Pyroxsulam; Pesticide Tolerances
Federal Register: February 27, 2008 (Volume 73, Number 39)
Rules and Regulations
Page 10398-10402
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
DOCID:fr27fe08-8
ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 180
EPA-HQ-OPP-2006-0785; FRL-8349-9]
Pyroxsulam; Pesticide Tolerances
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
SUMMARY: This regulation establishes tolerances for residues of pyroxsulam in or on wheat, forage; wheat, grain; wheat, hay and wheat, straw. Dow AgroSciences LLC requested this tolerance under the Federal
Food, Drug, and Cosmetic Act (FFDCA).
DATES: This regulation is effective February 27, 2008. Objections and requests for hearings must be received on or before April 28, 2008, and must be filed in accordance with the instructions provided in 40 CFR part 178 (see also Unit I.C. of the SUPPLEMENTARY INFORMATION).
ADDRESSES: EPA has established a docket for this action under docket identification (ID) number EPA-HQ-OPP-2006-0785. To access the electronic docket, go to http://www.regulations.gov, select ``Advanced
Search,'' then ``Docket Search.'' Insert the docket ID number where indicated and select the ``Submit'' button. Follow the instructions on the regulations.gov website to view the docket index or access available documents. All documents in the docket are listed in the docket index available in regulations.gov. Although listed in the index, some information is not publicly available, e.g., Confidential
Business Information (CBI) or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the Internet and will be publicly available only in hard copy form. Publicly available docket materials are available in the electronic docket at http://www.regulations.gov, or, if only available in hard copy, at the OPP Regulatory Public Docket in
Rm. S-4400, One Potomac Yard (South Bldg.), 2777 S. Crystal Dr.,
Arlington, VA. The Docket Facility is open from 8:30 a.m. to 4 p.m.,
Monday through Friday, excluding legal holidays. The Docket Facility telephone number is (703) 305-5805.
FOR FURTHER INFORMATION CONTACT: Erik Kraft, Registration Division
(7505P), Office of Pesticide Programs, Environmental Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460-0001; telephone number: (703) 308-9358; e-mail address: Kraft.Erik@epa.gov.
SUPPLEMENTARY INFORMATION:
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General Information
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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 entities may include, but are not limited to those engaged in the following activities:
Crop production (NAICS code 111), e.g., agricultural workers; greenhouse, nursery, and floriculture workers; farmers.
Animal production (NAICS code 112), e.g., cattle ranchers and farmers, dairy cattle farmers, livestock farmers.
Food manufacturing (NAICS code 311), e.g., agricultural workers; farmers; greenhouse, nursery, and floriculture workers; ranchers; pesticide applicators.
Pesticide manufacturing (NAICS code 32532), e.g., agricultural workers; commercial applicators; farmers; greenhouse, nursery, and floriculture workers; residential users.
This listing is not intended to be exhaustive, but rather to provide a guide for readers regarding entities likely to be affected by this action. Other types of entities not listed in this unit could also be affected. The North American Industrial Classification System
(NAICS) codes have been provided to assist you and others in determining whether this action might apply to certain entities. If you have any questions regarding the applicability of this action to a particular entity, consult the person listed under FOR FURTHER
INFORMATION CONTACT.
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How Can I Access Electronic Copies of this Document?
In addition to accessing an electronic copy of this Federal
Register document through the electronic docket at http:// www.regulations.gov, you may access this Federal Register document electronically through the EPA Internet under the ``Federal Register'' listings at http://www.epa.gov/fedrgstr. You may also access a frequently updated electronic version of EPA's tolerance regulations at 40 CFR part 180 through the Government Printing Office's pilot e-CFR site at http://www.gpoaccess.gov/ecfr.
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Can I File an Objection or Hearing Request?
