially
available boxes, cabinets, or blasting rooms. Blast cleaning cabinets
are used to clean relatively small objects that can be manipulated by
hand. When using blasting cabinets, the operator stands outside of the
enclosed cabinet and uses a set of attached gloves or remote controls
to perform the blasting operation inside the enclosure. The blasting
media is maintained inside the enclosed cabinet by negative pressure.
When operators use a properly designed and maintained blasting cabinet,
exposure to hazardous material is minimal.
The majority of abrasive blasting in mining is done on large
equipment at varied locations on the mine site. In these cases, the
primary means of controlling exposure is the NIOSH-approved abrasive
blasting hood. This hood has the advantage of providing safety
protection from the impact of projected particles, as well as
respiratory protection from toxic materials.
E. Summary and Explanation of Rule
Paragraph (a) of Secs. 58/72.610 is derived from existing Secs. 56/
57.5010 for metal and nonmetal mines. Sections 56/57.5010 prohibit the
use of materials containing more than 1 percent free silica as an
abrasive substance in abrasive blasting operations at surface areas of
metal and nonmetal mines, unless all exposed persons are protected with
full-flow respirators or equivalent. Under the final rule, when an
abrasive blasting operation is performed, all exposed miners must
properly use respirators approved for abrasive blasting by NIOSH or the
operation must be done in a totally enclosed device.
A commenter to the proposed rule recommended that MSHA require
supplied-air respirators at surface mines, unless the work being
performed was in a totally enclosed device with the operator outside
the device. This commenter stated that eliminating silica-containing
materials from abrasive blasting will not necessarily eliminate the
associated health hazards, because animal experiments with other
abrasive substitutes have produced fibrosis or scarring of the lungs.
In addition, NIOSH recommended that abrasive blasting respirators be
used whenever there is detectable silica in the abrasive blasting
material, even when it constitutes less than 1 percent.
MSHA agrees with the commenter that other abrasive materials can
present a health hazard in abrasive blasting. The final rule,
therefore, expands the scope of the proposed rule to address these
hazards by requiring respirators approved for abrasive blasting to be
used when abrasive blasting is conducted, unless the work is performed
in a totally enclosed device with the operator outside the device.
Abrasive blasting respirators will also provide the necessary safety
protection because they are designed to protect the wearer's head and
neck against impact and abrasion from rebounding material, as well as
provide respiratory protection. The impact of high-velocity rebounding
or ricocheting abrasive material from the blasted surface can penetrate
other types of personal protective equipment.
Existing metal and nonmetal Secs. 56/57.5010 require the use of
``full-flow respiratory protection or equivalent'' when using abrasives
containing more than 1 percent free silica. ``Full-flow'' is an
outdated term referring to a respirator that had a flow of air
mechanically forced into the facepiece, as opposed to a negative-
pressure respirator that requires inhalation by the wearer to bring air
through the filter into the facepiece. A ``full-flow'' respirator does
not easily correspond to current NIOSH certification of respiratory
protection. The proposed rule replaced ``full-flow respiratory
protection or equivalent'' with ``supplied-air respirator approved for
abrasive blasting'' which required NIOSH approval for that use.
Since the publication of the proposed rule, powered air-purifying
respirators have received NIOSH approval for use in abrasive blasting
operations. Powered air-purifying respirators approved by NIOSH for
abrasive blasting would meet the current standard of ``full-flow
respiratory protection or equivalent.'' Therefore, MSHA is deleting the
words ``supplied-air'' in the final rule to permit the use of any
respirator approved by NIOSH for abrasive blasting. This will not
result in any diminution of safety for the miner, but will permit the
use of any new respiratory protection that has been approved by NIOSH
for abrasive blasting operations.
NIOSH recommended banning the use of any product containing more
than 1 percent free silica as an abrasive substance at all mines. They
also recommended banning the use underground of any product that
contained any detectable silica, including those containing less than 1
percent. NIOSH suggested that at surface operations where abrasive
blasting products containing any detectable silica up to 1 percent are
used, MSHA should require the use of abrasive blasting respirators.
In the preamble to the proposed rule, MSHA used the terms
``quartz'' and ``free silica'' interchangeably in the discussion on
abrasive blasting, although the term ``1 percent quartz'' was used in
the proposed rule itself. NIOSH in its comments expressed concern about
the proposed exemption of material containing ``1 percent free silica
or less.'' In the final rule, MSHA is using ``1 percent free silica''
which is consistent with the wording of the current metal and nonmetal
standard and is the term used by NIOSH.
MSHA disagrees with the suggestion that substances containing more
than 1 percent free silica be banned at surface locations. Adequate
protection will be provided to miners with the requirement that miners
exposed to abrasive blasting use respirators approved for abrasive
blasting or the operation be conducted in totally enclosed devices.
Several types of abrasive blasting enclosures are commercially
available and can be used successfully to control exposure to all
contaminants, not just silica. Alternatively, abrasive blasting
respirators also offer protection against all contaminants, including
silica. As a result, the final rule does not ban the use of abrasive
blasting materials containing silica at surface operations.
One commenter recommended monitoring of the environment when
abrasive blasting products containing less than 1 percent free silica
are used. This commenter suggested that abrasive blasting respirators
or engineering controls be required if the level of exposure to
respirable quartz dust at surface operations exceeds 50 g/
m\3\. The requirement in the final rule requiring enclosure or abrasive
blasting respirators affords more protection to the miners.
Other commenters recommended that the proposed section on abrasive
blasting be deleted and that an exposure limit for silica sand govern
the exposure during abrasive blasting operations. Because of factors
previously discussed, specifying controls is necessary. Generally, it
is not practical to conduct monitoring in an abrasive blasting zone
because the sampling device could be destroyed or damaged by rebounding
material. In addition, because of the wide variability in blasting
operations, sampling is often inadequate as a means of assessing the
miners' exposures. The safety hazard associated with abrasive blasting
is such that hoods or enclosures are necessary to ensure better
protection for miners engaged in abrasive blasting activities.
