[Federal Register Volume 63, Number 164 (Tuesday, August 25, 1998)]
[Rules and Regulations]
[Pages 45176-45182]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-22787]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 180
[OPP-300696; FRL-6021-6]
RIN 2070-AB78
Zinc Phosphide; Pesticide Tolerances for Emergency Exemptions
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: This regulation establishes time-limited tolerances for
residues of phosphine resulting from the use of the rodenticide zinc
phosphide in or on timothy (seed, forage, hay), alfalfa (forage, hay),
and clover (forage, hay). This action is in response to EPA's granting
of an emergency exemption under section 18 of the Federal Insecticide,
Fungicide, and Rodenticide Act authorizing use of the pesticide on
timothy or timothy-alfalfa, clover stands in Washington. This
regulation establishes a maximum permissible level for residues of
phosphine in these food commodities pursuant to section 408(l)(6) of
the Federal Food, Drug, and Cosmetic Act, as amended by the Food
Quality Protection Act of 1996. The tolerances will expire and are
revoked on February 1, 2000.
DATES: This regulation is effective August 25, 1998. Objections and
requests for hearings must be received by EPA on or before October 26,
1998.
ADDRESSES: Written objections and hearing requests, identified by the
docket control number, [OPP-300696], must be submitted to: Hearing
Clerk (1900), Environmental Protection Agency, Rm. M3708, 401 M St.,
SW., Washington, DC 20460. Fees accompanying objections and hearing
requests shall be labeled ``Tolerance Petition Fees'' and forwarded to:
EPA Headquarters Accounting Operations Branch, OPP (Tolerance Fees),
P.O. Box 360277M, Pittsburgh, PA 15251. A copy of any objections and
hearing requests filed with the Hearing Clerk identified by the docket
control number, [OPP-300696], must also be submitted to: Public
Information and Records Integrity Branch, Information Resources and
Services Division (7502C), Office of Pesticide Programs, Environmental
Protection Agency, 401 M St., SW., Washington, DC 20460. In person,
bring a copy of objections and hearing requests to Rm. 119, Crystal
Mall #2, 1921 Jefferson Davis Hwy., Arlington, VA.
A copy of objections and hearing requests filed with the Hearing
Clerk may also be submitted electronically by sending electronic mail
(e-mail) to: [email protected]. Copies of objections and
hearing requests must be submitted as an ASCII file avoiding the use of
special characters and any form of encryption. Copies of objections and
hearing requests will also be accepted on disks in WordPerfect 5.1/6.1
file format or ASCII file format. All copies of objections and hearing
requests in electronic form must be identified by the docket control
number [OPP-300696]. No Confidential Business Information (CBI) should
be submitted through e-mail. Electronic copies of objections and
hearing requests on this rule may be filed online at many Federal
Depository Libraries.
FOR FURTHER INFORMATION CONTACT: By mail: Libby Pemberton, Registration
Division (7505C), Office of Pesticide Programs, Environmental
Protection Agency, 401 M St., SW., Washington, DC 20460. Office
location, telephone number, and e-mail address: Crystal Mall #2, 1921
Jefferson Davis Hwy., Arlington, VA, (703) 308-9364, e-mail:
[email protected].
SUPPLEMENTARY INFORMATION: EPA, on its own initiative, pursuant to
section 408(e) and (l)(6) of the Federal Food, Drug, and Cosmetic Act
(FFDCA), 21 U.S.C. 346a(e) and (l)(6), is establishing tolerances for
phosphine resulting from the use of the rodenticide zinc phosphide in
or on timothy (seed, forage, hay), alfalfa (forage, hay), and clover
(forage, hay) at 0.1 part per million (ppm). These tolerances will
expire and are revoked on February 1, 2000. EPA will publish a document
in the Federal Register to remove the revoked tolerances from the Code
of Federal Regulations.
I. Background and Statutory Authority
The Food Quality Protection Act of 1996 (FQPA) (Pub. L. 104-170)
was signed into law August 3, 1996. FQPA amends both the Federal Food,
Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 301 et seq., and the Federal
Insecticide, Fungicide, and Rodenticide Act (FIFRA), 7 U.S.C. 136 et
seq. The FQPA amendments went into effect
[[Page 45177]]
immediately. Among other things, FQPA amends FFDCA to bring all EPA
pesticide tolerance-setting activities under a new section 408 with a
new safety standard and new procedures. These activities are described
below and discussed in greater detail in the final rule establishing
the time-limited tolerance associated with the emergency exemption for
use of propiconazole on sorghum (61 FR 58135, November 13, 1996)(FRL-
5572-9).
