In mid-2000, as incidents of severe fluorosis in a village in Yavatmal district came to light, the Maharashtra government declared a special Rs 200 crore package for safe drinking water in tribal-dominated areas. The incidents had sparked off a major uproar and in an unprecedented move, the National Human Rights Commission too had passed strictures against the government asking it for a detailed report on the matter and threatening suo moto action if it failed to comply.
In Yavatmal, bordering Andhra Pradesh, incidence of fluorosis has been rising in recent years along side the mindless extraction of groundwater. Lack of rainfall has meant that the district is largely dependent on groundwater, both for irrigation and drinking water requirements. Incessant digging of borewells has given rise to sharp rise in the fluoride concentration in the ground water. Fluorides and other dissolved salts in drinking water have exceeded the safe limit in the past two decades. A high intake of fluoride (>1.5 mg/l) in drinking water over a prolonged period is known to cause damage to the enamel of the teeth, and eventually results in skeletal complications leading to fluorosis. A progressively increasing proportion of the population in Yavatmal including undernourished children is now infected with fluorosis.
Other areas with high fluoride content in groundwater as per the Nagpur based Central Ground Water Board (CGWB) periodic reports are Bhandara, Chandrapur, Nanded and Aurangabad.
Extent of the problem in India
Fluorine occurs in rocks in the form of fluoride-bearing minerals like fluorite and fluoroapatite. India has large resources of these minerals. In such areas, groundwater drawn through wells, hand-pumps and especially tube-wells is likely to contain excess fluoride due to the dissolution of fluoride from the fluoride bearing minerals. The problem of excess fluorosis in groundwater was detected in many states in India as early as the 1930s. Till 1999, as many as 17 states have been identified with the problem of excess fluoride in groundwater resources.
Rajasthan and Andhra Pradesh are the most severely affected states. Rural populations, which depend mainly on groundwater for their drinking water supply are the worst affected. Vulnerability to fluorosis is higher if the nutritional status is poor-malnourished children, pregnant women or lactating mothers are especially vulnerable.
To combat fluorosis, the preferred option is to find a supply of safe drinking water with safe fluoride levels. But where access to safe water is already limited, de-fluoridation may be the only solution. De-fluoridation of drinking water using domestic water filters, has been found to be by and large the most effective way to prevent excessive fluoride intake in fluorosis endemic villages. However, removal of excessive fluoride from drinking water is difficult and expensive. The methods include – use of bone charcoal, contact precipitation, use of Nalgonda or activated aluminae. Since all methods produce a sludge with very high concentration of fluoride that has to be disposed of, it is advocated that only water for drinking and cooking purposes should be treated, particularly in developing countries.
Two methods of de-fluoridation are currently in use.
a) The Nalgonda technique, under which calculated amounts of alum, lime and bleaching water are added to pre-treated water and the mixture is stirred. Fluorides are absorbed by the aluminium hydroxide complex compounds and settle as sludge at the bottom of reactors. However to ensure for optimum fluoride removal, alum and lime need to be added in certain proportions and a trained operator and chemist are required to operate this filter.
b) As against this, de-fluoridation plants based on activated aluminae are very simple to operate and even as recently demonstrated by villagers in Rajasthan’s Tonk district, local people themselves can handle these filters with some initial training. The only problem with the mass utilisation of these filters is that the cost of activated aluminae is comparatively high at about Rs 130 per kg.
Active Aluminae in Treating Fluorosis
UNICEF has been working closely with the Indian government of India and other NGOs to implement specific fluorosis mitigation programmes – initiated specifically at the grassroot level. A number of demonstration projects were initiated in fluorosis affected states in cooperation with state governments, panchayats and community groups and NGOs – Anantapur in Andhra Pradesh, Dungarpur and Tonk in Rajasthan, Kanpur Dehat in Uttar Pradesh and Chandrapur in Maharashtra.
In these areas, epidemiological surveys were conducted with help of doctors to understand the magnitude of the problem as well as to provide basic data on the health status of families in the area. This information is vital for subsequent impact assessment studies. In the project villages, testing of all drinking water sources was done. UNICEF facilitated the innovation of a Domestic De-fluoridation Unit (DDU) which used activated aluminae to remove excess fluoride from drinking water. Promotional camps highlighting the use, maintenance and regeneration aspects of domestic de-fluoridation units are held at village level.
