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Federal Register / Vol. 86, No. 147 / Wednesday, August 4, 2021 / Rules and Regulations the inhalation handler scenario from applying cypermethrin with a sprinkler can to home gardens. For assessing aggregate exposure to children, the Agency used exposures to children 1 to <2 years old dermal and incidental oral from post-application exposure to pets treated with the pet medallion/tag formulated with zeta-cypermethrin.
The PODs for the oral and dermal routes are based on the same effects:
Therefore, for children, the oral and dermal routes can be combined. Since the levels of concern for incidental oral risk and inhalation risk are different 100 and 30, the aggregate risk index ARI approach was used to calculate aggregate exposure and risk for adults.
An ARI 1 is not of concern.
Further information regarding EPA
standard assumptions and generic inputs for residential exposures may be found at http www2.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.
The Agency has determined that the pyrethroids and pyrethrins share a common mechanism of toxicity http
www.regulations.gov; EPAHQOPP
200804890006. As explained in that document, the members of this group share the ability to interact with voltagegated sodium channels ultimately leading to neurotoxicity. In 2011, after establishing a common mechanism grouping for the pyrethroids and pyrethrins, the Agency conducted a cumulative risk assessment CRA
which is available at http
www.regulations.gov; EPAHQOPP
20110746. In that document, the Agency concluded that cumulative exposures to pyrethroids based on pesticidal uses registered at the time the assessment was conducted did not present risks of concern. For information regarding EPAs efforts to evaluate the risk of exposure to this class of chemicals, refer to https
www.epa.gov/ingredients-usedpesticide-products/pyrethrins-andpyrethroids.
Since the 2011 CRA, for each new pyrethroid and pyrethrin use, the Agency has conducted a screen to evaluate any potential impacts on the CRA prior to those uses being granted.

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The most recent screen, which takes into account the previous uses and the new use on basil, demonstrates that the new uses will not significantly impact the cumulative assessment because dietary exposures comprise only a minor contribution to the total pyrethroid exposure. Therefore, there are no cumulative risks of concern for the pyrethroids and pyrethrins.
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.
No evidence of increased qualitative or quantitative susceptibility was noted in the developmental toxicity or reproduction studies for the cypermethrins. However, quantitative susceptibility was seen in the rat developmental neurotoxicity DNT
study with zeta-cypermethrin with an increased sensitivity in the offspring based on body weight changes in pups 510% in the absence of adverse, treatment-related effects in maternal animals. The results from the DNT
study are very similar to results observed in the reproduction studies where body weight BW changes decreased BW gain were seen in maternal and offspring animals at doses similar to those in the DNT study, with no indication of increased susceptibility. Therefore, there is no residual concern for effects observed in the study and a clear developmental NOAEL and LOAEL were identified.
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 the cypermethrins is complete.
ii. Like other pyrethroids, the cypermethrins cause neurotoxicity by interacting with sodium channels, leading to clinical signs of neurotoxicity. These effects are well
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characterized and adequately assessed by the available guideline and nonguideline studies. There are no residual uncertainties with regard to evidence of neurotoxicity for the cypermethrins.
iii. No evidence of increased qualitative or quantitative susceptibility was noted in the developmental toxicity or reproduction studies for the cypermethrins. However, quantitative susceptibility was seen in the rat developmental neurotoxicity DNT
study, but for the reasons discussed in Unit III.D.2, there is no residual concern for effects observed in the study and a clear developmental NOAEL and LOAEL were identified.
iv. There are no residual uncertainties identified in the exposure databases.
The dietary exposure assessments account for parent and metabolites of concern. The assessments include percent crop treated assumptions and conservative, default processing factors.
Furthermore, conservative, upper-bound assumptions were used to determine exposure through drinking water and residential sources, such that these exposures have not been underestimated.
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. Using the exposure assumptions described in this unit for acute exposure, EPA has concluded that acute exposure to zeta-cypermethrin from food and water will utilize 35% of the aPAD for adults 20 to 49 years old, the population group receiving the greatest exposure.
2. Chronic risk. A chronic dietary risk assessment is not required for zetacypermethrin because repeated exposure does not result in a POD lower than that resulting from acute exposure.
Therefore, the acute dietary risk assessment is protective of chronic dietary risk.
3. Short-term risk. Short-term aggregate exposure takes into account
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