Triasulfuron; Pesticide Tolerance

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: August 18, 1998 (Volume 63, Number 159)]
[Rules and Regulations]
[Page 44146-44152]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr18au98-13]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[OPP-300700; FRL 6023-8]
RIN 2070-AB78

Triasulfuron; Pesticide Tolerance

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This regulation establishes a tolerance for residues of
triasulfuron [3-(6-methoxy-4-methyl-1,3,5-triazin-2-yl)-1-(2-(2-
chloroethoxy)phenylsulfonyl)urea] in or on cattle, kidney; goat,
kidney; grass, forage; grass, hay; horse, kidney; and sheep, kidney.
Novartis Crop Protection, Inc., requested this tolerance under the
Federal Food, Drug and Cosmetic Act (FFDCA), as amended by the Food
Quality Protection Act of 1996 (Pub. L. 104-170).

DATES: This regulation is effective August 18, 1998. Objections and
requests for hearings must be received by EPA on or before October 19,
1998.

ADDRESSES: Written objections and hearing requests, identified by the
docket control number, [OPP-300700], 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-300700], 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, CM#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: opp-docket@epamail.epa.gov. 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
or ASCII file format. All copies of objections and hearing requests in
electronic form must be identified by the docket control number [OPP-
300700]. 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: Jim Tompkins, 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, 703-305-5697; e-mail:
tompkins.jim@epamail.epa.gov.

SUPPLEMENTARY INFORMATION: In the Federal Register of May 29, 1998 (63
FR 29401), (FRL 5791-2) EPA, issued a notice pursuant to section 408 of
the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a(e)
announcing the filing of a pesticide petition (PP 3F4225) for tolerance
by Novartis Crop Protection Inc., P.O. Box 18300, Greensboro, North
Carolina 27419-8300. This notice included a summary of the petition
prepared by Novartis Crop Protection Inc., the registrant. There were
no comments received in response to the notice of filing.
The petition requested that 40 CFR 180.459 be amended by
establishing a permanent tolerance for residues of the herbicide
triasulfuron in or on cattle, kidney at 0.5 parts per million (ppm);
goat, kidney at 0.5 ppm; grass, forage at 7.0 ppm; grass, hay at 2.0
ppm; horse, kidney at 0.5 ppm, and sheep, kidney at 0.5 ppm.

I. Risk Assessment and Statutory Findings

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. . . .''
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

[[Page 44147]]

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 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.

II. 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
triasulfuron and to make a determination on aggregate exposure,
consistent with section 408(b)(2), for a tolerance for residues of
triasulfuron on cattle, kidney at 0.5 ppm; goat, kidney at 0.5 ppm;
grass, forage at 7.0 ppm; grass, hay at 2.0 ppm; horse, kidney at 0.5
ppm, and sheep, kidney at 0.5 ppm. EPA's assessment of the dietary
exposures and risks associated with establishing the tolerance 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 sensitivities
of major identifiable subgroups of consumers, including infants and
children. The nature of the toxic effects caused by triasulfuron are
discussed below.

[[Page 44148]]

1. Acute Toxicity. A battery of acute studies were conducted. The
acute oral estimated lethal dose (LD<INF>50</INF>) which is acutely
lethal to 50% of the animals tested in rats is greater than (>) 5
grams/kilogram (g/kg) which is toxicity Category IV. The acute dermal
LD<INF>50</INF> in rats is > 2 g/kg which is toxicity Category III. The
acute inhalation lethal concentation LC<INF>50</INF> in the rat is >
5.19 mg/liter/4 hours of exposure for technical grade triasulfuron,
which is Toxicity Category IV. Triasulfon is classified in toxicity
Category III for eye irritation (rabbit), toxicity Category IV for skin
irritation, and did not cause dermal sensitization.
2. Subchronic Toxicity (technical). A 13-week subchronic feeding
study in rats produced a NOEL (no observable effect level) of 10/mg/kg/
day and a LOEL (lowest observable effect level) of 500 mg/kg/day based
on decreased weight gain and food intake in both sexes.
A 21-day dermal toxicity study in rabbits produced no NOEL for
systemic effects, a NOEL for irritation of 1,000 mg/kg/day, and a LOEL
for systemic effects of 10 mg/kg/day based on dyspnea, and ruffled fur
that were not considered appropriate endpoints for human risk
assessment.
3. Chronic toxicity (technical). A chronic feeding study in dogs
produced a NOEL of 2.5 mg/kg/day and a LOEL of 25 mg/kg/day based on
increased prostrate cystic hyperplasia.
An carcinogenicity study in mice produced a NOEL of 1.2 mg/kg/day
and a LOEL of 129 mg/kg/day based on centrilobular hepatocytomegaly in
male mice. There was no evidence of oncogenicity.
A chronic feeding/carcinogenicity study in rats produced a NOEL of
32.1 mg/kg/day and a LOEL of 220.8 mg/kg/day based on decreased mean
body weight and decreased body weight gain. There was no evidence of
carcinogenicity.

