Implications of inhalation bioaccessibility for the exposure assessment of drifting airborne pesticides caused by field spraying.

Pesticide contamination in ambient air due to spray drifting has received extensive attention. Quantifying the associated health risk highlights the importance of incorporating bioaccessibility into inhalation exposure assessments rather than using the total inhaled concentration of airborne pesticides. In this study, we measured the inhalation unit exposure (UE) of three typical pesticides (lambda-cyhalothrin, phoxim, and acetamiprid) during application and post-application drift at the recommended application dosage. The UE values were found to be 1.74-424.37 ng/m and 0.07-1.40 ng/m, respectively, with marked variation between different spraying nozzles and formulations. For the inhalation exposure assessment, an in vitro method was developed to determine the inhalation bioaccessibility of lambda-cyhalothrin, phoxim, and acetamiprid and its applicability was validated based on in vivo-in vitro correlations (IVIVC) analysis. Their conservative inhalation bioaccessibility values estimates were 46.09 %, 67.12 %, and 40.31 %, respectively. The calculated average daily dose values of the analyzed pesticides in both single and mixed formulations ranged from 8.03 × 10 to 4.35 × 10 mg/kg·day based on the bioaccessible UE, corresponding to 22.99-67.11 % of the total exposure. Collectively, these findings are of guiding significance for improving risk management in pesticide application.