New section 408(b)(2)(A)(i) of the FFDCA allows EPA to establish a
tolerance (the legal limit for a pesticide chemical residue in or on a
food) only if EPA determines that the tolerance is ``safe.'' Section
408(b)(2)(A)(ii) defines ``safe'' to mean that ``there is a reasonable
certainty that no harm will result from aggregate exposure to the
pesticide chemical residue, including all anticipated dietary exposures
and all other exposures for which there is reliable information.'' This
includes exposure through drinking water and in residential settings,
but does not include occupational exposure. Section 408(b)(2)(C)
requires EPA to give special consideration to exposure of infants and
children to the pesticide chemical residue in establishing a tolerance
and to ``ensure that there is a reasonable certainty that no harm will
result to infants and children from aggregate exposure to the pesticide
chemical residue. . . .''
Section 18 of FIFRA authorizes EPA to exempt any Federal or State
agency from any provision of FIFRA, if EPA determines that ``emergency
conditions exist which require such exemption.'' This provision was not
amended by FQPA. EPA has established regulations governing such
emergency exemptions in 40 CFR part 166.
Section 408(l)(6) of the FFDCA requires EPA to establish a time-
limited tolerance or exemption from the requirement for a tolerance for
pesticide chemical residues in food that will result from the use of a
pesticide under an emergency exemption granted by EPA under section 18
of FIFRA. Such tolerances can be established without providing notice
or period for public comment.
Because decisions on section 18-related tolerances must proceed
before EPA reaches closure on several policy issues relating to
interpretation and implementation of the FQPA, EPA does not intend for
its actions on such tolerance to set binding precedents for the
application of section 408 and the new safety standard to other
tolerances and exemptions.
II. Emergency Exemption for Zinc Phosphide on Timothy and Timothy-
Alfalfa/Clover and FFDCA Tolerances
A potential population of 500 voles per acre would result in
significant economic loss. The currently available methods of control,
including the use of zinc phosphide bait boxes and flood irrigation,
are inadequate and impractical. EPA has authorized under FIFRA section
18 the use of zinc phosphide on timothy and timothy-alfalfa/clover for
control of vole complex in Washington. After having reviewed the
submission, EPA concurs that emergency conditions exist for this state.
As part of its assessment of this emergency exemption, EPA assessed
the potential risks presented by residues of phosphine in or on timothy
(seed, forage, hay), alfalfa (forage, hay), and clover (forage, hay).
In doing so, EPA considered the new safety standard in FFDCA section
408(b)(2), and EPA decided that the necessary tolerances under FFDCA
section 408(l)(6) would be consistent with the new safety standard and
with FIFRA section 18. Consistent with the need to move quickly on the
emergency exemption in order to address an urgent non-routine situation
and to ensure that the resulting food is safe and lawful, EPA is
issuing this tolerance without notice and opportunity for public
comment under section 408(e), as provided in section 408(l)(6).
Although these tolerances will expire and are revoked on February 1,
2000, under FFDCA section 408(l)(5), residues of the pesticide not in
excess of the amounts specified in the tolerance remaining in or on
timothy (seed, forage, hay), alfalfa (forage, hay), and clover (forage,
hay) after that date will not be unlawful, provided the pesticide is
applied in a manner that was lawful under FIFRA, and the residues do
not exceed a level that was authorized by these tolerances at the time
of that application. EPA will take action to revoke these tolerances
earlier if any experience with, scientific data on, or other relevant
information on this pesticide indicate that the residues are not safe.
Because this tolerance is being approved under emergency conditions
EPA has not made any decisions about whether zinc phosphide meets EPA's
registration requirements for use on timothy (seed, forage, hay),
alfalfa (forage, hay), and clover (forage, hay) or whether permanent
tolerances for this use would be appropriate. Under these
circumstances, EPA does not believe that these tolerances serve as a
basis for registration of zinc phosphide by a State for special local
needs under FIFRA section 24(c). Nor does this tolerance serve as the
basis for any State other than Washington to use this pesticide on
these crops under section 18 of FIFRA without following all provisions
of section 18 as identified in 40 CFR part 166. For additional
information regarding the emergency exemption for zinc phosphide,
contact the Agency's Registration Division at the address provided
above.
III. Risk Assessment and Statutory Findings
EPA performs a number of analyses to determine the risks from
aggregate exposure to pesticide residues. First, EPA determines the
toxicity of pesticides based primarily on toxicological studies using
laboratory animals. These studies address many adverse health effects,
including (but not limited to) reproductive effects, developmental
toxicity, toxicity to the nervous system, and carcinogenicity. Second,
EPA examines exposure to the pesticide through the diet (e.g., food and
drinking water) and through exposures that occur as a result of
pesticide use in residential settings.