B. Toxicological Endpoints

1. Acute toxicity. A toxicological effect attributable to a single
exposure (dose) was not identified in the studies available in the data
base including the developmental toxicity studies in rats and rabbits.
Additionally, there were no data requirements for acute or subchronic
rat neurotoxicity studies since there was no evidence of neurotoxicity
in any of the toxicology studies at very high doses.
2. Short - and intermediate - term toxicity. The short- and
intermediate-term dermal and inhalation endpoints are based on oral
developmental and subchronic studies, respectively and route-to-route
extrapolation. The short-term dermal and inhalation No Observable
Effect Level (NOEL) dose of 100 mg/kg/day is based on decreased body
weight and decreased body weight gain in pregnant rats, while the
intermediate-term dermal and inhalation NOEL dose of 10 mg/kg/day is
based on decreased body weight and food intake in rats of both sexes.
3. Chronic toxicity. EPA has established the RfD for triasulfuron
at 0.01 milligrams/kilogram/day (mg/kg/day). This RfD is based on the
NOEL of 1.2 mg/kg/day established from the chronic feeding/
carcinogenicity study in mice.
4. Carcinogenicity. Classified as category E: not likely to be a
human carcinogen.

C. Exposures and Risks

1. From food and feed uses. Tolerances have been established (40
CFR 180.459) for the residues of triasulfuron, in or on a variety of
raw agricultural commodities. Permanent tolerances are already
established on barley, wheat, and various livestock commodities fat,
meat and meat by product of cattle, hogs, sheep, goats and horses other
than kidney, and milk. Risk assessments were conducted by EPA to assess
dietary exposures and risks from triasulfuron 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. An acute dietary risk assessment is
not required because no acute toxicological endpoints were identified
for triasulfuron.
ii. Chronic exposure and risk. The Dietary Risk Exposure System
(DRES) was used for conducting a chronic dietary (food only) exposure
analysis . The analysis evaluates individual food consumption, as
reported by respondents in the USDA 1977-78 Nationwide Food Consumption
Survey, and accumulates exposure to the chemical for each commodity.
In conducting this chronic dietary (food) risk assessment, the
Agency has made very conservative assumptions: that all commodities
having triasulfuron tolerances will contain residues of triasulfuron
and those residues will be at the level of the tolerance. This results
in an over estimate of human dietary exposure.
Using the assumptions and data parameters described above, the DRES
exposure analysis results in an exposure that is equivalent to the
following percentages of the RfD:

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Population Subgroup Exposure (mg/kg/day) %RfD
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U.S. Population (48 states).......................... 0.00046 4.6%

Nursing Infants (<1 year old)........................ 0.00040 4.0%

Non-Nursing Infants (<1 year old).................... 0.0015 15%

Children (1-6 years old)............................. 0.0011 11%

Children (7-12 years old)............................ 0.00073 7.3%

Females (13-19 years old, not preg. or nursing)...... 0.00040 4.0%

Hispanics............................................ 0.00056 5.6%

Non-Hispanic others................................. 0.00050 5.0%

Males (13-19 years old).............................. 0.00052 5.2%
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2. From drinking water. No monitoring data are available to perform
a quantitative drinking water risk assessment for triasulfuron at this
time. The Agency used a Tier I drinking water assessment. This
assessment utilized the SCI-GROW and GENEEC screening models to provide
estimates of ground and surface water contamination respectively from
triasulfuron, but did not consider the behavior of degradates.

