Residue Behavior, Processing Factors, and Dietary Exposure of Buprofezin and Etofenprox During Rice Processing

Rice processing can substantially alter pesticide residues before consumption. This study evaluated the residue behavior of buprofezin and etofenprox during rice processing, determined their processing factors (PFs), and assessed dietary exposure through rice and processed rice products. To ensure quantifiable residues throughout the study, both pesticides were applied at three times the recommended Korean good agricultural practice (GAP) rate. Relative to whole grain, buprofezin and etofenprox residues decreased by 91.9% and 96.8% in husked rice, respectively, with the greatest overall reductions observed in polished rice (99.0% and 99.5%, respectively). In contrast, higher residue concentrations were observed in hulls, with PFs of 6.45 for buprofezin and 3.60 for etofenprox. Cooking further reduced residues remaining in husked rice, whereas both pesticides were below the limit of quantification (LOQ) in cooked polished rice and rice cake. Despite application at three times the recommended GAP rate, estimated chronic dietary exposure was low, with maximum percentage of acceptable daily intake (%ADI) values of 1.303% for buprofezin and 0.261% for etofenprox. These findings indicate that milling was the predominant processing step reducing pesticide residues in edible rice fractions, and cooking provided an additional reduction before consumption.