Human Health Risk Assessment from Arsenic Pollution in a Groundwater–Soil–Crop System

Arsenic contamination is a critical global issue due to its toxicity and carcinogenicity. This study examined arsenic levels in groundwater, soil (at the surface, 50, and 150 cm depths), and grains from two humid subtropical regions: Bihar and Uttar Pradesh, India. Arsenic levels in samples were determined using inductively coupled plasma mass spectrometry. A comprehensive human health risk assessment, involving hazard identification, dose–response analysis, exposure assessment, and risk characterization, was conducted. Chronic daily intake rates were calculated to assess arsenic exposure, depending on the mobility of arsenic in the groundwater → soil → crop system. The study identified several districts in Bihar as highly vulnerable due to prolonged arsenic exposure over recent years. The study's findings reveal that arsenic contamination in groundwater, used predominantly for irrigation and drinking, enters the food chain, thereby posing health risks to humans. The significance of our findings lies in the elevated carcinogenic and non-carcinogenic health risks associated with arsenic exposure to adults and children, particularly an increased lifetime cancer risk (value for both age groups exceed acceptable threshold of 10−4) and adverse effects on neurological and cardiovascular health (children > adults). Due to their low body weight and developing immunity, children are more sensitive to toxic chemicals than adults, making them a highly vulnerable population. These results emphasize the urgent need for arsenic remediation strategies in India to safeguard nutritional quality and public health, calling for stricter regulations, enhanced monitoring, and sustainable mitigation measures to reduce exposure and associated risks.