Pesticides; tolerances in food, animal feeds, and raw agricultural commodities: Mesotrione,

[Federal Register: July 10, 2002 (Volume 67, Number 132)]

[Rules and Regulations]

[Page 45650-45656]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr10jy02-12]

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[OPP-2002-0117; FRL-7184-2]

Mesotrione; Pesticide Tolerances for Emergency Exemptions

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

SUMMARY: This regulation establishes time-limited tolerances for residues of mesotrione, 2-[4-(methylsulfonyl)-2-nitrobenzoyl]-1,3- cyclohexanedione, in or on sweet corn and sweet corn forage and stover. This action is in response to EPA's granting of an emergency exemption under section 18 of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) authorizing use of the pesticide on sweet corn. This regulation establishes maximum permissible levels for residues of mesotrione in these food commodities. The tolerances will expire and are revoked on June 30, 2004.

DATES: This regulation is effective July 10, 2002. Objections and requests for hearings, identified by docket control number OPP-2002- 0117, must be received on or before September 9, 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 VII. of the SUPPLEMENTARY INFORMATION. To ensure proper receipt by EPA, your objections and hearing requests must identify docket ID number OPP-2002-0117 in the subject line on the first page of your response.

FOR FURTHER INFORMATION CONTACT: By mail: Libby Pemberton, Registration Division (7505C), Office of Pesticide Programs, Environmental Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460; telephone number: (703) 308-9366; e-mail address: Pemberton.libby@epa.gov.

SUPPLEMENTARY INFORMATION:

1. General Information

   1. Does this Action Apply to Me?

      You may be potentially affected by this action if you are an agricultural producer, food manufacturer, or pesticide manufacturer. Potentially affected categories and entities may include, but are not limited to:

      Examples of Categories

      NAICS codes

      potentially affected entities

      Industry

      111

      Crop production 112

      Animal production 311

      Food manufacturing 32532

      Pesticide manufacturing

      This listing is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be affected by this action. Other types of entities not listed in the 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 action might apply to certain entities. If you have questions regarding the applicability of this action to a particular entity, consult the person listed under FOR FURTHER INFORMATION CONTACT.

   2. How Can I Get Additional Information, Including Copies of This Document and Other Related Documents?

      1. Electronically. You may obtain electronic copies of this document, and certain other related documents that might be available electronically, from the EPA Internet Home Page at http://www.epa.gov/. To access this document, on the Home Page select ``Laws and Regulations,'' ``Regulations and Proposed Rules,'' and then look up the entry for this document under the ``Federal Register''--Environmental Documents. You can also go directly to theFederal Register listings at http://www.epa.gov/fedrgstr/. A frequently updated electronic version of 40 CFR part 180 is available at http://www.access.gpo.gov/nara/cfr/ cfrhtml--00/Title--40/40cfr180--00.html, a beta site currently under development.

      2. In person. The Agency has established an official record for this action under docket ID number OPP-2002-0117. The official record consists of the documents specifically referenced in this action, and other information related to this action, including any information claimed as Confidential Business Information (CBI). This official record includes the documents that are physically located in the docket, as well as the documents that are referenced in those documents. The public version of the official record does not include any information claimed as CBI. The public version of the official record, which includes printed, paper versions of any electronic comments submitted during an applicable comment period is available for inspection in the Public Information and Records Integrity Branch (PIRIB), Rm. 119, 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 telephone number is (703) 305-5805.

2. Background and Statutory Findings

   EPA, on its own initiative, in accordance with sections 408(e) and 408(l)(6) of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a, is establishing tolerances for residues of the herbicide mesotrione, 2-[4-(methylsulfonyl)-2-nitrobenzoyl]-1,3-cyclohexanedione, in or on sweet corn, sweet corn forage, and sweet corn stover at 0.01, 0.50, and 2.0 part per million (ppm), respectively. These tolerances will expire and are revoked on June 30, 2004. EPA will publish a document in the Federal Register to remove the revoked tolerances from the Code of Federal Regulations.

   Section 408(l)(6) of the FFDCA requires EPA to establish a time- limited tolerance or exemption from the requirement for a tolerance for pesticide chemical residues in food that will result from the use of a pesticide under an emergency exemption granted by EPA under section 18 of FIFRA. Such tolerances can be established without providing notice or period for public comment. EPA does not intend for its actions on section 18 related tolerances to set binding precedents for the application of section 408 and the new safety standard to other tolerances and exemptions. Section 408(e) of the FFDCA allows EPA to establish a tolerance or an exemption from the requirement of a tolerance on its own initiative, i.e., without having received any petition from an outside party.

