hojai: Over a thousand children below the age of five have been crippled by fluorosis over the last six years in Hojai in Assam. The most pronounced symptoms are bent legs and crooked teeth.
Water contaminated by flouride, a natural mineral, has been implicated in the poisonings, according to officials from the Assam Public Health Engineering Department (PHED), who first discovered the relationship between the contamination and medical effects in 1999.
Fluoride levels in water above the permissible limit of 1 mg/litre have been found in 11 districts in the state — putting an estimated 356,000 people at risk, according to an official survey. Experts warned the numbers would rise if emergency measures were not taken.
“More than a thousand children below the age of five have been crippled because of fluoride contamination” in Hojai district a few years back, according to Najibuddin Ahmed, former additional chief engineer, Assam PHED.
The district’s main town, which goes by the same name, is 170 km southeast of Assam’s largest city, Guwahati.
The risk of fluoride contamination has increased in recent years as a result of the increase in groundwater usage — not just in Hojai but elsewhere in the state.
“If one were to go back in history, people were mostly dependent on surface water resources for their daily needs,” Ahmed said. “Today, only about 15 per cent of the population relies on surface water and 85 per cent use groundwater as the main source. Since the water table has gone down, the concentration of minerals like fluoride has gone up in groundwater, thereby increasing the risk of fluoride contamination.”
“Fluoride is a natural mineral found in water but there are reasons why its concentration has risen,” according to Dharani Saikia, secretary, Environment Conservation Centre, a local NGO that has been working on the issue for more than a decade. “One of them is the change in climatic patterns.”
Long dry spells have led to less rain water seeping into the ground and replenishing the groundwater table. Indiscriminate cutting of trees — for construction and otherwise — has added to the problem. “With ample rainfall, the fluoride concentration in water remains normal but with less rain, the concentration goes up,” Saikia said.
Another major reason, experts said, is the increase in drilling activity for hand pumps and borewells. With the lowering of the water table, the drills are also going deeper, thereby closing in towards the granitic rocks that are rich in minerals such as fluoride. Therefore, fluoride is making inroads into the water pumped up.
“In Guwahati, for instance, earlier they would bore 150-200 feet for water,” Saikia said.
“Now, with the mushrooming of flats and housing societies, the water demand has gone up. Since the water table has gone down, they bore up to 250-300 feet.”
A.B. Paul, former chief engineer, Assam PHED, who is credited with the official detection of both fluoride and arsenic in water in the state, said his discovery was accidental. It was in 1999, during an official visit to Tekelanguin village in Karbi Anglong district — one of the worst-affected districts in the state — that he saw a girl with mottled teeth.
“Many other people also showed symptoms of dental and skeletal fluorosis. On investigation, I found the fluoride content in the water varied from 5 to 23 mg/l when the WHO permissible limit is 1 mg/l.”
An unofficial survey, Saikia said, found that 50,000 children in 285 villages in Hojai district were affected by fluorosis — dental or skeletal. “A total of 485 villages in Nagaon and Hojai are afflicted with fluoride contamination,” he added.
As part of the mitigation efforts, the PHED has marked water sources (such as tubewells) with beyond-permissible limits of fluoride with red colour so that people avoid it for drinking or cooking purposes.
Laboratory facilities for testing water samples have been upgraded in four districts (Karbi Anglong, Nagaon, Hojai, Kamrup), and ring wells have been constructed in Karbi Anglong, Nagaon and Kamrup districts for safer drinking water even as more are coming up.
Eleven village panchayats in Nagaon district that were sanctioned funds for tube wells have now been asked to make ring wells. (IANS)
