Fluoride mess grips new terrain

Growing fluoride levels in groundwater are setting alarms off in Tamil Nadu where potable water is scarce. A study says flouride contamination is spreading to new areas, 16 districts in all.
Studies have shown that the level of fluoride contamination in districts like Erode, Karur and Virudhunagar has been rising. Till a decade ago these districts were considered safe from flouride hazard.
World Health Organisation (WHO) has set 1.0 milligram/litre (mg/l) as the permissible limit for flouride in drinking water. In the absence of alternative source, it can go up to 1.5 mg/L, says WHO. “In Erode and Karur, where the Cauvery and its tributaries crisscross, the increase in fluoride levels could be due to industrial pollution,” says an engineer of the Water Resource Organisation, a wing of the PWD.
Available data with the State Ground and Surface Water Resources Centre reveals that the fluoride levels in open dug wells in Dharapuram taluk of Erode district and Sattur taluk in Virudhunagar district have gone beyond 2.0 mg/l. In many peizometres (borewells dug up to measure fluoride levels) in Karur, Tiruchy and Vellore, the fluoride levels were above 1.5 mg/l. Borewells in Sathyamangalam taluk in Erode district showed 2.0 mg/l.
Across the country, contaminants, including salinity, iron, fluoride and arsenic, have affected groundwater in over 200 districts spread across 19 states. In a survey by the Water Resources Ministry in 2008, results for which were released recently,
Tamil Nadu is ranked sixth among states. Here, the distribution of fluoride in groundwater has been found to be above permissible limit in as many as 16 districts. Rajasthan tops the list with 30 districts followed by Karnataka with 20, Andhra Pradesh and Madhya Pradesh with 19 and Gujarat with 18 districts where fluoride distribution in groundwater is above permissible limit.
Children in the age group of 0 to 12 years are most prone to fluorosis as their body tissues are in a formative stage, say health experts. Statistics of public health department reveal that 31% of school children in Dindigul and Cuddalore suffer from dental fluorosis. “Mottling and colour change in teeth occurs due to fluorosis,” says Dr S Elango, director of public health. Long term exposure to fluoride has a crippling effect on bones and joints, he adds, emphasising that providing safe drinking water to the fluoride-hit habitations is the best solution.
“In about nine districts we have a few habitations with minor fluoride levels. Combined water system schemes have been implemented in districts like Salem, Namakkal and Erode to address the issue. It is a major issue in Dharmapuri and Krishnagiri districts and we have a major plan to tackle it,’’ says Swaran Singh, CMD, Tamil Nadu Water Supply and Drainage (TWAD) Board.
Another big worry for the state is the fast-depleting ground water. The Tamil Nadu water supply and drainage (TWAD) board has put 10 districts in the ‘black zone’ category, meaning that in these districts the rate of groundwater extraction had exceeded the replenishment rate.