High fluoride in groundwater and associated non-carcinogenic risks at Tiruvannamalai region in Tamil Nadu, India

The present investigation in the Tiruvannamalai region is about high fluoride contamination of groundwater samples from bore wells and open wells. About 75% of groundwater samples were found predominantly containing the fluoride content greater than the acceptable limit of 1.5 mg/L in the ranges 1.51 – 2.00 mg/L (23%), 2.01 – 3.00 mg/L (36%) and greater than or equal to 3.01 mg/L (16%) as per WHO. The other water quality parameters were found within the permissible limit of WHO. Taking the groundwater sources into consideration, the non – carcinogenic risk due to high fluoride concentration in groundwater sources revealed that teen – aged (98%), Children (92%) and Infant (98%) categories were at greater risk than those under Men (50%) and Women (69%) categories. The mapping was done on the spatial distribution of fluoride concentration in groundwater and the associated health risk by Ordinary Kriging. The correlation coefficients among the parameters witnessed that the hydro-chemical facies are interdependent. Box – Whisker plots illustrated the dispersion of various water quality parameters. The WQI data represented the quality of groundwater in view of potable nature due to dissolved ions. The Gibbs, bivariate mixing and the scatter plots ascribed the dissolution of carbonate and silicate minerals which dominate the groundwater chemistry. The factor analysis detailed the extracted loadings of different parameters of groundwater sources and differentiated the percentage variance values between bore well and open well sources.