Under section 408(g) of FFDCA, any person may file an objection to any aspect of this regulation and may also request a hearing on those objections. You must file your objection or request a hearing on this regulation in accordance with the instructions provided in 40 CFR part 178. To ensure proper receipt by EPA, you must identify docket ID number EPA-HQ-OPP-2006-0785 in the subject line on the first page of your submission. All requests must be in writing, and must be mailed or delivered to the Hearing Clerk as required by 40 CFR part 178 on or before April 28, 2008.
In addition to filing an objection or hearing request with the
Hearing Clerk as described in 40 CFR part 178, please submit a copy of the filing that does not contain any CBI for inclusion in the public docket that is described in ADDRESSES. Information not marked confidential pursuant to 40 CFR part 2 may be disclosed publicly by EPA without prior notice. Submit this copy, identified by docket ID number
EPA-HQ-OPP-2006-0785, by one of the following methods:
Federal eRulemaking Portal: http://www.regulations.gov.
Follow the on-line instructions for submitting comments.
Mail: Office of Pesticide Programs (OPP) Regulatory Public
Docket (7502P), Environmental Protection Agency, 1200 Pennsylvania
Ave., NW., Washington, DC 20460-0001.
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Delivery: OPP Regulatory Public Docket (7502P),
Environmental Protection Agency, Rm. S-4400, One Potomac Yard (South
Bldg.), 2777 S. Crystal Dr., Arlington, VA. Deliveries are only accepted during the Docket's normal hours of operation (8:30 a.m. to 4 p.m., Monday through Friday, excluding legal holidays). Special arrangements should be made for deliveries of boxed information. The
Docket Facility telephone number is (703) 305-5805.
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Petition for Tolerance
In the Federal Register of September 29, 2006 (71 FR 57507) (FRL- 8094-1), EPA issued a notice pursuant to section 408(d)(3) of FFDCA, 21
U.S.C. 346a(d)(3), announcing the filing of a pesticide petition (PP 6F7101) by Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268-1054. The petition requested that 40 CFR part 180 be amended by establishing tolerances for residues of the herbicide pyroxsulam, N-
(5,7-dimethoxy[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)-2-methoxy-4-
(trifluoromethyl)-3-pyridinesulfonamide, in or on wheat, forage at 0.04 parts per million (ppm); wheat, grain at 0.01 ppm; wheat, hay at 0.01 ppm; and wheat, straw at 0.01 ppm. That notice referenced a summary of the petition prepared by Dow AgroSciences LLC, the registrant, which is available to the public in the docket, http://www.regulations.gov.
Comments were received on the notice of filing. EPA's response to these comments is discussed in Unit IV.C.
Based upon review of the field residue data supporting the petition, EPA has modified the tolerance levels for wheat, forage from 0.04 to 0.06 ppm and for wheat, straw from 0.01 ppm to 0.03 ppm.
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Aggregate Risk Assessment and Determination of Safety
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 the tolerance is ``safe.'' Section 408(b)(2)(A)(ii) of FFDCA 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) of FFDCA 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....'' These provisions were added to FFDCA by the Food Quality
Protection Act (FQPA) of 1996.
Consistent with FFDCA section 408(b)(2)(D), and the factors specified in FFDCA 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 and to make a determination on aggregate exposure for the petitioned-for tolerances for residues of pyroxsulam on wheat, forage at 0.06 ppm; wheat, grain at 0.01 ppm; wheat, hay at 0.01 ppm and wheat, straw at 0.03 ppm. EPA's assessment of exposures and risks associated with establishing the tolerances follows.
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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.
Pyroxsulam has low or minimal acute toxicity via the oral (Acute
Toxicity Category III), dermal and inhalation (Acute Toxicity Category
IV) routes of exposure. It is non-irritating to the eyes and skin. It is a dermal sensitizer.
