Trihalomethane Levels in Municipal Drinking Water of Madrid (Spain) and Health Risk Assessment for Oral Exposure

Abstract Trihalomethanes (THMs) are generated in the drinking water treatment plant, due to reaction of halogenated disinfection compounds with natural organic matter (NOM). They related health problems both from point view cancer development and other important diseases. This study aimed assess quality tap Madrid terms prevention control THMs risks supply treated by Canal de Isabel II (CYII) a total 108 samples throughout 2015 2020, distinguish different 21 districts or types buildings, seasonality estimate risk exposure population Madrid. The variables considered include year, seasonality, district sampling point. concentrations detected all were within current legal limit (100 µg/l). Chloroform was compound highest contribution sum THMs. A decreasing trend observed over years removal NOM use chloramines. THM levels higher central area than peripheral lowest summer. Regarding assessment, results non-carcinogenic indicate that there is no potential consumption for adult population. For carcinogenic risk, only between 50 75 µg/l could constitute high consumers.