Health Risk Assessment of 10 Pollutants in a City's Drinking Water

Objectives To evaluate the health risk of arsenic (As) and other 9 pollutants in drinking water of a city through drinking water exposure, and to provide theoretical basis for drinking water health risk management.

Methods In 2017, 128 monitoring sites were selected for monitoring, and 128 water samples were collected in both wet season and dry season according to water supply area of the city municipal waterworks. The non-carcinogenic risk values and carcinogenic risk values of 2 metalloids, As and Se, 6 heavy metals, Cd, Cr(Ⅵ), Pb, Hg, Cu, and Zn, as well as 2 organic matters, CHCl₃ and CCl₄, in drinking water of the city were quantitatively analyzed by using the four-step environmental health risk assessment method.

Results All of the concentrations of the above ten pollutants in drinking water met the requirements of Drinking Water Sanitary Standard (GB 5749-2006), the standard compliance rate was 100%. The total non-carcinogenic risk value of residents' oral intake of tap water was 0.122, which was within the acceptable range. The total risk value of carcinogenesis was 2.59×10^-5, indicating carcinogenic risk. As exposure contributed the most to both non-carcinogenic and carcinogenic risks, and the carcinogenic risk of CHCl₃ was higher than the acceptable risk of 10^-6. The risk value of Cu in tap water and secondary water supply was higher than that of finished water, and the risk value of Zn was lower than that of finished water. The total carcinogenic risk in wet season was higher than that in dry season. The total non-carcinogenic risk was lower in the advanced treatment water samples.

Conclusions The carcinogenic risk of drinking water in the city exceeds the acceptable risk level, and As has the highest health risk.