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Fluorosis is becoming a global environmental toxicological problem and is most commonly found in water-stressed regions. In order to evaluate the geochemical mechanism of fluoride enrichment in groundwater and health implications in the Padwakodari environs of eastern part of India, a total of twenty two samples were collected and analysed for physico-chemical parameters spreading across the study area. Geologically, the area mainly comprises of phyllites, granite gneiss, mica schist and sandstone. High fluoride concentrations found mainly in the granite gneisses which are situated central to northwestern parts of the study area. The concentration of fluoride in the groundwater samples ranges from 0.3 to 11 mg/l with an average of 2 mg/l. 64% of the groundwater samples containing fluoride concentration that exceed the WHO drinking water guidelines value of 1.5 mg/l. Chronic ingestion of high doses has been linked to the development of dental fluorosis, and in extreme cases, skeletal fluorosis. The dominant geochemical facies present in water are Na–Ca–Mg–HCO 3 (11 samples), Na–Mg–Ca–HCO 3 (5 samples), Ca–Na–Mg–HCO 3 (5 samples) and Ca–Mg–Na–HCO 3 (1 sample). Sodium and bicarbonate ions being major component in majority of the water types (located mostly in the granite gneiss formation) has a tendency to increase fluoride concentration in groundwater by dissolving the fluoride from fluoride bearing minerals. The oversaturation of half of the samples with respect to calcite and majority of samples undersaturation with respect to fluorite makes it feasible for fluoride to get released in to the groundwater. Decreasing Ca activity downgradient (recharge to discharge) leads to a dominance of fluorite-unsaturated conditions and consequently to mobilization of fluoride in groundwater. The results indicate that the fluoride concentration in groundwater is mainly governed by high weathering of fluoride bearing minerals (i.e. apatite and biotite) in granite gneiss contains abundant fluoride, alkaline hydrogeological environment, high temperature, low rainfall, evapotranspiration and ion exchange. [ABSTRACT FROM AUTHOR]

Fluoride (F¯) concentration over and above the permissible limits (1.5 mg/l) in drinking water leads to human health hazards, such as dental and skeletal fluorosis affecting millions of people in many parts of India. Preliminary investigations indicate that severe health disorders have been identified in parts of the Kachnarwa region, which is in the upper Panda river basin, Sonbhadra District, Uttar Pradesh, due to excess intake of fluoride through drinking water. The lithological units of the study area mainly consist of granite and gneissic complex rocks of the Chota-Nagpur Plateau. In order to understand the probable source of fluoride and its concentration, 17 groundwater samples mostly from granite and phyllite regions were collected for fluoride estimation during May 2006. The concentration of fluoride in the groundwater of the study area varies from 0.483 to 6.7 mg/l. Among the 17 samples analysed, 8 exceeded the maximum permissible limits of fluoride in the study area. The source of fluoride in the groundwater of the study area is mainly from geological occurrence (i.e. fluoridebearing minerals, viz. apatite and biotitic mica). Microscopic analysis of the rock samples showed 5-10% apatite and 20-25% biotite, but other fluoride-bearing minerals like fluorite and hornblende were characteristically absent. X-ray diffraction studies showed that apatite mineral peak profile of the rock samples corroborated with the fluorapatite of the standard set by the JCPDS. The worst fluoride-affected villages are Rohiniyadamar, Madhuri, Neruiyadamar, Gobardaha and Kunrwa. Most people in these villages suffer from dental and skeletal fluorosis such as mottling of teeth, deformation of ligaments, bending of spinal column and ageing problem. An urgent need is to educate the people on the causes of fluorosis, encouraging rainwater harvesting and providing fluoride-free drinking water in the study area. [ABSTRACT FROM AUTHOR]