Pesticides; tolerances in food, animal feeds, and raw agricultural commodities: Triflusulfuron methyl,
[Federal Register: June 12, 2002 (Volume 67, Number 113)]
[Rules and Regulations]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 180
Triflusulfuron Methyl; Pesticide Tolerance
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
SUMMARY: This regulation establishes tolerances for residues of triflusulfuron methyl in or on beet, sugar, roots; beet, sugar, tops; and chicory, roots. Interregional Research Project 4 (IR-4) and E. I. Dupont de Nemours & Company requested these tolerances under the Federal Food, Drug, and Cosmetic Act (FFDCA), as amended by the Food Quality Protection Act of 1996 (FQPA).
DATES: This regulation is effective June 12, 2002. Objections and requests for hearings, identified by docket ID number OPP-2002-0082, must be received on or before August 12, 2002.
ADDRESSES: Written objections and hearing requests may be submitted by mail, in person, or by courier. Please follow the detailed instructions for each method as provided in Unit VI. of the SUPPLEMENTARY INFORMATION. To ensure proper receipt by EPA, your objections and hearing requests must identify docket ID number OPP-2002-0082 in the subject line on the first page of your response.
FOR FURTHER INFORMATION CONTACT: By mail: James A. Tompkins or Hoyt Jamerson, Registration Division (7505C), Office of Pesticide Programs, Environmental Protection Agency, 1200 Pennsylvania Ave., NW.,Washington, DC 20460; telephone number: (703) 305-5697 or (703) 308-9368; e-mail address: email@example.com or firstname.lastname@example.org.
Does this Action Apply to Me?
You may be affected by this action if you are an agricultural producer, foodmanufacturer, or pesticide manufacturer. Potentially affected categories and entities may include,but are not limited to:
Table 1.--Examples of Potentially Affected Entities
Examples of Categories
potentially affected entities
Crop production 112............... Animal production 311............... Food manufacturing 32532............. Pesticide manufacturing
This listing is not intended to be exhaustive, but rather provides a guide forreaders regarding entities likely to be affected by this action. Other types of entities not listed inthe table could also be affected. The North American Industrial Classification System (NAICS)codes have been provided to assist you and others in determining whether or not this actionmight apply to certain entities. If you have questions regarding the applicability of this action toa particular entity, consult the persons listed under FOR FURTHER INFORMATION CONTACT.
How Can I Get Additional Information, Including Copies of this Document andOther Related Documents?
Electronically. You may obtain electronic copies of thisdocument, and certain other related documents that might be available electronically, from theEPA Internet Home Page at http:// www.epa.gov/. To access this document, on the Home Pageselect ``Laws and Regulations,'' ``Regulations and Proposed Rules,'' and then look up the entry for this document under the ``Federal Register--Environmental Documents.'' You canalso go directly to the Federal Register listings athttp://www.epa.gov/fedrgstr/. A frequently updated electronic version of 40 CFR part 180 is available athttp://www.access.gpo.gov/nara/cfr/ cfrhtml--00/Title--40/40cfr180--00.html, a beta site currently under development. To access the OPPTS HarmonizedGuidelines referenced in this document, go directly to the guidelines athttp://www.epa.gov/ opptsfrs/home/guidelin.htm.
In person. The Agency has established an official recordfor this action under docket ID number OPP-2002-0082. The official recordconsists of the documents specifically referenced in this action, and other information related tothis action, including any information claimed as Confidential Business Information (CBI). Thisofficial record includes the documents that are physically located in the docket, as well as thedocuments that are referenced in those documents. The public version of the official record doesnot include any information claimed as CBI. The public version of the official record, whichincludes printed, paper versions of any electronic comments submitted during an applicablecomment period is available for inspection in the Public Information and Records IntegrityBranch (PIRIB), Rm. 119, Crystal Mall 2, 1921 Jefferson Davis Hwy., Arlington, VA,from 8:30 a.m. to 4 p.m., Monday through Friday, excluding legal holidays. The PIRIB telephonenumber is (703) 305-5805.
Background and Statutory Findings
In the Federal Register of December 22, 1999(64 FR 71760) (FRL- 6391-1) and August 8, 2001 (66 FR 41593) (FRL-6795-4), EPA issued a notice pursuant to section 408 of FFDCA, 21 U.S.C. 346a, as amended by FQPA (Public Law 104-170), announcing the filing of a pesticide petition (PP) by IR-4 and E. I. Dupont de Nemours & Company, 681 US Highway 1 South North Brunswick, NJ 08902-3390, and E.I. DuPont de
Nemours & Company, DuPont Agricultural Products, Barley Mill Plaza,Wilmington, DE 19880-0038. This notice included a summary of the petition prepared by E.I.DuPont de Nemours, the registrant. There were no comments received in response to thenotice of filing.