Paragraph (b) of Secs. 58/72.610 is derived from existing metal and
nonmetal Sec. 57.5016 and prohibits the use of silica sand or other
materials containing more than 1 percent free silica as an abrasive
substance in abrasive blasting at underground mines. Currently, MSHA
does not explicitly regulate abrasive blasting underground at coal
mines. However, Sec. 75.1720 requires protective clothing for
protection against the impact of particles from such operations. NIOSH
and the majority of commenters recommended that abrasive blasting
materials containing more than 1 percent free silica be banned
underground. MSHA agrees because airborne respirable silica could be
carried from an abrasive blasting operation throughout the mine by the
ventilation system, thus exposing unprotected miners. In addition,
there are substitute abrasives that have been used effectively for this
type of work underground. Accordingly, the Agency has retained the
provision from the proposed rule which would ban the use underground of
abrasive blasting materials containing more than 1 percent free silica.
Because Secs. 58/72.500, respiratory protection, of the proposed
Air Quality standard have not been promulgated, MSHA uses the term
``properly used'' and ``approved by NIOSH'' in Sec. 72.610(a) to assure
protection. Section 58.610 refers to Secs. 56/57.5005 to assure
continued proper use of respiratory protection. When the respiratory
protection provisions of the Air Quality rulemaking are promulgated,
Secs. 58/72.610 will be modified to refer to that section.
IV. Drill Dust Control
A. Introduction
Drilling operations have long been recognized as causing
respiratory hazards in mining. Most rock drilling produces respirable,
silica-bearing dust that can cause silicosis and alveolar proteinosis.
All types of silicosis have been documented in drillers. In 1958, the
Public Health Service, in conjunction with the Bureau of Mines, issued
a report on silicosis in metal and nonmetal mining that identified
drilling as one of the most prolific dust-producing operations. In
August 1992, the CDC/NIOSH of the Public Health Service again
reemphasized its earlier warnings on silicosis occurring in rock
drillers. In this Alert, NIOSH described 23 cases of silicosis
occurring in rock drillers, including 11 rock drillers in coal mines.
MSHA believes that control of drill dust also will prevent the
development of pulmonary alveolar proteinosis, as well as a mixed dust
fibrosis and silico-proteinosis.
MSHA has recognized the health hazard presented by drilling in
underground coal mining and that surface coal mines also need the
additional protection set forth in this final rule. In metal and
nonmetal mines under existing regulations over the past 13 years, MSHA
had three reports of pneumoconiosis in rock drillers and two cases in
driller helpers. Over the past 10 years, there were 30 cases of
pneumoconiosis reported to MSHA in highwall drill operators and helpers
at surface coal mines.
In addition, Banks (1983) identified three cases of acute silicosis
in coal miners. Parker et al. (1989) identified nine cases of silicosis
in surface miners in a 10-year period in West Virginia. The median age
of the miners was 35 years. All were drillers, driller helpers, or
supervisors with a median of 6 years above-ground exposure. Four were
nonsmokers. Two had acute silicosis, one of whom died within 2 years of
diagnosis. Five had accelerated silicosis, one of whom had silico-
tuberculosis. Two with longer periods of exposure were diagnosed as
having chronic silicosis. Parker concluded that there were a number of
inadequately protected individuals among above-ground workers.
All drillers and other miners must be protected from the inhalation
hazard of respirable drill dust. In the history of rock drilling,
various control techniques have been developed to reduce the amount of
dust emitted from the drill. Installing drill dust controls at the
source can reduce the amount of dust emitted and is effective in
protecting all miners at a mine. Many of these source-control
techniques are readily available and effective in the prevention of
pneumoconiosis.
B. Background
1. Metal and Nonmetal Mining
The Public Health Service has reported that drilling was one of the
most prolific dust-producing operations to which miners were exposed
(Silicosis in the Metal Mining Industry, 1963). In that study, 11
percent of the samples collected for drilling operations contained
excessive concentrations of silica-bearing dust. The study also cited
improper ventilation, dry collaring of holes, and defective equipment
as the primary causes of overexposure. In Medicine in the Mining
Industries (1972), wet drilling was recognized as an efficient means of
dust control.
Existing Secs. 56/57.5003 for metal and nonmetal mines require that
drill holes be collared and drilled wet or that other efficient dust
control measures be used when drilling non-water-soluble materials.
Efficient dust control measures also are required when drilling water-
soluble materials. MSHA issues a citation when a drill dust control is
missing, defective, or obviously ineffective by sight. In those cases
where it is not obvious that a control is ineffective, an MSHA
inspector has the option of reviewing the manufacturer's specifications
or other pertinent data, or sampling to determine its effectiveness.
Currently, MSHA issues about 90 citations and 3 orders per year for
violations of Secs. 56/57.5003.
2. Coal Mining
The development of silicosis and pneumoconiosis among underground
coal miners has been well documented, particularly among roof bolters
and transportation workers. Existing Secs. 70.400 through 70.400-3
address drill dust controls at underground coal mines. MSHA issues a
citation for a violation of Sec. 70.400 if visual observation indicates
that the drill dust controls on the equipment are not functioning
properly. Currently, MSHA issues about 15 such citations per year.
Section 72.630 of the final rule is comparable to existing Secs. 70.400
through 70.400-3 and MSHA's current interpretation of the regulation.
Likewise, Sec. 72.630 is a work practice standard that does not require
sampling.
Surface coal miners were not recognized as facing as serious a risk
as underground coal miners for many years (Parker et al., 1989).
