Assessing trace element-related health risks in urban centralized drinking water sources in China

Excessive exposure to trace elements through water absorption has raised growing concerns due to their adverse health effects on humans. While previous studies have shed light on health risks associated with trace elements in surface water and tap water using short-term monitoring data, the risks linked specifically to water sources remain poorly understood. This study addresses this research gap by providing a nationwide assessment of health risks associated with 21 trace elements across 1193 water sources in 321 Chinese cities, based on time-series data from 2016 to 2021. The magnitude and frequency of non-carcinogenic and carcinogenic health risks were evaluated at both the source and city levels. Six trace elements, i.e., As, Mo, F, Mn, Sb, and Fe, were identified as posing health risks to urban populations. At the source level, 45 urban water sources (3.8 %) posed potential health risks to children, while 21 (1.8 %) posed risks to adults. At the city level, 26 cities (8.1 %) were identified as having health risks to children. Health risks were more frequent and concentrated in North China, particularly in the Songliao and Yellow River basins. Larger, more economically developed cities with greater water endowment tend to experience lower health risks from their water sources. The comparison of health risks at different stages of the urban water supply system suggests that risks associated with As, F, Mo, and Sb are primarily attributable to their elevated concentrations in urban water sources. These findings highlight the need for proactive water quality protection at the source and integrated quality management throughout the entire water supply system.