Correlation studies of fluoride with alkalinity and hardness

Tamil Nadu in South India, is identified as a state with high prevalence rate of dental fluorosis. Our studies have confirmed the fluoride endemicity of Dindigdul district of Tamil Nadu. Thirteen out of fourteen revenue blocks of this district have their groundwater sources contaminated with high levels of fluoride (Karthikeyan and Appa rao, 1992). This is further supported by the high prevalence rate of dental fluorosis and the associated symptoms of nonskeletal fluorosis among the people of this region. Three revenue blocks, viz., Shanarpatty, Vadamadurai and Reddiarchatram are chosen as the study area in this investigation. All available drinking water sources of the villages belonging to these three blocks were chemically examined to estimate the quality parameters like pH, Total hardness(TH), Total alkalinity(TA), fluoride, sulphate, chloride and chemical oxygen demand(COD). Correlation analysis was carried out to determine the influence of total alkallinity (TA) and total hardness(TH) on fluoride content of the water and the dependence of these parameters on fluoride toxicity.