Recently, the project saw a successful beginning in Rajasthan’s Tonk district and will be replicated in other areas too where the studies were carried out. In these Tonk villages, fluorosis affected villagers have now been able to come to terms with the problem. The solution has been community participation – NGOs have trained the villagers to filter the water of excessive fluoride through a simple chemical treatment. Although the method is not all that simple, villagers have learnt to determine the percentage of fluoride in drinking water by treating the water with a chemical compound called zirconilered. Then the excess fluoride from the water is removed by passing it through a chemical called activated aluminae.
The UNICEF and a couple of local NGOs are focussing on setting up community as well as household de-fluoridation projects in these areas. Initially the UNICEF is providing most of the fund required in buying the activated aluminae to set up de-fluoridation units. The rest of the money is to be contributed by the community or owner of particular households. The maintenance is the owner’s responsibility.
Even regeneration of activated aluminae which becomes useless after being used for de-fluoridation for five to six months, is being done by the villagers themselves by using caustic soda/potash and sulphuric acid. UNICEFF provides part of the initial fund to set up at least one regeneration unit per village and responsibility is entrusted to a village representative seen to have acquired some degree of expertise in handling the process. The NGOs and the UNICEF believe that domestic as well as community de-fluoridation of water will be sustained here as the community has shown tremendous interest in it.
The involvement of local community in fighting fluorosis holds out much hope. Earlier government efforts failed because they did not educate communities and did not relate fluorosis, viewed as a public health issue, to the environment.
The older Nalgonda technique was developed by the National Environmental Engineering Research Institute (NEERI) in Nagpur that has been involved in research and development activities on de-fluoridation of water since the 1960s. It was at Nalgonda in Andhra Pradesh that the first community de-fluoridation plant for removal of fluoride from drinking water was constructed in Nalgonda’s Kathri town, and hence the technology now in use worldwide also came to be known as the Nalgonda technique.
In this technology, raw water is mixed with adequate lime and alum. But it is important that the doses of alum and lime are determined after assessing the fluoride content and alkalinity of water. The alum solution is added after the addition of lime, stirred gently for 10 minutes and the flocs formed are allowed to settle. This process of floc formation and settling requires an hour. In rural areas where the people practice domestic de-fluoridation, the advice given is to mix the water with lime and alum and leave it overnight, so that the next morning the clean supernatant is decanted for use and is safe for consumption. In the Nalgonda technique, besides fluoride, turbidity, colour, odour, pesticides and organic substances, if any, are also removed. Bacterial contamination is also reduced significantly.
The merit of the technique is that it can be used at both the domestic and community levels. Operations are possible manually. NEERI also developed a variety of designs and models for use in different locations. But the major concern with the lime and alum technology is that if the dose of alum is not adhered to, there could be a possibility of excess aluminium contaminating the water. Due to the concern shown regarding possible health hazards, aluminium-caused alternative coagulants and coagulant aids are now being recommended.
Researchers in Nagpur University now suggest that bauxite, an abundantly available aluminium ore, could form a cheap substitute agent for removal of excess fluoride from drinking water. Bauxite can be used as a defluorinating agent in domestic water filters in place of activated aluminae, which is more expensive.
About eight samples of bauxite from different ore deposits all over the country were tested and found to be suitable as a cheaper substitute for de-fluoridation of drinking water. It was also found that after its use as medium for fluoride removal, bauxite still retains its use as ore of aluminium, with certain value addition. The rejected bauxite from de-fluoridation units can also be effectively used for aluminium metallurgy. Bauxite also happens to be a natural resource that is widely available in almost all regions of the country.
Besides de-fluoridation, health education regarding appropriate use of fluorides is a must. It is now established that fluorosis is restricted to rural areas where the populace does not have access to treated drinking water. Among the rural populace, the tribals are found to be more severely affected, pointing that economic status and dietary habits may have a major role to play.
According to A N Deshmukh of Nagpur university’s geology department who was once part of the UNICEF project at Chandrapur, most of the fluorosis victims were found to have a very poor dietary intake, particularly with regard to calcium rich food (milk and other dairy products). Calcium is known to nullify the effect of fluoride in body, as it has the capability to absorb fluoride ions. Calcium supplementation — through calcium tablets or through calcium rich food — has thus been suggested as one of the corrective measures. Mothers in affected areas should be encouraged to breastfeed since breast milk is usually low in fluoride.
It is also known that fluorosis, in its severe forms, is mostly restricted to a particular climate zone in the world — the areas with semi-arid tropical conditions. In these areas, the consumption of drinking water is high and the populace is thus more vulnerable to the disease as compared to their counterparts in colder areas with low consumption of water, though the fluoride content of water in both the areas may be the same.