A nationwide assessment of four diamide insecticides (DAIs) across 47 Chinese cities and nine major river basins has found that cyantraniliprole (CYTP) is the most abundant compound, but broflanilide (BFA) poses the greatest screening-level concern for benthic midges. The study, published in Environmental Chemistry and Ecotoxicology, provides the first nationwide snapshot of DAI pollution in Chinese rivers and underscores that environmental concentration alone does not determine ecological risk.
DAIs are newer alternatives to conventional pesticides, designed with improved selectivity, but their environmental footprint has remained largely unexamined. 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 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. Although BFA was not the most abundant pollutant, it became the primary 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 study also modeled a conservative scenario of direct ingestion of untreated surface water. Children aged 0–6 years had a 95th-percentile cumulative daily intake of 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 elevated exposure for children suggests they warrant additional attention in monitoring and risk assessment.
Corresponding author Yanhao Zhang emphasizes that monitoring should combine nationwide occurrence data with compound- and species-specific toxicity. The findings imply that current regulatory frameworks, which often rely on total concentrations or limited toxicity data, may underestimate risks from less abundant but more toxic compounds. The study also highlights the role of agricultural practices in shaping pollution signatures, suggesting that targeted management of specific crops and regions could be more effective than broad restrictions.
For policymakers, the research supports a shift toward risk-based monitoring that accounts for sensitive species and vulnerable populations. The authors note that land-use and meteorological variables could not explain the nationwide distribution, reinforcing the importance of crop-specific pesticide-use data. As DAIs continue to replace older pesticides, their environmental fate and ecological effects require ongoing scrutiny to prevent unintended consequences for aquatic ecosystems.
