D. K. S. Reddy and K.L. N. Rao : Incidence of Fluorosis in India
81
2.2 Fluoride in soils
Leachable fluoride absorbed in the soil and clays are the main sources of fluoride
in ground water. The fluoride content of ground water in India varies
considerably. Apart from drinking water, the other sources of fluoride intake are
food, cosmetics, drugs and industrial fumes (WHO, 1984). Among factors which
control the concentration of fluorides are the climate of the area such as tropicality
of regions with abnormal temperatures, scanty rainfall and rocky terrain, and the
presence of the accessory minerals, fluorite and/or apatite in the rock-mineral
assemblage through which ground water circulates. Regional and tectonic factors
also play some part in affecting the fluoride concentration of ground water.
There is no treatment or cure for this disease, but it can be prevented by using
defluoridated water. Roholm (1937), Largent (1954), Forbes et al (1978) and
others have noted that humans removed from excessive fluoride exposures
continue to excrete markedly elevated fluoride concentrations in the urine for
long periods of time, indirect evidence of the mobilization of fluoride from the
skeleton. So fluoride from the skeleton can be mobilized and excreted primarily
in the urine by using defluoridated water.
In the present investigation, a survey was conducted to pinpoint the districts of
Andhra Pradesh (Fig. 2), affected by "excess fluoride". These districts are
Prakasam, Anantapur, Guntur, Krishna, Mahaboobnagar, Cuddapah, Nalgonda and
Ranga Reddy. The data is presented in Table 1.
A total of 6586 water samples from each village in 21 districts of Andhra Pradesh
was taken and analysed for fluoride content only (Table 1). The lowest fluoride
concentration (1.0 mg/l) is recorded in Nellore and Cuddapah districts, and the
highest (18.0 mg/I) in Medak district. The average fluoride concentration in
Andhra Pradesh is 2.49 mg/l; minimum average fluoride concentration (1.94 mg/l)
is in Srikakulam district and maximum (3.38 mg/l) in Chittoor district.
Only 13 villages (0.20%) of Andhra Pradesh have fluoride content in water within
the permissible limit (1.5 mgll); 5490 villages (83.36%) have fluoride content
between 1.5 and 3.0 mgll and 1083 villages (16.4%) beyond 3.0 mg/I. The
maximum number of villages i.e., 1385 (25.23%) affected by dental fluorosis is in
Anantapur district and the minimum i.e., 12 (0.21 %) in West Godavari district.
Similarly the maximum number of villages i.e., 184 (16.99%) affected by skeletal
fluorosis is in Prakasam district and the minimum i.e., 2 (0.18%) in West Godavari
district.
By and large, the number of villages in Andhra Pradesh with fluoride
concentration in drinking waters within the permissible limit seems negligible.
Most villages have been affected by fluorosis, either dental or skeletal, or
sometimes both together and this is shown in phi diagram (Fig. 3).
81
2.2 Fluoride in soils
Leachable fluoride absorbed in the soil and clays are the main sources of fluoride
in ground water. The fluoride content of ground water in India varies
considerably. Apart from drinking water, the other sources of fluoride intake are
food, cosmetics, drugs and industrial fumes (WHO, 1984). Among factors which
control the concentration of fluorides are the climate of the area such as tropicality
of regions with abnormal temperatures, scanty rainfall and rocky terrain, and the
presence of the accessory minerals, fluorite and/or apatite in the rock-mineral
assemblage through which ground water circulates. Regional and tectonic factors
also play some part in affecting the fluoride concentration of ground water.
There is no treatment or cure for this disease, but it can be prevented by using
defluoridated water. Roholm (1937), Largent (1954), Forbes et al (1978) and
others have noted that humans removed from excessive fluoride exposures
continue to excrete markedly elevated fluoride concentrations in the urine for
long periods of time, indirect evidence of the mobilization of fluoride from the
skeleton. So fluoride from the skeleton can be mobilized and excreted primarily
in the urine by using defluoridated water.
In the present investigation, a survey was conducted to pinpoint the districts of
Andhra Pradesh (Fig. 2), affected by "excess fluoride". These districts are
Prakasam, Anantapur, Guntur, Krishna, Mahaboobnagar, Cuddapah, Nalgonda and
Ranga Reddy. The data is presented in Table 1.
A total of 6586 water samples from each village in 21 districts of Andhra Pradesh
was taken and analysed for fluoride content only (Table 1). The lowest fluoride
concentration (1.0 mg/l) is recorded in Nellore and Cuddapah districts, and the
highest (18.0 mg/I) in Medak district. The average fluoride concentration in
Andhra Pradesh is 2.49 mg/l; minimum average fluoride concentration (1.94 mg/l)
is in Srikakulam district and maximum (3.38 mg/l) in Chittoor district.
Only 13 villages (0.20%) of Andhra Pradesh have fluoride content in water within
the permissible limit (1.5 mgll); 5490 villages (83.36%) have fluoride content
between 1.5 and 3.0 mgll and 1083 villages (16.4%) beyond 3.0 mg/I. The
maximum number of villages i.e., 1385 (25.23%) affected by dental fluorosis is in
Anantapur district and the minimum i.e., 12 (0.21 %) in West Godavari district.
Similarly the maximum number of villages i.e., 184 (16.99%) affected by skeletal
fluorosis is in Prakasam district and the minimum i.e., 2 (0.18%) in West Godavari
district.
By and large, the number of villages in Andhra Pradesh with fluoride
concentration in drinking waters within the permissible limit seems negligible.
Most villages have been affected by fluorosis, either dental or skeletal, or
sometimes both together and this is shown in phi diagram (Fig. 3).