The petition requested that 40 CFR 180.492 be amended by establishing a tolerance for residues of the herbicide, triflusulfuron methyl, methyl 2-[[[[[4-(dimethylamino)-6-(2,2,2-trifluoroethoxy)- 1,3,5-triazin-2-yl]amino]carbonyl]amino]sulfonyl]-3-methylbenzoate, in or on chicory, root at 0.05 parts per million (ppm) (PP 0E6214). PP 4F4278 proposed that the currently established time-limited tolerances forsugar beet, root at 0.05 ppm and sugar beet, top at 0.05 ppm be converted to permanenttolerances and to revise the commodities to read beet, sugar, roots at 0.05 ppm and beet,sugar, tops at 0.05 ppm.
Section 408(b)(2)(A)(i) of 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 thetolerance is ``safe.'' Section 408(b)(2)(A)(ii) of FFDCA defines``safe'' to mean that ``there is a reasonable certainty that no harmwill result from aggregate exposure to the pesticide chemical residue, including all anticipateddietary exposures and all other exposures for which there is reliable information.''This includes exposure through drinking water and in residential settings, but does not includeoccupational exposure. Section 408(b)(2)(C) of FFDCA requires EPA to give special consideration toexposure of infants and children to the pesticide chemical residue in establishing a tolerance andto ``ensure that there is a reasonable certainty that no harm will result to infants andchildren from aggregate exposure to the pesticide chemical residue....''
EPA performs a number of analyses to determine the risks from aggregateexposure to pesticide residues. For further discussion of the regulatory requirements of section408 of FFDCA and a complete description of the risk assessment process, see the final rule on BifenthrinPesticide Tolerances (62 FR 62961, November 26, 1997) (FRL- 5754-7).
Aggregate Risk Assessment and Determination of Safety
Consistent with section 408(b)(2)(D) of FFDCA, EPA has reviewed the available scientificdata and other relevant information in support of this action. EPA has sufficient data to assess thehazards of and to make a determination on aggregate exposure, consistent with section 408(b)(2) of FFDCA,for tolerances for residues of triflusulfuron methyl on chicory, root at 0.05 ppm; and to convert the time-limited tolerances for beet, sugar, root at 0.05 ppm and beet, sugar, top at 0.05 to permanent tolerances. EPA'sassessment of exposures and risks associated with establishing the tolerances follows.
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 ofmajor identifiable subgroups of consumers, including infants and children. The nature of thetoxic effects caused by triflusulfuron methyl are discussed in Table 2 of this unit, as well asthe no- observed-adverse-effect-level (NOAEL) and the lowest-observed-adverse- effect-level(LOAEL) from the toxicity studies reviewed.
Table 2.-- Subchronic, Chronic, and Other Toxicity
90-Day oral toxicity
NOAEL = 6.56/7.71 (m/f) mg/kg/day rodents
(milligram/kilogram/day) (two studies submitted)... LOAEL = 133/153 (m/f) mg/kg/day based on decreased body weight gain and food efficiency in males; increased incidence of histopathological changes (kidney and spleen) in females. NOAEL = 6.20/7.54 (m/f) mg/kg/day LOAEL = 127/150 (m/f) mg/kg/day; based on decreased mean body weight gain, decreased mean food consumption (f), decreased mean food efficiency, alterations in hematology parameters (m); hemosiderin in kidneys (f)
90-Day oral toxicity in NOAEL = 3.9/3.7 (m/f) mg/kg/day nonrodents
LOAEL = 146.9/159.9 (m/f) mg/kg/day based on decreased mean body weight and body weight gain, decreased hematocrit, hemoglobin, RBC`s, SGOT, SGPT, ALP, absolute and relative liver and testes weight; microscopic abnormalities of the liver and testes.
21/28-Day dermal toxicity NOAEL = 1,000 mg/kg/day LOAEL = 1,000 mg/kg/day based on limit dose.
Pre-natal developmental in Maternal NOAEL = 120 mg/kg/day rodents
LOAEL = 350 mg/kg/day based on decreased body weight gain, decreased food consumption and lower food efficiency. Developmental NOAEL = >1,000 mg/kg/day limit dose LOAEL = >1,000 mg/kg/day.
