Overlooked secondary toxicity of culinary solvothermal transformation products of pesticides

JX Zhu and R Wei and JN Zhang and NQ Ren and SJ You, WATER RESEARCH, 287, 124328 (2025).

DOI: 10.1016/j.watres.2025.124328

Water and oil are the most commonly used liquid media for food cooking under solvothermal conditions. In this study, we first report an important yet previously overlooked secondary toxicity associated with culinary solvothermal transformation products (CSTPs) of pesticides, i.e. pretilachlor (Pr), imidacloprid (Im) and isoprothiolane (Is) in water, water-oil mixture and oil during 25-min heating. Imidacloprid showed higher instability in heated water, with 57.6 % and 36.1 % conversion in water and water-oil, respectively. Pretilachlor transformed minimally in water (0.3 %) but reached 19.3 % in water-oil, while isoprothiolane showed similar to 25 % transformation in both. All pesticides transformed substantially in heated oil (78.5 %-94.1 %). Transformation in water and water-oil is attributed to changes in water's dielectric constant, viscosity, diffusion coefficient, and pKw at 100 degrees C. In oil, high reactivity from organic radicals at 180 degrees C initiates pesticide transformation. Based on toxicity assessment, CSTPs exhibited higher secondary cytotoxicity in oil groups, indicated by reduction of half-maximal inhibitory concentration by 26.9-78.5 % in 24-hour and cell viability by 14.9-97.4 % under 5-day exposure than parents. This work highlights the need for considering toxicity associated with CSTPs within the context of long-term and low- dosage exposure during food cooking.

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