This research aims to determine the health consequences of fluoride contamination of groundwater in the Namakkal region in south India using the groundwater quality index (GWQI). Study area latitude and longitude: 11° 00' and 11° 30' in the north, and 77° 45' and 78° 15' in the east. Statewide, it is among the largest districts in the state. The study region occupies an area of 3406.37 km2. The geology of the studied area is mainly based on the Archaean crystalline and metamorphic complex. The district's major aquifer systems are composed of crystalline rocks that are weathered and fractured and of colluvial deposits.  Alluvium and colluvium are examples of porous formations in the cross-section. Only the main river channels have alluvial deposits. The phreatic properties of groundwater Depending on the topography, these aquifers may reach 5 m saturation thickness. Groundwater samples were obtained from 58 bore well sites across the study area during the North-East Monsoon (NEM) of 2015. pH concentrations in suitable drinking water regions during the seasons assist in limiting the availability of groundwater for drinking purposes. TDS are an important factor in determining water suitability for various purposes. The groundwater sample in the study area shows cation domination in ascending order of Na+ > Ca2+ > Mg2+ > K+ due to the dissolution of aquifer minerals in rainfall in the study area. In the NEM seasons, rock dominance and anthropogenic contributions to higher Na+ > Mg2+ > Ca2+ > K+ values. Fluoride concentration differentiates into three groups such as < 0.5 indicates low risk, 0.5 to 1.5 indicates moderate risk, and > 1.5 means high risk. More than 2 fluoride implies very high risk, whereas fluoride in the range of 1.5 to 2.24 suggests a very high risk. The appraisal of non-carcinogenic risk was done to stress the health issues that succeed due to the intake and dermal contact of drinking water in the Namakkal district. The percentage of risk HQ >1 shows that 48 men groundwater samples, followed by 46 groundwater samples women and 30 groundwater samples children, constitute possible health hazards. Overall, health risk estimation results showed that all the groundwater samples have surpassed the permissible limit of HQ <1 for children.

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.