Health risk assessment of oral exposure to 9 metals/ metalloids in drinking water for adults in Zibo, Shandong Province

Background Oral exposure to metals/metalloid elements in drinking water may be harmful to human health.

Objective To assess potential health risks of oral exposure to 9 metals/metalloids in drinking water in Zibo City of Shandong Province from 2019 to 2023, and provide reference for the development of local drinking water management policies.

Method From 2019 to 2023, a total of 1178 drinking water samples were collected from 261 rural water monitoring sites and 14 urban water monitoring sites in 8 districts and counties of Zibo City. The US Environmental Protection Agency's (EPA) four-step health assessment model was used to evaluate the health risks of oral exposure to 9 metals/metalloids in drinking water for adults.

Results A total of 1178 water samples were collected, including 561 urban water samples and 617 rural water samples; 769 samples of tap water and 409 samples of finished water; 634 samples collected in wet season and 544 in dry season. The median carcinogenic risk (CR) of arsenic exposure in drinking water for adults was 3.53×10⁻⁵, and the median hazard quotient (HQ) was 7.85×10⁻². The HQs of arsenic and zinc showed an upward trend in recent years, while the HQ of aluminum showed a downward trend. The stratified analysis results showed that there was no statistically significant difference in the CR of arsenic between males and females or between urban water and rural water. The CR of arsenic in dry season was higher than that in wet season, and the CR of arsenic in tap water was higher than that in finished water (P<0.05). There was no statistically significant difference in the HQs of 9 metals/metalloids in drinking water between males and females. The HQs of aluminum, copper, arsenic, selenium, and cadmium in tap water were higher than those in finished water (P<0.05). In dry season, the HQs of aluminum, manganese, copper, zinc, arsenic, and selenium were higher than those in wet season (P<0.05). The HQs of aluminum, copper, zinc, cadmium, and lead in urban water were higher than those in rural water (P<0.05).

Conclusion The overall health risks of 9 metal/metalloid pollutants in drinking water in Zibo City are lower than the maximum acceptable risk recommended by the US EPA, and suggest an acceptable level and no significant harm to adult health. The health risk of arsenic is relatively high and should be given priority by relevant departments in drinking water risk management.