   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

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   chemical residue, including all anticipated dietary exposures and all other exposures for which there is reliable information.'' This includes exposure through drinking water and in residential settings, but does not include occupational exposure. Section 408(b)(2)(C) requires EPA to give special consideration to exposure of infants and children to the pesticide chemical residue in establishing a tolerance and to ``ensure that there is a reasonable certainty that no harm will result to infants and children from aggregate exposure to the pesticide chemical residue....''

   Section 18 of FIFRA authorizes EPA to exempt any Federal or State agency from any provision of FIFRA, if EPA determines that ``emergency conditions exist which require such exemption.'' This provision was not amended by the Food Quality Protection Act (FQPA). EPA has established regulations governing such emergency exemptions in 40 CFR part 166.

3. Emergency Exemption for Mesotrione on Sweet Corn and FFDCA Tolerances

   Due to an unusually warm winter, a non-routine and urgent situation has occurred in Wisconsin due to volunteer potatoes. EPA has authorized under FIFRA section 18 the use of mesotrione on sweet corn for control of volunteer potatoes in Wisconsin. After having reviewed the submission, EPA concurs that emergency conditions exist for this State.

   As part of its assessment of this emergency exemption, EPA assessed the potential risks presented by residues of mesotrione in or on sweet corn. In doing so, EPA considered the safety standard in FFDCA section 408(b)(2), and EPA decided that the necessary tolerance under FFDCA section 408(l)(6) would be consistent with the safety standard and with FIFRA section 18. Consistent with the need to move quickly on the emergency exemption in order to address an urgent non-routine situation and to ensure that the resulting food is safe and lawful, EPA is issuing these tolerances without notice and opportunity for public comment as provided in section 408(l)(6). Although these tolerances will expire and are revoked on June 30, 2004, under FFDCA section 408(l)(5), residues of the pesticide not in excess of the amounts specified in the tolerances remaining in or on sweet corn, sweet corn forage, and sweet corn fodder after that date will not be unlawful, provided the pesticide is applied in a manner that was lawful under FIFRA, and the residues do not exceed a level that was authorized by these tolerances at the time of that application. EPA will take action to revoke these tolerances earlier if any experience with, scientific data on, or other relevant information on this pesticide indicate that the residues are not safe.

   Because these tolerances are being approved under emergency conditions, EPA has not made any decisions about whether mesotrione meets EPA's registration requirements for use on sweet corn or whether permanent tolerances for this use would be appropriate. Under these circumstances, EPA does not believe that these tolerances serve as a basis for registration of mesotrione by a State for special local needs under FIFRA section 24(c). Nor do these tolerances serve as the basis for any State other than Wisconsin to use this pesticide on this crop under section 18 of FIFRA without following all provisions of EPA's regulations implementing section 18 as identified in 40 CFR part 166. For additional information regarding the emergency exemption for mesotrione on sweet corn, contact the Agency's Registration Division at the address provided under FOR FURTHER INFORMATION CONTACT.

4. Aggregate Risk Assessment and Determination of Safety

   EPA performs a number of analyses to determine the risks from aggregate exposure to pesticide residues. For further discussion of the regulatory requirements of section 408 and a complete description of the risk assessment process, see the final rule on Bifenthrin Pesticide Tolerances (62 FR 62961, November 26, 1997) (FRL-5754-7).

   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 mesotrione and to make a determination on aggregate exposure, consistent with section 408(b)(2), for time-limited tolerances for residues of mesotrione, 2-[4-(methylsulfonyl)-2-nitrobenzoyl]-1,3- cyclohexanedione, in or on sweet corn, sweet corn forage, and sweet corn stover at 0.01, 0.50, and 2.0 ppm, respectively. EPA's assessment of the dietary exposures and risks associated with establishing these tolerances follows.

   1. Toxicological Endpoints

      The dose at which no adverse effects are observed (the NOAEL) from the toxicology study identified as appropriate for use in risk assessment is used to estimate the toxicological endpoint. However, the lowest dose at which adverse effects of concern are identified (the LOAEL) is sometimes used for risk assessment if no NOAEL was achieved in the toxicology study selected. An uncertainty factor (UF) is applied to reflect uncertainties inherent in the extrapolation from laboratory animal data to humans and in the variations in sensitivity among members of the human population as well as other unknowns. An UF of 100 is routinely used, 10X to account for interspecies differences and 10X for intra species differences.

