A 1990 fluoride study suggested an increase in cancers of the oral mucus membranes in rats; a rare form of osteosarcoma appeared at double the rate in males as females; and there was an increase in thyroid follicular cell tumors, and liver cancer. However, a 1991 review by the U.S.Public Health Service concluded that there is no evidence that fluoride causes cancer in humans. The incidence of bone cancer in males below the age of 20 has risen since 1973, but the panel concluded that this is not related to fluoridation... Full Text