Highest fluorine contamination in groundwater in Rajasthan; Jaisalmer worst-affected in India: study

The latest study by a team from the Hyderabad-based National Remote Sensing Centre (NRSC) noted that the fluoride contamination was found to be highest during the dry, summer pre-monsoon months. During the March-May period, the country’s fluoride concentration in the groundwater jumped to 8.65 per cent above the permissible limit. And it continued to remain significantly high during the post-monsoon months when it was 7.1 per cent above normal. The NRSC, operating under the aegis of the Indian Space Research Organisation (ISRO), hosts groundwater data of the 3.287 million sq km area of India.

The average concentration of fluoride in groundwater was higher in dry, western Indian regions. Rajasthan topped the charts, where the pre-monsoon concentration was 1.41mg/litre and the post-monsoon was 1.44mg/litre, both values close to the maximum permissible limit of India. Jaisalmer district fared the worst in fluorine contamination in the groundwater, the study concluded. Along with Rajasthan, the post-monsoon concentration of fluorine was found to be above normal in Karnataka, Tamil Nadu and Jharkhand.

The study concluded that there prevailed a high risk of skeletal fluorosis even when the fluoride concentration was around 2 per cent, whereas dental decay was a worry if the concentration of fluorine concentration went up to 40 per cent in the groundwater.

“Lithology, soil type, geomorphology and lineaments control played a crucial role in the fluorine contamination in the groundwater,” the study said. This, in addition to the climatic conditions, had a direct role on the fluorine contamination. The contamination in humid and wet areas was relatively low in comparison to arid and dry areas, thus making groundwater in western India regions highly contaminated.

Anjali Marar is a science communicator at Raman Research Institute.