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Underground wells 120 million Indians at risk of fluorosis, says Swiss study

Man drinking at a well

Rural areas that depend on underground wells are most at risk.


Researchers in Switzerland estimate that 9% of the Indian population, mainly in rural areas, could be affected by excess fluoride present in underground wells. A hazard map offers authorities the possibility of targeted testing in problem areas. 

Fluoride ends up underground due to natural weathering and enters groundwater. However, excess fluoride (above World Health Organization threshold level of 1.5 milligrams per litre) can cause growth disorders, damage to teeth and bone deformation. 

Scientists at the Swiss Federal Institute of Aquatic Science and Technology (Eawagexternal link) have developed a computer model based on 13,000 fluoride measurements carried out by the Indian Central Ground Water Board between 2013 and 2015. Geology, topography, temperature and precipitation values were also fed into the model. A hazard mapexternal link created by the researchers shows that northwestern (Delhi, Gujarat, Haryana, Punjab, and Rajasthan) and southern (Andhra Pradesh, Karnataka, Tamil Nadu and Telangana) parts of the country are most at risk. 

Hazard map

The map is meant to serve as a guide and not to determine directly which wells are safe and which unsafe. 

“This is the first comprehensive map showing a pattern of affected areas and populations,” study leader Joel Podgorski told “India is good at testing, but now authorities responsible for rural wells will have an overview of which of the thousands of wells to test.”

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