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Federal Register / Vol. 86, No. 165 / Monday, August 30, 2021 / Rules and Regulations
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Consistent with FFDCA section 408b2D, and the factors specified in FFDCA section 408b2D, 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 thiabendazole including exposure resulting from the tolerances established by this action.
EPAs assessment of exposures and risks associated with thiabendazole follows.
A. Toxicological Profile EPA has evaluated the available toxicity data and considered its validity, completeness, and reliability as well as the relationship of the results of the studies to human risk. EPA has also considered available information concerning the variability of the sensitivities of major identifiable subgroups of consumers, including infants and children.
Decreased body weight is the most sensitive effect of exposure to thiabendazole observed even in young rat pups during lactation.
Histopathological changes in the spleen congestion and pigmentation and kidney calculus and hyperplasia of transitional epithelium were noted in a subchronic rat study, and splenic erythropoiesis and hemosiderosis were reported in a chronic dog study. Other target organs of thiabendazole toxicity are the liver and thyroid. Increased quantitative susceptibility was observed in the rat and rabbit developmental toxicity studies, in which developmental effects occurred in the absence of maternal toxicity. Increased quantitative susceptibility was not observed in the prenatal developmental toxicity study in mice and in the 2generation reproduction study in rats. In an acute neurotoxicity rat study ACN, reduced locomotor activity was identified, although no morphological or histopathological effects were noted in the brain. No signs of neurotoxicity were seen in the subchronic neurotoxicity study. Thiabendazole is classified as Likely to be carcinogenic to humans at doses high enough to cause a disturbance of the thyroid hormonal balance. It is not likely to be carcinogenic at doses lower than those which could cause a disturbance of this hormonal balance.
Additional information on the toxicological profile can be found at http www.regulations.gov in the document titled Thiabendazole:
Human Health Risk Assessment for the Establishment of Permanent Tolerances and Registration for Use on Animal feed, nongrass, group 18; Brassica, leafy
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greens, subgroup 416B; and Sweet Potato; and Crop Group Conversions/
Expansions to Fruit, citrus, group 10
10; Fruit, pome, group 1110; Kohlrabi;
Vegetable, Brassica, head and stem, group 516; Vegetable, root, except sugar beet, subgroup 1B; and Vegetable, tuberous and corm, subgroup 1C, except sweet potato hereinafter Thiabendazole Human Health Risk Assessment in docket ID number EPAHQOPP20200054.
B. Toxicological Points of Departure/
Levels of Concern Once a pesticides toxicological profile is determined, EPA identifies toxicological points of departure POD
and levels of concern 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 no adverse effects are observed the NOAEL and the lowest dose at which adverse effects of concern are identified the LOAEL. Uncertainty/
safety factors are used in conjunction with the POD to calculate a safe exposure levelgenerally referred to as a population-adjusted dose PAD or a reference dose RfDand 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
www2.epa.gov/pesticide-science-andassessing-pesticide-risks/assessinghuman-health-risk-pesticide.
A summary of the toxicological endpoints for thiabendazole used for human risk assessment can be found in the Thiabendazole Human Health Risk Assessment.
C. Exposure Assessment 1. Dietary exposure from food and feed uses. In evaluating dietary exposure to thiabendazole, EPA
considered exposure under the petitioned-for tolerances. EPA assessed dietary exposures from thiabendazole 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
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possibility of an effect of concern occurring as a result of a 1-day or single exposure.
In conducting the acute dietary exposure assessment, EPA used the 20032008 food consumption data from the U.S. Department of Agricultures National Health and Nutrition Examination Survey, What We Eat in America NHANES/WWEIA. The acute dietary exposure assessment is partially refined and incorporated established and recommended tolerance-level residues for some commodities, maximum field trial residues for the remaining commodities according to blending classification, 100 percent crop treated PCT, and default processing factors except for apple juice, grapefruit juice, lemon juice, lime juice, orange juice, pear juice, potato granules/flakes, and tangerine juice.
ii. Chronic exposure. In conducting the chronic dietary exposure assessment, EPA used the 20032008
food consumption data from the USDAs NHANES/WWEIA. The chronic dietary exposure assessment is partially refined and incorporated established and recommended tolerance-level residues for some commodities, average field trial residues for the remaining commodities according to blending classification, 100 PCT, and default processing factors except for apple juice, grapefruit juice, lemon juice, lime juice, orange juice, pear juice, potato granules/flakes, and tangerine juice.
iii. Cancer. Thiabendazole is classified as Likely to be carcinogenic at doses high enough to cause a disturbance of the thyroid hormonal balance but not likely to be carcinogenic at doses lower than those which could cause a disturbance of this hormonal balance. EPA is regulating chronic exposure based on a reference dose that is lower than and thus protective of the level that would cause a disturbance in the thyroid hormonal balance, making tumor formation highly unlikely; therefore, a cancer dietary exposure assessment is not required.
The current partially refined chronic dietary risk assessment is conservative and is protective for cancer effects.
iv. Anticipated residue and PCT
information. EPA used some tolerancelevel residues and some anticipated residue data for assessing tolerances.
Section 408b2E of FFDCA
authorizes EPA to use available data and information on the anticipated residue levels of pesticide residues in food and the actual levels of pesticide residues that have been measured in food. If EPA
relies on such information, EPA must require pursuant to FFDCA section 408f1 that data be provided 5 years
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