Fluoride lowers IQ, causes bone cancer in boys and young men, and can damage both kidney and liver function in children.
Fluoridation is also a cause of fluorosis - or mottled teeth.

In recent years, scientists and health professionals have been sounding a warning about the dangers of water fluoridation.

The Canadian Cancer Society states: "We know that fluoride helps to prevent tooth decay, but some recent studies have raised fears that water fluoridation may be linked to an increased risk of osteosarcoma especially in boys." The Canadian Cancer Society recommends that fluoride in drinking water be reduced to the lowest possible level.

The health impact of too much fluoride

Excessive fluoride is a concern in regard to young children. One possible result of taking in too much fluoride during the tooth-forming years is a condition called dental fluorosis. Excess fluoride affects the cells in the tooth that form enamel. As a result, the enamel of the tooth becomes hypomineralized and more porous. In most cases, the enamel exhibits faint white lines or streaks. In more severe cases, the surface of the enamel is stained yellow or brown and pitted.

Fluoride and cancer: the evidence

While decades of research have shown that water fluoridation helps to prevent tooth decay, there is also evidence suggesting a potential relationship between exposure to high levels of fluoride in drinking water and cancer, particularly osteosarcoma in boys younger than 19. Osteosarcoma is a type of rare bone cancer . According to Canadian Cancer Statistics, 170 cases of osteosarcoma were reported in between 1997 and 2001, an average of 34 cases per year.