Assessment of human health risk from exposure to groundwater fluoride and iron by entropy-based water quality index and Monte Carlo simulation

Groundwater quality of a frontier community development (CD) Block, Balurghat in eastern India was evaluated with a focus on non-carcinogenic health risks associated with fluoride and iron. For survival of mankind, groundwater is one of the main sources of fresh water. The fresh groundwater supply in the study region has been significantly reduced due to overexploitation for agriculture. The management of groundwater system and preservation of water quantity and quality depend heavily on the assessment of groundwater potential zone. A multidimensional framework, combining an Entropy-based Water Quality Index (EWQI), GIS, statistical analyses, and Monte Carlo simulation to address uncertainties and sensitivities, was applied to assess the current groundwater conditions. Apart from EWQI, irrigation water quality indices like SAR, SSP, RSC, KI, PI etc. were also evaluated for the thirty-seven water samples collected during post monsoon season of 2023 covering the entire block. Primary result indicated that fluoride (F⁻) and iron (Fe) concentrations exceeded the permissible limits of the Indian Standards in 24.32% and 94.59% of the groundwater samples, respectively. Estimated total hazard index (THI) values for adult, children and infant groups of the area were found to be more than unity in most cases, in the order of THIChildren> THIInfant> THIAdult which was further confirmed by Monte Carlo simulation. The EWQI reflected that only 21.6% groundwater samples could be deemed safe for drinking. Most groundwater samples of the area were found suitable for irrigation in terms of irrigation water quality indices except for RSC, as per which 3 samples were marginally suitable. The findings highlight the urgent need for continuous monitoring, community awareness programmes, and practical mitigation measures to reduce human exposure to poor quality water.