Pre-natal developmental in Maternal NOAEL = 90 mg/kg/day nonrodents
LOAEL = 270 mg/kg/day based on clinical signs including absent/reduced stool and stained fur, maternal death, increased abortions, decreased body weight gain, and lower-food efficiency. Developmental NOAEL = 90 mg/kg/day LOAEL = 270 mg/kg/day based on increased abortions.
Reproduction and fertility Parental/Systemic NOAEL = 5.81/7.75 (m/f) effects
mg/kg/day LOAEL = 44/58 mg/kg/day based on decreased body weight, decreased body weight gain, decreased food consumption, and decreased- food efficiency. Reproductive NOAEL = 89.5/115 (m/f) mg/kg/ day based on the absence of reproductive effects at the highest dose tested (HDT). LOAEL = >115 mg/kg/day. Offspring NOAEL = 5.81/7.75 (m/f) mg/kg/day LOAEL = 44/58 (m/f) mg/kg/day based on decreased F1 pup body weight on days 14 and 21 due to exposure via milk and in the diet.
Chronic toxicity rodents NOAEL = 2.44 mg/kg/day LOAEL = 30.6 mg/kg/day based on decreased body weight and body weight gain, alteration in hematology (mainly males) and increased incidences of interstitial cell hyperplasia in testes.
Chronic toxicity dogs NOAEL = 26.9 mg/kg/day LOAEL = 116.6 mg/kg/day based on increased liver weight, alkaline phosphatase, and hepatocellular hypertrophy.
Carcino-genicity rats NOAEL = 2.44 mg/kg/day LOAEL = 30.6 mg/kg/day based on decreased body weight and body weight gain, alteration in hematology (mainly males) and increased incidences of interstitial cell hyperplasia in the testes. (Possible) evidence of carcinogenicity
Carcino-genicity mice NOAEL = 14.6 mg/kg/day LOAEL = 349 mg/kg/day based on increased liver weight and increased hepatic cell tumors (adenomas and/or carcinomas combined. (Possible) evidence of carcinogenicity
No genotoxic effect in Ames assay using S. typhimurium. (two studies)
No genotoxic effect in Chinese hampster ovary (CHO) gene mutation assay
Positive effects in the presence of 870.5395...............................
metabolic activation, but inconclusive in the absence of metabolic activation in a chromosomal aberration/human lymphocyte study. Mouse micronucleus assay negative for genotoxic effects.
NOAEL = >2,000 mg/kg/day HDT screening battery
LOAEL = Not established
Subchronic neurotoxicity NOAEL = 92.7/7.1 (m/f) mg/kg/day screening battery
LOAEL = 186.2/51.6 (m/f) mg/kg/day based on decreased body weight and body weight gain.
Urine major route of excretion at low doses pharmacokinetics
and the feces at high doses. N-desmethyl triflusulfuron methyl, the upper urinary metabolite composed between 25-44% of the dose at the low dose level (single and repeated). Parent was the major component in the high dose feces and liver.
No dermal absorption studies were available. A 27% absorption was calculated from a ratio of the LOAEL from a developmental and 21-day dermal toxicity studies in rabbits.
Special studies: In vivo The purpose of these studies was to and in vitro mechanic investigate the mechanism of Leydig cell studies
tumor induction in the testes of male rats. A dose-dependent decrease in aromatase enzyme activity was seen in vitro, but was inconclusive in vivo.
The dose at which no adverse effects are observed, the NOAEL, from thetoxicology study identified as appropriate for use in risk assessment is used to estimate thetoxicological level of concern (LOC). However, the lowest dose at which adverse effects ofconcern are identified, the LOAEL, is sometimes used for risk assessment if no NOAEL wasachieved in the toxicology study selected. An uncertainty factor (UF) is applied to reflectuncertainties inherent in the extrapolation from laboratory animal data to humans and in thevariations in sensitivity among members of the human population as well as other unknowns. AnUF of 100 is routinely used, 10X to account for interspecies differences and 10X for intraspecies differences.
For dietary risk assessment (other than cancer) the Agency uses the UF to calculatean acute or chronic reference dose (acute RfD or chronic RfD) where the RfD is equal to theNOAEL divided by the appropriate UF (RfD = NOAEL/
UF). Where an additional safety factor isretained due to concerns unique to the FQPA, this additional factor is applied to the RfD bydividing the RfD by such additional factor. The acute or chronic Population Adjusted Dose(aPAD or cPAD) is a modification of the RfD to accommodate this type of FQPA safety factor.