Evidence has indicated that highwall drill operators and helpers at
surface coal mines have an increased risk of pneumoconiosis. Re-
analysis by Banks et al. (1983) of data from a previous U.S. Public
Health Service survey of surface coal miners, after exclusion of miners
with underground mining experience, showed that 38 percent of the cases
of pneumoconiosis in surface coal miners occurred in drill-crew members
even though this group comprised only 11 percent of the study
population.
In a 1984 evaluation of the prevalence of pneumoconiosis in surface
coal mine drillers, Amandus et al. found a significantly higher
incidence of category 1 or higher pneumoconiosis in persons with more
than 10 years surface drilling experience than in those with less than
10 years or no drilling experience. Results of this study also
indicated that the average coal mine dust level was significantly
higher among drillers than that found for all miners.
Later Piacitelli et al. (1990) reported that the respirable coal
mine dust samples submitted by coal mine operators and MSHA inspectors
from 1982 to 1986 were usually well below the 2.0 mg/m3 allowable
limit for all surface job categories. However, samples collected for
highwall drillers and helpers indicated that 78 percent and 77 percent,
respectively, exceeded the quartz exposure limit and that 10 to 15
percent of miners in both categories exceeded the 2.0 mg/m3
respirable coal mine dust standard.
Between 1989 and 1993, MSHA issued 112 citations for exceeding the
allowable limit for respirable dust on highwall drill operators and
helpers, of which 62 were for exceeding the 2.0 mg/m3 respirable
dust standard. The remaining 50 citations were issued for exceeding the
reduced respirable dust standard due to quartz content. As of July
1993, MSHA had placed 79 active highwall drills on a reduced respirable
dust standard due to the quartz concentration in respirable dust
samples collected on the drill operators. Also, there are 410 active
roof bolters in underground coal mines on a reduced respirable dust
standard due to quartz concentration on collected respirable dust
samples.
Notwithstanding Agency enforcement efforts, cases of silicosis
continue to be reported among surface coal miners. Therefore, in 1989,
MSHA proposed that drillers be protected at surface operations and that
the requirements be clarified for underground drillers. The final rule
is a work practice standard that does not require sampling. This
standard, in conjunction with existing regulations, is intended to
provide miners with more protection from exposures to harmful amounts
of silica and respirable coal mine dust.
C. Drill Dust--Toxicity
Pneumoconiosis began to receive increased attention toward the end
of the last century as a result of the introduction of machine drills
and the large quantities of dust they generate. Silicosis has long been
recognized as a health risk in rock drillers (Silicosis in the Metal
Mining Industry, 1963). In the past, rock drillers in underground coal
mines were known to have developed silicosis, but drillers at surface
coal mines were not considered to be at significant risk (Fairman et
al., 1977). However, more recent studies indicate that surface rock
drillers are being diagnosed with silicosis as well as other
pneumoconioses (Banks et al., 1983; Parker et al., 1989; Goodman et
al., 1992; Amandus et al., 1984; Piacitelli et al., 1990). A study
conducted by NIOSH in 1987 of silica dust exposure to drill crews
drilling overburden on a highwall at a surface coal mine indicated the
occurrence of significant overexposures and a prevalence of
pneumoconiosis five times greater than other surface workers (NIOSH
MHETA 87-173-1882).
The August 1992 CDC/NIOSH Alert on Rock Drillers referenced a
number of cases of silicosis among miners. One case involved an
individual who first experienced respiratory symptoms in 1986 at age 33
(Goodman et al., 1992). The subject was a quarry driller using wet
methods to suppress drill dust from 1973 to 1983. After 1983, he worked
primarily as a driller at a surface coal mine using no controls. The
miner died in 1991 of progressive respiratory failure.
Another driller reported respiratory problems in 1979 at age 34
(Banks et al., 1983). His history indicated that for the previous 5
years he had operated a rotary drill at a surface coal mine using dry
drilling methods. This miner died of respiratory failure in 1981. A
medical survey of nine other drillers working for the same company
found two additional miners, ages 28 and 31, with accelerated silicosis
after fewer than 6 years exposure.
One hospital in West Virginia reported seven cases of silicosis in
surface miners from 1978 to 1988. The cases involved miners with a
median age of 35 working in surface drilling for an average of 6 years
(Parker et al., 1989). One case had active tuberculosis. In addition, a
second possible case of tuberculosis was identified.
Ezenwa (1982) studied environmental and host factors in mines and
mills. In Quebec metal mines, Ezenwa found that a significantly larger
portion of miners who worked in drilling and crushing (associated with
high dust levels) developed silicosis in 15 years relative to other
occupations over the same time period. Of the 35 men with accelerated
silicosis, 37 percent had working experience as drillers.
D. Drill Dust Control--Technology
Various effective drill dust control techniques have been developed
that control the dust at the source. Many of these techniques are
readily available and effective in the prevention of respirable drill
dust overexposures. In addition, these dust control techniques can
reduce the hazard from drill dust for other miners in the mine as
opposed to personal respiratory protection equipment that only protects
the individual wearing it, and then only if worn properly.
Most failures of drill dust controls are readily identified and
easily corrected. Rather than mechanical breakdown of the controls,
malfunctions are generally the result of oversights or poor
maintenance, such as failure to turn on water, to fill water-holding
tanks, or to empty filters.
The general types of dust controls for rock drilling are wet
methods, dry methods, and ventilation control in underground coal
mines. Wet drilling methods are known to be effective for dust control
with non-water-soluble materials. These methods have been used as early
as 1922 and are inexpensive, practical, reliable, and effective in
controlling drill dust (Silicosis in the Metal Mining Industry, 1963).
Examples of wet drilling controls include the introduction of water
through a hollow drill stem, flooding of drill-holes, and water sprays.
