Concentration characteristics and health risk of 11 elements in drinking water in Luohu District, Shenzhen, China

Objective To investigate the concentration characteristics of Fe, Cd, Al, Mn, Cu, Zn, As, Se, Hg, Pb, and Cr(VI) in drinking water in Luohu District, Shenzhen, China, and to evaluate their health risks.

Methods A total of 162 samples of finished water, tap water, and secondary water supply were collected by the simple random sampling method from four water treatment plants in Luohu District, and the concentrations of Fe, Cd, Al, Mn, Cu, Zn, As, Se, Hg, Pb, and Cr(VI) in the water samples were analyzed according to the Standard Examination Method for Drinking Water (GB/T 5750-2006). Heavy metal pollution index (HPI) and heavy metal evaluation index (HEI) were performed to evaluate the pollution levels of Fe, Cd, Mn, Cu, Zn, Hg, Pb, and Cr(VI). The carcinogenic health risks and non-carcinogenic health risks of detected elements were evaluated by the Technical Guide for Environmental Health Risk Assessment of Chemical Exposure (WS/T 777-2021). The uncertainty and sensitivity were analyzed by Monte Carlo simulation method.

Results The concentration of 11 elements in drinking water was analyzed, and the result showed that the concentrations of Al in 1 finished water and 3 tap water samples collected from Wutong Shanshui Water Treatment Plant in the spring of 2019 exceeded the national standard (0.2 mg/L), with 0.25, 0.28, 0.24, and 0.24 mg/L, respectively. Other metal elements did not exceed the standards in all samples. The HPI and HEI of Fe, Cd, Mn, Cu, Zn, Hg, Pb, and Cr(VI) were 0.1034 and 0.2631, respectively, which indicated low pollution levels. The HQ of Fe, Al, Mn, Cu, Zn, As, and Se were well below 1, and the non-carcinogenic health risks of these 7 elements were mostly negligible. The CR of As was 3.07×10^-5±1.32×10^-5, which did not exceed the maximum acceptable risk level of 1×10^-4. The sensitivity analysis showed that As concentration was the most sensitive parameter.

Conclusion The Al concentrations in some drinking water samples in Luohu District exceed the standard, which requires careful attention to ensure the safety of drinking water. Drinking water has low health risks related to the 11 elements and is safe for consumption.