For non-dietary risk assessments (other than cancer) the UF is used to determinethe LOC. For example, when 100 is the appropriate UF (10X to account for interspeciesdifferences and 10X for intraspecies differences) the LOC is 100. To estimate risk, a ratio of theNOAEL to exposures (margin of exposure (MOE) = NOAEL/exposure) is calculated andcompared to the LOC.
The linear default risk methodology (Q*) is the primary method currently used bythe Agency to quantify carcinogenic risk. The Q* approach assumes that any amount of exposurewill lead to some degree of cancer risk. A Q* is calculated and used to estimate risk whichrepresents a probability of occurrence of additional cancer cases (e.g., risk is expressed as1 x 10-\6\ or one in a million). Under certain specificcircumstances, MOE calculations will be used for the carcinogenic risk assessment. In this non-linear approach, a ``point of departure'' is identified below whichcarcinogenic effects are not expected. The point of departure is typically a NOAEL based on anendpoint related to cancer effects though it may be a different value derived from the doseresponse curve. To estimate risk, a ratio of the point of departure to exposure (MOEcancer= point of departure/exposures) is calculated. A summary of thetoxicological endpoints for triflusulfuron methyl used for human risk assessment is shown in Table 3 of this unit:
Table 3.-- Summary of Toxicological Dose and Endpoints for Triflusulfuron Methyl for Use in Human Risk Assessment
Dose used in risk FQPA SF* and LOC for Study and toxicological Exposure scenario
Acute Dietary (all population
No toxicological subgroups)
effects attributable to a single exposure (dose) were observed in oral toxicity studies. Therefore, an acute RfD can not be established and an acute dietary risk assessment will not be conducted for the general population.
Chronic Dietary (all populations) NOAEL = 2.44 mg/kg/day FQPA SF = 1x
Chronic Toxicity in UF = 100............... cPAD = chronic RfD /... Rats Chronic RfD = 0.024 mg/ FQPA SF = 0.024 mg/kg/ LOAEL = 30.6 mg/kg/day kg/day.
based on decreased body weight and body weight gain, alter. In hematology (mainly males), increased incidence of interstitial cell hyperplasia in testes.
Cancer (oral, dermal, inhalation)
Triflusulfuron methyl is classified as a Group C--possible human carcinogen chemical.
* The reference to the FQPA safety factor refers to any additional safety factor retained due to concerns unique to the FQPA.
Dietary exposure from food and feed uses. Tolerances have been established (40 CFR 180.492) for the residues of triflusulfuron methyl in or on sugar beet, root and sugar beet, top. Riskassessments were conducted by EPA to assess dietary exposures from triflusulfuron methyl in food as follows:
i. Acute exposure. 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 1-day or single exposure. There are no effects attributable to a single, oral dose of triflusulfuron methyl. Therefore, an acute dietary risk assessment was not conducted.
ii. Chronic exposure. In conducting this chronic dietary riskassessment, the Dietary Exposure Evaluation Model (DEEM\TM\) analysisevaluated the individual food consumption as reported by respondents in the United States Department of Agriculture 1989-1992 Nationwide Continuing Surveys of Food Intake by Individuals (CSFII) and accumulated exposure to the chemical for each commodity. The following assumptions were made for the chronic exposure assessments: Tolerance level residues and that 100% of the crop is treated. Because suitable data depicting residues of triflusulfuron methyl in drinking were not available for incorporation into the dietary exposure model,the dietary exposure estimates do not include potential exposure from drinking water. The dietary exposure is based on sugar beets, because chicory was not reported as being consumed in the 1989-1992 CSFII. Therefore, inclusion of chicory in the dietary analysiswould not alter the exposure or risk estimates from those obtained from sugar beets. The cRfD or 0.024 mg/kg/day was determined where the NOAEL of 2.44 mg/kg/ day is based on decreased body weight gain, alterations in hematology (mainly in males) and increases in the incidence of interstitial hyperplasia in the testes at the LOAEL of 30.6 mg/kg/day. A 100-fold UF for interspecies extrapolation and intraspecies variability was applied.
