Health risk assessment of physicochemical and heavy metals exposures of the usage of shallow groundwater located at the proximity to Citarum River, Indonesia

Shallow groundwater is commonly used for daily needs in Indonesia, and the water quality is affected by surrounding land uses with anthropogenic activities. The study aimed to evaluate shallow groundwater quality and public health risks. 51 groundwater samples located <150 m from the river were collected from agriculture, industrial, and domestic areas along the Upper Citarum River, supporting millions of people's activities. Physicochemical, heavy metals and microbiological parameters were measured. Water quality was compared to the government standards, and the statistical correlation and Principal Component Analysis were used to analyze the potential sources. The health risk was estimated using the Hazard Quotient, Hazard Index, and Excess Cancer Risks approach. The results showed that some heavy metals contaminated shallow groundwater were the dominant source of health risk. Pb concentration has statistically inversely correlated with distance from the river. Non-carcinogenic risk of children is higher than that in adults, with the rank of agriculture > industrial > domestic regions, and only suitable for dermal exposure. Meanwhile, the carcinogenic risk is unacceptable for both dermal and oral intakes and risk in agriculture > industrial > domestic areas. Higher distance from the river shows decreasing risk values, and the estimated safe distance from the river follows the sequences of industrial > agriculture > domestic area affected by the hydrogeological condition and flooding prone in industrial areas. These findings underscore the potential impact on public health and the urgency of addressing this issue through pollution source prevention, buffer-safe distance management, and education for the public.