For more than a decade, Assam has been in the limelight for its multiple insurgencies. Because of this almost exclusive focus on violence, a new danger confronting Assamese society may go unnoticed to the point where it assumes an uncontrollable magnitude. Hydrofluorides have begun to threaten a potential health disaster and today over one hundred thousand people of the state suffer from hydrofluorosis, a disorder caused by continuous consumption of ground water contaminated by excess fluorides. Hundreds of villages on the southern bank of the Brahmaputra in middle Assam are affected by the contamination. The problem is so serious that, besides the Assam valley, the rainforest belt of Karbi Anglong and regions neighbouring the state's Nagaon district have now been included in the "fluoride map" of India. Karbi Anglong, which has an area of 10,332 square kilometres, is by far the worst affected, with 10 per cent of its population of 700,000 suffering from dental or skeletal fluorosis. Of the Assamese population afflicted by flourosis, 70 per cent are from Karbi Anglong. The affected areas include Tekelangjun, Dokmaka, Lungnit, Taradubi, Tuplem, Garampani, Karbi Anglong, Ratiagaon, Haldiati, Parakhowa, and the Neelbagan area of Nagaon district.
The first fluorosis case in the Northeast was discovered in 1999 in the Tekelangjun area of Karbi Anglong, where fluoride levels were found to be as high as 5 to 23 mg/ litre. According to World Health Organisation guidelines, the permissible limit of fluoride in drinking water is only 1 mg/litre. This creeping tragedy came to light following a study conducted by the Public Health Engineering Department (PHED) of Assam. Subsequent independent studies conducted by various organisations, including the Central Ground Water Board (New Delhi), The All India Institute of Hygiene and Public Health (Calcutta), The School of Environmental Studies (Jadavpur University, Calcutta) and the Public Analyst in Guwahati, have corroborated the findings of the PHED survey. Interestingly, as late as 1998, the country's geological and public health scientists had declared the Northeastern region safe from fluoride contamination.
Available statistics indicate that all over India more than six million people are seriously afflicted by fluorosis and another 62 million are exposed to it. In Assam, at least 20,000 young people suffer from severe fluorosis. Fluorosis has no cure but deterioration can be arrested if the disease is diagnosed sufficiently early. Fluorides, when consumed in excess, replace hydroxide in bones, causing a chronic condition called skeletal fluorosis. It affects people of all ages. Victims of skeletal fluorosis suffer severe pain in the joints, back bone and hips, as well as increased bone density, calcification of ligaments and paralysis. Fluorosis also leads to severe anemia, painful and restricted movement, mottled teeth, loosened muscles, kidney failure and premature death. Many victims are crippled for life.
Fluorides enter the human body through edibles, toothpaste, oral rinses and, most swiftly, through drinking water. A colorless and odorless natural pollutant, fluoride comes into contact with groundwater from its source of origin a mineral rocks. The concentration of fluoride in ground water basically depends on extended contact of the water with fluoride-bearing minerals. Three major sources of fluoride in India are fluorspars, rock phosphates and phosphorities. Most fluoride compounds in the earth's upper crust are soluble in water. Because of differences in geographical, chemical and physical characteristics of water bearing aquifers, the porosity of rocks, the pH and temperature, fluoride content in ground water varies between 1 to 25 mg/litre. When fluoride-bearing minerals in rocks and soil come into contact with ground water, they release fluoride into water by the process of hydrolysis. Geologically, Karbi Anglong and parts of the Nagaon district have numerous joints, fractures and faults. In addition, the area also has large quantities of sedimentary rocks and unconsolidated material like gravel, sand, clay with intrusive granite and quartz shale, all of which are known for their high fluoride content.