Abstract: Objective To examine the concentration of trihalomethanes （THMs） in drinking water in Longgang District,Shenzhen,and to evaluate the potential risk of THMs to human health. Methods The concentration of THMs in the municipal water supply of Longgang District,Shenzhen was monitored from 2019 to 2023. An evaluation of the health risk associated with THMs exposure through drinking water and bathing in Longgang District,Shenzhen was conducted using a health risk assessment model. Results The detection rates of trichloromethane （TCM） were all 100.00%. The detection rates of bromo-dichloromethane （DCBM） were over 97.00%,and the detection rates of dibromo-chloromethane （DBCM） ranged from 76.34% to 95.83%. The lowest detection rate was found for tribromomethane （TBM）. The carcinogenic risk of THMs through drinking water exceeded that through skin exposure,while the carcinogenic risk of THMs through skin exposure was below 1.0×10^-6. Additionally,the carcinogenic risk of THMs exposed to peripheral water through drinking water was greater than 1.0×10^-6 but less than 1.0×10^-4. Furthermore,the non-carcinogenic risks of THMs in different exposure paths,various water sample types,and diverse water collection periods were found to be <1. Conclusions The carcinogenic risk values of TCM,DCBM,and DBCM in drinking water exceed the recommended levels set by USEPA,indicating a certain level of health risk within an acceptable range. The carcinogenic risk of exposure through drinking water is higher than that through bathing skin.

Key words: Drinking water, Trihalomethanes, Disinfection by-products, Health risk