A. Toxicity
1. Threshold and non-threshold effects. For many animal studies, a
dose response relationship can be determined, which provides a dose
that causes adverse effects (threshold effects) and doses causing no
observed effects (the ``no-observed effect level'' or ``NOEL'').
Once a study has been evaluated and the observed effects have been
determined to be threshold effects, EPA generally divides the NOEL from
the study with the lowest NOEL by an uncertainty factor (usually 100 or
more) to determine the Reference Dose (RfD). The RfD is a level at or
below which daily aggregate exposure over a lifetime will not pose
appreciable risks to human health. An uncertainty factor (sometimes
called a ``safety factor'') of 100 is commonly used since it is assumed
that people may be up to 10 times more sensitive to pesticides than the
test animals, and that one person or subgroup of the population (such
as infants and children) could be up to 10 times more sensitive to a
pesticide than another. In addition, EPA assesses the potential risks
to infants and children based on the weight of the evidence of the
toxicology studies and determines whether an additional uncertainty
factor is warranted. Thus, an aggregate daily exposure to a pesticide
residue at or below the RfD (expressed as 100% or less of the RfD) is
generally considered
[[Page 45178]]
acceptable by EPA. EPA generally uses the RfD to evaluate the chronic
risks posed by pesticide exposure. For shorter term risks, EPA
calculates a margin of exposure (MOE) by dividing the estimated human
exposure into the NOEL from the appropriate animal study. Commonly, EPA
finds MOEs lower than 100 to be unacceptable. This 100-fold MOE is
based on the same rationale as the 100-fold uncertainty factor.
Lifetime feeding studies in two species of laboratory animals are
conducted to screen pesticides for cancer effects. When evidence of
increased cancer is noted in these studies, the Agency conducts a
weight of the evidence review of all relevant toxicological data
including short-term and mutagenicity studies and structure activity
relationship. Once a pesticide has been classified as a potential human
carcinogen, different types of risk assessments (e.g., linear low dose
extrapolations or MOE calculation based on the appropriate NOEL) will
be carried out based on the nature of the carcinogenic response and the
Agency's knowledge of its mode of action.
2. Differences in toxic effect due to exposure duration. The
toxicological effects of a pesticide can vary with different exposure
durations. EPA considers the entire toxicity data base, and based on
the effects seen for different durations and routes of exposure,
determines which risk assessments should be done to assure that the
public is adequately protected from any pesticide exposure scenario.
Both short and long durations of exposure are always considered.
Typically, risk assessments include ``acute,'' ``short-term,''
``intermediate term,'' and ``chronic'' risks. These assessments are
defined by the Agency as follows.
Acute risk, by the Agency's definition, results from 1-day
consumption of food and water, and reflects toxicity which could be
expressed following a single oral exposure to the pesticide residues.
High end exposure to food and water residues are typically assumed.
Short-term risk results from exposure to the pesticide for a period
of 1-7 days, and therefore overlaps with the acute risk assessment.
Historically, this risk assessment was intended to address primarily
dermal and inhalation exposure which could result, for example, from
residential pesticide applications. However, since enaction of FQPA,
this assessment has been expanded to include both dietary and non-
dietary sources of exposure, and will typically consider exposure from
food, water, and residential uses when reliable data are available. In
this assessment, risks from average food and water exposure, and high-
end residential exposure, are aggregated. High-end exposures from all
three sources are not typically added because of the very low
probability of this occurring in most cases, and because the other
conservative assumptions built into the assessment assure adequate
protection of public health. However, for cases in which high-end
exposure can reasonably be expected from multiple sources (e.g.
frequent and widespread homeowner use in a specific geographical area),
multiple high-end risks will be aggregated and presented as part of the
comprehensive risk assessment/characterization. Since the toxicological
endpoint considered in this assessment reflects exposure over a period
of at least 7 days, an additional degree of conservatism is built into
the assessment; i.e., the risk assessment nominally covers 1-7 days
exposure, and the toxicological endpoint/NOEL is selected to be
adequate for at least 7 days of exposure. (Toxicity results at lower
levels when the dosing duration is increased.)
Intermediate-term risk results from exposure for 7 days to several
months. This assessment is handled in a manner similar to the short-
term risk assessment.
Chronic risk assessment describes risk which could result from
several months to a lifetime of exposure. For this assessment, risks
are aggregated considering average exposure from all sources for
representative population subgroups including infants and children.
