World Health Organization (WHO) has set the upper limit of fluoride concentration in drinking water at 1.5 mg/l, and the Bureau of Indian Standards, has therefore, laid down Indian standards as 1.0 mg/l as maximum permissible limit of fluoride with further remarks as ‘lesser the better’. Intake of fluoride higher than the optimum level is the main reason for dental and skeletal fluorosis. The main source in groundwater is from fluoride rich rocks. Most of the people affected by high fluoride concentration in groundwater live in the tropical countries where the per capita consumption of water is more because of the prevailing climate.
India is one of the worst fluorosis affected countries, with large number of people suffering. This is because a large number of Indians rely on groundwater for drinking purposes and water at many places is rich in fluoride among other reasons. In India, 62 million people, including 6 million children are estimated to have serious health problems due to consumption of fluoride contaminated water (Arlapa et al., 2013).
As reported by the states on Integrated Management Information System (IMIS) of the Ministry of Drinking Water and Sanitation as on February 2, 2016 there are 3,37,60,872 rural population residing in 60,504 rural habitation which are at risk due to excess arsenic, fluoride, iron, salinity and nitrate in drinking water. The number of people at risk due to the presence of excess fluoride in drinking water is 83,08,250 in 11,285 rural habitations. According to the same report there are about 1311 arsenic affected habitations in six states—West Bengal, Assam, Bihar, Uttar Pradesh, Karnataka and Punjab as of February 2016. However, information about number of arsenicosis affected persons in these states is not available.
According to the National Programme for Prevention and Control of Fluorosis (NPPCF) Guidelines 2014, in the endemic states, the geological crust is heavily loaded with fluoride bearing minerals which leaches out into the drinking water. The drinking water fluoride so far detected in the country ranges from 0.2 to 48 mg/l. However, the information on fluoride content in agricultural crops and other ready to consume food items and industrial emissions from various industries with high fluoride content is a matter of concern. Several of the ready to serve foods, beverages, snacks, etc. have high content of black rock salt (NaCl) or ‘kala namak’ which has 157 part per million (ppm) fluoride. The consumption of such packaged or ready to serve foods have also increased with the change in food habit. This can be achieved only through mass awareness programmes. As the damage/change in skeletal system and teeth due to prolonged exposure to high fluoride levels is irreversible, the focus of management of fluorosis is on prevention, health promotion, deformity correction and rehabilitation.
According to the 2014 Report by the Ministry of Health and Family Welfare, a total of 117 lakh people have been reportedly affected by fluorosis. Figure 1 shows the ten states with the highest number of fluorosis affected people in India.
Even though states like Rajasthan, Karnataka, Andhra Pradesh have the highest number of affected people, the fluoride content range is comparatively lower as against states like Delhi, Punjab, Assam and Haryana where the status of fluoride content in groundwater is highest but the affected number of people is much lower that it doesn’t figure in the top ten list. Table 1 shows the range of fluoride in groundwater in 19 states. From the two tables, it is perceived that differences in drinking water treatment may be the factor behind the peculiar trend. It is likely that Delhi, Haryana and Punjab have access to better water treatment facilities.
The latest information shows that fluorosis is endemic in at least 25 countries across the globe. The total number of people affected is not known, but a conservative estimate would number in the tens of millions. In 1993, 15 of India’s 32 states were identified as endemic for fluorosis. In Mexico, 5 million people (about 6 per cent of the population) are affected by fluoride in groundwater. Fluorosis is prevalent in some parts of central and western China and caused not only by drinking fluoride in groundwater but also by breathing airborne fluoride released from the burning of fluoride-laden coal. Worldwide, such instances of industrial fluorosis are on the rise.
Governments are not yet fully aware of the fluoride problem and rarely quantify its adverse impact on their populations. Efforts are therefore needed to support more research on the subject and promote systematic policy responses by governments.
For prevention and control of fluorosis, the NPPCF is being implemented since 2008-09 in a phased manner. So far, 111 districts in 19 states have been covered under the programme. The important components of the programme are surveillance of fluorosis in the community, capacity building in the form of training and manpower support, establishment of diagnostic facilities, management of fluorosis cases including treatment, surgery, rehabilitation and health education. Revised Guidelines on NPPCF have been issued to 19 states and financial assistance is being provided to these states. The Ministry of Drinking Water and Sanitation has already been providing alternate sources of safe drinking water in areas affected by water contaminants. Further, efforts are made to spread awareness regarding problem due to water contamination through mass media as well as local media in affected areas.
Since, fluorosis is irreversible; its prevention is imperative with valuable and meaningful interventions, using various intervention measures. Fluoride poisoning can be prevented or minimised by using alternative water sources, by removing excessive fluoride from drinking water, and by improving the nutritional status of populations at risk. The simple interventions include conservation of surface water, rainwater and consumption of low-fluoride groundwater. Other interventions are defluoridation of water through flocculation and adsorption.
UNICEF also brought out a list of preventive measures for fluorosis:
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