Occurence and distribution of fluoride in groundwaters of central Rajasthan, India.

High fluoride in groundwater has been reported from many parts of India, particularly its impact on human health. Waterborne fluorosis is prevalent in parts of Ajmer and Jaipur districts in central Rajasthan which can be correlated to excessive concentration of the toxic fluoride ions in drinking water. The area, falling under the semiarid terrain of central Rajasthan, is geologically occupied by Precambrian rocks where groundwater occurs under unconfined conditions. Fluoride concentration in shallow aquifer samples of the study area ranges between 0.12 to 16.9 mg/L. Presence of fluoride bearing minerals in the host rock and their interaction with water is considered to be the main cause for fluoride in groundwater. Chemical weathering under arid to semiarid conditions with relatively high alkalinity favours high concentration of fluoride in groundwater, which has resulted in dental and skeletal fluorosis in the study area. The incidence of fluorosis, caused by an excess of fluoride compounds in drinking water, has been rising at an alarming rate in the state.