Human health risk assessment (HHRA) involves characterization of both hazard and exposure, however many of the traditional test guideline mammalian toxicity studies do not contribute data to the final HHRAs. The challenge is to focus on developing those data that materially contribute to the HHRA. To address this challenge, we have explored ways of making the best use of exposure and hazard data for existing pesticides to identify toxicity studies relevant for HHRA of a new pesticide. The premise is that exposure can be predicted based on the use scenario, regardless of the chemistry or pesticidal mode of action. A case study of a new fungicide will be described. Scenarios were determined based on registered agricultural uses for fungicides as they are applied in the USA. Exposure prediction was determined from existing crop residue data for substances with comparable use on the same or similar crops. Predictions were made for acute and chronic dietary exposure including contributions from predicted drinking water concentrations. Occupational exposure was also predicted for the identified use scenarios. To provide a point of comparison for the exposure predictions, data were collated for dietary and occupational reference doses concluded by USEPA as part of regulatory decision making for substance registration. Reference dose ranges were defined for fungicides, insecticides, and herbicides to provide a point of comparison for the predicted range of exposures and allow an initial judgement on acceptability of the potential risks to human health. To visualize and contextualize the level of potential concern for the exposure prediction, the exposure predictions and range of hazard endpoints were compared using RISK21 plots (www.risk21.org). The evaluation determined that the majority of dietary exposure was through drinking water. In the present case, the contribution of additional crops to the use scenario and the impact of those crops on the exposure and risk were evaluated. Adding additional crops to the use scenario did not result in a significant impact on dietary risk. The major contribution to dietary risk was through drinking water

Agricultural use and human exposure driven data generation: Impact of drinking water on dietary exposure

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.