美国修订氯氰菊酯（Zeta-cypermethrin）的残留限量要求(Zeta-cypermethrin; Pesticide Tolerances)

　　II. Summary of Petitioned-For Tolerance

 

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　　In the Federal Register of January 28, 2015 (80 FR 4525) (FRL-9921-55), EPA issued a document pursuant to FFDCA section 408(d)(3), 21 U.S.C. 346a(d)(3), announcing the filing of a pesticide petition (PP 4F8290) by FMC Corporation, 1735 Market St., Philadelphia, PA 19103. The petition requested to amend the tolerances in 40 CFR 180.418 for residues of the insecticide zeta-cypermethrin, S-cyano (3-phenoxyphenyl) methyl (±))(cis-trans 3-(2-2-dichloroethenyl)-2,2 dimethylcyclopropanecarboxylate, in or on corn, field, forage from 0.2 parts per million (ppm) to 9.0 ppm; corn, field, stover from 3.0 ppm to 30.0 ppm; and corn, pop, stover from 3.0 ppm to 30.0 ppm. That document referenced a summary of the petition prepared by FMC Corporation, the registrant, which is available in the docket, http://www.regulations.gov. Comments were received on the notice of filing. EPA's response to these comments is discussed in Unit IV.C.

 

　　Instead of the proposed tolerances in field corn stover (30.0 ppm) and popcorn stover (30.0 ppm), the Agency is establishing the tolerances at 30 ppm. The Agency establishes tolerances using whole numbers for tolerances of 10 ppm or more, per the OECD's User Guide ENV/JM/MONO (2011)2 for the OECD tolerance calculation procedure.

 

　　III. Aggregate Risk Assessment and Determination of Safety

 

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　　Section 408(b)(2)(A)(i) of FFDCA allows EPA to establish a tolerance (the legal limit for a pesticide chemical residue in or on a food) only if EPA determines that the tolerance is “safe.” Section 408(b)(2)(A)(ii) of FFDCA defines “safe” to mean that “there is a reasonable certainty that no harm will result from aggregate exposure to the pesticide chemical residue, including all anticipated dietary exposures and all other exposures for which there is reliable information.” This includes exposure through drinking water and in residential settings, but does not include occupational exposure. Section 408(b)(2)(C) of FFDCA requires EPA to give special consideration to exposure of infants and children to the pesticide chemical residue in establishing a tolerance and to “ensure that there is a reasonable certainty that no harm will result to infants and children from aggregate exposure to the pesticide chemical residue. . . .”

 

　　Consistent with FFDCA section 408(b)(2)(D), and the factors specified in FFDCA section 408(b)(2)(D), 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 zeta-cypermethrin including exposure resulting from the tolerances established by this action. EPA's assessment of exposures and risks associated with zeta-cypermethrin follows.

 

　　Zeta-cypermethrin is an enriched isomer of the pyrethroid insecticide cypermethrin. In addition, alpha-cypermethrin is also an enriched isomer of cypermethrin. Although cypermethrin, zeta-cypermethrin, and alpha-cypermethrin are separate active ingredients with different end-use products, they are included together in the hazard evaluation for the purpose of human health risk assessment. The toxicology database for the cypermethrins includes studies with cypermethrin and both of its enriched isomers, and is considered complete for the purpose of risk assessment.

 

　　The aggregate risk assessment for zeta-cypermethrin must consider potential exposure from all cypermethrins (i.e., cypermethrin, zeta-cypermethrin, and alpha-cypermethrin), since the three active ingredients are considered to be essentially the same from the mammalian toxicity perspective. The revised tolerances are associated with decreased pre-harvest intervals (PHIs) for field corn and popcorn—from 30 days for grain and stover and 60 days for forage to 7 days for all these commodities—and have no impact on the existing dietary exposure assessment for the cypermethrins. Corn forage and stover are livestock feed items and are not directly entered into the dietary exposure assessment, and EPA has determined that the existing tolerances for livestock commodities are adequate to support the changed use pattern. The existing zeta-cypermethrin use on corn was included in previous dietary exposure assessments. Decreasing the PHI and increasing the zeta-cypermethrin tolerances for field corn forage, field corn stover, and popcorn stover will have no impact on the dietary risk estimates, as they are already covered in the existing dietary assessment.

 

　　In the final rule published in the Federal Register of December 7, 2012(77 FR 72975) (FRL-9371-7), EPA established tolerances for residues of zeta-cypermethrin in multiple commodities. Since the publication of that final rule, the toxicity profile of zeta-cypermethrin has not changed, and since the revised tolerances associated with decreased PHIs for field corn and popcorn have no impact on the existing dietary and aggregate risk determinations, the risk assessments that supported the establishment of the zeta-cypermethrin tolerances published in the December 7, 2012 Federal Register final rule remain valid. Therefore, EPA is relying on those risk assessments in order to support the revised tolerances for zeta-cypermethrin in field corn forage, field corn stover, and popcorn stover.