Little toxicity was observed in the repeat-dose toxicology studies via the oral and dermal routes of exposure. No treatment-related adverse effects were observed in the subchronic studies (mice, rats, or dogs). There was evidence of increased serum cholesterol levels in the subchronic exposures, but in light of a 28-day satellite recovery group in the subchronic rat study, where the cholesterol levels returned to normal after cessation of treatment, these effects were considered to be adaptive and non-adverse. Increased liver weights were observed in several of the subchronic and chronic studies; however, in the absence of corroborating changes in histopathology, the increased liver weights were not considered adverse. No adverse effects were observed in the chronic dog study or chronic/carcinogenicity study in rats. In the carcinogenicity study in mice, the lowest-observed-adverse-effect-level
(LOAEL) was 1,000 milligrams/kilogram/day (mg/kg/day), based on increased liver weights with corroborating evidence of increased incidence of clear cell foci of alteration in hepatocytes in males. The no-observed-adverse-effect-level (NOAEL) was 100 mg/kg/day.
There was no evidence of maternal or offspring toxicity in the developmental or 2-generation reproduction studies in rats up to 1,000 mg/kg/day. Considered in conjunction with the range-finding study, the developmental study in rabbits showed no signs of maternal or offspring toxicity up to 600 mg/kg/day. None of these studies showed signs of increased quantitative or qualitative susceptibility. Pyroxsulam is not mutagenic; it is classified as ``not likely to be carcinogenic to humans.''
Specific information on the studies received and the nature of the adverse effects caused by pyroxsulam as well as the NOAEL and the LOAEL from the toxicity studies can be found at http://www.regulations.gov.
The referenced document is available in the docket established by this action, which is described under ADDRESSES, and is identified as
``Pyroxsulam Human Health Risk Assessment for Proposed Uses on Wheat.''
PC Code: 108702, Petition No: 6F7101, DP Barcode: D335496 in that docket.
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Toxicological Endpoints
For hazards that have a threshold below which there is no appreciable risk, the toxicological level of concern (LOC) is derived from the highest dose at which no adverse effects are observed (the
NOAEL) in the toxicology study identified as appropriate for use in risk assessment. However, if a NOAEL cannot be determined, the lowest dose at which adverse effects of concern are identified (the LOAEL) is sometimes used for risk assessment. Uncertainty/safety factors (UFs) are used in conjunction with the LOC to take into account 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. Safety is assessed for acute and chronic risks by comparing aggregate exposure to the pesticide to the acute population adjusted dose (aPAD) and chronic population adjusted dose
(cPAD). The aPAD and cPAD are calculated by dividing the LOC by all applicable UFs. Short-term, intermediate-term, and long-term risks are evaluated by comparing aggregate exposure to the LOC to ensure that the margin of exposure (MOE) called for by the product of all applicable
UFs is not exceeded.
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For non-threshold risks, the Agency assumes that any amount of exposure will lead to some degree of risk and estimates risk in terms of the probability of occurrence of additional adverse cases.
Generally, cancer risks are considered non-threshold. For more information on the general principles EPA uses in risk characterization and a complete description of the risk assessment process, see http:// www.epa.gov/fedrgstr/EPA-PEST/1997/November/Day-26/p30948.htm.
A summary of the toxicological endpoints for pyroxsulam used for human risk assessment can be found at http://www.regulations.gov in document ``Pyroxsulam Human Health Risk Assessment for Proposed Uses on
Wheat.'' PC Code: 108702, Petition No: 6F7101, DP Barcode: D335496 at page 23 in docket ID number EPA-HQ-OPP-2006-0785.
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Exposure Assessment 1. Dietary exposure from food and feed uses. In evaluating dietary exposure to pyroxsulam, EPA considered exposure under the petitioned- for tolerances. EPA assessed dietary exposures from pyroxsulam in food as follows: i. Acute exposure. Quantitative acute dietary exposure and 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.
