Dimethenamid; Pesticide Tolerances
Federal Register, Volume 80 Issue 34 (Friday, February 20, 2015)
Federal Register Volume 80, Number 34 (Friday, February 20, 2015)
Rules and Regulations
Pages 9209-9215
From the Federal Register Online via the Government Printing Office www.gpo.gov
FR Doc No: 2015-03458
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ENVIRONMENTAL PROTECTION AGENCY
EPA-HQ-OPP-2013-0670; FRL-9922-08
Dimethenamid; Pesticide Tolerances
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: This regulation establishes tolerances for residues of dimethenamid in or on cottonseed subgroup 20C and cotton, gin byproducts. BASF Corporation requested these tolerances under the Federal Food, Drug, and Cosmetic Act (FFDCA).
DATES: This regulation is effective February 20, 2015. Objections and requests for hearings must be received on or before April 21, 2015, 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: The docket for this action, identified by docket identification (ID) number EPA-HQ-OPP-2013-0670, is available at http://www.regulations.gov or at the Office of Pesticide Programs Regulatory Public Docket (OPP Docket) in the Environmental Protection Agency Docket Center (EPA/DC), West William Jefferson Clinton Bldg., Rm. 3334, 1301 Constitution Ave. NW., Washington, DC 20460-0001. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the OPP Docket is (703) 305-5805. Please review the visitor instructions and additional information about the docket available at http://www.epa.gov/dockets.
FOR FURTHER INFORMATION CONTACT: Susan Lewis, Registration Division (7505P), Office of Pesticide Programs, Environmental Protection Agency, 1200 Pennsylvania Ave. NW., Washington, DC 20460-0001; main telephone number: (703) 305-7090; email address: RDFRNotices@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. The following list of North American Industrial Classification System (NAICS) codes is not intended to be exhaustive, but rather provides a guide to help readers determine whether this document applies to them. Potentially affected entities may include:
Crop production (NAICS code 111).
Animal production (NAICS code 112).
Food manufacturing (NAICS code 311).
Pesticide manufacturing (NAICS code 32532).
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How can I get electronic access to other related information?
You may access a frequently updated electronic version of EPA's tolerance regulations at 40 CFR part 180 through the Government Publishing Office's e-CFR site at http://www.ecfr.gov/cgi-bin/text-idx?&c=ecfr&tpl=/ecfrbrowse/Title40/40tab_02.tpl.
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How can I file an objection or hearing request?
Under FFDCA section 408(g), 21 U.S.C. 346a, 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-2013-0670 in the subject line on the first page of your submission. All objections and requests for a hearing must be in writing, and must be received by the Hearing Clerk on or before April 21, 2015. Addresses for mail and hand delivery of objections and hearing requests are provided in 40 CFR 178.25(b).
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 (excluding any Confidential Business Information (CBI)) for inclusion in the public docket. Information not marked confidential pursuant to 40 CFR part 2 may be disclosed publicly by EPA without prior notice. Submit the non-CBI copy of your objection or hearing request, identified by docket ID number EPA-HQ-OPP-2013-0670, by one of the following methods:
Federal eRulemaking Portal: http://www.regulations.gov. Follow the online instructions for submitting comments. Do not submit electronically any information you consider to be CBI or other information whose disclosure is restricted by statute.
Mail: OPP Docket, Environmental Protection Agency Docket Center (EPA/DC), (28221T), 1200 Pennsylvania Ave. NW., Washington, DC 20460-0001.
Hand Delivery: To make special arrangements for hand delivery or delivery of boxed information, please follow the instructions at http://www.epa.gov/dockets/contacts.html.
Additional instructions on commenting or visiting the docket, along with more information about dockets generally, is available at http://www.epa.gov/dockets.
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Summary of Petitioned-For Tolerance
In the Federal Register of October 25, 2013 (78 FR 63938) (FRL-
9901-96), EPA issued a document pursuant to FFDCA section 408(d)(3), 21 U.S.C. 346a(d)(3), announcing the filing of a pesticide petition (PP 3F8197) by BASF Corporation, 26 Davis Drive, P.O. Box 13528, Research Triangle Park, NC 27709-3528. The petition requested that 40 CFR 180.464 be amended by establishing tolerances for residues of the herbicide dimethenamid (1(RS)-2-chloro-N-(1-methyl-2-methoxy)ethyl-N-
(2,4-dimethylthien-3-yl)acetamide) in or on cottonseed, subgroup 20C at 0.01 parts per million (ppm); cotton, gin byproducts at 1.5 ppm; and cotton, seed, refined oil at 0.02 ppm. Compliance with the tolerance levels is to be determined by measuring only parent. Tolerances would apply to either dimethenamid-P (a 90:10 mixture of S- and R-isomers, a mixture enriched in S-isomer) or dimethenamid (a 50:50 racemic mixture of S- and R-isomers). The enforcement method is not enantiomer specific. That document referenced a summary of the petition prepared by BASF Corporation, the registrant, which is available in the docket, http://www.regulations.gov. There were no comments received in response to the notice of filing.
