A nationwide survey of four diamide insecticides (DAIs) in 47 Chinese cities and nine major river basins has found widespread contamination, with cyantraniliprole (CYTP) the most abundant compound but broflanilide (BFA) the primary screening-level concern for benthic midges. The study, published in Environmental Chemistry and Ecotoxicology, highlights that environmental concentration alone does not fully capture ecological risk, with implications for monitoring and regulation of these newer pesticides.
DAIs are increasingly used as alternatives to conventional pesticides because of their improved selectivity, but their environmental footprint had not been systematically assessed across China. The researchers detected all four compounds at concentrations ranging from below detection limit to 119 ng/L, with a national median total concentration of 40 ng/L. CYTP was found at every sampling site, with a median concentration of 17 ng/L. Regional composition patterns varied: CYTP dominated in southern basins, while BFA contributed more in northern basins, likely reflecting local crop-planting patterns and crop-specific pesticide use.
The key finding is a mismatch between concentration and ecological risk. 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. Screening risk quotients for BFA exceeded 1 at 22% of sampling sites. 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 the screening framework.
The study also modeled a conservative scenario of direct ingestion of untreated surface water. 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, although all hazard quotients remained below 1. Spatial exposure patterns followed crop-use patterns. Corresponding author Yanhao Zhang noted that monitoring should combine nationwide occurrence data with compound- and species-specific toxicity, with additional attention to sensitive groups such as children.
The research was funded by the National Natural Science Foundation of China and the Natural Science Foundation of Henan Province, and supported by Chuanlink Innovations.