B. Aggregate Exposure
In examining aggregate exposure, FFDCA section 408 requires that
EPA take into account available and reliable information concerning
exposure from the pesticide residue in the food in question, residues
in other foods for which there are tolerances, residues in groundwater
or surface water that is consumed as drinking water, and other non-
occupational exposures through pesticide use in gardens, lawns, or
buildings (residential and other indoor uses). Dietary exposure to
residues of a pesticide in a food commodity are estimated by
multiplying the average daily consumption of the food forms of that
commodity by the tolerance level or the anticipated pesticide residue
level. The Theoretical Maximum Residue Contribution (TMRC) is an
estimate of the level of residues consumed daily if each food item
contained pesticide residues equal to the tolerance. In evaluating food
exposures, EPA takes into account varying consumption patterns of major
identifiable subgroups of consumers, including infants and children.
The TMRC is a ``worst case'' estimate since it is based on the
assumptions that food contains pesticide residues at the tolerance
level and that 100% of the crop is treated by pesticides that have
established tolerances. If the TMRC exceeds the RfD or poses a lifetime
cancer risk that is greater than approximately one in a million, EPA
attempts to derive a more accurate exposure estimate for the pesticide
by evaluating additional types of information (anticipated residue data
and/or percent of crop treated data) which show, generally, that
pesticide residues in most foods when they are eaten are well below
established tolerances.
Percent of crop treated estimates are derived from federal and
private market survey data. Typically, a range of estimates are
supplied and the upper end of this range is assumed for the exposure
assessment. By using this upper end estimate of percent of crop
treated, the Agency is reasonably certain that exposure is not
understated for any significant subpopulation group. Further, regional
consumption information is taken into account through EPA's computer-
based model for evaluating the exposure of significant subpopulations
including several regional groups, to pesticide residues. For this
pesticide, the most highly exposed population subgroup (children 1-6
years old) was not regionally based.
IV. Aggregate Risk Assessment and Determination of Safety
Consistent with section 408(b)(2)(D), EPA has reviewed the
available scientific data and other relevant information in support of
this action, EPA has sufficient data to assess the hazards of zinc
phosphide and to make a determination on aggregate exposure, consistent
with section 408(b)(2), for a time-limited tolerance for phosphine
resulting from the use of the rodenticide zinc phosphide of zinc
phosphide on timothy (seed, forage, hay), alfalfa (forage, hay), and
clover (forage, hay) at 0.1 ppm. EPA's assessment of the dietary
exposures and risks associated with establishing the tolerances
follows.
A. Toxicological Profile
EPA has evaluated the available toxicity data and considered its
validity, completeness, and reliability as well as the relationship of
the results of the studies to human risk. EPA has also considered
available information concerning the variability of the
[[Page 45179]]
sensitivities of major identifiable subgroups of consumers, including
infants and children. The nature of the toxic effects caused by zinc
phosphide are discussed below.
1. Acute toxicity. No toxicology studies were identified by OPP
which demonstrated the need for an acute dietary risk assessment.
2. Short - and intermediate - term toxicity. Since 10% zinc
phosphide tracking powder has been classified in Toxicity Category IV
(LC50 > 19.6 mg/L), inhalation exposure resulting from this
section 18 action is not considered toxicologically significant. For
short-term and intermediate dermal MOE calculations, Health Effects
Division (HED), OPP recommended use of the adjusted acute dermal
LD50 NOEL of 1,000 milligrams/kilogram (mg/kg) from the
acute dermal toxicity study in rabbits. In the absence of other dermal
toxicity data, the acute NOEL dose of 1,000 mg/kg was divided by a 100-
fold uncertainty factor to approximate a 3-month dermal NOEL for worker
dermal exposure. The 3-month dermal NOEL is 10 mg/kg/day. At the lowest
effect level (LEL) of 2,000 mg/kg in the rabbit dermal LD50
study, the animals lost weight, but no mortalities were observed up to
5,000 mg/kg highest dose tested (HDT). Actual risk from dermal exposure
is likely to be significantly less, since zinc phosphide reacts with
water and stomach acid to produce the toxic gas phosphine from oral,
but not dermal, exposure.
3. Chronic toxicity. EPA has established the RfD for zinc phosphide
at 0.003 (mg/kg/day). This RfD is based on an LEL of 3.48 mg/kg/day
from an open literature 90-day rat feeding study. Effects observed at
the LEL were decreased food consumption and body weight. An uncertainty
factor of 10,000 was used due to data gaps and the absence of a NOEL in
the study. The Agency has reviewed a 90-day gavage study in rats which
had a NOEL of 0.1 mg/kg/day and a LEL of 1.0 mg/kg/day. The LEL of 1.0
mg/kg/day was based on increased mortality and kidney-nephrosis in male
rats.
4. Carcinogenicity. Zinc phosphide has not been reviewed for
carcinogenicity. OPP has waived carcinogenicity data requirements for
zinc phosphide on the basis that exposures to zinc phosphide are
controlled to prevent exposures to humans. Applications to crop areas
are such that the zinc phosphide will dissipate.
