The European Scientific Committee on Health and Environmental Risks (SCHER) reviewed the evidence on water fluoridation in 2010. It concluded that the evidence linking fluoride in water to osteosarcoma was โequivocal,โ and that therefore โfluoride cannot be classified as to its carcinogenicity.โ
https://www.cancer.org/cancer/cancer-causes/water-fluoridation-and-cancer-risk.html
Over the past 30 years, expert agencies around the world have reviewed the available evidence on water fluoridation and whether it is linked to an increased risk of cancer. These agencies include the International Agency for Research on Cancer (IARC)(1987)5, the US Public Health Service (1991)6, the Medical Research Council (2002)7, the European Scientific Committee on Health and Environmental Risks (SCHER)(2011)8, California's Identification Committee (CIC)9 and Royal Society of New Zealand (2014)10. The consensus has been either that there is not enough quality evidence to draw a conclusion one way or the other, or the evidence does not show a link between water fluoridation and any type of cancer.
https://www.cancerwa.asn.au/resources/cancermyths/fluoride-cancer-myth/
Claims have been made that fluoride is associated with osteosarcoma. The Department of Health and Human Services has collaborated with Cancer Council Victoria to provide balanced, evidence-based advice about these claims.
Epidemiological studies show no clear association between fluoride in drinking water and osteosarcoma.
https://www2.health.vic.gov.au/public-health/water/water-fluoridation/fluoride-and-osteosarcoma
For the studies that did show a link between fluoridation and bone cancer, itโs important to acknowledge their limitations. In the 1991 rat study, for example, levels of fluoride used in the study were much higher than what would be found in a community fluoridation program.
In the 2006 Harvard University study, there may have been a potential selection bias because of how hospitals were chosen in the study. Also, the number of cases of bone cancer within this age group would have been extremely small. This limits the statistical power of the study.
In 2011, results of the second part of the Harvard study were published. It compared fluoride levels in bones near osteosarcoma tumors to those in bones with other types of tumors. The researchers found no difference in fluoride levels between the different tumors.
https://www.healthline.com/health/fluoride-cancer#the-research