No such effects were identified in the toxicological studies for pyroxsulam; therefore, a quantitative acute dietary exposure assessment is unnecessary. ii. Chronic exposure. In conducting the chronic dietary exposure assessment EPA used the food consumption data from the United States
Department of Agriculture (USDA) 1994-1996, and 1998; Nationwide
Continuing Surveys of Food Intakes by Individuals (CSFII). As to residue levels in food, EPA assumed all foods for which there are tolerances were treated and contain tolerance-level residues. iii. Cancer. Pyroxsulam was negative for carcinogenicity in feeding studies in rats and mice and was classified as ``not likely to be a human carcinogen.'' Therefore, a quantitative exposure assessment to evaluate cancer risk is unnecessary. 2. Dietary exposure from drinking water. The Agency lacks sufficient monitoring data to complete a comprehensive dietary exposure analysis and risk assessment for pyroxsulam 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 environmental fate characteristics of pyroxsulam. Further information regarding EPA drinking water models used in pesticide exposure assessment can be found at http:// www.epa.gov/oppefed1/models/water/index.htm.
Based on the Pesticide Root Zone Model /Exposure Analysis Modeling
System (PRZM/EXAMS) and Screening Concentration in Ground Water (SCI-
GROW) models, the estimated environmental concentrations (EECs) of pyroxsulam for chronic exposures are estimated to be 0.102 parts per billion (ppb) for surface water and 0.465 ppb for ground water.
Modeled estimates of drinking water concentrations were directly entered into the dietary exposure model. For chronic dietary risk assessment, the water concentration of value 0.465 ppb was used to assess the contribution of the estimated drinking water concentration to the dietary risk assessment. 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).
Pyroxsulam is not registered for use on any sites that would result in residential exposure. 4. Cumulative effects from substances with a common mechanism of toxicity. 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.''
Unlike other pesticides for which EPA has followed a cumulative risk approach based on a common mechanism of toxicity, EPA has not made a common mechanism of toxicity finding as to pyroxsulam and any other substances and pyroxsulam 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 pyroxsulam 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
EPA's website at http://www.epa.gov/pesticides/cumulative.
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Safety Factor for Infants and Children 1.In general. Section 408 of FFDCA provides that EPA shall apply an additional (``10X'') 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 based on reliable data that a different margin of safety will be safe for infants and children. This additional margin of safety is commonly referred to as the FQPA safety factor. In applying this provision, EPA either retains the default value of 10X when reliable data do not support the choice of a different factor, or, if reliable data are available, EPA uses a different additional FQPA safety factor value based on the use of traditional UFs and/or special
FQPA safety factors, as appropriate. 2. Prenatal and postnatal sensitivity. There is no evidence of quantitative and/or qualitative susceptibility and there are no residual uncertainties with regard to prenatal toxicity following in utero exposure to rats or rabbits. 3. Conclusion. EPA has determined that reliable data show that it would be safe for infants and children to reduce the FQPA safety factor to 1X. That decision is based on the following findings: i. The toxicity database for pyroxsulam is complete. ii. There is no indication that pyroxsulam is a neurotoxic chemical and there is no need for a developmental neurotoxicity study or additional UFs to account for neurotoxicity. iii. There is no evidence that pyroxsulam results in increased susceptibility to rats or rabbits in utero in the prenatal developmental studies or in young rats in the 2-generation reproduction study. iv. There are no residual uncertainties identified in the exposure databases. The dietary (food and drinking water) exposure assessment will not underestimate the potential exposure for infants, children, and/or women of childbearing age. There is no potential for residential exposure.
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Aggregate Risks and Determination of Safety
Safety is assessed for acute and chronic risks by comparing aggregate exposure to the pesticide to the aPAD and cPAD. The aPAD and cPAD are calculated by dividing the LOC by all applicable UFs. For linear cancer risks, EPA calculates the probability of additional cancer cases given aggregate
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exposure. Short-term, intermediate-term, and long-term risks are evaluated by comparing aggregate exposure to the LOC to ensure that the
MOE called for by the product of all applicable UFs is not exceeded. 1. Acute risk. There were no effects observed in oral toxicity studies including developmental toxicity studies in rats and rabbits that could be attributable to a single dose (exposure). Therefore, pyroxsulam is not expected to pose an acute risk. 2. Chronic risk. Using the exposure assumptions described in this unit for chronic exposure, EPA has concluded that exposure to pyroxsulam from food and water will utilize
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