Dry methods include various methods to capture the dust at the source
(the drill-hole), usually by vacuum, with subsequent removal of the
dust from the work area air by filtration or other means. Effective dry
dust collectors are readily available from several equipment
manufacturers for drilling both water-soluble and non-water-soluble
materials. General ventilation is not usually effective in underground
coal mines for drill dust control, unless it can rapidly disperse and
carry away the drill dust as well as direct the dust away from any
workers in the area.
E. Summary and Explanation of Rule
1. Sections 58/72.620
Section 58.620 is a recodification with no substantive change of
existing Secs. 56/57.5003, which addresses drill dust control at metal
and nonmetal mines. Section 72.620 established new requirements for
drill dust control at surface coal mines and surface areas of
underground coal mines. The final rule provides that drill holes be
collared and drilled wet or that other effective dust control measures
be used when drilling non-water-soluble material. The final rule also
requires effective dust control measures when drilling water-soluble
material.
NIOSH supported establishing rules for drill dust control at
surface coal mines because the potential exists for significant
overexposure to respirable free silica.
Many commenters objected to the specific control requirements
contained in proposed Secs. 58/72.620. These commenters recommended
that MSHA delete all of the existing and proposed drill dust control
standards and suggested that any new regulations addressing this issue
be performance oriented. Commenters stated that when judging how to
reduce miners' exposure to drill dust, operators should be given wide
discretion and be allowed to take into account differences in mine
conditions and mining operations.
Other commenters stated that MSHA should provide the same
compliance options to metal and nonmetal and surface coal mine
operators as are currently provided to underground coal mine operators.
These commenters recommended that the language of proposed Sec. 72.630
be made applicable to all mines. These commenters stated that by
requiring wet drilling, MSHA would be suppressing the development of
new technology and that the Agency was not taking into consideration
other effective measures of dust control, such as positive pressure
cabs.
The final rule allows mine operators the option of using controls
that are both practical and effective in controlling miners' exposures
to drill dust. The methods listed in the final rule are basic and
effective control technologies that are readily available to mine
operators. In addition, the phrase ``or other effective dust control
measures'' is included in the final rule to enable mine operators to
use methods other than those specifically listed in the standard.
MSHA's primary concern is that any drill dust control method relied
upon by the operator for the protection of miners' health have a level
of proven effectiveness. As a result, the proposed language in
Secs. 58/72.620 is retained in the final rule.
Likewise, it is MSHA's intent that the final rule allow new
technology. New methods of drill dust control may be used if their
effectiveness can be demonstrated. In the same manner, new types of
drilling may be developed and used if they include controls that are
effective in controlling drill dust. Metal and nonmetal and surface
coal mine operators do not have to seek MSHA approval before installing
``effective'' dust control technology.
MSHA agrees that positive pressure cabs are effective in
controlling exposures to dust for persons located within the cabs.
However, other miners may be working in the area. Because cabs do not
control drill dust at the source of generation, they are not adequate
to protect the health of miners located outside the cabs who are
exposed to the drill dust.
Many commenters also stated that the proposed standards would be
redundant and burdensome. They expressed concern that controls would be
required without regard to actual exposures which mine operators are
otherwise required to maintain within permissible exposure limits.
These commenters stated that the presumption that all drill operators
are overexposed unless there is a dust control system installed on the
drill is not valid. These commenters recommended that citations for
drill dust control be issued only when sampling data indicates that a
miner is overexposed.
MSHA disagrees with these commenters because the hazard associated
with drilling operations is so serious and the exposure so variable
that a permissible exposure limit alone cannot be relied upon as the
primary means of controlling drill dust exposure. The final rule
requires that effective drill dust controls be provided, regardless of
exposure. MSHA's experience has shown that drilling without effective
dust controls is highly likely to result in overexposure, not only to
the drill operator but also to other workers in the drilling area. Dust
generated by drills underground can be carried to other areas of the
mine by the ventilation system, creating contaminated air throughout
the mine and exposing unprotected miners. There is evidence that the
percentage of time that drill operators are overexposed is high enough
to warrant controls (Banks et al., 1983). In addition, due to the
nature of the drilling activity, the exposure concentration is not
always consistent and, in some instances, a miner can be acutely
exposed before sampling data indicates an overexposure.
One commenter recommended deleting the second sentence of Secs. 58/
72.620, ``or other effective dust control measures,'' and stated that
collaring and wet drilling should be the preferred means of drill dust
control. This commenter stated that a standard requiring only collaring
and wet drilling would be easier for MSHA to enforce because the
provision for ``alternative methods'' would require the Agency to
assess data. This commenter also suggested that operators could file a
petition for modification with MSHA if they wanted to use an
alternative dust control method.
MSHA recognizes that wet drilling is an established practice at
metal and nonmetal mines. However, there are other methods of drill
dust control, such as dry dust collectors, which are also effective in
controlling drill dust. A requirement permitting only wet drilling and
dry dust collection could stifle new technology that could be effective
in the control of drill dust. MSHA has had experience enforcing this
standard at metal and nonmetal mines and will enforce the requirements
similarly at surface operations of coal mines. In addition, the Mine
Act does not allow mine operators to petition for modification of
health standards.
Some commenters expressed concern that the proposed standards on
drill dust control would give too much discretion to MSHA inspectors.
One commenter stated that an inspector could arrive at a mine, observe
some dust coming from a drill, and issue a citation based solely on his
subjective conclusion that the dust control method being used was ``not
effective.'' Some commenters recommended that an inspector be allowed
to issue a citation only when an operator fails to have drill dust
controls in place or when sampling results indicate an overexposure.