      For dietary risk assessment (other than cancer) the Agency uses the UF to calculate an acute or chronic reference dose (acute RfD or chronic RfD) where the RfD is equal to the NOAEL divided by the appropriate UF (RfD = NOAEL/UF). Where an additional safety factor is retained due to concerns unique to the FQPA, this additional factor is applied to the RfD by dividing 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 determine the level of concern (LOC). For example, when 100 is the appropriate UF (10X to account for interspecies differences and 10X for intraspecies differences) the LOC is 100. To estimate risk, a ratio of the NOAEL to exposures (margin of exposure (MOE) = NOAEL/exposure) is calculated and compared to the LOC.

      The linear default risk methodology (Q*) is the primary method currently used by the Agency to quantify carcinogenic risk. The Q*approach assumes that any amount of exposure will lead to some degree of cancer risk. A Q*is calculated and used to estimate risk which represents a probability of occurrence of additional cancer cases (e.g., risk is expressed as 1 x 10-6 or one in a million). Under certain specific circumstances, MOE calculations will be used for the carcinogenic risk assessment. In this non-linear approach, a ``point of departure'' is identified below which carcinogenic effects are not expected. The point of departure is typically a NOAEL based on an endpoint related to cancer effects though it may be a different value derived from the dose response curve. To estimate risk, a ratio of the point of departure to exposure (MOEcancer= point of departure/exposures) is calculated. A summary of the toxicological endpoints for mesotrione used for human risk assessment is shown in the following Table 1:

      [[Page 45652]]

      Table 1.--Summary of Toxicological Dose and Endpoints for Mesotrione for Use in Human Risk Assessment\1\

      Dose Used in Risk FQPA SF and LOC for Study and Toxicological Exposure Scenario

      Assessment, UF

      Risk Assessment

      Effects

      Acute dietary all populations

      Not applicable

      Not applicable

      No appropriate study available.

      Chronic dietary all populations

      LOAEL= 2.1 mg/kg/day FQPA SF = 10X

      Reproduction Study - UF = 300............... cPAD = chronic RfD..... mouse Chronic RfD = 0.007 mg/ FQPA SF = 0.0007 mg/kg/ Offspring LOAEL = 2.1 kg/day.

      day.

      mg/kg/day based upon tyrosinemia in F1and F2aoffspring and ocular discharge in F1 pups.

      Short-Term\1\ Incidental Oral (1-7 NOAEL = 100 mg/kg/day LOC for MOE = 1000 Developmental Toxicity days)

      (Residential)

      Study - rat (Residential)........................

      Maternal LOAEL = 300 mg/ kg/day based upon decreased body weight gains during treatment and decreased food consumption.

      Intermediate-Term\1\ Incidental Oral LOAEL = 2.1 mg/kg/day LOC for MOE = 3000 Reproduction Study - (7 days - several months)

      (Residential)

      mouse (Residential)

      Offspring LOAEL = 2.1 mg/kg/day based upon tyrosinemia in F1and F2aoffspring and ocular discharge in F1 pups.

      Short-Term\1\ dermal (1-7 days)

      Oral study

      LOC for MOE = 300

      Developmental toxicity (Occupational/Residential)

      LOAEL = 100 mg/kg/day (Occupational)

      study - rat (dermal-absorption LOC for MOE = 3,000 Developmental LOAEL = rate = 25%).

      (Residential).

      100 mg/kg/day based upon delays in skeletal ossification and changes in manus/ pes ossification assessments.

      Intermediate-Term\1\ Dermal (1 week - Oral study

      LOC for MOE = 300

      Reproduction Study - several months) (Occupational/

      LOAEL = 2.1 mg/kg/day (Occupational)

      mouse Residential)

      (dermal- absorption LOC for MOE = 3,000 Offspring LOAEL = 2.1 rate = 25%).

      (Residential).

      mg/kg/day based upon tyrosinemia in F1and F2aoffspring and ocular discharge in F1 pups.

      Long-Term\1\ Dermal (several months - Oral study

      LOC for MOE = 300

      Reproduction Study - lifetime)(Occupational/Residential) LOAEL = 2.1 mg/kg/day (Occupational)

      mouse (dermal- absorption LOC for MOE = 3,000 Offspring LOAEL = 2.1 rate = 25%).

      (Residential).

      mg/kg/day based upon tyrosinemia in F1and F2aoffspring and ocular discharge in F1 pups.

      Short-Term 1 Inhalation (1-7 days) Oral study LOAEL = 100 LOC for MOE = 300

      Developmental Toxicity (Occupational/Residential)

      mg/kg/day (inhalation- (Occupational)

      Study - rat absorption rate = LOC for MOE = 3,000 Developmental LOAEL = 100%)

      (Residential).