[[Page 44149]]

i. Acute exposure and risk. An acute drinking water risk assessment
is not required because no acute toxicological endpoints were
identified for triasulfuron.
ii. Chronic exposure and risk. Based on the chronic dietary (food)
exposure and using default body weights and water consumption figures,
chronic drinking water levels of concern (DWLOC) for drinking water
were calculated. To calculate the DWLOC, the chronic dietary food
exposure was subtracted from the RfD.
Chronic water exposure (mg/kg/day) x (body weight)
DWLOC<INF>chronic</INF> = consumption (L) x 10<SUP>-3</SUP> mg/
<greek-m>g where chronic water exposure (mg/kg/day) = RfD - (chronic
food + residential exposure (mg/kg/day)
The Agency's default body weights and water consumption values used
to calculate DWLOCs are as follows: 70 kg/2L (adult male), 60 kg/2L
(adult female), and 10 kg/1L (child).
For the most highly exposed populations subgroup, non-nursing
infants (< 1 year old), chronic dietary (food only) exposure occupies
15% of the RfD. This is a conservative risk estimate for reasons
described above. The chronic DWLOC for the non-nursing infants (< 1
year old) subgroup is 85 ppb. The predicted 56-day average surface
water concentration by the GENEEC model is 1.68 g/L (ppb) and the
estimated ground water concentration by the SCI-GROW model is 0.19 g/L
(ppb). Therefore, exposure from water is below EPA's DWLOC for chronic
dietary exposure for all of the populations examined.
3. 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 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 triasulfuron 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,
triasulfuron 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 triasulfuron has a common mechanism of
toxicity with other substances.

D. Aggregate Risks and Determination of Safety for U.S. Population

1. Acute risk. The Agency has concluded that the acute aggregate
risk from the proposed use is acceptable. A toxicological effect
attributable to a single exposure dose was not identified in any of the
studies available in the data base .
2. Chronic risk. Using the TMRC exposure assumptions described
above, EPA has concluded that aggregate exposure to triasulfuron from
food will utilize 4.6% of the RfD for the U.S. population. The major
identifiable subgroup with the highest aggregate exposure is 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 triasulfuron in
drinking water and the diet, EPA does not expect the aggregate exposure
to exceed 100% of the RfD. There are no registered residential uses of
triasulfuron.
3. Aggregate cancer risk for U.S. population. In 1991, the Agency
classified triasulfuron as a ``Group E - Evidence of non-
carcinogenicity for humans.'' Therefore, the proposed use is not
expected to pose an unacceptable carcinogenic risk.
4. Conclusion. Aggregate exposure to residues of triasulfuron in
the diet and drinking water is not expected to exceed 100% of the
reference dose. EPA concludes that there is a reasonable certainty that
no harm will result from aggregate exposure to triasulfuron residues in
food and drinking water.

E. Aggregate Risks and Determination of Safety for Infants and Children

1. Safety factor for infants and children--i. In general. In
assessing the potential for additional sensitivity of infants and
children to residues of triasulfuron, EPA considered data from
developmental toxicity studies in the rat and rabbit and a two-
generation reproduction study in the rat. 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
uncertainty factor usually 100 for combined inter- and intra-species
variability and not the additional tenfold MOE/uncertainty is not
necessary because EPA has a complete data base under existing
guidelines and when the severity of the

[[Page 44150]]