Based upon review of the data supporting the petition, EPA has determined that a separate tolerance in cotton, seed, and refined oil is not needed. The reason for these changes are explained in Unit IV.C.
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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. . . .''
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 dimethenamid including exposure resulting from the tolerances established by this action. EPA's assessment of exposures and risks associated with dimethenamid 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.
The existing toxicological database is comprised of studies conducted with both dimethenamid, which is a racemic mixture of S- and R-isomers (50:50, S:R), and dimethenamid-P, which is mixture of S- and R-isomers enriched in the S-isomer (90:10, S:R). Both sets of data for dimethenamid and dimethenamid-P show similar toxicity and together are adequate for risk assessment. Because of the similarity of the two mixtures, EPA relies on data for both to assess the hazard of each mixture.
The primary target organ is the liver. The toxicity in 90-day feeding studies in rats showed decreased body weights, increased cholesterol and changes in liver weights along with histopathology showing microscopic effects (centrilobular hypertrophy, periportal eosinophilic inclusions and necrosis) in the liver. Chronic studies in the rat, mouse, and dog showed decreases in body weight and food efficiency as accompanying effects over time. At higher dose levels, liver pathology (hepatic lesions, bile duct hyperplasia, and tumors), stomach hyperplasia, and some indications of kidney effects were noted. Two 21-day dermal toxicity studies in rabbits were conducted and in one of those studies minor skin irritation was observed at all doses tested and a decrease in body weight (bw) gain was also seen at the lowest effect level.
The acute neurotoxicity study resulted in effects such as partially closed eyelids, lacrimation, and slight salivation at the highest dose tested of (600 milligrams/kilograms/body weight (mg/kg/bw)). There were no treatment-related or toxicologically significant findings during the gross examination of rats or in the microscopic examination of neurological tissues. In the subchronic neurotoxicity study, there were no clinical signs seen and no adverse effects seen up to 323/390 mg/kg/
bw day. Systemic effects seen were renal pelvic dilation in males (considered incidental) and a trend of higher liver weights in females was found at the lowest dose tested and
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were not considered adverse nor were they corroborated with any other guideline studies submitted. There were no liver histopathology or clinical chemistry measurements in the subchronic neurotoxicity study; however, the adversity of this finding is supported by the observation of multiple liver effects (increased cholesterol, increased total serum protein, increased liver weights, and enlarged centrilobular hepatocytes) in the 90-day rat study at doses of 98/119 (Male/Female) milligrams/kilograms/day (mg/kg/day) and above. There was no neurotoxicity observed at higher doses nor in other guideline studies.
Developmental toxicity studies show increased post-implantation loss and minor skeletal variations in the rat, and late resorptions and minor skeletal variations in the rabbit at the highest dose tested (lowest observed adverse effect level: LOAEL, 425 mg/kg/day). In the rabbit, the developmental effects occurred at the same dose as maternal toxicity (LOAEL, 150 mg/kg/day), whereas in the rat, the developmental toxicity occurred at much higher doses than in the dams (LOAEL, 215 mg/
kg/day). The chosen no observed adverse effect level (NOAEL) of 75 mg/
kg/day is considered protective for effects seen in both studies. The reproduction study resulted in decreases in body weight in both pups and parental animals at the same dose levels. The only other effects noted at the LOAEL of 150 mg/kg/day were increases in liver weights in both male and female parental animals.
A review of the immunotoxicity study resulted in no immunotoxicity effects at the limit dose of 1,167 milligrams/kilograms (mg/kg), although increased absolute and relative liver weights were seen at this dose level. Dimethenamid-P is classified as group ``C'' possible human carcinogen, based on weak evidence for carcinogenicity.
The agency concluded that quantification of cancer risk using a non-linear approach would adequately account for all chronic toxicity (including carcinogenicity) that could result from exposure to dimethenamid based on the following weight of evidence considerations:
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No statistically significant increase in liver tumors (only an increasing trend for liver tumors in one sex (male) and one species (rat)).
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No evidence of carcinogenicity in male or female mice.
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Equivocal evidence for mutagenicity.
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The POD of 5 mg/kg/day used for human health risk assessment is 15-fold lower than the dose (75 mg/kg/day) that caused the liver tumors and thus considered protective for cancer.
