Occurrence, mixture neurotoxicity risk, and prioritization of neonicotinoid and diamide insecticides in urban residential soils.

The widespread use of neonicotinoid (NEO) and diamide (DAI) insecticides has led to their frequent environmental occurrence, yet their presence and associated health risks in urban residential soils remain poorly understood. This study collected 200 residential soils from 10 provinces of China, revealing widespread detection of both NEOs and DAIs. Concentrations of ∑11NEOs and ∑8DAIs ranged from 0.31 - 1878 ng/g and ND - 6.27 ng/g, respectively, with imidacloprid (IMI) and chlorantraniliprole (CTP) as the dominant compounds. Both NEOs and DAIs exhibited marked spatial variability across cities, with relatively higher concentrations observed in several northern cities. While conventional exposure assessment indicated negligible health risks via soil-related pathways, a field-informed computational framework integrating mixture quantitative structure-activity relationship (QSAR) and toxicological priority index (ToxPi) was developed to characterize predicted mixture neurotoxicity potential and identify priority compounds. QSAR modeling indicated that DAI mixtures exhibited higher predicted mixture neurotoxicity potential than NEO mixtures despite substantially lower environmental concentrations, whereas NEO mixtures were characterized by higher residue levels and exposure-weighted intake. ToxPi analysis identified IMI and CTP as top-ranked priority compounds within NEOs and DAIs, respectively. This study advances mixture-level risk prioritization of co-occurring insecticides by integrating exposure characterization with QSAR-based neurotoxicity predictions, providing a complementary approach to conventional concentration-based monitoring.