Assessing the Portion of Diet Taken by Birds and Mammals from a Pesticide-Treated Area-Proposal for a Joint Way Forward.

An environmental risk assessment for birds and mammals is an important part of any application package for potential registration of pesticides in Europe. A realistic estimation of the exposure of a certain species to the pesticide under field conditions is a refinement factor in long-term higher-tier risk assessments. Although guidance on how to collect specific exposure data is provided, there is not yet a harmonized view on how to use and assess existing and newly recorded field data. Exposure is defined as the portion of diet taken from a pesticide-treated crop field over time (the PT factor), and it is set equal to the time a (tracked) individual is active (= foraging) in the crop of concern at the crop growth stage relevant to the pesticide application being assessed. While the PT factor is set to 1 in a first tier, it can be refined in higher tiers. Differences in the methodologies influencing the robustness of a data set and intraindividual variance in PT data are currently not considered. Our study, based on data recording in accordance with the European Food Safety Authority's recommendations, shows this variance for different species in different crops for both breeding and nonbreeding periods, with tracking sessions showing both interindividual as well as intraindividual variation across several days. We discuss PT data quality and how it can be used, considering intraindividual variance in a manner that is protective and conforms to current European guidance. The present study intends to support the planned revision of the current European guidance on how to conduct environmental bird and mammal risk assessments, and its further purpose is to open constructive discussions about how and which kind of PT data can be used. Environ Toxicol Chem 2022;41:1344-1354. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.