Under the final rule, MSHA will cite a mine operator when a dust
control is missing, defective, or obviously ineffective by visual
inspection. In those cases where it is not obvious that a control is
effective, MSHA inspectors would have the option of reviewing
manufacturer's specifications or other pertinent data relative to the
design and operation of the dust control or, if practical, collecting
samples to evaluate its effectiveness.
One commenter stated that MSHA needed to consider that climatic
conditions play an important role in ``effective'' dust control. This
commenter used wet and dry dust-collection systems and, under certain
conditions, each method could be rendered inoperable. This commenter
stated that the wet systems fail in cold temperatures, and the dry
vacuum systems tend to plug when the drill bit enters moist areas. This
commenter recommended that, as a temporary solution, operators be
allowed to issue respiratory protection to the affected miners when
controls fail due to temporary weather conditions.
MSHA agrees that problems can be encountered by drillers when using
wet or dry drilling methods. However, there are precautions that the
operator can take to reduce these problems, such as adding antifreeze
to the water. Because of the need to control drill dust at the source,
effective drill dust controls would not include personal protective
equipment or administrative controls. After reviewing the comments
received, MSHA has retained the proposed language in the final rule.
2. Section 72.630
Section 72.630, which addresses drill dust control at underground
coal mines, recodifies existing Secs. 70.400 through 70.400-3 and
strengthens the maintenance requirement for dust collectors.
Paragraph (a) recodifies existing Sec. 70.400 and requires that
dust resulting from drilling in rock be controlled by use of
permissible dust collectors, or by water, or water with a wetting
agent, or by ventilation, or by any other method or device approved by
the Secretary in the ventilation plan that is as effective in
controlling the dust. This requirement is not intended to limit the
introduction of new technology into the mining environment. However,
because of health and safety concerns at underground coal mines, MSHA
believes that the Agency should evaluate the effectiveness of new
technology before it is used.
Some commenters objected to the specific control requirements
contained in the standard. Many recommended that MSHA delete all of the
existing and proposed drill dust control standards and suggested that
any new regulations addressing this issue be performance oriented. Some
stated that, when judging how to reduce miners' exposure to drill dust,
operators should be given wide discretion to take into account
differences in mine conditions and mining operations.
A specific standard addressing the health hazards associated with
drill dust continues to be necessary due to the likelihood of
overexposure inherent in such operations. Underground coal mine
operators have the option of using controls which are both practical
and effective in controlling miners' exposure to drill dust. The
methods listed in the final rule are basic and effective control
technologies that are readily available to underground coal mine
operators. In addition, the phrase ``or by any other method or device
approved by the Secretary that is as effective in controlling the
dust'' is included in the final rule in order to enable mine operators
to use methods other than those specifically listed in the standard. As
a result, the final rule makes only nonsubstantive editorial changes to
Secs. 70.400 through 70.400-3 and recodifies them as Sec. 72.630.
As with Sec. 72.620, many commenters stated that the proposed
standard would be redundant and burdensome because controls would be
required with no consideration of actual exposures. These commenters
stated that the presumption that all drill operators are overexposed
unless there is a dust control system installed on the drill is not
valid. These commenters recommended that citations for drill dust
control be issued only when sampling data indicates that a miner is
overexposed. As stated above, because the hazard associated with
drilling operations is so serious and exposure so variable, a
permissible exposure limit alone cannot be relied upon as the primary
means of controlling drill dust exposure.
As stated previously, MSHA will continue to cite a mine operator
when a dust control is missing, defective, or obviously visually
ineffective. In those cases where it is not obvious that a control is
effective, MSHA inspectors will continue to have the option of
reviewing manufacturer's specifications or other pertinent data
relative to the design and operation of the dust control, or of
sampling to determine its effectiveness.
Paragraph (b) recodifies existing Sec. 70.400-1 which requires
control of drill dust through the use of permissible dust collectors.
In addition, as proposed, a new provision clarifies that dust
collectors must be maintained in permissible and operating condition
when they are provided as a method of controlling dust. The majority of
commenters supported MSHA in requiring that dust collectors be
maintained in permissible and operating condition. NIOSH commented that
they supported MSHA's proposed rule for drill dust control at
underground coal mines and that the proposed addition of maintenance
requirements for dust collectors was appropriate for limiting the
exposure of miners in these operations to respirable free silica.
Paragraph (c) recodifies Sec. 70.400-2 with no change in the
existing requirement that water used to control drill dust be applied
through a hollow drill steel or stem or by the flooding of vertical
drill holes in the floor. Some commenters recommended that paragraph
(c) be deleted because they stated that the provision would place
limits on the options available to mine operators for the control of
drill dust at underground coal mines. One commenter stated that the
wording in the proposed rule would place unnecessary limits on the
methods by which water could be used to control dust. Another commenter
stated that the wording in the proposed rule would limit the use of new
technology and that the requirement to wet drill would be infeasible
and difficult to implement in areas of low water availability and high
altitude.
MSHA does not intend for this standard to be technology stifling.
As indicated earlier, the operator is not restricted to the methods
listed in the standard and, if circumstances are such that wet drilling
is not practical or feasible, the operator has the option of using
other effective methods approved by the Secretary of Labor. Wet
drilling can be an inexpensive, practical, and effective means of
controlling miners' exposure to drill dust at underground coal mines.
This practice is currently in use at underground coal mines for
drilling non-water-soluble materials.
Paragraph (d) recodifies existing Sec. 70.400-3 with no change in
the existing requirement that air currents be so directed that the dust
is readily dispersed and carried away from the drill operator or other
workers in the area. Many commenters stated that this provision was
unnecessary because a mine operator would be instructed by MSHA not to
direct the ventilation current toward a drill operator. Other
commenters stated that the provision that permits the use of
``ventilation * * * that is effective in controlling the dust'' implies
that MSHA will have to determine noncompliance through the
demonstration of an overexposure to a permissible exposure limit. One
commenter recommended deleting paragraph (d), stating that the
preferred means of drill dust control should be limited to permissible
dust collectors, water, or water with a wetting agent. This commenter
stated that ventilation is less effective in the control of drill dust
and harder for MSHA to enforce.
