The Environment Protection Agency (EPA) extended the comment date on its draft guidance, Pesticide Cumulative Risk Assessment: Framework for Screening Analysis, in a Federal Register notice published on August 28, 2015.  EPA’s draft framework provides guidance on how the EPA will screen groups of pesticides for cumulative evaluation.  EPA proposes using a two-step approach, beginning with the evaluation of available toxicological information and, if necessary, followed by a risk-based screening approach.  This framework supplements the existing guidance documents for establishing common mechanism groups (CMG) and conducting cumulative risk assessments (CRA).  Additionally, EPA is also seeking comments on a draft copy of the human health risk assessment where the cumulative assessment was conducted in conjunction with pending actions for abamectin.

EPA has described a process that is data intensive and that requires sophisticated knowledge and modeling.  EPA acknowledges that “the level of refinement provided by this approach is not necessary or even feasible for all existing pesticide classes.”  The policy documents for conducting the first step in the process, “developing CMGs,” are still being refined.

This document provides the guidance for screening information to identify candidate CMGs and does not outline how actually to conduct CRAs.  Rather, this document relies on policies and principles provided in other documents found on the EPA cumulative risk assessment website.  These additional policies and principles were developed during the conduct of five CRAs for chemical groups such as the organophosphates and carbamates.

One of the major questions raised by the issuance of this document is the extent of the information that EPA will require for each chemical to determine if there are CMGs.  The five CMGs currently assessed have relatively well defined mechanisms of action.  It is not clear, however, what EPA will consider to be adequate justification that there are no other chemicals with the same mechanism of action for other chemicals of concern.

Requirements for EPA to determine and assess the risks of possible common mechanism of action among groups of similar pesticides was one of the most far-reaching new requirements imposed by the Food Quality Protection Act.  Some observers expected a larger impact on pesticide use than what has occurred to date; whether EPA’s new approach results in more groupings or otherwise leads to restrictions on more groups of pesticides remains to be seen.

Comments on the draft guidance are due September 28, 2015.  More information regarding EPA’s assessment of pesticide cumulative risk is available online.

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