B. Exposures and Risks
1. From food and feed uses. Tolerances have been established (40
CFR 180.284(a) and (b)) for residues of the phosphine resulting from
the use of the rodenticide zinc phosphide in or on a variety of raw
agricultural commodities. There is no reasonable expectation of
secondary residues in meat, milk, poultry, or eggs (Category 3 of 40
CFR 180.6(a)). Any residues of zinc phosphide ingested by livestock
would be metabolized to naturally occurring phosphorous compounds. No
human food items are derived from timothy grown for seed or mixed
stands of timothy-alfalfa-clover produced for hay. Therefore, humans
will receive no additional dietary exposure to phosphine as a result of
establishment of these tolerances. Risk assessments were conducted by
EPA to assess dietary exposures and risks from zinc phosphide as
follows:
i. Acute exposure and risk. Acute dietary risk assessments are
performed for a food-use pesticide if a toxicological study has
indicated the possibility of an effect of concern occurring as a result
of a one day or single exposure.
ii. Chronic exposure and risk. For the purpose of assessing chronic
dietary exposure from zinc phosphide, EPA assumed tolerance level
residues and 100% of crop treated for the proposed and existing food
uses of zinc phosphide. These conservative assumptions result in
overestimation of human dietary exposures.
2. From drinking water. Zinc phosphide degrades rapidly to Zn2+ and
phosphine gas which absorp strongly to soil and are common nutrients in
soil. Zinc phosphide and its degradation products appear to have a low
potential for ground water and surface water contamination. There is no
information on zinc phosphide (phosphine) residues in ground water and
runoff in the EFED One-Liner Data Base. There is no established Maximum
Concentration Level (MCL) for residues of zinc phosphide (phosphine) in
drinking water. No drinking water health advisory levels have been
established for zinc phosphide (phosphine). There is no entry for zinc
phosphide (phosphine) in the ``Pesticides in Groundwater Database''
(EPA 734-12-92-001, September 1992). Based on the available studies
used in EPA's assessment of environmental risk, EPA does not anticipate
exposure to residues of zinc phosphide (phosphine) in drinking water.
3. From non-dietary exposure. Zinc phosphide is currently
registered for use on the following residential non-food sites: hand-
applied bait to underground burrows in/on the following sites/settings:
bulb crops, golf course turfgrass, lawns, ornamentals, nurseries,
parks, homes, industrial, commercial, and agricultural buildings.
These registrations could result in non-occupational exposure and
EPA acknowledges that there may be short-, intermediate-, and long-term
non-occupational, non-dietary exposure scenarios. At this time, the
Agency has insufficient information to assess the potential risks from
such exposure.
4. Cumulative exposure to substances with common mechanism of
toxicity. Section 408(b)(2)(D)(v) requires that, when considering
whether to establish, modify, or revoke a tolerance, the Agency
consider ``available information'' concerning the cumulative effects of
a particular pesticide's residues and ``other substances that have a
common mechanism of toxicity.'' The Agency believes that ``available
information'' in this context might include not only toxicity,
chemistry, and exposure data, but also scientific policies and
methodologies for understanding common mechanisms of toxicity and
conducting cumulative risk assessments. For most pesticides, although
the Agency has some information in its files that may turn out to be
helpful in eventually determining whether a pesticide shares a common
mechanism of toxicity with any other substances, EPA does not at this
time have the methodologies to resolve the complex scientific issues
concerning common mechanism of toxicity in a meaningful way. EPA has
begun a pilot process to study this issue further through the
examination of particular classes of pesticides. The Agency hopes that
the results of this pilot process will increase the Agency's scientific
understanding of this question such that EPA will be able to develop
and apply scientific principles for better determining which chemicals
have a common mechanism of toxicity and evaluating the cumulative
effects of such chemicals. The Agency anticipates, however, that even
as its understanding of the science of common mechanisms increases,
decisions on specific classes of chemicals will be heavily dependent on
chemical specific data, much of which may not be presently available.
Although at present the Agency does not know how to apply the
information in its files concerning common mechanism issues to most
risk assessments, there are pesticides as to which the common mechanism
issues can be resolved. These pesticides include pesticides that are
toxicologically dissimilar to existing chemical substances (in which
case the Agency can conclude that it is unlikely that a pesticide
shares a common mechanism of activity with other
[[Page 45180]]
substances) and pesticides that produce a common toxic metabolite (in
which case common mechanism of activity will be assumed).