MSHA recognizes that ventilation may not always be a practical
method of drill dust control and that it is not the predominant method
used in underground coal mines. Under some circumstances, continuous
mining machines and roof bolters work on a single split of air, and
this can result in only the drillers being protected while persons
working downwind could be exposed. If proper precautions are taken,
however, ventilation can be an effective method of drill dust control.
MSHA, therefore, has not deleted paragraph (d). MSHA will continue to
determine compliance with this requirement under the final rule as it
has enforced Sec. 70.400-3; i.e., through the measurement of air
quantity or other measures set forth in a mine's ventilation and
methane and dust control plan. MSHA does not intend that exposure
samples be the routine method of determining compliance with this
paragraph.
V. References
Amandus, H.E. et al., ``A Re-evaluation of Radiological Evidence
from a Study of U.S. Strip Coal Miners,'' Arch Environ Health
39(5):346-351, September/October 1984.
Bailey, W.C. et al., ``Silico-Mycobacterial Disease in
Sandblasters,'' Am Rev Respir Dis 110:115-125, 1974.
Banks, D.E. et al., ``Silicosis in surface coalmine drillers,''
Thorax 38:275-278, 1983.
Berkow, R., ed., The Merck Manual of Diagnosis and Therapy (15th
Edition), 1987. pp. 679-681.
Buechner, H.A. and A. Ansari, ``Acute Silico-Proteinosis,'' Dis
Chest 55(4):274-284, April 1969.
CDC (Centers for Disease Control), ``Silicosis: Cluster in
Sandblasters--Texas, and Occupational Surveillance for Silicosis,''
MMWR 39(25):433-437, June 1990.
CDC/NIOSH, ``Alert--Preventing Lead Poisoning in Construction
Workers (Rev. Ed.),'' DHHS (NIOSH) Pub. No. 91-116a, April 1992.
CDC/NIOSH, ``Alert--Preventing Silicosis and Deaths From
Sandblasting,'' DHHS (NIOSH) Pub. No. 92-102, August 1992.
CDC/NIOSH, ``Alert--Preventing Silicosis and Deaths in Rock
Drillers,'' DHHS (NIOSH) Pub. No. 92-107, August 1992.
Claypool, W.D., ``Pulmonary Alveolar Proteinosis,'' Ch. 57 in
Pulmonary Diseases and Disorders (2nd Edition), Vol. 2, by A.P.
Fishman, 1988. pp. 893-900.
Craighead, J.E. et al., ``Diseases Associated with Exposure to
Silica and Nonfibrous Silicate Minerals,'' Arch Pathol Lab Med
112:673-720, July 1988.
Ezenwa, A.O., ``Studies of Environmental and Host Factors
Influencing Personal Differences in Response to Industrial Silica
Dust Exposure,'' Ann Occup Hyg 26(1-4):745-752, 1982.
Fairman, R.P. et al., ``Respiratory Status of Surface Coal Miners in
the United States,'' Arch Environ Health 32(1):211-215, September/
October 1977.
Goodman, G.B. et al., ``Acute Silicosis Responding to Corticosteroid
Therapy,'' Chest 101:366-370, 1992.
Heppleston, A.G. et al., ``Experimental Alveolar Lipo-Proteinosis
Following the Inhalation of Silica,'' J Path 101(4):293-307, 1970.
MacKay, G.R. et al., ``Fibrogenic potential of slags used as
substitutes for sand in abrasive blasting operations,'' AIHAJ
41:836-842, November 1980.
Merchant, J.A., ed., Occupational Respiratory Diseases, DHHS (NIOSH)
Pub. No. 86-102, September 1986, pp. 219-241.
Merewether, E.R.A., ``The Risk of Silicosis in Sand-Blasters,''
Tubercle 17(25):385-391, June 1936.
Mickelsen, R.L. and P.A. Froehlich, ``Lead-Based Paint Removal Using
Recyclable Steel Abrasive (Abstract),'' Paper presented at American
Industrial Hygiene Conference & Exposition '93, New Orleans, LA, May
15-21, 1993, p. 9.
Morrow, P.E., ``Possible Mechanisms to Explain Dust Overloading of
the Lungs,'' Fundamental and Applied Toxicology 10:369-384, 1988.
NIOSH, ``Health Hazard Evaluation Report,'' (MHETA 87-173-1882) at
Jeddo Highland Coal Co., West Pittston, PA, August 1987.
NIOSH, ``Occupational Exposure to Crystalline Silica,'' HEW (NIOSH)
Pub. No. 75-120, 1974.
Owens, M.W. et al., ``Case Report: Sandblaster's Lung with
Mycobacterial Infection,'' Am J Med Sci 295(6):554-557, June 1988.
Parker, J.E. et al., ``Surface Coal Mine Drillers and Silicosis: The
Ten Year West Virginia Experience (Abstract),'' Am Rev Respir Dis
139:A490, 1989.
Piacitelli, G.M. et al., ``Respirable Dust Exposures in U.S. Surface
Coal Mines (1982-1986),'' Arch Environ Health 45(4):202-209, July/
August 1990.
Public Health Service and Bureau of Mines, ``Silicosis in the Metal
Mining Industry,'' Public Health Service Pub. No. 1076, 1963.
Rekus, J.F., ``Working on Structural Steel: The Lead Hazard,''
Journal of Protective Coatings & Linings 5(10):38-44, 1988.
Rogan, J.M., ed., Medicine in the Mining Industries, 1972.
