Fate and risk of pesticides in drinking water: From source to tap using a comprehensive analysis and prioritization approach.

Ensuring the quality and safety of drinking water is crucial for public health. Yet our understanding of pesticides contamination and associated in drinking water systems remains incomplete. In this study, we conducted a comprehensive analysis combining target, suspect, and nontarget screening to investigate pesticide presence from source to tap in a drinking water treatment plant in Jiangsu, China. We identified 162 pesticides, including 10 transformation products, with a composition of 41.3 % herbicides, 29 % insecticides, and 27.7 % fungicides. Triazole fungicides were detected at concentrations up to 281.2 ng/L, while atrazine was the most concentrated pesticide at 153.2 ng/L. Post-treatment, 65.6 % of pesticides were removed, 20.3 % were reduced, and 14.1 % were retained. Three prohibited pesticides in China, metsulfuron-methyl, monocrotophos, and isofenphos-methyl, were detected in source water, along with 22 endocrine-disrupting pesticides and 25 fluorinated pesticides. No substances with persistence, bioaccumulation, mobility, and toxic (PBMT) properties were identified in household tap water. However, flucycloxuron was identified as a PBT substance, while epoxiconazole was classified as a PMT substance. All Hazard Quotient values for adults, children, and infants were below 1. A prioritization method, considering occurrence, classification, preliminary hazard assessment, and human health risk, identified atrazine, flucycloxuron, and epoxiconazole as the highest risk. This study provides a comprehensive characterization of pesticide distribution and risk throughout the drinking water system, highlighting the need for further research on their occurrence, fate, and risk, and providing essential data to inform pollution control and environmental protection strategies in drinking water systems.