In-silico prediction of dislodgeable foliar residues and regulatory implications for plant protection products

Yi Shi; Kanak Choudhury; Xiaoyi Sopko; Sarah Adham; Edward Chikwana

doi:10.1038/s41370-024-00675-w

In-silico prediction of dislodgeable foliar residues and regulatory implications for plant protection products

J Expo Sci Environ Epidemiol. 2024 Apr 27. doi: 10.1038/s41370-024-00675-w. Online ahead of print.

Authors

Yi Shi¹, Kanak Choudhury², Xiaoyi Sopko², Sarah Adham³, Edward Chikwana⁴

Affiliations

¹ Department of Biostatistics & Health Data Science, Indiana University Richard M. Fairbanks School of Public Health, 1050 Wishard Blvd, Indianapolis, IN, 46202, USA.
² Corteva Agriscience LLC, 9330 Zionsville Road, Indianapolis, IN, 46268, USA.
³ Corteva Agriscience LLC, Abingdon, OX14 4RY, United Kingdom.
⁴ Corteva Agriscience LLC, 9330 Zionsville Road, Indianapolis, IN, 46268, USA. edward.chikwana@corteva.com.

PMID: 38678132
DOI: 10.1038/s41370-024-00675-w

Abstract

Background: When experimentally determined dislodgeable foliar residue (DFR) values are not available, regulatory agencies use conservative default DFR values as a first-tier approach to assess post-application dermal exposures to plant protection products (PPPs). These default values are based on a limited set of field studies, are very conservative, and potentially overestimate exposures from DFRs.

Objective: Use Random Forest to develop classification and regression-type ensemble models to predict DFR values after last application (DFR0) by considering experimentally-based variability due to differences in physical and chemical properties of PPPs, agronomic practices, crop type, and climatic conditions.

Methods: Random Forest algorithm was used to develop in-silico ensemble DFR0 prediction models using more than 100 DFR studies from Corteva Agriscience^TM. Several variables related to the active ingredient (a.i.) that was applied, crop, and climate conditions at the time of last application were considered as model parameters.

Results: The proposed ensemble models demonstrated 98% prediction accuracy that if a DFR0 is predicted to be less than the European Food Safety Authority (EFSA) default DFR0 value of 3 µg/cm²/kg a.i./ha, it is highly indicative that the measured DFR value will be less than the default if the study is conducted. If a value is predicted to be larger than or equal to the EFSA default, the model has an 83% prediction accuracy.

Impact statement: This manuscript is expected to have significant impact globally as it provides: A framework for incorporating in silico DFR data into worker exposure assessment, A roadmap for a tiered approach for conducting re-entry exposure assessment, and A proof of concept for using existing DFR data to provide a read-across framework that can easily be harmonized across all regulatory agencies to provide more robust assessments for PPP exposures.

Keywords: Dermal Exposure; Dislodgeable Foliar Residues (DFR) Prediction; In-silico Model; Post-application Exposure; Random Forest; Worker Exposure.