A nationwide survey of four diamide insecticides (DAIs) in rivers across 47 Chinese cities and nine major river basins has found that cyantraniliprole (CYTP) is the most abundant compound, but broflanilide (BFA) drives the highest screening-level ecological concern for benthic midges. The study, published in Environmental Chemistry and Ecotoxicology, provides the first nationwide snapshot of these newer pesticides in Chinese surface waters.
DAIs are increasingly used as alternatives to conventional pesticides because of their improved selectivity, but their environmental footprint had not been systematically assessed. The researchers detected all four compounds at concentrations ranging from below the 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 patterns in chemical composition tracked local crop-planting practices. CYTP contributed most in southern basins, while BFA made a larger contribution in northern basins, according to corresponding author Yanhao Zhang. Land-use and meteorological variables did not explain the nationwide distribution, suggesting that crop-specific pesticide use is the dominant driver.
The study highlights a mismatch between environmental concentration and ecological risk. Although BFA was not the most abundant pollutant, it became the main screening-level driver for the benthic midge Chironomus dilutus because its species-specific chronic effect threshold is 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 per day, about 2.4 times the adult value of 3.7 ng/kg body weight per day. All hazard quotients remained below 1, indicating no immediate health concern, but the disparity underscores the greater vulnerability of young children.
“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 findings have implications beyond China, as diamide insecticides are registered and used globally. The study was funded by the National Natural Science Foundation of China and the Natural Science Foundation of Henan Province. Additional information about the research group is available at http://chuanlink-innovations.com.