Specific information on the studies received and the nature of the adverse effects caused as well as the NOAEL and the LOAEL from the toxicity studies can be found at http://www.regulations.gov in document titled, ``Dimethenamid/Dimethenamid-P. Human Health Risk Assessment for Proposed New Use on Cottonseed Subgroup 20C.,'' on pg. 42-48, in docket ID number EPA-HQ-OPP-2013-0670.
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Toxicological Points of Departure/Levels of Concern
Once a pesticide's toxicological profile is determined, EPA identifies toxicological POD and levels of concern (LOC) to use in evaluating the risk posed by human exposure to the pesticide. For hazards that have a threshold below which there is no appreciable risk, the toxicological POD is used as the basis for derivation of reference values for risk assessment. PODs are developed based on a careful analysis of the doses in each toxicological study to determine the dose at which the NOAEL and the LOAEL are identified. Uncertainty/safety factors are used in conjunction with the POD to calculate a safe exposure level--generally referred to as a population-adjusted dose (PAD) or a reference dose (RfD)--and a safe margin of exposure (MOE). For non-threshold risks, the Agency assumes that any amount of exposure will lead to some degree of risk. Thus, the Agency estimates risk in terms of the probability of an occurrence of the adverse effect expected in a lifetime. 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/pesticides/factsheets/riskassess.htm. A summary of the toxicological endpoints for Dimethenamid/Dimethenamid-P used for human risk assessment is shown in Table 1 of this unit.
Table 1--Summary of Toxicological Doses and Endpoints for Dimethenamid/Dimethenamid-P for Use in Human Health
Risk Assessment
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Point of departure
Exposure/scenario and uncertainty/ RfD, PAD, LOC for Study and toxicological effects
safety factors risk assessment
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Acute dietary (General population NOAEL = 200 mg/kg/ Acute RfD = 2.0 mg/ Acute Neurotoxicity.
including infants and children). day kg/day. LOAEL = 600 mg/kg/day based on
UFA = 10x........... aPAD = 2.0 mg/kg/ lacrimation, salivation,
UFH = 10x........... day. irregular and accelerated
FQPA SF = 1x........ respiration, slight tremors,
reduced exploration, unsteady
gait, and significantly reduced
rearing.
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Acute dietary (Females 13-49 NOAEL = 75 mg/kg/day Acute RfD = 0.75 mg/ Developmental Rabbit Study
years of age). UFA = 10x........... kg/day. Maternal. LOAEL = 150 mg/kg/day
UFH = 10x........... aPAD = 0.75 mg/kg/ based on abortions (not
FQPA SF = 1x........ day. considered acute effect).
Developmental; LOAEL = 150 mg/kg/
day based on post-implantation
loss.
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Chronic dietary (All populations) NOAEL = 5 mg/kg/day Chronic RfD = 0.05 Chronic/Carcinogenicity Rat Study.
UFA = 10x........... mg/kg/day. LOAEL = Male/Female; 36/49 mg/kg/
UFH = 10x........... cPAD = 0.05 mg/kg/ day based on decreased body
FQPA SF = 1x........ day. weight and body weight gain in
both sexes, increased food
conversion ratios in females, and
increased microscopic hepatic
lesions in both sexes.
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Incidental oral short-term and NOAEL = 10 mg/kg/day LOC for MOE = 100.. Subchronic/Chronic Oral Dog
intermediate-term (1 to 6 UFA = 10x........... Studies.
months). UFH = 10x........... Chronic NOAEL = 10 mg/kg/day.
FQPA SF = 1x........ Chronic LOAEL = 48.7 mg/kg/day.
Subchronic NOAEL = 4.72 mg/kg/day.
Subchronic LOAEL = 33.6 mg/kg/day
based on decreased body weight in
females, increased relative to
body liver weight in both sexes,
increased periportal cytoplasmic
vacuolation in liver in both
sexes, and dilation of liver
sinusoids in females.
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Dermal short-term (1 to 30 days) NOAEL = 300 mg/kg/ LOC for MOE = 100.. 21-Day Dermal Rabbit Study.
and intermediate-term (1-6 day LOAEL = 500 mg/kg/day based on
months). UFA = 10x........... decreased body weight gain only
UFH = 10x........... (non-specific).
FQPA SF = 1x........
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Inhalation short-term (1 to 30 NOAEL = 10 mg/kg/day LOC for MOE= 100... Subchronic/Chronic Oral Dog
days). UFA = 10x........... Studies.
UFH = 10x........... Chronic NOAEL = 10 mg/kg/day.
FQPA SF = 1x........ Chronic LOAEL = 48.7 mg/kg/day.
Subchronic NOAEL = 4.72 mg/kg/day.
