Sing Ingti, 39, a watchman at a local high school in Asom (formerly Assam) state in Northeast India, has been suffering from serious, ill-defined bodily pain since 1995. His teeth are mottled, his leg bones are distorted and his legs are losing strength from what seems a mysterious ailment. But actually this is an all-too-common disease now afflicting hundreds of thousands of people in the region. What’s more, it is man-made.

The culprit, as in much of the developing world, appears to be the naturally occurring fluoride prevalent in wells drilled deep into the aquifers of India, Pakistan, Bangladesh and other countries to provide pure water for poverty-stricken rural villagers.

Millions of people die across the third world every year from dysentery and other diseases from drinking impure ground water and deep wells were originally thought to be the answer. But the water too often has for some proven a curse. Tube wells, as they are called, have famously been blamed for poisoning millions of people with arsenic.

But another condition – fluorosis from seemingly benign fluoride -- which is added to the water supply in many advanced countries to protect against tooth decay and to strengthen bones – is ruining millions of lives. A little fluoride is good. Too much can be devastating.

The story began in the 1970s, when the United Nations, the World Bank and other aid agencies mobilized to fix the problem of polluted drinking water by drilling down from 20 to 75 feet to hit pure groundwater. Millions of tube wells were drilled all the way across the developing world, with the water accessed by relatively simple pumps.

Arsenic poisoning was the first to surface, particularly in Bangladesh, probably from natural arsenic originating in the Himalayas in thick layers of alluvial mud laid down by the Ganges and Brahmaputra Rivers. As vast amounts of water were pumped out of the aquifer, the arsenic-bearing pyrites were exposed to the air, flushing the poison into the groundwater. One study called arsenic pollution in ground water “possibly the largest mass poisoning case in history.”

But fluorosis is not far behind. According to a UNICEF study, across the developing world fluorosis is endemic in at least 25 countries, with perhaps tens of millions of people affected. As long ago as 1993, according to one study, 20 of India’s 32 states were identified as facing problems. Fluorosis was recorded in Andhra Pradesh as early as the 1930s.

Some governments, the study found, even today are not yet fully aware of the fluoride problem or convinced of its adverse impact on their populations. In the meantime, it is possible to find hundreds of families like Sing Ingti’s – as many as 100,000 in Asom alone. Villagers in Karbi Anglong, Nagaon and Kamrup are reported to be suffering from severe anemia, stiff joints, painful and restricted movement, mottled teeth, slack muscles, kidney failure and premature death. Bodies become so stiff that, in the words of a study of one 30-year-old adult, “he has to turn his whole body sideways to see someone standing next to him, and he has to lie on a bed to see an airplane.”

There appears to be no cure unless diagnosis takes place at an early state or age. Women and children are more prone to the disease as they remain at home and thus are in contact with the contaminated water for a longer period. Moreover, malnutrition during childhood makes women more vulnerable. Statistics show more than six million children below the age of 14 across the world are in the grip of the ailment.

Well-known for its scenic beauty and thick rainforest, Karbi Anglong district was included in the fluorosis-affected map of India after the first case was discovered in May 1999, with fluoride levels as high as 5-23 mg per litre against a World Health Organization guideline of only 1.5 mg per litre. As late as 1998, the preponderance of India’s geologists and health experts had declared the Northeast safe from fluoride contamination. .

Like the problems with arsenic poisoning, when fluoride containing minerals comes into contact with ground water, the fluoride is released through hydrolysis. Geologically the Karbi Anglong and its adjoining Nagaon district is full of fractures and faults and a complex geology results in fluoride being absorbed.

Efforts are being made to address the problem by the Department of Drinking Water Supply. The government says it will set up a Fluorosis Mitigation Center. But on the ground, reality remains the same. At least for victims of fluorosis in Asom, these acts provide little benefit. Often fluorosis is overlooked by physicians who find it difficult to differentiate at the early stage from common bone diseases like arthritis or osteoporosis.

Moreover, malnutrition and the burden of child-bearing make women more vulnerable, particularly in Asom, where almost 70 percent of the population is acutely poor, illiteracy is high and health care awareness is limited.

Recognizing the scope of the problem, UNICEF and local NGOs have sought urgently to provide safe drinking water from alternative sources and medication for the victims. They are also encouraging self-help groups in the affected areas. Unfortunately, the two most widely known and used de-fluoridation processes are reportedly very complicated and time-consuming. Rainwater harvesting, simple in operation and cost-effective, may be adopted as Asom is a rain-fed state.

A nutritious diet and calcium and Vitamin C supplements is encouraged, particularly for pregnant women to reduce the high incidence of stillborn babies and infant health problems. There is no denying that fluorosis has emerged as one of the region’s greatest health tragedies and a massive program must be launched unless millions more are affected, not only in Northeast India but across the developing world.