A nationwide survey of four diamide insecticides (DAIs) across 47 cities and nine major Chinese river basins has found the compounds in rivers nationwide, with concentrations ranging from below detection to 119 ng/L and a national median total concentration of 40 ng/L, according to a study published in Environmental Chemistry and Ecotoxicology.
Cyantraniliprole (CYTP) was the predominant contaminant, with a median concentration of 17 ng/L and a 100% detection frequency. The chemical composition patterns varied by region: CYTP contributed most in southern basins, while broflanilide (BFA) made a larger contribution in northern basins. Local crop-planting patterns and crop-specific pesticide use potentially shaped those regional pollution signatures, the researchers said, while land-use and meteorological variables could not explain the nationwide distribution differences.
Notably, the study found 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. BFA screening risk quotients 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 researchers also 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. Spatial exposure patterns showed regional tendencies consistent with crop-use patterns, and all hazard quotients remained below 1.
"Our results showed that environmental concentration alone could not tell the whole risk story," corresponding author Yanhao Zhang said. "Monitoring should combine nationwide occurrence data with compound- and species-specific toxicity, while giving additional attention to sensitive groups such as children."
The findings matter because diamide insecticides are promoted as new alternatives to conventional pesticides with improved selectivity, yet their environmental footprint has remained poorly characterized at national scale. The study's central implication is that regulators and water managers cannot rely on abundance rankings alone: a less prevalent compound such as BFA can still drive ecological concern, and children face disproportionately higher modeled exposure from raw surface-water ingestion. The authors recommend pairing nationwide occurrence data with compound- and species-specific toxicity in monitoring programs. The research was funded by the National Natural Science Foundation of China (22376190 and 22576191) and the Natural Science Foundation of Henan Province (242300421128).