EPA does not have, at this time, available data to determine
whether zinc phosphide has a common mechanism of toxicity with other
substances or how to include this pesticide in a cumulative risk
assessment. Unlike other pesticides for which EPA has followed a
cumulative risk approach based on a common mechanism of toxicity, zinc
phosphide does not appear to produce a toxic metabolite produced by
other substances. For the purposes of this tolerance action, therefore,
EPA has not assumed that zinc phosphide has a common mechanism of
toxicity with other substances.
C. Aggregate Risks and Determination of Safety for U.S. Population
1. Chronic risk. Using the TMRC exposure assumptions described
above, EPA has concluded that aggregate exposure to zinc phosphide from
food will utilize 27.5% of the RfD for the U.S. population. The major
identifiable subgroup with the highest aggregate exposure is children 1
to 6 years old ``discussed below.'' EPA generally has no concern for
exposures below 100% of the RfD because the RfD represents the level at
or below which daily aggregate dietary exposure over a lifetime will
not pose appreciable risks to human health. Despite the potential for
exposure to zinc phosphide from non-dietary, non-occupational exposure,
EPA does not expect the aggregate exposure to exceed 100% of the RfD.
EPA concludes that there is a reasonable certainty that no harm will
result from aggregate exposure to zinc phosphide residues.
2. Short- and intermediate-term risk. Short- and intermediate-term
aggregate exposure takes into account chronic dietary food and water
(considered to be a background exposure level) plus indoor and outdoor
residential exposure.
D. Aggregate Cancer Risk for U.S. Population
Zinc phosphide has not been reviewed for carcinogenicity. OPP has
waived carcinogenicity data requirements for zinc phosphide on the
basis that exposures to zinc phosphide are controlled to prevent
exposures to humans. Applications to crop areas are such that the zinc
phosphide will dissipate.
E. Aggregate Risks and Determination of Safety for Infants and Children
1. Safety factor for infants and children--In general. In assessing
the potential for additional sensitivity of infants and children to
residues of zinc phosphide, EPA considered data from developmental
toxicity studies in the rat and mouse. The developmental toxicity
studies are designed to evaluate adverse effects on the developing
organism resulting from maternal pesticide exposure during gestation.
Reproduction studies provide information relating to effects from
exposure to the pesticide on the reproductive capability of mating
animals and data on systemic toxicity.
FFDCA section 408 provides that EPA shall apply an additional
tenfold margin of safety for infants and children in the case of
threshold effects to account for pre-and post-natal toxicity and the
completeness of the database unless EPA determines that a different
margin of safety will be safe for infants and children. Margins of
safety are incorporated into EPA risk assessments either directly
through use of a MOE analysis or through using uncertainty (safety)
factors in calculating a dose level that poses no appreciable risk to
humans. EPA believes that reliable data support using the standard MOE
and uncertainty factor (usually 100 for combined inter- and intra-
species variability)) and not the additional tenfold MOE/uncertainty
factor when EPA has a complete data base under existing guidelines and
when the severity of the effect in infants or children or the potency
or unusual toxic properties of a compound do not raise concerns
regarding the adequacy of the standard MOE/safety factor.
There were no developmental findings in rats up to a maternally
toxic dose of 4.0 mg/kg/day zinc phosphide nor in mice at 4.0 mg/kg/day
(HDT). A comparison of the NOEL of 0.1 mg/kg/day in the recent 90-day
rat gavage study and the NOELs for developmental toxicity in rats and
mice (4.0 mg/kg/day) provides a 40-fold difference, which demonstrates
that there are no special pre-natal sensitivities for infants and
children. OPP has waived teratogenicity in the rabbit and the 2-
generation reproduction study in the rat data requirements for zinc
phosphide on the basis that exposures to zinc phosphide are controlled
to prevent exposures to humans. Applications to crop areas are such
that the zinc phosphide will dissipate. Since there are no reproduction
studies with zinc phosphide, the post-natal potential for effects from
zinc phosphide in infants and children cannot be fully evaluated.
However, the above information, together with the uncertainty factor of
10,000 utilized to calculate the RfD for zinc phosphide, is considered
adequate protection for infants and children with respect to prenatal
and postnatal development against dietary exposure to zinc phosphide
residues, and therefore, EPA has determined that an additional 10-fold
safety factor is not appropriate.
2. Chronic risk. Using the conservative exposure assumptions
described above, EPA has concluded that aggregate exposure to zinc
phosphide from food will utilize from 6.8% of the RfD for nursing
infants (<1 year old) and up to 59.9% children 1 to 6 years old. EPA
generally has no concern for exposures below 100% of the RfD because
the RfD represents the level at or below which daily aggregate dietary
exposure over a lifetime will not pose appreciable risks to human
health. Despite the potential for exposure to zinc phosphide from non-
dietary, non-occupational exposure, EPA does not expect the aggregate
exposure to exceed 100% of the RfD. EPA concludes that there is a
reasonable certainty that no harm will result to infants and children
from aggregate exposure to zinc phosphide residues.
