Survey of fluoride concentration in drinking water sources of Makoo county and qualitative zoning of fluoride by GIS and health effects on provalence dental fluorosis

Abstract

In Iran more than 95% of rural communities are depended on ground water for water supply. Among environmental characteristics the earth properties have a significant role in water quality, especially chemical aspects of the water. Therefore, the general quality of ground water is strongly affected by the geology of the area. Fluoride occurs in all of the natural water with different concentration. It is one of the chemical materials that can cause significant effects on human via potable water. The beneficial and harmful effects of fluoride in drinking water have been known since early of 1940s. The bad effects include dental fluorosis and skeletal fluorosis depending on the concentration of fluoride in water and period of exposure. The main aim of this study was determination and zoning of fluoride concentration in the rural water resources of Makou County. The other objective of this research was the survey of prevalence of dental fluorosis in area. Water samples were taken from water sources of all of the villages in the studied area in the spring and summer according to the standard method and carried to the laboratory. Fluoride concentration was determined with SPANDS method. Then the zoning of fluoride concentration was done by Arc GIS software. For the survey of prevalence and intensity of fluorosis and DMFT, the 239 school children were selected according clustering random sampling method from two group of villages: 1(polluted villages with average fluoride concentration of drinking water of 6.98 mg/l) and group 2 (not polluted villages with average fluoride concentration of drinking water was 0.45 mg/l). Then the results of survey of fluorosis and DMFT were analyzed with Chi-square test and Mann– Whitney tests. The results of study indicated that the average concentration of fluoride in the spring was 1.6±1.4mg/L, while that was 2.6±3.2mg/L in the summer. The maximum concentration of in the spring and summer was determined 6.68mg/L 11.14mg/L respectively in one of studied village water sources. The fluoride concentration in the 26 villages was more than recommended concentration of 0.5mg/L to 1.5 mg/L. The results of survey of fluorosis indicated: The percentage of fluorosis in groups 1 and 2 were 3.7 and 0.046 respectively. The DMF index in groups 1 and 2 was 0.99 and 0.42. There was statistically significant relation between fluorosis and fluoride concentration of drinking water. According to Dean,s criteria high percentage of students in group 1 had dental fluorosis (grades 2 to 5) (p<0.001), while the second group had healthy teeth. The meanII DMFT score in group 1 was D= 0.95, M=0.025 and F0.01 and group 2: D=0.4, M=0.025 and F= 0. Results indicate that there is coordination between the high prevalence of dental fluorosis and high concentration of fluoride drinking water in the area. Due to high concentrations of fluoride in some potable water sources of studied villages and also severe prevalence of fluorosis in those polluted communities, the application of suitable measures to remove of the excessive fluoride from drinking water strongly propose.