Abstract
Disinfection is a critical process to ensure the safety of drinking water. To curb the spread of various bacteria and viruses, disinfectants are extensively employed in communities, hospitals, sewage treatment plants, and other settings. However, disinfectants can produce disinfection by-products (DBPs) that threaten human health. Despite their importance, research and systematic analyses of these risks remain limited. This study monitored DBPs in drinking water across 13 districts and counties in Hangzhou, conducting a risk assessment based on the health risk assessment model recommended by the United States Environmental Protection Agency. Concentrations of 12 DBPs ranged from 0.01 µg/L to 120 µg/L, with levels in 2020-2022 generally exceeding those in 2018-2019. Notably, median concentrations of trichloromethane peaked at 18.00 µg/L in 2021. Most DBPs are detected at higher concentrations in the central and northern parts. However, the spatial distribution of DBPs in drinking water was determined to be random. The health risks associated with most DBPs were higher in 2021 compared to other years. Cancer risks of DBPs ranged between 10(- 6) and 10(- 4) and noncarcinogenic risks were below 1. This study demonstrates that increased disinfectant use during water treatment may elevates DBPs concentrations.