Fluoride Action Network

A warning whose time has come

Source: The Hindu Business Line | June 2nd, 2017 | By Azera Parveen Rahman
Location: India

Threat of fluoride contamination in crops looms large in Assam

Dilwar Hussain may not be able to give you the exact scientific explanation for how excessive fluoride can harm one’s bones and teeth, but he knows that it crippled his young son, causing his legs to bend.

Children suffering from skeletal and dental fluorosis — marked by stained and crooked teeth, and bent legs — are a common sight in Hussain’s village, Tapatjuri, in Assam. Fluoride-contaminated water, as the State’s Public Health Engineering Department (PHED) has found out, is the main culprit, and the entire Hojai district is among the worst-affected.

What is more worrisome now is the high fluoride content in agricultural produce as well, including rice and tea, the two main crops of the State.

Dharani Saikia, secretary of voluntary organisation Environment Conservation Centre, has been working on the issue for more than a decade and government agencies approach him for his expertise. He recalls that the first time they detected high fluoride levels in food produce was in 2012. Until then, public awareness was limited to discouraging the use of groundwater from tube-wells. Ring-wells were recommended instead.

“On a hunch, we decided to test the rice grown on a 10-bigha field in the village. We took samples to the Pollution Control Board office in Guwahati and found they had a fluoride level of 74 ppm. The borewell water that was used for irrigation had 12 ppm fluoride,” Saikia said. The WHO standard for permissible fluoride limit is 1 mg/l (0.6-1.5 ppm). Since the same water source was used over and over again for irrigation, the levels were escalated in the crop.

A wake-up call

The findings led to officials finally sitting up and taking note of the problem. Saikia says the PHED set up a Fluoride Mitigation Centre, led by the district collector. Saikia, too, was part of the intervention.

“Climate change is a major reason for high fluoride levels in groundwater. Less rainfall means less water replenishes the water table… Bore-wells are being drilled closer to the granitic rocks that are rich in minerals like fluoride. So that’s how the concentration of fluoride is increasing in groundwater,” he explains.

In Tapatjuri, farmers like Hussain, Lakhmi Kalita and Indra Basomatary were reliant on groundwater, which had been pumped up by drilling down to 250-300 ft. After the findings, the use of such water was stopped even for agriculture. All groundwater had to be tested first for safety.

“We are not taking any more chances. We have many ponds in our village from which we now source water for agriculture,” Hussain says. After Hojai, a Fluoride Mitigation Centre was also set up in the adjoining Nagaon district.

But the problem of fluoride contamination is not Tapatjuri’s alone. An official survey found water with fluoride levels above the permissible limit in 11 districts in the State.

Dread in a teacup

Saikia says that in 2016 he tested tea from the local market at the health department’s lab and found 5.6 ppm fluoride. Green tea, he adds, is known to have 2 ppm fluoride.

AK Barooah, director of the Tocklai Tea Research Institute in Assam, however shrugged off any worry over the threat of fluoride contamination in the ‘cup that cheers’. “Tea naturally contains fluoride, which it absorbs from the soil, and there is nothing to be concerned about it at the moment.”

Experts like Najibuddin Ahmed, former additional chief engineer of the Assam PHED, call for extensive studies on food contamination. “The Jorhat-based Rice Research Centre is studying contamination of rice. But there isn’t enough data,” he says.

Scientist RN Bhagat, who was associated with Tocklai until recently, agreed. “There has been some research on the correlation of water contamination with tea. But such studies are sporadic.”

Saikia believes that along with research, coping mechanisms have to be developed. “Going back to nature and to surface water, like ponds and rivers, after it is treated is the way forward,” he says.

• Original article online at http://www.thehindubusinessline.com/specials/india-interior/a-warning-whose-time-has-come/article9718578.ece