Rubin, E. et al., ``Pulmonary Alveolar Proteinosis,'' Radiology
135:35-41, April 1980.
Samimi, B. et al., ``Respirable Silica Dust Exposure of Sandblasters
and Associated Workers in Steel Fabrication Yards,'' Arch Environ
Health 29:61-66, August 1974.
Stettler, L.E. et al., ``Fibrogenicity and Carcinogenic Potential of
Smelter Slags Used as Abrasive Blasting Substitutes,'' J Toxicol and
Environ Health 25:35-56, 1988.
Suratt, P.M. et al., ``Case Reports: Acute Silicosis in Tombstone
Sandblasters,'' Am Rev Respir Dis 115:521-529, 1977.
Vallyathan, V. et al., ``Generation of Free Radicals from Freshly
Fractured Silica Dust,'' Am Rev Respir Dis 138:1213-1219, 1988.
Ziskind, M. et al., ``State of the Art: Silicosis,'' Am Rev Respir
Dis 113:643-665, 1976.
VI. Executive Order 12866 and the Regulatory Flexibility Act
In accordance with Executive Order 12866, MSHA prepared a final
regulatory impact analysis (RIA) to determine the incremental costs and
benefits associated with the final rule on drill dust control and
abrasive blasting. MSHA has determined in its RIA that this rule would
neither result in major cost increases nor have an effect of $100
million or more on the economy. The RIA, which is available from MSHA
upon request, is summarized as follows.
Benefits
The final rule enhances safety and health, and none of these
revisions reduce miner protection. In providing an estimate of the
potential benefits that is based on previous coal miner cases, it needs
to be noted that some of these miners may have received a majority of
their exposures in mining activities other than highwall drilling. In
addition, metal and nonmetal mines, which have had to comply with these
drill dust controls, perform considerably more highwall drilling than
do coal mines. Whereas 30 surface coal miner pneumoconiosis cases were
reported to MSHA during the previous 10 years, only 5 metal and
nonmetal pneumoconiosis cases were reported to MSHA during this period.
As a result, MSHA determined that compliance with the new requirements
for drill dust controls at surface coal mines would have prevented
between 10 and 20 of the 30 surface coal miner pneumoconiosis cases
reported to MSHA during the preceding 10 years, for an average of 1 to
2 cases prevented annually.
Even though MSHA was unable to identify any specific case that
would have been prevented by the new abrasive blasting requirements,
compliance with the final rule will help to prevent potential future
cases of silicosis and other dust diseases of the lungs.
Costs
MSHA has compared the costs associated with the existing
requirements with the costs of the new requirements. Noting that
approximately 250 coal highwall drillers will require some retrofitting
at unit costs of about $2,500 for adding a collector or baghouse, about
$8,000 for installing a dry dust collecting system, and about $7,000
for installing a wet drilling system, MSHA calculated that compliance
with the final rule for drill dust controls will cost the coal mining
industry about $950,000 in first-year costs, which would translate into
about $155,000 in annualized costs. Annual costs for such items as
maintenance of dust-collection systems, filter replacement, etc., are
estimated to be about $95,000. Thus, the total annualized plus annual
compliance cost is projected to be about $250,000.
With respect to the abrasive blasting requirements, MSHA determined
that about 55 metal and nonmetal mines and 20 coal mines would be
required to purchase new respiratory protective equipment. The unit
costs for this equipment can range from $900 for a powered, air-
purifying respirator (PAPR); $1,450 for an air-supplied hood
retrofitted with an existing air compressor; $2,200 for an air-supplied
hood retrofitted with an air distribution system; and between $1,000
and $1,500 for an abrasive blasting cabinet.
MSHA calculated that compliance with the final rule for abrasive
blasting will cost the metal and nonmetal mining industry about
$103,000 in first-year costs, which would translate into about $17,000
in annualized costs. Annual costs for such items as maintenance, filter
replacement, etc., are estimated to be about $10,000. Thus, the total
metal and nonmetal annualized plus annual compliance cost is projected
to be about $27,000.
For coal mining, MSHA calculated that compliance with the final
rule for abrasive blasting will cost about $40,000 in first-year costs,
which would translate into about $7,000 in annualized costs. Annual
costs for such items as maintenance, filter replacement, etc., will be
about $4,000. Thus, the total coal annualized plus annual compliance
cost will be about $11,000.
MSHA's final rule will have a minimal impact upon labor
productivity, profits, prices, mining output, and mining employment.
The Agency foresees no detrimental economic impact to this industry.
Regulatory Flexibility Act
The Regulatory Flexibility Act requires that agencies evaluate and
include, wherever possible, compliance alternatives that minimize any
adverse impact on small businesses when developing regulatory
standards. This final rule includes alternative compliance methods,
several of which will directly affect small mining operations.
MSHA determined that small mines will incur first-year costs of
about $248,000, or annualized costs of about $41,000. Annual costs for
small mines will be about $25,000. At the same time, MSHA determined
that large mines will incur first-year costs of about $846,000, or
annualized costs of about $138,000. Annual costs for large mines will
be about $84,000.
MSHA determined that these new provisions will not generate a
substantial cost increase for small mines. The lack of a substantial
cost increase for small mines in conjunction with the fact that similar
hazards exist in both large and small mining operations indicates that
regulatory relief is not warranted for small mining operations.
Therefore, MSHA has determined that the final rule will not have a
significantly adverse impact upon a substantial number of small
entities.
VII. Paperwork Reduction Act
This final rule contains no information paperwork requirements
subject to the Paperwork Reduction Act of 1980.
Derivation Table
The following derivation table lists the final rule with the
existing standard numbers from which it is derived.
------------------------------------------------------------------------
New section Old section
------------------------------------------------------------------------
58.610(a)....................................... 56 and 57.5010.
58.610(b)....................................... 57.5016.
