Assessment of groundwater quality and human health risk impact on fluoride concentration: A case study of Namakkal district, South India

Abstract This study evaluates the health hazards of fluoride contamination of groundwater in the Namakkal district of south India based on the water quality index. The samples were collected during the NEM season from bore wells and analysed for major anion and cation. There is generally no smell or colour to the groundwater in the study area. The pH of the groundwater samples is acidic to alkaline in nature. Higher EC was noted at 7650 µS/cm during the NEM season. Na+ is the most abundant ion in groundwater, followed by Ca2+, Mg2+, K+, then Cl-, SO42- > HCO3-, and then F-. The majority of ions like Sodium, Potassium, Calcium, Magnesium, Cl-, SO4-, HCO3, and F- recorded higher concentrations during NEM seasons, representing the action of leaching, dissolution, and weathering anthropogenic influences on the groundwater quality. Hill-Piper plot showed the majority of the groundwater samples fall in CaHCO3, NaCl, and Mixed CaNaHCO3, CaMgCl, with minor representations in CaCl and NaHCO3 being noted during the NEM. The Gibbs plot shows all the water samples belonging to rock dominance. The WQI value varies between 22.08 and 211.64 throughout the NEM seasons, with a mean of 78.90. According to the Water Quality Index (WQI), 26%, 33%, and 14% of water types have good, poor, and extremely poor quality, respectively. The average F- level is 1.12 mg/l and ranges from 0.27 to 0.39 mg/l. There is excessive fluoride concentration in 76 % of the groundwater samples (WHO 2011). Children, women, and men should undergo health risk assessments based on non-carcinogenic risk estimates for fluoride oral and dermal pathways. The health risk assessment for this study is that children are the most susceptible to fluoride intake. Consequently, more treatments must be initiated to appraise the water as good quality, and government organizations need to select and provide appropriate groundwater for the inhabitants.