Several human epidemiological studies have found an association between fluoride in drinking water and the occurrence of osteosarcoma (bone cancer) in young males (Bassin 2006; Cohn 1992; Hoover 1991). These studies are consistent with the National Toxicology Program’s (NTP) cancer bioassay which found that fluoride-treated male rats had an dose-dependent increase in osteosarcoma (Bucher 1991). Although a number of studies have failed to detect an association between fluoride and osteosarcoma, none of these studies have measured the risk of fluoride at specific windows in time, which is the critical question with respect to fluoride and osteosarcoma. (FLUORIDE ACTION NETWORK)