58.620.......................................... 56 and 57.5003.
72.610.......................................... New.
72.620.......................................... New.
72.630(a)....................................... 70.400.
72.630(b)....................................... 70.400-1.
72.630(c)....................................... 70.400-2.
72.630(d)....................................... 70.400-3
------------------------------------------------------------------------
Redesignation Table
The following redesignation table lists the existing standard with
the final rule standard numbers.
------------------------------------------------------------------------
Old section New section
------------------------------------------------------------------------
56 and 57.5003........................................ 58.620
56 and 57.5010........................................ 58.610(a)
57.5016............................................... 58.610(b)
70.400................................................ 72.630(a)
70.400-1.............................................. 72.630(b)
70.400-2.............................................. 72.630(c)
70.400-3.............................................. 72.630(d)
------------------------------------------------------------------------
List of Subjects in 30 CFR Parts 56, 57, 58, 70, and 72
Mine safety and health, Surface mining, Underground mining.
Dated: February 11, 1994.
J. Davitt McAteer,
Assistant Secretary for Mine Safety and Health.
Accordingly, chapter I of title 30 of the Code of Federal
Regulations is amended as set forth below:
PART 56--[AMENDED]
1. The authority citation for part 56 continues to read as follows:
Authority: 30 U.S.C. 811, 957, and 961.
Sec. 56.5003 [Removed]
2. Section 56.5003 is removed.
Sec. 56.5010 [Removed]
3. Section 56.5010 is removed.
PART 57--[AMENDED]
4. The authority citation for part 57 continues to read as follows:
Authority: 30 U.S.C. 811, 957, and 961.
Sec. 57.5003 [Removed]
5. Section 57.5003 is removed.
Sec. 57.5010 [Removed]
6. Section 57.5010 is removed.
Sec. 57.5016 [Removed]
7. Section 57.5016 is removed.
8. A new part 58 is added to subchapter N, 30 CFR chapter I to read
as follows:
PART 58--HEALTH STANDARDS FOR METAL AND NONMETAL MINES
Subpart A--General
Sec.
58.1 Scope.
Subparts B Through D--[Reserved]
Subpart E--Miscellaneous
58.610 Abrasive blasting.
58.620 Drill dust control.
Authority: 30 U.S.C. 811, 957, and 961.
Subpart A--General
Sec. 58.1 Scope.
The health standards in this part apply to all metal and nonmetal
mines.
Subpart E--Miscellaneous
Sec. 58.610 Abrasive blasting.
(a) Surface and underground mines. When an abrasive blasting
operation is performed, all exposed miners shall use in accordance with
Secs. 56/57.5005 respirators approved for abrasive blasting by NIOSH or
the operation shall be performed in a totally enclosed device with the
miner outside the device.
(b) Underground areas of underground mines. Silica sand or other
materials containing more than 1 percent free silica shall not be used
as an abrasive substance in abrasive blasting.
Sec. 58.620 Drill dust control.
Holes shall be collared and drilled wet, or other effective dust
control measures shall be used, when drilling non-water-soluble
material. Effective dust control measures shall be used when drilling
water-soluble materials.
PART 70--[AMENDED]
9. The authority citation for part 70 is revised to read as
follows:
Authority: 30 U.S.C. 811, 813(h), 957, and 961.
Secs. 70.400, 70.400-1, 70.400-2 and 70.400-3 [Removed].
10. Sections 70.400, 70.400-1, 70.400-2, and 70.400-3 are removed.
11. A new part 72 is added to subchapter O to read as follows:
PART 72--HEALTH STANDARDS FOR COAL MINES
Subpart A--General
Sec.
72.1 Scope.
Subparts B Through D--[Reserved]
Subpart E--Miscellaneous
72.610 Abrasive blasting.
72.620 Drill dust control at surface mines and surface areas of
underground mines.
72.630 Drill dust control at underground areas of underground
mines.
Authority: 30 U.S.C. 811, 813(h), 957, and 961.
Subpart A--General
Sec. 72.1 Scope.
The health standards in this part apply to all coal mines.
Subpart E--Miscellaneous
Sec. 72.610 Abrasive blasting.
(a) Surface and underground mines. When an abrasive blasting
operation is performed, all exposed miners shall properly use
respirators approved for abrasive blasting by NIOSH, or the operation
shall be performed in a totally enclosed device with the miner outside
the device.
(b) Underground areas of underground mines. Silica sand or other
materials containing more than 1 percent free silica shall not be used
as an abrasive substance in abrasive blasting.
Sec. 72.620 Drill dust control at surface mines and surface areas of
underground mines.
Holes shall be collared and drilled wet, or other effective dust
control measures shall be used, when drilling non-water-soluble
material. Effective dust control measures shall be used when drilling
water-soluble material.
Sec. 72.630 Drill dust control at underground areas of underground
mines.
(a) Dust resulting from drilling in rock shall be controlled by use
of permissible dust collectors, or by water, or water with a wetting
agent, or by ventilation, or by any other method or device approved by
the Secretary that is as effective in controlling the dust.
(b) Dust collectors. Dust collectors shall be maintained in
permissible and operating condition. Dust collectors approved under
Part 33--Dust Collectors for Use in Connection with Rock Drilling in
Coal Mines of this title or under Bureau of Mines Schedule 25B are
permissible dust collectors for the purpose of this section.
(c) Water control. Water used to control dust from drilling rock
shall be applied through a hollow drill steel or stem or by the
flooding of vertical drill holes in the floor.
(d) Ventilation control. To adequately control dust from drilling
rock, the air current shall be so directed that the dust is readily
dispersed and carried away from the drill operator or any other miners
in the area.
[FR Doc. 94-3591 Filed 2-17-94; 8:45 am]
BILLING CODE 4510-43-P