Requirements Fluorine is found in small amounts in normal bones and teeth. Since water containing 1-2ppm fluorine prevents dental caries and does not do any harm, the fluorine requirements of the body are met by the quantity normally present in drinking water (1-2ppm) in most of the regions. The safe and adequate RDA of fluoride in the diet is 0.25 mg for children and 1.5 to 4.0 mg for adults.
Toxicity High levels of fluoride in water >3 ppm can cause mottling of teeth and chronic dental fluorosis; in which the tooth enamel becomes dull and unglazed with some pitting (mottled enamel). Chalky white patches with a secondary infiltration of yellow or brown staining are found irregularly over the surface of the teeth. Fluoride levels greater than 8 ppm in water can lead to arthritic type of symptoms. Bone and teeth deformities may result due to long-term consumption of fluoride above 50 mg daily. When fluoride level in drinking water is more than 10 ppm severe bone deformities may occur categorized as skeletal fluorosis.