CONTENTS-
Abstract
Introduction
Material and Methods
Results and Discussion
Conclusion
References

Mylaudy, a village near Kanyakumari, Tamilnadu, is one of the places where drinking water is found to contain fluoride above the permissible limit.   Fluorosis has been prevalent in Mission Vilai, a   part of Mylaudy village for about fifteen years.   Hence, it was decided to analyse the fluoride ion concentration in drinking water obtained from this place.   Eleven water samples were collected and analysed for different physico-chemical parameters. A door-to-door survey was also conducted in the form of questionnaire, to determine the severity of the disease.

Fluorine is an important trace element necessary for good health.   It is often called a twin-edged blade as inadequate ingestion is associated with dental caries.   Excessive intake leads to dental and skeletal fluoroisis. Though fluorine is abundant in nature, it is firmly bound to minerals and chemicals.   Its bio-availability is governed by many factors like acidity of the soil, pressure of other minerals, chemicals, nature and solubility of the fluoride in water and the chemical nature of water. The most common fluoride-bearing minerals, which contribute to the natural source for fluoride in drinking water are fluorite, apatite, rock phosphate and topaz 1. The epidemiologic prevalence of endemic fluorosis is directly related to the distribution of fluoride-bearing minerals in various endemic areas.   Fluoride enters the water cycle by leaching from soils and minerals.

India is among the 23 nations around the world, where health problems occur due to the consumption of fluoride-contaminated water.   Endemic fluorosis is widespread in India affecting mainly the states of Andhra Pradesh, Punjab, Rajasthan, Gujarat, Tamilnadu, Karnataka and Uttar Pradesh.   An estimated 62 million people including 6 million children suffer from fluorosis   (Teotia, et al., 1981).            

Researchers have long studied the significance of fluoride in drinking water.   Fluorosis was reported by Eager   as early as 1901 and in India the first case was reported by Shortt et.al   in 1937 in the Madras Presidency.   The principal sources of fluoride intake in man are water, edible vegetation, marine animals and industrial dust.   The presence of fluoride in water and food is universal and, therefore, its intake in the diet is virtually inevitable.   The chief factors, which determine fluoride toxicity are the fluoride ion concentrations in drinking water and the duration of exposure to this hazard.   Inspite of identical concentration of fluoride in water, variations in the incidence of the disease had been noticed which are attributed to other chemical constituents of water such as alkalinity, total hardness, calcium, and magnesium hardness (Rajyalakshmi and Ramamohana Rao., 1985).   Concentration of fluoride in water varies not only from place to place but also within the same locality.   Even in the same village, different wells often show wide divergent fluoride content.   Water with high fluoride content is found at the foot of high mountains and in areas with geological deposits of marine origin. Fluoride concentration also varies depending upon the water source.   Alkaline water shows high levels of fluoride. Surface water contains less fluoride than ground water.

Water samples from eleven sources in and around Mission Vilai of Mylaudy village were collected in polythene bottles.   The samples were analysed for fluoride ion concentration, pH, alkalinity and total hardness.

Fluoride ion concentration was determined   using Orion EA920-9409 having a   fluoride ion selective electrode.  Alkalinity and total hardness were determined by titrimetric method using standard procedures. pH was determined by a Systronics – 324 pH meter.

A door-to-door survey was conducted using a questionnaire to record data regarding age, sex, occupation, food habits, health complaints, etc.   Dean's (1933) classification was used for recording the severity of the disease.

The results of the analysis are given in Table 1.   The survey revealed the existence of dental and skeletal fluorosis in Mission Vilai area of Mylaudy.   It was found that out of 1164 interviewed, 276 (23.71%) people were found to be affected by dental fluorosis and only one male was affected by both dental and skeletal fluorosis Mostly people below the age of 30 years have been affected by the disease.   According to the reports, the development of yellowishness of the teeth started arising about 15 years back.   From the survey it was found that 140 people were affected out of 364 (38.5%) in the age group 15-30 years, and 136 were affected out of 236 (57.6%) in the age group of 5-15 years.

Water from sources    S1, S2 and S3 were collected from Mission Vilai   and fluoride ion concentration was found to be less than 1.0ppm, but was not used by the residents due to its high hardness. Mission Vilai gets its drinking water supply from sources S4, S5 and S6.   Source S4 contains 0.8ppm of fluoride ion concentration while the other two contain greater than 1.0ppm.   Though Mission Vilai got its water-supply from source S4 earlier, due to shortage of water-supply from source S4, water has been supplied from sources S5 and S6   for the last 15 years.   This has caused the prevalence of fluorosis in the   area.

