FLUORIDE ACTION NETWORK
As acknowledged by the U.S. National Toxicology Program there is a "biological plausibility" of a link between fluoride exposure and osteosarcoma. The biological plausibility centers around three facts: 1) Bone is the principal site of fluoride accumulation, particularly during the growth spurts of childhood; 2) Fluoride is a mutagen when present at sufficient concentrations, and 3) Fluoride can artificially stimulate the proliferation of bone cells (osteoblasts).
In addition to its biological plausibility, there is now a substantive body of evidence indicating that fluoride can in fact induce osteosarcomas in both animals and humans.
Most notably, a recent national case control study conducted by scientists at Harvard University found a significant relationship between fluoride exposure and osteosarcoma among boys, particularly if exposed to fluoridated water between the ages of 6 and 8 (the mid-childhood growth spurt).
The Harvard study's findings are consistent with the U.S. National Toxicology Program's congressionally-mandated fluoride/cancer study in rats; the National Cancer Institute's 1990 analysis of osteosarcoma rates among young males in fluoridated versus unfluoridated areas in the U.S., and the New Jersey Department of Health's 1992 analysis of osteosarcoma rates among young males in fluoridated versus unfluoridated areas of Central New Jersey.
In addition, two later independent analyses of NCI's national cancer data also found a relationship between fluoridation and osteosarcoma among young males (Yiamouyiannis 1993; Takahashi 2001).
Taken together as a whole, the evidence - laboratory, animal, and human - suggests that fluoride could either directly initiate, or contribute to, the development of osteosarcoma in boys under the age of 20.