Diamide insecticides (DAIs) have been promoted as newer alternatives to conventional pesticides with improved selectivity, but their environmental footprint has remained largely unexamined. A nationwide study published in Environmental Chemistry and Ecotoxicology now provides a pollution snapshot across nine major Chinese river basins and 47 cities, showing that four DAIs are widely present at concentrations ranging from below detection limit to 119 ng/L, with a national median total concentration of 40 ng/L.
Cyantraniliprole (CYTP) was the most abundant compound, with a median concentration of 17 ng/L and a 100% detection frequency. However, the study found that concentration alone does not predict ecological risk. Broflanilide (BFA) was not the most abundant pollutant, yet it became the main screening-level driver for the benthic midge Chironomus dilutus because its species-specific chronic effect threshold was much lower. BFA screening risk quotients exceeded 1 at 22% of sampling sites, signaling potential chronic effects on this sensitive organism.
The research also revealed that chemical composition patterns varied by region. CYTP contributed most in southern basins, while BFA made a larger contribution in northern basins. Local crop-planting patterns and crop-specific pesticide use potentially shaped these regional pollution signatures, whereas land-use and meteorological variables could not explain the nationwide distribution differences.
For Daphnia magna, the combined risk of the four DAIs exceeded the medium-risk threshold at 22% of sites, while cumulative risks for fish and aquatic plants remained negligible in this screening framework. The study further modeled a conservative scenario in which untreated surface water is ingested directly. The 95th-percentile cumulative daily intake for children aged 0–6 years was 9.1 ng/kg body weight/day, about 2.4 times the adult value of 3.7 ng/kg body weight/day. All hazard quotients remained below 1, but the disparity highlights that children may face higher exposure.
Corresponding author Yanhao Zhang emphasized that environmental concentration alone cannot tell the whole risk story. "Monitoring should combine nationwide occurrence data with compound- and species-specific toxicity, while giving additional attention to sensitive groups such as children," Zhang said. The findings imply that regulatory monitoring for DAIs should move beyond abundance-based assessments and incorporate species-specific chronic thresholds, especially for compounds like BFA that can drive ecological risk at low concentrations. The study was funded by the National Natural Science Foundation of China and the Natural Science Foundation of Henan Province.