Water sources S7, S8 and S9 are nearer to S4.   Sources S7 and S8 contain fluoride ion concentration less than 1.0ppm and S9 contains   more than 1.0ppm.            

Water sources S10 and S11 are nearly 5km away from Mission Vilai and both of them contain fluoride ion concentration greater than 1.0ppm.

The results showed that pH and alkalinity of water containing fluoride greater than 1.0ppm was higher but the total hardness was found to be low.   This was in accordance with other reports. The incidence of fluorosis is directly related to the fluoride ion concentration in drinking water.   In Mission Vilai, drinking water supplied was found to contain fluoride ion concentration greater than 1.0ppm.   The permissible level of fluoride ion concentration in drinking water was fixed as 1.0 ppm by I.C.M.R. (Apparao and Karthikeyan., 1986))

But the severity of the disease depends mainly upon the alkalinity and total hardness of water.   Water containing higher concentration of fluoride is associated with high alkalinity and low hardness.   In the report of Teotia et.al, when the fluoride ion concentration was 1.0ppm the alkalinity was 193.6ppm and the hardness was 242ppm.   When the fluoride ion concentration was 8 to 10ppm the alkalinity was 450ppm and hardness was 80ppm.

When the fluoride ion concentration in water is identical, the difference in the incidence of fluorosis is directly related to the alkalinity of water.   Water analysis of some of the villages in Nalconda District of Andhra Pradesh by Rajylakshmi et.al (1985) revealed that the fluoride ion concentrations in two villages were found to be 4.8 and 6.9ppm, the alkalinity was 536 and 530 ppm, and the incidence of skeletal fluorosis was 32.5% and 35% respectively.   But when the fluoride ion concentrations were 6.9 and 7.8ppm, the alkalinity was 530 and 720 ppm and the incidence of skeletal fluorosis was 35% and 71.6% respectively.   For a slight variation in fluoride ion concentration the alkalinity varied and the extent of fluorosis also varied.

            Jolly et.al, (1973) analysed water samples from two districts of Punjab and found that alkalinity and hardness of water contributed much to skeletal fluorosis for identical concentration of fluoride ion in water.   Fluoride ion concentration of 5.20 and 5.49 ppm corresponded to the alkalinity 514 and 578 ppm and total hardness 135 and 281ppm respectively.   The percentage of skeletal fluorosis was found to be 52.2 and 29.6. It is clear that total hardness helped to cause a reduction in skeletal fluorosis.

        Though drinking water of Mission Vilai contains a maximum of 1.3ppm fluoride ion concentration, the high alkalinity (421ppm) and low total hardness (105ppm) are supposed to have contributed much towards dental fluorosis.

It was concluded that change of water source caused the prevalence of fluorosis in Mission Vilai. It is decided to send a report to the local Panchayat and District Administration so that suitable action could be taken at the earliest.

•  Teotia, S.P.S. Teotia, M and Singh, R.K., (1981)Hydro-Geochemical Aspects of Endemic Fluorosis in India-An Epidemiologic Study, Fluoride, 14 (2),.

•  Eager J.M., (1901) Public Health Report, Washington, 16, 2576,.

•  Shortt, H.E., Mc.Robert, G.R, Barnard, T.W, Nayyar. A.S.M. (1937) Endemic fluorosis in Madras Presidency, Ind. Journ. Med. Res, 25, 533. .

•  Rajyalakshmi, K and Ramamohana Rao, N.V (1985). Fluorosis in Nalconda District in Relation to Chemical Characteristics of Potable Water and Staple Food, Fluoride, 18, (4)..

•  Dean, H.J., (1933) Amer.J. Dent. Assoc., 20, 319.

•  Apparao, B.V, Karthikeyan, G., (1986) Permissible Limits of Fluoride Ion in Drinking Water in Indian Rural Environment. Indian J. Environmental Protection, 6, (3),.

•  Jolly, S.S, Prasad, S, Sharma, R, and Chander, R., (1973) Endermic Fluorosis is Punjab, Fluoride, 6, (1).

1 Department of Chemistry, Manonmanian Sunderanar University, Tirunelveli – 627012.Tamil Nadu. India.

2 Department of Chemistry, SPK College, Alwarkurichi – 627 412. Tamil Nadu. India.

3 Department of Chemistry, Sivanthi Aditanar College, Pillayarpuram – 629501. Tamil Nadu. India.

4 Department of Chemistry, Morning Star Polytechnic, Chunkankadai – 629 807. Tamil Nadu. India.