iii. Cancer. Triflusulfuron methyl is classified as a Group C-- possible human carcinogen chemical and for the purpose of risk characterization the RfD approach should be used for quantification of human risk. This decision was based on evidence of statistically significant, dose related increases in the incidence of interstitialcell adenomas of the testes at two doses, as well as statistically significant positive trend for these tumors in male rats. The testicular interstitial cell adenomas observed in the rat werebenign. There was no reported increased tumor incidences of any type in the female ratand the dosing was adequate for assessing the carcinogenic potential of triflusulfuron methyl. Evidence of a hormonal mechanism for development of these benign tumors inrats does exist, however, the data were suggestive but not conclusive. Although there wassome evidence of clastogenic activity for triflusulfuron methyl, positive results were onlyseen with activation in human lymphocytes/ chromosomal aberration assay. Triflusulfuron methyl is a member of a class of chemicals known as sulfonylureas. Of the 12
analogsstructurally related to triflusulfuron methyl, three sulfonylureas have been associated withcarcinogenicity in rodents. Primisulfuron methyl and prosulfuron are classified as Group Dcarcinogens (not classifiable as to human carcinogenicity). Only tribenuron methyl isclassified as a Group C carcinogen (possible human carcinogen), however, a Q* for cancer risk assessment is not required because there is noevidence of genotoxicity and the increased incidence of mammary gland tumors is observed at doses which exceed the maximum tolerated dose. Therefore the RfD approach is appropriate for quantification of human cancer risk.
Dietary exposure from drinking water. The Agency lacks sufficient monitoring exposure data to complete acomprehensive dietary exposure analysis and risk assessment for triflusulfuron methyl indrinking water. Because the Agency does not have comprehensive monitoring data, drinking water concentration estimates are made by reliance on simulation or modeling taking intoaccount data on the physical characteristics of triflusulfuron methyl.
The Agency uses the First Index Reservoir Screening Tool (FIRST) or the Pesticide Root Zone/Exposure Analysis Modeling System (PRZM/EXAMS), to produce estimates of pesticide concentrations in an index reservoir. The SCI-GROW model is used topredict pesticide concentrations in shallow ground water. For a screening-level assessment forsurface water EPA will use FIRST (a tier 1 model) before using PRZM/EXAMS (a tier 2 model).The FIRST model is a subset of the PRZM/EXAMS model that uses a specific high-end runoffscenario for pesticides. While both FIRST and PRZM/EXAMS incorporate an index reservoirenvironment, the PRZM/EXAMS model includes a percent crop area factor as an adjustment toaccount for the maximum percent crop coverage within a watershed or drainage basin.
None of these models include consideration of the impact, processing (mixing,dilution, or treatment) of raw water for distribution as drinking water would likely have on theremoval of pesticides from the source water. The primary use of these models by the Agency atthis stage is to provide a coarse screen for sorting out pesticides for which it is highly unlikely thatdrinking water concentrations would ever exceed human health LOCs.
Since the models used are considered to be screening tools in the risk assessmentprocess, the Agency does not use estimated environmental concentrations (EECs) from thesemodels to quantify drinking water exposure and risk as a %RfD or %PAD. Instead drinking waterlevels of comparison (DWLOCs) are calculated and used as a point of comparison against themodel estimates of a pesticide's concentration in water. DWLOCs are theoretical upper limits ona pesticide's concentration in drinking water in light of total aggregate exposure to a pesticide infood, and from residential uses. Since DWLOCs address total aggregate exposure totriflusulfuron methyl they are further discussed in the aggregate risk sections in Unit III. E.
Based on the PRZM/EXAMS and SCI-GROW models the EECs of triflusulfuron methyl for acute exposures areestimated to be 0.42 parts per billion (ppb) for surface water and 0.5 ppb for ground water. TheEECs for chronic exposures are estimated to be 0.005 ppb for surface water and 0.5 ug/L (micrograms/Liter) forground water.
From non-dietary exposure. The term``residential exposure'' is used in this document to refer to non-occupational,non-dietary exposure (e.g., for lawn and garden pest control, indoor pest control, termiticides, andflea and tick control on pets).
Triflusulfuron methyl is not registered for use on any sites that would result inresidential exposure.
Cumulative exposure to substances with a common mechanism oftoxicity. Section 408(b)(2)(D)(v) of FFDCA 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.''