V. Other Considerations
A. Metabolism In Plants and Animals
The metabolism of zinc phosphide in plants and animals is
adequately understood for the purposes of these tolerances. The residue
of concern is unreacted zinc phosphide, measured as phosphine, that may
be present.
B. Analytical Enforcement Methodology
Adequate methods for purposes of data collection and enforcement of
tolerances for zinc phosphide residues as phosphine gas are available.
Methods for determining zinc phosphide residues of as phosphine gas are
described in PAM, Vol. II, as Method A.
C. Magnitude of Residues
Residues of phosphine resulting from this use of zinc phosphide in
timothy (seed, forage, hay), alfalfa (forage, hay) and clover (forage,
hay) will not exceed 0.1 part per million (ppm).
D. International Residue Limits
There are no Codex tolerances for timothy (seed, forage, hay),
alfalfa (forage, hay) and clover (forage, hay).
VI. Conclusion
Therefore, these tolerances are established for phosphine resulting
from the use of the rodenticide zinc phosphide in timothy (seed,
forage,
[[Page 45181]]
hay), alfalfa (forage, hay), and clover (forage, hay) at 0.1 ppm.
VII. Objections and Hearing Requests
The new FFDCA section 408(g) provides essentially the same process
for persons to ``object'' to a tolerance regulation issued by EPA under
new section 408(e) and (l)(6) as was provided in the old section 408
and in section 409. However, the period for filing objections is 60
days, rather than 30 days. EPA currently has procedural regulations
which govern the submission of objections and hearing requests. These
regulations will require some modification to reflect the new law.
However, until those modifications can be made, EPA will continue to
use those procedural regulations with appropriate adjustments to
reflect the new law.
Any person may, by October 26, 1998, file written objections to any
aspect of this regulation and may also request a hearing on those
objections. Objections and hearing requests must be filed with the
Hearing Clerk, at the address given above (40 CFR 178.20). A copy of
the objections and/or hearing requests filed with the Hearing Clerk
should be submitted to the OPP docket for this rulemaking. The
objections submitted must specify the provisions of the regulation
deemed objectionable and the grounds for the objections (40 CFR
178.25). Each objection must be accompanied by the fee prescribed by 40
CFR 180.33(i). If a hearing is requested, the objections must include a
statement of the factual issues on which a hearing is requested, the
requestor's contentions on such issues, and a summary of any evidence
relied upon by the requestor (40 CFR 178.27). A request for a hearing
will be granted if the Administrator determines that the material
submitted shows the following: There is genuine and substantial issue
of fact; there is a reasonable possibility that available evidence
identified by the requestor would, if established, resolve one or more
of such issues in favor of the requestor, taking into account
uncontested claims or facts to the contrary; and resolution of the
factual issues in the manner sought by the requestor would be adequate
to justify the action requested (40 CFR 178.32). Information submitted
in connection with an objection or hearing request may be claimed
confidential by marking any part or all of that information as CBI.
Information so marked will not be disclosed except in accordance with
procedures set forth in 40 CFR part 2. A copy of the information that
does not contain CBI must be submitted for inclusion in the public
record. Information not marked confidential may be disclosed publicly
by EPA without prior notice.
VIII. Public Record and Electronic Submissions
EPA has established a record for this rulemaking under docket
control number [OPP-300696] (including any comments and data submitted
electronically). A public version of this record, including printed,
paper versions of electronic comments, which does not include any
information claimed as CBI, is available for inspection from 8:30 a.m.
to 4 p.m., Monday through Friday, excluding legal holidays. The public
record is located in Room 119 of the Public Information and Records
Integrity Branch, Information Resources and Services Division (7502C),
Office of Pesticide Programs, Environmental Protection Agency, Crystal
Mall #2, 1921 Jefferson Davis Highway, Arlington, VA.
Electronic comments may be sent directly to EPA at:
[email protected].
Electronic comments must be submitted as an ASCII file avoiding the
use ofspecial characters and any form of encryption.
The official record for this rulemaking, as well as the public
version, as described above will be kept in paper form. Accordingly,
EPA will transfer any copies of objections and hearing requests
received electronically into printed, paper form as they are received
and will place the paper copies in the official rulemaking record which
will also include all comments submitted directly in writing. The
official rulemaking record is the paper record maintained at the
Virginia address in ``ADDRESSES'' at the beginning of this document.
