Probabilistic Assessment of Non-Carcinogenic Health Risks Posed by Groundwater Iron and Fluoride in Indo-Bangladesh International Frontier Town in West Bengal, India

During the post-monsoon season of 2023, groundwater quality in 25 wards of Balurghat Municipality, a frontier town in Dakshin Dinajpur District of West Bengal along the Indo-Bangladesh border, was evaluated. Information on groundwater quality, its suitability for drinking, and associated health risks in this area are scarce, despite this region's growing reliance on it. A comprehensive assessment of fluoride (F⁻) and iron (Fe) concentration, hydrogeochemical facies, and estimation of the entropy-weighted water quality index (EWQI) in conjunction with health risk modeling addresses the said research gap. The findings indicate that 96% and 64% of the samples had Fe and F⁻ levels above the respective BIS and WHO safe limits. Hydrogeochemical analysis revealed Na-HCO₃ and Ca-HCO₃ as the two principal types of water. According to the EWQI, only 8% of the samples were fit for human consumption, 64% were moderately fit, while 28% were not fit. As per non-carcinogenic health risk assessment by deploying Hazard Quotient (HQ) values, F⁻ exposure was estimated to be > 1 in all age groups, with children having the highest HQ values, followed by infants and adults. For both F⁻ and Fe, Monte Carlo simulations (10,000 and 5000 trials using Microsoft Excel and Oracle Crystal Ball software) verified increased risks, especially in younger populations. This study provides a robust insight into groundwater quality in an international border region and highlights the pressing need for the provision of clean drinking water towards protection of public health.