The International Estimated Short-Term Intake: Conservatisms and Appropriateness for Estimating Acute Dietary Exposure to Pesticides

摘要

The International Estimate of Short-Term Intake (IESTI) is used to estimate acute dietary exposures to pesticide residues as part of the process for establishing and reviewing maximum residue limits (MRLs) on foods in some regions (e.g., EU & Codex countries). The IESTI calculation is based on consumption of a large portion of a food item combined with a high-end estimate of the residues possible on that food item (the highest residue (or median for blended foods) from pesticide field trials). In late 2015, changes to the current IESTI calculations were proposed in a joint FAO/WHO workshop. Subsequent discussions at the Codex Committee on Pesticide Residues (CCPR) and an associated electronic working group focused on whether change is needed and potential impacts of proposed changes. No decision has been made on final proposed equations, but the appropriate level of conservatism has been a focus of discussion. The 2015 proposed equations included: use of the MRL in place of residue trial data, removal of consideration of unit weight, introduction of a new conversion factor accounting for metabolites not included in the MRL, and use of large portion consumption data on a body weight rather than per person basis. Preliminary assessments have projected an increase in calculated dietary intakes, despite statements that changes to the IESTI should not lead to substantial changes in the level of conservativeness (CX/PR 17/49/12; discussion paper from IESTI eWG at 49th CCPR meeting). The ultimate impact on MRLs critical for the free global trade of food remains unclear. Based on these events, it has become apparent that benchmarking the conservatisms in the IESTI approach will be necessary in order to better understand the need for any changes and the implications of those changes. In this presentation, we will provide a history of the proposed changes and provide case studies illustrating the conservatisms within the IESTI approach for estimating acute dietary exposures.