[Federal Register Volume 63, Number 159 (Tuesday, August 18, 1998)]
[Rules and Regulations]
[Pages 44146-44152]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-22192]


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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: [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 
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: 
[email protected].

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 (LD50) 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 
LD50 in rats is > 2 g/kg which is toxicity Category III. The 
acute inhalation lethal concentation LC50 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           
----------------------------------------------------------------------------------------------------------------
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) 
DWLOCchronic = consumption (L) x 10-3 mg/
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:
    [email protected].


    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