A nationwide pollution snapshot of four diamide insecticides (DAIs) across 47 Chinese cities and nine major river basins has found widespread contamination, with cyantraniliprole (CYTP) the most abundant compound but broflanilide (BFA) producing the highest screening-level concern for benthic midges because of its lower species-specific chronic threshold. The study, published in Environmental Chemistry and Ecotoxicology, is important because it shows that environmental concentration alone cannot predict ecological risk and that monitoring must account for compound- and species-specific toxicity, especially for sensitive groups such as children.
“We found four DAIs across rivers in 47 Chinese cities,” said corresponding author Yanhao Zhang. “The compounds were found at concentrations from below detection limit to 119 ng/L, with a national median total concentration of 40 ng/L.” CYTP was the predominant contaminant, with a median concentration of 17 ng/L and a 100 percent detection frequency. Regional composition differed: 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.
The study's 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,” Zhang said. “BFA screening RQs exceeded 1 at 22% of sampling sites.” For Daphnia magna, the combined risk of the four DAIs exceeded the medium-risk threshold at 22 percent of sites, while cumulative risks for fish and aquatic plants remained negligible in this screening framework. This matters for regulators and water managers because it suggests that focusing only on the most abundant compounds could overlook species at greater risk.
The study also modeled a conservative scenario of direct ingestion of untreated surface water. The 95th-percentile cumulative daily intake for children aged 0 to 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 showed regional tendencies consistent with crop-use patterns. “Our results showed that environmental concentration alone could not tell the whole risk story,” 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 research was funded by the National Natural Science Foundation of China (22376190 and 22576191) and the Natural Science Foundation of Henan Province (242300421128). Additional information is available through Chuanlink Innovations.
