More than 65 years of research and practical experience have shown fluoridation is safe and effective. The best available scientific evidence does not support any connections between cancer and community water fluoridation. It is the single most effective public health measure to prevent tooth decay and has been named by the CDC as one of 10 great health achievements of the 20th century.
A Answers (2)
American Dental Association answered
Riverside Cancer Care Center answered
The possible relationship between fluoridated water and cancer has been debated at length. The debate resurfaced in 1990 when a study by the National Toxicology Program, part of the National Institute of Environmental Health Sciences, showed an increased number of osteosarcomas (bone tumors) in male rats given water high in fluoride for 2 years. However, other studies in humans and in animals have not shown an association between fluoridated water and cancer.
In a February 1991 Public Health Service (PHS) report, the agency said it found no evidence of an association between fluoride and cancer in humans. The report, based on a review of more than 50 human epidemiological (population) studies produced over the past 40 years, concluded that optimal fluoridation of drinking water "does not pose a detectable cancer risk to humans" as evidenced by extensive human epidemiological data reported to date.
In one of the studies reviewed for the PHS report, scientists at the National Cancer Institute evaluated the relationship between the fluoridation of drinking water and the number of deaths due to cancer in the United States during a 36-year period, and the relationship between water fluoridation and number of new cases of cancer during a 15-year period. After examining more than 2.2 million cancer death records and 125,000 cancer case records in counties using fluoridated water, the researchers found no indication of increased cancer risk associated with fluoridated drinking water.
In 1993, the Subcommittee on Health Effects of Ingested Fluoride of the National Research Council, part of the National Academy of Sciences, conducted an extensive literature review concerning the association between fluoridated drinking water and increased cancer risk. The review included data from more than 50 human epidemiological studies and six animal studies. The Subcommittee concluded that none of the data demonstrated an association between fluoridated drinking water and cancer. A 1999 report by the CDC supported these findings. The report concluded that studies to date have produced "no credible evidence" of an association between fluoridated drinking water and an increased risk for cancer.
This answer is based on source information from the National Cancer Institute.