Subchronic LOAEL = 33.6 mg/kg/day
based on decreased body weight in
females, increased relative to
body liver weight in both sexes,
increased periportal cytoplasmic
vacuolation in liver in both
sexes, and dilation of liver
sinusoids in females.
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Cancer (Oral, dermal, inhalation) ``C'' Possible human carcinogen. The chronic RfD is considered protective of
the cancer effects.
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FQPA SF = Food Quality Protection Act Safety Factor. LOAEL = lowest-observed-adverse-effect-level. LOC = level
of concern. mg/kg/day = milligram/kilogram/day. MOE = margin of exposure. NOAEL = no-observed-adverse-effect-
level. PAD = population adjusted dose (a = acute, c = chronic). RfD = reference dose. UFA = extrapolation from
animal to human (interspecies). UFH = potential variation in sensitivity among members of the human population
(intraspecies).
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Exposure Assessment
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Dietary exposure from food and feed uses. In evaluating dietary exposure to dimethenamid-P and/or dimethenamid, EPA considered exposure under the petitioned-for tolerances as well as all existing dimethenamid tolerances in 40 CFR 180.464 which are established for either of the herbicides dimethenamid-P (an enriched S-isomer with 90:10 mixture of the S- and R-isomers) or dimethenamid (a 50:50 racemic mixture of the S- and R-isomers). Therefore, EPA assessed dietary exposures from dimethenamid-P and/or dimethenamid 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. Such effects were identified for dimethenamid and dimethenamid-P. In estimating acute dietary exposure, EPA used food consumption information from the United States Department of Agriculture (USDA) 2003-2008 Nationwide Continuing Surveys of Food Intake by Individuals (CSFII). The acute dietary analysis was conducted for dimethenamid and/or dimethenamid-P assuming tolerance level residues, default processing factors, and 100% crop treated (CT) information.
ii. Chronic exposure. In conducting the chronic dietary exposure assessment EPA used the food consumption data from the USDA 2003-2008 CSFII. The chronic dietary exposure assessment was conducted for dimethenamid and/or dimethenamid-P assuming tolerance level residues, default processing factors, and 100% CT information.
iii. Cancer. As discussed in Unit III.A, EPA has concluded that cancer dietary risk concerns due to long-term consumption of dimethenamid residues are adequately addressed by the chronic dietary exposure analysis using the reference dose; therefore, a separate cancer dietary exposure analysis was not performed.
iv. Anticipated residue and percent crop treated (PCT) information. Tolerance level residues and 100% CT were assumed for all food commodities.
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Dietary exposure from drinking water. The Agency used screening level water exposure models in the dietary exposure analysis and risk assessment for dimethenamid-P and/or dimethenamid in drinking water. These simulation models take into account data on the physical, chemical, and fate/transport characteristics of dimethenamid-P and/or dimethenamid. 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 Surface Water Concentration Calculator (SWCC) and the Pesticide Root Zone Model for Ground Water (PRZM-GW), estimated drinking water concentrations (EDWCs) were calculated for the parent compound plus its ethanesulfonic acid and oxanilic acid degradates, which are residues of concern in drinking water as follows: For acute exposures, EDWCs are estimated to be 73 parts per billion (ppb) for surface water and 153 ppb for ground water; for chronic exposures, EDWCs for non-cancer assessments are estimated to be 27 ppb for surface water and 140 ppb for ground water.
Modeled estimates of drinking water concentrations were directly entered into the dietary exposure model.
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Because there was little difference between the maximum EDWCs for acute and chronic exposures, the maximum water concentration value of 153 ppb was used to assess the contribution to drinking water for both the acute and chronic dietary risk assessments.
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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). Although there are no currently registered uses of dimethenamid that could result in residential exposures, dimethenamid-P is currently registered for the following uses that could result in residential exposures: Turf grass, ornamentals, and tree plantations. Only short-term residential exposures to dimethenamid-P are expected based on the 2012 Residential Standard Operating Procedures (SOPs). Potential exposure/risk scenarios identified for residential handlers include:
Mixing/loading/applying liquid formulations to lawns/turf with a hose-end and/or backpack sprayer, and a manually-pressurized hand wand.
Mixing/loading/applying liquid formulations to garden/
trees with a sprinkler can and a hose-end sprayer.
Mixing/loading/applying granular formulations to lawns/
turf with a push-type rotary sprayer and a belly grinder.
Mixing/loading/applying granular formulations to garden/
trees with a shaker can/cup, a spoon or by hand dispersal.
The scenarios, routes of exposure, and lifestages of potential post-application exposure include:
Physical activities on turf: Adults (dermal) and children 1 to Mowing: Adults (dermal) and children 11 to Golfing: Adults (dermal), children 11 to Contact with Treated Gardens and Trees: Adults (dermal) and children 6 to
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