effect in infants or children or the potency or unusual toxic
properties do not raise concerns regarding the adequacy of the standard
MOE/safety factor.
ii. Developmental toxicity studies. Triasulfuron was evaluated in a
developmental study in Tif: RAIF (SPF) rats. The following dose levels
were administered by gavage on days 6-15 of gestation: 0, 100, 300 or
900 mg/kg/day. The maternal NOEL was 100 mg/kg/day and the maternal
LOEL was 300 mg/kg/day based on decreased body weight and decreased
body weight gain during gestation. The developmental NOEL and LOEL were
300 and 900 mg/kg/day (HDT), respectively based on reduced ossification
of vertebrae, metatarsals and phalanges.
Triasulfuron was administered to pregnant female chinchilla
rabbits by gavage at dose levels of 0, 40, 120, or 240 mg/kg from days
6 through 18 of gestation. Triasulfuron did not elicit evidence of
developmental toxicity at doses up to and including the high dose of
240 mg/kg/day. The developmental toxicity NOEL is > 240 mg/kg/day.
Maternal toxicity was observed at 240 mg/kg/day manifested as decreased
body weight gain during gestation. The maternal toxicity LOEL is 240
mg/kg/day and the NOEL is 120 mg/kg/day.
iii. Reproductive toxicity study. Triasulfuron was evaluated in a
2-generation reproduction study in the Sprague-Dawley rat. Dosage
levels employed were 0, 0.5, 50, or 250 mg/kg/day. The parental LOEL is
250 mg/kg/day based on significant decreases in premating and total
body weight gain for the F0 and F1 parental animals. The parental NOEL
is 50 mg/kg/day. The reproductive NOEL and LOELs are 50 and 250 mg/kg/
day, respectively based on reduced F1a pup weights at birth and during
lactation .
iv. Pre- and post-natal sensitivity. The data provided noindication
of increased susceptibility of rats or rabbits to in utero and/or
postnatal exposure to triasulfuron. In the prenatal developmental
toxicity study in rats, developmental toxicity was seen only in the
presence of maternal toxicity. In the developmental toxicity study in
rabbits, no evidence of developmental toxicity was seen, even in the
presence of maternal toxicity at the highest dose tested. In the two-
generation reproduction study in rats, effects in the offspring were
observed only at or above treatment levels that resulted in evidence of
parental toxicity. In addition, there is no indication that
triasulfuron is a neurotoxic herbicide. No additional safety factor is
needed.
v. Conclusion. The database is complete and the data provided no
indication of increased susceptibility of rats or rabbits to in utero
and/or postnatal exposure to triasulfuron. Therefore, EPA concluded
that no additional safety factor is needed to protect the safety of
infants and children.
2. Chronic risk. Using the conservative exposure assumptions
described above, EPA has concluded that aggregate exposure to
triasulfuron from food will utilize 15% of the RfD for infants and
children. 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
triasulfuron in drinking water and the diet, EPA does not expect the
aggregate exposure to exceed 100% of the RfD. There are no registered
residential uses of triasulfuron. EPA concludes that there is a
reasonable certainty that no harm will result to infants and children
from aggregate exposure to triasulfuron residues in food and drinking
water.

III. Other Considerations

A. Metabolism In Plants and Animals

In the rat, triasulfuron is excreted primarily in the urine (70-
99%) with lesser amounts excreted in the feces. The majority of
excretion occurs in the first 24 hours following exposure. Residue
levels in the tissues are < 0.1% of the administered dose. The major
excretion product is unchanged triasulfuron in both urine and feces.
In plants, residues of triasulfuron are systemic, and the residue
of regulating conern is exclusively the parent compound. In wheat, the
nature of triasulfuron residues and metabolism are adequately
understood, where metabolism proceeds by hydroxylation of the pheny
ring and hydrolytic cleavage of the urea dridge. EPA has concluded that
triasulfuron metabolism in wheat can be translated to grasses, and that
only the parent compound is of regulatory concern in grasses. The
nature of the residue in ruminants and poultry is adequately
understood. The nature of regulatory concern is the parent compound.

B. Analytical Enforcement Methodology

1. Plants. Suitable analytical methodology exists to enforce the
extension of the tolerances on grasses. Method AG-500B column switching
HPLC with UV detection has undergone successful petition method
validations on wheat grain and straw and has been accepted by the
Agency as the enforcement analytical method for wheat and barley. The
registrant has validated this method in grass forage and hay at the
limit of quantitation (LOQ), 0.05 ppm. The Agency has previously
concluded that Method AG-500B is acceptable to enforce tolerances on
grass hay and forage.
2. Animals. Suitable analytical methodology exists to enforce the
tolerances on animal commodities, including the tolerances on kidneys.
Method AG-508B revised column switching HPLC with UV detection has
undergone successful petition method validation on milk, beef muscle
and kidney and has been accepted by the Agency as the enforcement
analytical method for animal commodities. The validated LOQ is 0.01 ppm
for milk; 0.05 ppm for beef muscle, fat, liver, and kidney; 0.05 ppm
for eggs; and 0.05 ppm for poultry meat, fat, and liver.
3. Multiresidue methods. Triasulfuron and four of its metabolites
were tested through the FDA multiresidue protocols. The submission was
forwarded to FDA for evaluation. Triasulfuron was not determinable by
any of the protocols .

