Meta-analysis of neonicotinoid insecticides in global surface waters

Neonicotinoids (NEOs) are a class of insecticides that have high insecticidal activity and are extensively used worldwide. However, increasing evidence suggests their long-term residues in the environment and toxic effects on nontarget organisms. NEO residues are frequently detected in water and consequently have created increasing levels of pollution and pose significant risks to humans. Many studies have focused on NEO concentrations in water; however, few studies have focused on global systematic reviews or meta-analyses of NEO concentrations in water. The purpose of this review is to conduct a meta-analysis on the concentration of NEOs in global waters based on published detections from several countries to extend knowledge on the application of NEOs. In the present study, 43 published papers from 10 countries were indexed for a meta-analysis of the global NEO distribution in water. Most of these studies focus on the intensive agricultural area, such as eastern Asia and North America. The order of mean concentrations is identified as imidacloprid (119.542 ± 15.656 ng L^-1) > nitenpyram (88.076 ± 27.144 ng L^-1) > thiamethoxam (59.752 ± 9.068 ng L^-1) > dinotefuran (31.086 ± 9.275 ng L^-1) > imidaclothiz (24.542 ± 2.906 ng L^-1) > acetamiprid (23.360 ± 4.015 ng L^-1) > thiacloprid (11.493 ± 5.095 ng L^-1). Moreover, the relationships between NEO concentrations and some environmental factors are analyzed. NEO concentrations increase with temperature, oxidation-reduction potential, and the percentage of cultivated crops but decrease with stream discharge, pH, dissolved oxygen, and precipitation. NEO concentrations show no significant relations to turbidity and conductivity.