Chemical contamination of drinking water sources, particularly with fluoride and nitrate, is posing a serious health hazard to people in the villages of Gulbarga district. Sources in the District Surveillance Unit and the National Fluorosis Prevention and Control unit told The Hindu here that as per water quality tests conducted by the surveillance unit and the Rural Development and Panchayat Raj Ddepartment in September 2010, drinking water sources in 91 villages in the district is not fit for drinking and fluoride content was in excess of the permissible limits. The Rural Development and Panchayat Raj Department is yet to provide potable drinking water from alternative drinking water sources to the affected villages and people continue to suffer, as they are forced to consume water contaminated with fluoride regularly. However, the National Fluorosis Prevention and Control Unit has now taken up a detailed survey in the entire district to study the health status of people affected by excess fluoride in drinking water. Sources in the unit said that the study team has come across several cases of deformities in bones and discolouring and loss of teeth among children and adults in the affected areas. District Surveillance Officer Amaresh Kollur, who conducted a study on the health condition of students studying in the Government Primary School at Farhatabad, said that of the 100 students, more than 80 suffered from the effects of excess consumption of fluoride. Children from neighbouring villages, including Kiranagi, study in the Farhatabad government primary school. As per the September 2010 tests, fluoride content in one of the water sources was 2 mg per litre as against the permissible limit of less than 1 mg per litre, and in another source — a deep borewell, the fluoride content was found to be 2.50 mg per litre. The details of the exact number of villages where alternative drinking water sources have been provided are not readily available. Detailed survey of fluoride-hit areas taken up