      100 mg/kg/day based upon delays in skeletal ossification and changes in manus/ pes ossification assessments.

      Intermediate-Term 1 Inhalation (1 Oral study LOAEL = 2.1 LOC for MOE = 300

      Reproduction Study - week - several months)(Occupational/ mg/kg/day (inhalation- (Occupational)

      mouse Residential)

      absorption rate = LOC for MOE = 3,000 Offspring LOAEL = 2.1 100%)

      (Residential).

      mg/kg/day based upon tyrosinemia in F1and F2aoffspring and ocular discharge in F1 pups.

      Long-Term 1 Inhalation (several

      Oral study LOAEL = 2.1 LOC for MOE = 300

      Reproduction Study - months - lifetime) (Occupational/ mg/kg/day (inhalation- (Occupational)

      mouse Residential)

      absorption rate = LOC for MOE = 3,000 Offspring LOAEL = 2.1 100%)

      (Residential).

      mg/kg/day based upon tyrosinemia in F1and F2aoffspring and ocular discharge in F1 pups.

      Cancer (oral, dermal, inhalation) ``not likely''

      Not Applicable

      Acceptable oral rat and mouse carcinogenicity studies; no evidence of carcinogenic or mutagenic potential.

      UF = uncertainty factor, FQPA SF = FQPA safety factor, NOAEL = no observed adverse effect level, LOAEL = lowest observed adverse effect level, PAD = population adjusted dose (a = acute, c = chronic) RfD = reference dose, MOE = margin of exposure, LOC = level of concern.

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      \1\ HED has revised the definitions used in its human health risk assessments to describe occupational and residential exposure durations (Memo, M. Stasikowski, 04-JUN-2001, ``Changes in the Definition of Exposure Durations for Occupational/Residential Risk Assessments Performed in the Health Effects Division''). The new exposure durations are as follows: 1. short-term, defined as lasting from 1 day to 1 month; 2. intermediate- term, defined as lasting from 1 to 6 months; 3. long-term, defined as lasting longer than 6 months. The toxicity endpoints originally selected for the short- (1-7 days) and intermediate-term (1 week to several months) incidental oral and the short- (1-7 days), intermediate- (1 week - several months) and long-term (several months - lifetime) dermal and inhalation endpoints are also applicable for the new exposure duration definitions for these routes of exposure.

   2. Exposure Assessment

      1. Dietary exposure from food and feed uses. Tolerances have been recently established (40 CFR 180.571) for the residues of mesotrione, in or on field corn forage, grain, and stover. Risk assessments were conducted by EPA to assess dietary exposures from mesotrione 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 one day or single exposure. No appropriate study available show any acute dietary effects of concern.

         ii. Chronic exposure.In conducting this chronic dietary risk assessment the Dietary Exposure Evaluation Model (DEEM[reg]) analysis evaluated the individual food consumption as reported by respondents in the USDA 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: Residue levels are at the recommended tolerances for field and sweet corn, and 100% of the crop is treated with mesotrione. The %cPAD for the general U.S. population is 2.1% and for the most sensitive population subgroups, Children (1-6 years old), is 5%.

         iii. Cancer. Acceptable oral rat and mouse carcinogenicity studies showed no evidence of carcinogenic or mutagenic potential.

      2. Dietary exposure from drinking water. The Agency lacks sufficient monitoring exposure data to complete a comprehensive dietary exposure analysis and risk assessment for mesotrione in drinking water. Because the Agency does not have comprehensive monitoring data, drinking water concentration estimates are made by reliance on simulation or modeling taking into account data on the physical characteristics of mesotrione.

         The Agency uses the Generic Estimated Environmental Concentration (GENEEC) or the Pesticide Root Zone/Exposure Analysis Modeling System (PRZM/EXAMS) to estimate pesticide concentrations in surface water and SCI-GROW, which predicts pesticide concentrations in groundwater. In general, EPA will use GENEEC (a tier 1 model) before using PRZM/EXAMS (a tier 2 model) for a screening-level assessment for surface water. The GENEEC model is a subset of the PRZM/EXAMS model that uses a specific high-end runoff scenario for pesticides. GENEEC incorporates a farm pond scenario, while PRZM/EXAMS incorporate an index reservoir environment in place of the previous pond scenario. The PRZM/EXAMS model includes a percent crop area factor as an adjustment to account 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 the removal of pesticides from the source water. The primary use of these models by the Agency at this stage is to provide a coarse screen for sorting out pesticides for which it is highly unlikely that drinking water concentrations would ever exceed human health levels of concern.

