Whereas low amount of fluoride has positive effect on teeth, its high concentrations in potable water, amplified by other sources of contaminant, could result harm to people. Hem (1989) stated that major part of fluorine present in groundwater sources, since it is stored in rock minerals, unlike chlorine that is mostly present in seawater. Thus, it leads us to a conclusion that significant part of fluorine intake …show more content…
Concentrations above this value carry an increasing risk of dental fluorosis, and much higher concentrations lead to skeletal fluorosis. The value is higher than that recommended for artificial fluoridation of water supplies, which is usually 0.5–1.0 mg/litre. In setting national standards or local guidelines for fluoride or in evaluating the possible health consequences of exposure to fluoride, it is essential to consider the intake of water by the population of interest and the intake of fluoride from other sources (e.g., from food and air). Where the intakes are likely to approach, or be greater than, 6 mg/day, it would be appropriate to consider setting a standard or local guideline at a concentration lower than 1.5 mg/litre (WHO,