EPA does not have, at this time, available data to determine whethertriflusulfuron methyl has a common mechanism of toxicity with other substances or how toinclude this pesticide in a cumulative risk assessment. Unlike other pesticides for which EPA hasfollowed a cumulative risk approach based on a common mechanism of toxicity, triflusulfuron methyl does not appear to produce a toxic metabolite produced by other substances. For thepurposes of this tolerance action, therefore, EPA has not assumed that triflusulfuron methylhas a common mechanism of toxicity with other substances. For information regarding EPA'sefforts to determine which chemicals have a common mechanism of toxicity and to evaluate thecumulative effects of such chemicals, see the final rule for Bifenthrin Pesticide Tolerances (62 FR 62961, November 26, 1997).
Safety Factor for Infants and Children
In general. Section 408 of FFDCA provides that EPA shallapply an additional 10-fold margin of safety for infants and children in the case of thresholdeffects to account for pre-natal and post-natal toxicity and the completeness of the data base ontoxicity and exposure unless EPA determines that a different margin of safety will be safe forinfants and children. Margins of safety are incorporated into EPA risk assessments either directlythrough use of a MOE analysis or through using uncertainty (safety) factorsin calculating a dose level that poses no appreciable risk to humans.
Pre-natal and post-natal sensitivity. There is noquantitative or qualitative evidence of increased susceptibility of rat or rabbit fetuses to in utero exposure in the developmental studies. No developmental toxicity was seen at thelimit dose (1,000 mg/kg/day) in rats. In rabbits, developmental toxicity manifested asabortions in the presence of severe maternal toxicity (mortality, abortions, clinical signs,decreased body weight, and food efficiency). In the 2-generation reproductive toxicity study,the effects in the offspring (decreased pup body weight in F1 on days 14 and 21; latelactation) can be attributed to the decreases in body weights seen in the parental animals.In addition, this decrease was seen only in the F1 generation but not in the secondgeneration. There is no indication for a developmental neurotoxicity study since noneuropathological or neurobehavioral effects in the acute or subchronic neurotoxicitystudies were observed; no alteration of the fetal nervous system was observed; and noevidence of neurotoxicity was found in other studies in the data base.
Conclusion. The toxicity data base for triflusulfuronmethyl is complete except for a 28-day inhalation (nose only) toxicity study. This study is ofmarginal value for the FFDCA determination because there are no residential uses oftriflusulfuron methyl. Exposure data are complete or are estimated based on data that reasonably accounts for potentialexposures. Based on these reasons, the FQPA Safety Factor for the protection of childrenhas been removed (i.e. reduced to 1x.)
Aggregate Risks and Determination of Safety
To estimate total aggregate exposure to a pesticide from food, drinking water,
andresidential uses, the Agency calculates DWLOCs which are used as a point of comparison againstthe model estimates of a pesticide's concentration in water. DWLOC values are notregulatory standards for drinking water. DWLOCs are theoretical upper limits on a pesticide'sconcentration in drinking water in light of total aggregate exposure to a pesticide in food andresidential uses. In calculating a DWLOC, the Agency determines how much of the acceptableexposure (i.e., the PAD) is available for exposure through drinking water (e.g., allowable chronicwater exposure (mg/kg/day) = cPAD - (average food + residential exposure)). This allowableexposure through drinking water is used to calculate a DWLOC.
A DWLOC will vary depending on the toxic endpoint, drinking water consumption,and body weights. Default body weights and consumption values as used by the EPA Office of Water are used to calculate DWLOCs: 2L/70 kg (adult male), 2L/60 kg (adult female), and 1L/10kg (child). Default body weights and drinking water consumption values vary on an individualbasis. This variation will be taken into account in more refined screening-level and quantitativedrinking water exposure assessments. Different populations will have different DWLOCs.Generally, a DWLOC is calculated for each type of risk assessment used: Acute, short-term, intermediate-term, chronic, and cancer.
When EECs for surface water and ground water are less than the calculatedDWLOCs, OPP concludes with reasonable certainty that exposures to the pesticide in drinkingwater (when considered along with other sources of exposure for which OPP has reliable data)would not result in unacceptable levels of aggregate human health risk at this time. Because OPPconsiders the aggregate risk resulting from multiple exposure pathways associated with apesticide's uses, levels of comparison in drinking water may vary as those uses change. If newuses are added in the future, OPP will reassess the potential impacts of residues of the pesticide indrinking water as a part of the aggregate risk assessment process.
Acute risk. Because there are no effects attributable to asingle, oral dose of triflusulfuron methyl is not expected to pose anacute risk.
Chronic risk. Using the exposure assumptions described in this unit for chronic exposure, EPA has concluded that exposure to triflusulfuron methyl from food will utilize 02-14501Filed6-11-02; 8:45 am] BILLING CODE 6560-50-S