Carcinogenic and Non-Carcinogenic Health Risk Assessment of Heavy Metals in Drinking Water near the Batang Masumai River, Indonesia

Abstract

Contamination of drinking water by heavy metals poses a serious public health concern due to their persistence, bioaccumulation, and potential toxic effects on human health. This study evaluated both carcinogenic and non-carcinogenic health risks associated with seven heavy metals (Hg, Cd, Ni, Fe, Cu, Mn, and Pb) in drinking water sources surrounding the Batang Masumai River, Indonesia. A total of 30 water samples were collected from municipal water supplies (PDAM), refill drinking water depots (AMIU), and groundwater wells, and analyzed using Atomic Absorption Spectrometry (AAS). Health risk assessment was conducted based on the United States Environmental Protection Agency (USEPA) model, including Chronic Daily Intake (CDI), Hazard Quotient (HQ), Hazard Index (HI), and Total Cancer Risk (CRtotal). The results showed that all PDAM samples had HI values below the acceptable limit (HI<1), indicating negligible non-carcinogenic risk. However, HI values exceeding the acceptable threshold were observed in one AMIU sample and one groundwater sample (HI = 1.4), suggesting potential health concerns. In contrast, carcinogenic risk was found to be significantly higher across all water sources, with 90% of PDAM samples and 100% of AMIU and groundwater samples exceeding the acceptable limit (CRtotal>1×10⁻4). The highest carcinogenic risk was detected in groundwater, reaching 4.6×10-3, which is substantially above the recommended safety threshold. The findings reveal that while non-carcinogenic risks are generally within acceptable limits, carcinogenic risks are widespread and pose serious long-term health threats. This study highlights the urgent need for stricter water quality control, continuous monitoring, and targeted mitigation strategies to reduce heavy metal exposure in the study area.