 

　　An updated aggregate risk assessment was not needed to support the proposed increased tolerances for residues in field corn forage, field corn stover, and popcorn stover, and the increased tolerances will not result in a change in the previously estimated dietary (food and water) or residential exposure estimates for zeta-cypermethrin. For a detailed discussion of the aggregate risk assessments and determination of safety, refer to the December 7, 2012 Federal Register final rule and its supporting documents, available at http://www.regulations.gov in docket ID number EPA-HQ-OPP-2010-0472. EPA is relying on those supporting risk assessments and findings to support this final rule.

 

　　Based on the risk assessments and information described in this unit, 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 zeta-cypermethrin residues. Additional information can be found in the document: “Zeta-Cypermethrin—Human Health Risk Assessment for a Petition to Amend (Increase) the Established Tolerances for the Insecticide in Field Corn and Popcorn Stover, and in Field Corn Forage,” available in docket ID number EPA-HQ-OPP-2014-0889.

 

　　IV. Other Considerations

 

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　　A. Analytical Enforcement Methodology

 

　　Adequate tolerance enforcement methods are available in Pesticide Analytical Manual (PAM) Volume II for determining residues of alpha-cypermethrin, cypermethrin, and zeta-cypermethrin in plant (Method I) and livestock (Method II) commodities. Both methods are gas chromatographic methods with electron-capture detection (GC/ECD), and have undergone successful Agency petition method validations (PMVs). These methods are not stereospecific; thus no distinction is made between residues of cypermethrin (all 8 stereoisomers), alpha-cypermethrin (enriched in 2 isomers), and zeta-cypermethrin (enriched in 4 isomers). The January 1994 Food and Drug Administration (FDA) PESTDATA database (PAM Volume I) indicates that residues of cypermethrin are completely recovered (>80%) using multi-residue method sections 302 (Luke), 303 (Mills, Onley, and Gaither), and 304 (Mills fatty food).

 

　　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 408(b)(4). The Codex Alimentarius is a joint United Nations Food and Agriculture Organization/World Health Organization food standards program, and it is recognized as an international food safety standards-setting organization in trade agreements to which the United States is a party. EPA may establish a tolerance that is different from a Codex MRL; however, FFDCA section 408(b)(4) requires that EPA explain the reasons for departing from the Codex level.

 

　　There are no Codex MRLs for cypermethrin, which includes both alpha- and zeta-cypermethrin, established in corn forage or stover.

 

　　C. Response to Comments

 

　　One comment was received from the general public, urging the Agency to deny the request. The commenter particularly addressed toxicity to bees and other insects, and human toxicological and reproductive effects.

 

　　The Agency understands the commenter's concerns, and recognizes that some individuals believe that certain pesticide chemicals should not be permitted in food. Regarding effects to bees and other insects, the safety standard for approving tolerances under section 408 of FFDCA focuses on potential harms to human health and does not permit consideration of effects on other species or the environment. The existing legal framework provided by section 408 of FFDCA states that tolerances may be set when persons seeking such tolerances or exemptions have demonstrated that the pesticide meets the safety standard imposed by that statute. When new or amended tolerances are requested for residues of a pesticide in food or feed, the Agency, as is required by Section 408 of FFDCA, estimates the risk of the potential exposure to these residues by performing an aggregate risk assessment. Such a risk assessment integrates the individual assessments that are conducted for food, drinking water, and residential exposures. Additionally, the Agency, as is further required by Section 408 of the FFDCA, considers available information concerning what are termed the cumulative toxicological effects of the residues of that pesticide and of other substances having a common mechanism of toxicity. Therefore, these assessments consider both exposure and toxicological effects—including information concerning the reproductive effects of the pesticide—in reaching a conclusion as to whether or not the reasonable certainty of no harm decision can be made. The Agency has concluded after this assessment that there is a reasonable certainty that no harm will result from exposure to the residues of zeta-cypermethrin. Therefore, the proposed tolerances are found to be acceptable.

 

　　V. Conclusion

 

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　　Therefore, tolerances are established for residues of zeta-cypermethrin, S-cyano (3-phenoxyphenyl) methyl (±))(cis-trans 3-(2-2-dichloroethenyl)-2,2 dimethylcyclopropanecarboxylate, in or on corn, field, forage at 9.0 ppm; corn, field, stover at 30 ppm; and corn, pop, stover at 30 ppm. 原文下载：  Zeta-Cypermethrin; Pesticide Tolerances.pdf