C. Magnitude of Residues

The field trial data on grasses support tolerance levels of 7 ppm
in grass forage and 2 ppm in grass hay for residues of triasulfuron in
conjunction with the proposed use pattern. Also see Meat, Milk,
Poultry, and Eggs. No additional field trial data are required for this
petition.
1. Meat, milk, poultry, and eggs. Grasses are feedstuffs for beef
and dairy cattle. An acceptable feeding study in dairy cattle conducted
at 15, 75, and 150 ppm has previously been reviewed and various animal
commodity tolerances were subsequently established (milk, 0.02 ppm;
meat, fat, and meat by-products of cattle, goats, hogs, horses, and
sheep at 0.1 ppm). The existing tolerances for triasulfuron in animal
commodities are adequate to cover the use of triasulfuron on grasses
with the exception of the tolerances on kidneys. Accordingly, higher
triasulfuron tolerances of 0.5 ppm for the kidneys of cattle, goats,
horses, and sheep are required to support the tolerances on grasses.
2. Processed Food/Feed. There are no processed commodities
associated with grasses.

D. International Residue Limits

There are no CODEX, Canadian, or Mexican maximum residue limits for
residues of triasulfuron.

[[Page 44151]]

E. Rotational Crop Restrictions

There are extensive, very specific rotational crop restrictions on
the product label for the crops: barley, rye, oats, Bermudagrass, proso
millet, field corn, grain sorghum, soybeans, sugar beets, sunflowers,
and onions. There are no rotational or reseeding restrictions for the
planting of wheat.

IV. Conclusion

Therefore, the tolerances are established for residues of
triasulfuron in cattle, goat, horse, and sheep kidney at 0.5 ppm, grass
forage at 7 ppm, grass hay at 2 ppm.

V. 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 19, 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
Confidential Business Information (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.

VI. Public Record and Electronic Submissions

EPA has established a record for this rulemaking under docket
control number [OPP-300700] (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 Rm. 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:
opp-docket@epamail.epa.gov.

Electronic comments must be submitted as an ASCII file avoiding the
use of special 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.

VII. Regulatory Assessment Requirements

This final rule establishes a tolerance under FFDCA section 408(d)
inresponse 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 tolerances and exemptions that are established
on the basis of a petition under FFDCA section 408(d), such as the
tolerance 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
haspreviously 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 actions published on May
4, 1981 (46 FR 24950) and was provided to the Chief Counsel for
Advocacy of the Small Business Administration.

VIII. 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 Fariness 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

[[Page 44152]]

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.

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 180.459, is amended as follows:
i. By adding a heading to paragraph (a).
ii. In paragraph (b), by alphabetically adding the commodities to
the table in paragraph (a), removing the remaining text, and by
reserving and adding a heading.
iii. By adding heading and reserving paragraphs (c) and (d) to read
as follows.

Sec. 180.459 Triasulfuron; tolerances for residues

(a) General.* * *

------------------------------------------------------------------------
Parts per
Commodity million
------------------------------------------------------------------------
Cattle, kidney.............................................. 00.5

Goat, kidney................................................ 00.5

Grass, forage............................................... 07.0

Grass, hay.................................................. 02.0

Horses, kidney.............................................. 00.5

Sheep, kidney............................................... 00.5
------------------------------------------------------------------------

(b) Section 18 emergency exemptions. [Reserved]
(c) Tolerances with regional registrations. [Reserved]
(d) Indirect or inadvertent residues. [Reserved]

[FR Doc. 98-22192 Filed 8-17-98; 8:45 am]
BILLING CODE 6560-50-F

Triasulfuron; Pesticide Tolerance

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