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Fluorides are chemicals that help prevent tooth decay. They’re found in nature – in rocks and soil, in fresh water and in ocean water. They’re also found in some types of food.

Decades of research have shown that adding fluoride to water (this is called fluoridation) helps prevent tooth decay. In some communities, natural levels of fluoride in the water supply match the ideal level to prevent tooth decay. In many others, the level of fluoride is too low and it has to be added to the water supply.

Studies by Health Canada, the US Food and Drug Administration, and independent academic investigators haven’t shown a link between water fluoridation and cancer. But a small and very weak body of evidence suggests there is a relationship between exposure to high levels of fluoride in drinking water and osteosarcoma (a rare type of bone cancer) in boys younger than 19.

There are also a small number of studies showing that rats and mice exposed to very high levels of fluoride (100 to 200 times the recommended level in Canada) may have a higher risk of developing osteosarcoma. The evidence in these studies is uncertain and has not been confirmed in further studies.

Our perspective

Based on current evidence, CCS believes it is unlikely that adding fluoride to water raises the risk of cancer, including osteosarcoma, in humans. At the same time, we know that there are many benefits to water fluoridation, especially for people who have less access to dental care. We will continue to watch this area of research and update our information as we learn more.

We urge the governments of Canada to make sure people are aware of the fluoride levels in their drinking water. We also ask government agencies to work together to make sure that fluoride in drinking water is reduced to the lowest level needed to have the maximum health benefit.

Learn more about fluoride and oral health.

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