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Federal Register / Vol. 86, No. 231 / Monday, December 6, 2021 / Rules and Regulations
this provision, EPA either retains the default value of 10X, or uses a different additional safety factor when reliable data available to EPA support the choice of a different factor.
2. Prenatal and postnatal sensitivity.
There is no evidence of increased qualitative or quantitative susceptibility in the rat and rabbit developmental toxicity studies or the 2-generation rat reproduction study. In the rat developmental study, developmental effects decrease fetal weights, increased incidence of small fetuses, and increased incidence of a skeletal variation un-ossification of thoracic vertebral body were observed in the presence of maternal toxicity decreased maternal body weight. In the rabbit developmental toxicity study, no significant developmental or maternal effects were seen. In the 2-generation reproductive toxicity study in rats, parental toxicity was manifested as decreases in body weights and food consumption in P and F1 parents;
increases in liver weights and spleen weights P and F1 parents; decreases in thymus weights P and F1 females; and increased incidences of microscopic findings in the liver centrilobular hepatic hypertrophy, thymus thymic atrophy of P and F1 females. Offspring toxicity decreased body weights and delayed physical development delayed eye opening and reproductive toxicity decreased ovary and uterus weights, atrophy of the endometrium and myometrium in the uterus, and atrophy of the ovaries were observed in the presence of parental toxicity.
3. Conclusion. EPA has determined that reliable data show the safety of infants and children would be adequately protected if the FQPA SF
were reduced to 1X. That decision is based on the following findings:
i. The toxicity database for isoprothiolane is complete at this time.
ii. Although acute ACN and subchronic SCN neurotoxicity studies were not available, neurobehavior functional observation battery FOB
and motor activity was assessed in two 13-week oral studies in rats and mice on isoprothiolane; no changes in FOB and motor activity were observed. There was no evidence of neurotoxicity in the isoprothiolane database including subchronic studies or in the routine clinical observations of the chronic studies. EPAs Hazard and Science Policy Council recommended waiving the acute and subchronic neurotoxicity studies at this time. There is no indication that isoprothiolane is a neurotoxic chemical and there is no need for a developmental neurotoxicity
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study or additional UFs to account for neurotoxicity.
iii. There is no evidence that isoprothiolane results in increased susceptibility in in utero rats or rabbits 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.
Tolerance-level residues or adjusted tolerance level residues adjusted to account for the residue of concern, were used for the commodities. An assumption of 100% crop treated was also used for the chronic dietary analysis. There are no residual uncertainties in the exposure database.
The residue database is adequate. The Human Health Risk Assessment will not underestimate the exposure and risks posed by isoprothiolane.
E. Aggregate Risks and Determination of Safety EPA determines whether acute and chronic dietary pesticide exposures are safe by comparing aggregate exposure estimates to the acute PAD aPAD and chronic PAD cPAD. For linear cancer risks, EPA calculates the lifetime probability of acquiring cancer given the estimated aggregate exposure. Short-, intermediate-, and chronic-term risks are evaluated by comparing the estimated aggregate food, water, and residential exposure to the appropriate PODs to ensure that an adequate MOE
exists.
1. Acute risk. An acute aggregate risk assessment takes into account acute exposure estimates from dietary consumption of food and drinking water. No adverse effect resulting from a single oral exposure was identified and no acute dietary endpoint was selected. Therefore, isoprothiolane 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 chronic exposure to isoprothiolane from food and water will utilize 5.8% of the cPAD for all infants <1 year old, the population group receiving the greatest exposure. There are no residential uses for isoprothiolane.
3. Shortand intermediate-term risk.
Shortand intermediate-term aggregate exposure takes into account shortand intermediate-term residential exposure plus chronic exposure to food and water considered to be a background exposure level. Because isoprothiolane is not registered in the United States, the only exposures will be dietary, from residues in or on imported rice commodities or banana; therefore, no
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short-term or intermediate-term residential exposure is expected.
Because there is no shortor intermediate-term residential exposure and chronic dietary exposure has already been assessed under the appropriately protective cPAD which is at least as protective as the POD used to assess short-term risk, no further assessment of shortor intermediateterm risk is necessary, and EPA relies on the chronic dietary risk assessment for evaluating short or intermediate-term risk for isoprothiolane.
4. Aggregate cancer risk for U.S.
population. As stated in Unit III.A., EPA
has concluded that the chronic reference dose will adequately account for all repeated exposure/chronic toxicity, including carcinogenicity, that could result from exposure to isoprothiolane. Based on the lack of chronic risk at regulated levels of exposure, EPA concludes that isoprothiolane will not pose an aggregate cancer risk.
5. Determination of safety. Based on these risk assessments, EPA concludes that there is a reasonable certainty that no harm will result to the general population, or to infants and children from aggregate exposure to isoprothiolane residues.
IV. Other Considerations A. Analytical Enforcement Methodology Adequate enforcement methodology 88449M is available to enforce the tolerance expression in/on banana.
Method No. 88449M includes analysis by liquid chromatography with tandem mass spectroscopy LC/MS/MS. For rice, the Joint FAO/WHO Meeting on Pesticide Residues JMPR review indicated that the QuEChERS quick, easy, cheap, effective, rugged, and safe method is adequate for the determination of isoprothiolane.
The method may be requested from:
Chief, Analytical Chemistry Branch, Environmental Science Center, 701
Mapes Rd., Ft. Meade, MD 207555350;
telephone number: 410 3052905;
email address: residuemethods@
epa.gov.
B. International Residue Limits In making its tolerance decisions, EPA
seeks to harmonize U.S. tolerances with international standards whenever possible, consistent with U.S. food safety standards and agricultural practices. EPA considers the international maximum residue limits MRLs established by the Codex Alimentarius Commission Codex, as required by FFDCA section 408b4.
The Codex Alimentarius is a joint
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