         Since the models used are considered to be screening tools in the risk assessment process, the Agency does not use EECs from these models to quantify drinking water exposure and risk as a %RfD or %PAD. Instead, drinking water levels of comparison (DWLOCs) are calculated and used as a point of comparison against the model estimates of a pesticide's concentration in water. DWLOCs are theoretical upper limits on a pesticide's concentration in drinking water in light of total aggregate exposure to a pesticide in food, and from residential uses. Since DWLOCs address total aggregate exposure to mesotrione they are further discussed in the aggregate risk sections below.

         Based on the GENEEC (Version 1.2) and SCI-GROW models the EECs of mesotrione for acute exposures are estimated to be 20 parts per billion (ppb) for surface water and 0.15 ppb for ground water. The EECs for chronic exposures are estimated to be 13 ppb for surface water and 0.15 ppb for ground water.

      3. 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, and flea and tick control on pets). Mesotrione is not registered for use on any sites that would result in residential exposure.

      4. Cumulative exposure to substances with a 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.''

         EPA does not have, at this time, available data to determine whether mesotrione 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, mesotrione 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 mesotrione has a common mechanism of toxicity with other substances. For information regarding EPA's efforts to determine which chemicals have a common mechanism of toxicity and to evaluate the cumulative effects of such chemicals, see the final rule for Bifenthrin Pesticide Tolerances (62 FR 62961, November 26, 1997).

   3. Safety Factor for Infants and Children

      1. In general. 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 prenatal and postnatal toxicity and the completeness of the database on toxicity and exposure 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 margin of exposure (MOE) analysis or through using uncertainty (safety) factors in calculating a dose level that poses no appreciable risk to humans.

      2. Prenatal and postnatal sensitivity. There is quantitative evidence of increased susceptibility demonstrated in the oral prenatal developmental toxicity studies in rats, mice, and rabbits.

         [[Page 45654]]

         Delayed ossification was seen in the fetuses at doses below those at which maternal toxic effects were noted. Maternal toxic effects in the rat were decreased body weight gain during treatment and decreased food consumption and in the rabbit, abortions and GI effects.

      5. Conclusion. The FQPA safety factor (10X) is retained in assessing the risk posed because there is quantitative evidence of increased susceptibility of the young exposed to mesotrione in the prenatal developmental toxicity studies in mice, rats, and rabbits and in the multi-generation reproduction study in mice, there is qualitative evidence of increased susceptibility of the young exposed to mesotrione in the multi-generation reproduction study in rats; and a Developmental Neurotoxicity Study is required to assess the effects of tyrosinemia on the developing nervous system exposed to mesotrione.

   4. Aggregate Risks and Determination of Safety

      To estimate total aggregate exposure to a pesticide from food, drinking water, and residential uses, the Agency calculates DWLOCs which are used as a point of comparison against the model estimates of a pesticide's concentration in water. DWLOC values are not regulatory standards for drinking water. DWLOCs are theoretical upper limits on a pesticide's concentration in drinking water in light of total aggregate exposure to a pesticide in food and residential uses. In calculating a DWLOC, the Agency determines how much of the acceptable exposure (i.e., the PAD) is available for exposure through drinking water [e.g., allowable chronic water exposure (mg/kg/day) = cPAD - (average food + chronic non-dietary, non-occupational exposure)]. This allowable exposure 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 USEPA's Office of Water are used to calculate DWLOCs: 2L/70 kg (adult male), 2L/60 kg (adult female), and 1L/10 kg (child). Default body weights and drinking water consumption values vary on an individual basis. This variation will be taken into account in more refined screening-level and quantitative drinking 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 groundwater are less than the calculated DWLOCs, EPA concludes with reasonable certainty that exposures to mesotrione in drinking water (when considered along with other sources of exposure for which EPA has reliable data) would not result in unacceptable levels of aggregate human health risk at this time. Because EPA considers the aggregate risk resulting from multiple exposure pathways associated with a pesticide's uses, levels of comparison in drinking water may vary as those uses change. If new uses are added in the future, EPA will reassess the potential impacts of mesotrione on drinking water as a part of the aggregate risk assessment process.

      1. Acute risk. Acute doses and endpoints were not selected for the general U.S. population (including infants and children) or the females (13-50 years old) population subgroup for mesotrione; therefore, an acute dietary exposure analysis was not performed.

      2. Chronic risk. Using the exposure assumptions described in this unit for chronic exposure, EPA has concluded that exposure to mesotrione from food will utilize 2.1% of the cPAD for the U.S. population, 4.4% of the cPAD for all infants 02-17265Filed7-9-02; 8:45 am] BILLING CODE 6560-50-S