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Federal Register / Vol. 86, No. 165 / Monday, August 30, 2021 / Rules and Regulations reliable data, such margin will be safe for infants and children.
In applying the FQPA safety factor provision, EPA has interpreted it as imposing a presumption in favor of retaining it as an additional 10X safety factor. Ref. 5 at 4, 11. Thus, EPA
generally refers to the 10X factor as a presumptive or default 10X factor. EPA
has also made clear, however, that this presumption or default in favor of the 10X is only a presumption. The presumption can be overcome if reliable data demonstrate that a different factor is safe for children. Id.. In determining whether a different factor is safe for children, EPA focuses on the three factors listed in FFDCA section 408b2Cthe completeness of the toxicity database, the completeness of the exposure database, and potential preand post-natal toxicity. In examining these factors, EPA strives to make sure that its choice of a safety factor, based on a weight-of-theevidence evaluation, does not understate the risk to children. Id. at 2425, 35.
EPAs 2020 HHRA assessed the potential risks from exposures to chlorpyrifos in two wayswith one scenario being the retention of the default 10X FQPA SF, and the other scenario being the reduction of the FQPA SF to 1X. The purpose of using both values was to provide an indication of what the potential risk estimates would be under either scenario. The 2020 document, however, retained the 10X and did not adopt or offer support for reducing to 1X. To reduce the FQPA safety factor to 1X, the FFDCA requires that EPA determine that reliable data demonstrate that the 1X would be safe for infants and children. The 2020 document did not make that determination. For chlorpyrifos, of the three factors mentioned in the previous paragraph, the primary factor that undercuts a determination that a different safety factor would be safe for children is the uncertainty around the potential for preand post-natal toxicity for infants and children in the area of neurodevelopmental outcomes.
Based on the weight of the evidence concerning the potential for neurodevelopmental outcomes as discussed in Unit VI.B.2. above, there is ample qualitative evidence of a potential effect on the developing brain;
however, there remains uncertainty around the levels at which these potential neurodevelopmental outcomes occur. Although the laboratory animal studies do not support a conclusion that neurodevelopmental outcomes are more sensitive than AChE inhibition, the
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mechanistic data are, at this time, incomplete in their characterization of dose-response. This conclusion may be further evaluated upon EPAs completion of the review of the 2020
FIFRA SAP report concerning NAMs;
however, due to the time constraints of this rule, EPA has not been able to include that information in the current assessment of chlorpyrifos. Finally, while the epidemiology data indicates an association between chlorpyrifos and adverse neurodevelopmental outcomes, there remains some uncertainty in the dose-response relationship. As such, because the data available at this time indicate remaining uncertainties concerning preand post-natal toxicity due to insufficient clarity on the levels at which these outcomes occur, the Agency is unable to conclude, at this time, that a different safety factor would be safe for infants and children; thus, the Agency is retaining the default 10X
FQPA safety factor.
4. Total Uncertainty Factors and PADs In conclusion, the Agency used a total uncertainty factor of 100X for determining the food and drinking water PADs for females of childbearing age 1X interspecies factor, 10X intraspecies factor, and 10X FQPA safety factor; 40X for determining the food PADs for remaining populations 1X
interspecies factor, 4X intra-species factor, and 10X FQPA safety factor; and 50X for determining the PADs for drinking water for remaining populations 1X interspecies factor, 5X
intra-species factor, and 10X FQPA
safety factor.
Taking into consideration the PoDs, intra-species extrapolation factors, and FQPA safety factor, the Agency calculated acute PADs aPADs and steady state PADs ssPADs for infants less than 1 year old, children 1 to 2
years old, children 6 to 12 years old, youths 13 to 19 years old, and females 1349 years old; these subpopulations will be protective of other subpopulations. Ref. 9 at 3032.
Values may be found in table 5.0.1 in the 2020 HHRA.
VII. EPAs Exposure Assessment for Chlorpyrifos Risk is a function of both hazard and exposure. Thus, equally important to the risk assessment process as determining the hazards posed by a pesticide and the toxicological endpoints for those hazards is estimating human exposure. Under FFDCA section 408, EPA must evaluate the aggregate exposure to a pesticide chemical residue. This means that EPA
is concerned not only with exposure to
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pesticide residues in food but also exposure resulting from pesticide contamination of drinking water supplies and from use of pesticides in the home or other non-occupational settings. See 21 U.S.C.
346ab2Dvi.
Pursuant to FFDCA section 408b, EPA has evaluated chlorpyrifoss risks based on aggregate exposure to chlorpyrifos. By aggregate exposure, EPA is referring to exposure to chlorpyrifos by multiple pathways of exposure, i.e., food, drinking water, and residential. EPA uses available data and standard analytical methods, together with assumptions designed to be protective of public health, to produce separate estimates of exposure for a highly exposed subgroup of the general population, for each potential pathway and route of exposure.
The following reflect a summary of the Agencys exposure assessment from the 2020 HHRA unless otherwise specified. Ref. 10.
A. Exposure From Food 1. General Approach for Estimating Food Exposures There are two critical variables in estimating exposure in food: 1 The types and amount of food that is consumed; and 2 The residue level in that food. Consumption is estimated by EPA based on scientific surveys of individuals food consumption in the United States conducted by the U.S.
Department of Agriculture USDA, Ref.
11 at 12. Information on residue values can come from a range of sources including crop field trials; data on pesticide reduction or concentration due to processing, cooking, and other practices; information on the extent of usage of the pesticide; and monitoring of the food supply. Id. at 17.
Data on the residues of chlorpyrifos in foods are available from both field trial data and monitoring data, primarily the USDAs Pesticide Data Program PDP
monitoring data. Monitoring data generally provide a characterization of pesticide residues in or on foods consumed by the U.S. population that closely approximates real world exposures because they are sampled closer to the point of consumption in the chain of commerce than field trial data, which are generated to establish the maximum level of legal residues that could result from maximum permissible use of the pesticide immediately after harvest.
EPA uses a computer program known as the Dietary Exposure Evaluation Model and Calendex software with the Food Commodity Intake Database
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