Neonicotinoid and bisamide insecticides in wild freshwater fish from the Wanquan River, Hainan, China: Factors affecting tissue distribution and a risk assessment

Abstract

A growing number of studies have reported that neonicotinoid (NEO) and bisamide (BIS) insecticides are widespread in multimedium; however, limited information is available on their occurrence in wild freshwater fish. Therefore, in the Wanquan River with national aquatic germplasm resource reserves in Hainan, China, 502 fish containing 22 species were collected to investigate the occurrence of twelve NEOs and six BISs. The results showed that six NEOs and three BISs were detected in liver (ND-26.1515 ng/g wet weight (ww), whereas five NEOs and three BISs were detected in muscle (ND-1.6067 ng/g ww). Clothianidin had the highest detection frequency in liver (35.26%) and muscle (53.39%); however, imidacloprid (0.2106 ng/g ww) and dinotefuran (0.0353 ng/g ww) had the highest mean concentrations. Furthermore, the results indicated significant differences in insecticide concentrations between fish with different feeding habits, habitats, and spatial distributions. Benthic fish tend to accumulate BISs in liver and carnivorous fish have highest NEOs concentration in muscle. In addition, fish in the midstream and downstream regions had higher NEOs and total concentrations than those in the upstream region. Spearman’s correlation analysis revealed significant weak negative correlations between the concentration of almost all insecticides with body length and weight. Health risk assessments indicated that the hazard quotient for all insecticides was below 1, suggesting no immediate health risk to humans from consuming freshwater fish. These findings reveal previously unrecognized contamination of BISs in wild freshwater fish and expand the dataset on NEOs occurrence in fish from different sources, establishing a critical foundation for toxicologic research, insecticide pollution control, and human health protection.