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Federal Register / Vol. 86, No. 42 / Friday, March 5, 2021 / Rules and Regulations
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inputs for residential exposures may be found at https www.epa.gov/pesticidescience-and-assessing-pesticide-risks/
standard-operating-proceduresresidential-pesticide.
4. Cumulative effects from substances with a common mechanism of toxicity.
Section 408b2Dv 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 pesticides residues and other substances that have a common mechanism of toxicity.
EPA has not found picarbutrazox to share a common mechanism of toxicity with any other substances, and picarbutrazox does not appear to produce a toxic metabolite produced by other substances. For the purposes of this tolerance action, therefore, EPA has assumed that picarbutrazox does not have a common mechanism of toxicity with other substances. For information regarding EPAs efforts to determine which chemicals have a common mechanism of toxicity and to evaluate the cumulative effects of such chemicals, see EPAs website at http
www2.epa.gov/pesticide-science-andassessing-pesticide-risks/cumulativeassessment-risk-pesticides.
D. Safety Factor for Infants and Children 1. In general. Section 408b2C of FFDCA provides that EPA shall apply an additional tenfold 10X 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 SF. In applying 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 prenatal susceptibility in rats or rabbits or postnatal susceptibility in rats, with no adverse effects observed in the developmental toxicity studies.
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 picarbutrazox is complete.

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ii. There is no indication that picarbutrazox 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 picarbutrazox 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.
The dietary food exposure assessments were performed based on 100 PCT, tolerance-level residues, default processing factors, and modeled drinking water estimates. EPA made conservative protective assumptions in the ground and surface water modeling used to assess exposure to picarbutrazox in drinking water. EPA used similarly conservative assumptions to assess postapplication exposure of children as well as incidental oral exposure of toddlers.
These assessments will not underestimate the exposure and risks posed by picarbutrazox.
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. 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, picarbutrazox 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 picarbutrazox from food and water will utilize <1% of the cPAD for all infants <1 year old, the population group receiving the greatest exposure. Based on the explanation in Unit III.C.3., regarding residential use patterns, chronic residential exposure to residues of picarbutrazox is not expected.
3. Short-term and Intermediate-term risk. Short-term and intermediate-term aggregate exposure takes into account short-term or intermediate-term residential exposure plus chronic
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exposure to food and water considered to be a background exposure level.
Picarbutrazox is currently proposed for uses that could result in short-term and intermediate-term residential exposure, and the Agency has determined that it is appropriate to aggregate chronic exposure through food and water with short-term or intermediate-term residential exposures to picarbutrazox.
Using the exposure assumptions described in this unit for short-term and intermediate-term exposures, EPA has concluded the combined short-term or intermediate-term food, water, and residential exposures result in aggregate MOE of 950 for children 1 to <2 years old from dietary food and drinking water and incidental oral exposure from hand-to-mouth activities from post-application exposure to turf applications. Because EPAs level of concern for picarbutrazox is an MOE of 30 or below, these MOEs are not of concern.
4. Aggregate cancer risk for U.S.
population. As stated in Unit III.A., a separate cancer analysis was not conducted as the chronic assessment adequately accounts for all chronic toxicity, including potential carcinogenicity. Based on the lack of chronic risk, EPA concludes that aggregate exposure to picarbutrazox will not pose a 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 picarbutrazox residues.
IV. Other Considerations A. Analytical Enforcement Methodology Adequate enforcement methodology liquid chromatography with tandem mass spectroscopy LC/MS/MS and high-performance liquid chromatography HPLC/MS/MS is available to enforce the tolerance expression.
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 United Nations Food and Agriculture Organization/World Health Organization food standards program,
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