Fluoride is the 13th most abundant element in the earth’s crust (625 mg/kg) and exists in trace amounts in almost all groundwaters across the world. According to estimations from UNESCO, more than 200 million people worldwide rely on drinking water with fluoride concentrations exceeding the present WHO guideline of 1.5 mg/L. Fluorosis, associated with elevated fluoride concentrations in drinking water has been reported in a range of countries.
While low fluoride intake may prevent dental caries, excess intake causes different types of fluorosis; primarily dental and skeletal fluorosis. White line striations on the teeth followed by brown patches and, in severe cases, brittling of the enamel are common symptoms of dental fluorosis. This is not only a health problem but also has psychological and social impacts, as people are ashamed and possibly ostracised due to their bad teeth. Skeletal fluorosis first causes pain in different joints, then limits joint movement, leading to stiffness and skeletal crippling. Besides dental and skeletal fluorosis, other manifestations such as nervousness, depression and muscle weakness have been reported in connection with high fluoride intake.
Water Quality Section of the Catholic Diocese of Nakuru, Kenya
International Society for Fluoride Research
WHO: Fluoride in Drinking Water