IX. Regulatory Assessment Requirements
This final rule establishes tolerances under FFDCA section 408(d)
in response to a petition submitted to the Agency. The Office of
Management and Budget (OMB) has exempted these types of actions from
review under Executive Order 12866, entitled Regulatory Planning and
Review (58 FR 51735, October 4, 1993). This final rule does not contain
any information collections subject to OMB approval under the Paperwork
Reduction Act (PRA), 44 U.S.C. 3501 et seq., or impose any enforceable
duty or contain any unfunded mandate as described under Title II of the
Unfunded Mandates Reform Act of 1995 (UMRA) (Pub. L. 104-4). Nor does
it require any prior consultation as specified by Executive Order
12875, entitled Enhancing the Intergovernmental Partnership (58 FR
58093, October 28, 1993), or special considerations as required by
Executive Order 12898, entitled Federal Actions to Address
Environmental Justice in Minority Populations and Low-Income
Populations (59 FR 7629, February 16, 1994), or require OMB review in
accordance with Executive Order 13045, entitled Protection of Children
from Environmental Health Risks and Safety Risks (62 FR 19885, April
23, 1997).
In addition, since these tolerances and exemptions that are
established under FFDCA section 408 (l)(6), such as the tolerances in
this final rule, do not require the issuance of a proposed rule, the
requirements of the Regulatory Flexibility Act (RFA) (5 U.S.C. 601 et
seq.) do not apply. Nevertheless, the Agency has previously assessed
whether establishing tolerances, exemptions from tolerances, raising
tolerance levels or expanding exemptions might adversely impact small
entities and concluded, as a generic matter, that there is no adverse
economic impact. The factual basis for the Agency's generic
certification for tolerance acations published on May 4, 1981 (46 FR
24950), and was provided to the Chief Counsel for Advocacy of the Small
Business Administration.
X. Submission to Congress and the Comptroller General
The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. EPA will submit a report containing this rule and other
required information to the U.S. Senate, the U.S. House of
Representatives, and the Comptroller General of the United States prior
to publication of the rule in the Federal Register. This rule is not a
``major rule'' as defined by 5 U.S.C. 804(2).
List of Subjects in 40 CFR Part 180
Environmental protection, Administrative practice and procedure,
Agricultural commodities, Pesticides and pests, Reporting and
recordkeeping requirements.
[[Page 45182]]
Dated: August 11, 1998.
James Jones,
Director, Registration Division, Office of Pesticide Programs.
Therefore, 40 CFR chapter I is amended as follows:
PART 180--[AMENDED]
1. The authority citation for part 180 continues to read as
follows:
Authority: 21 U.S.C. 346a and 371.
2. Section 180.284 is revised to read as follows:
Sec. 180.284 Zinc phosphide; tolerances for residues.
(a) General. Tolerances are established for residues of the
phosphine resulting from the use of the rodenticide zinc phosphide in
or on the raw agricultural commodities as follows:
------------------------------------------------------------------------
Parts per
Commodity million
------------------------------------------------------------------------
Grapes..................................................... 0.01
Grasses (rangeland)........................................ 0.1
Sugarcane.................................................. 0.01
------------------------------------------------------------------------
(b) Section 18 emergency exemptions. Time-limited tolerances are
established for residues of phosphine resulting from the use of the
rodenticide zinc phosphide in connection with use of the pesticide
under FIFRA section 18 emergency exemptions granted by EPA. The
tolerances are specified in the following table. The tolerances expire
on the date specified in the table.
------------------------------------------------------------------------
Parts per Expiration/
Commodity million RevocationDate
------------------------------------------------------------------------
Alfalfa (forage)........................ 0.1 02/01/00
Alfalfa (hay)........................... 0.1 02/01/00
Clover (forage)......................... 0.1 02/01/00
Clover (hay)............................ 0.1 02/01/00
Timothy (forage)........................ 0.1 02/01/00
Timothy (hay)........................... 0.1 02/01/00
Timothy (seed).......................... 0.1 02/01/00
------------------------------------------------------------------------
(c) Tolerances with regional registrations. Tolerances with
regional registration, as defined in Sec. 180.1(n), are established for
residues of phosphine resulting from the use of the rodenticide zinc
phosphide in or on the following raw agricultural commodities as
follows:
------------------------------------------------------------------------
Parts per
Commodity million
------------------------------------------------------------------------
Artichoke (globe).......................................... 0.01
Sugar beet (roots)......................................... 0.04
Sugar beet (tops).......................................... 0.02
------------------------------------------------------------------------
(d) Indirect or inadvertent residues. [Reserved]
[FR Doc. 98-22787 Filed 8-24-98; 8:45 am]
BILLING CODE 6560-50-F