Analysis of heavy metal contamination in groundwater and associated probabilistic human health risk assessment using Monte Carlo simulation: A case study in Gaya, Bihar

The occurrence of heavy metal contamination in groundwater poses significant health risks through ingestion and dermal exposure, with potential links to cancer and other diseases. This study evaluated groundwater samples for 10 heavy metals (Al, As, Cr, Cu, Cd, Fe, Mn, Ni, Pb, and Zn) using ICP-OES. While cadmium and chromium levels were within acceptable limits prescribed by the Bureau of Indian Standards, aluminum and iron exceeded these limits in 56 and 58% of samples, respectively. Other metals surpassed limits in 2-20% of cases. Health risk analysis revealed non-carcinogenic risks for 28% of adults and 44% of children, alongside carcinogenic risks from arsenic (36% of samples) and nickel (46% of samples), especially affecting children. Sensitivity analysis highlighted heavy metal concentration as the key variable influencing risk, and principal component analysis suggested geogenic sources, like rock weathering, as major contributors to contamination. Despite these risks, the heavy metal pollution index remained within acceptable limits for all samples. The study emphasizes the necessity for continuous monitoring and targeted mitigation strategies to address heavy metal contamination and protect public health.