Fluoride contamination in groundwater of the middle Gangetic plains of India: A comparative geochemical and health risk assessment.

The widespread health impacts of fluoride toxicity have emerged as a global concern, especially in the densely populated regions of the world. The study conducts a comprehensive health risk assessment of fluoride toxicity, and the geochemical investigation of the genesis, and mobility of fluoride in the groundwater of the middle Gangetic plains of India. The comparative analysis of the spatial variation (2015-2020), has noted a 10.22% increase in the average fluoride concentration, where Faizabad and Rohtas have witnessed the highest percentage increase of 133.04 %, and 127.76 % respectively. The maximum hazard quotient for fluoride exposure was computed as 1.80 for adults, and 2.70 for children in 2014-15, which has increased slightly to 1.81 and 2.73, respectively, in 2019-20. Geochemical investigations revealed the dominance of silicate weathering, and clay minerals, as the possible driver of rising fluoride levels in groundwater. Moreover, an increase in the level of Na+ might have accelerated the dissolution process of fluoride -bearing minerals in the groundwater from 2015 to 2020. Further, the study alarms at the escalating health risks in the near future.