Cancer myth: Fluoride and cancer
Origin of the misconception
Fluoride is routinely added to drinking water in many countries. As a consequence, there are many theories about the health effects of fluoride. There are countless websites linking fluoride to cancer, fractures, heart disease, birth defects and anaemia, to name a few.
Many of these theories propose that fluoride interferes with the normal biology or genetics of the body and causes disease. It is often suggested that fluoride is linked to the development of osteosarcoma (a relatively uncommon bone cancer).
Fluoride (F) is the 13th most abundant element on earth. In people, fluoride is an important part of calcified tissue (bone and teeth). At relatively low doses fluoride has repeatedly been proven to prevent and repair decay and cavities in teeth (dental caries).1- 2 In the first ten years of fluoridated water in Australia decay rates dropped by up to 60 percent.3 Fluoridation was considered one of, "Ten Great Public Health Achievements - United States, 1900-1999" by the Centres for Disease Control and Prevention (CDC).4, 5
In Australia, approximately 70 percent of the population live in areas with fluoridated water.6 The Australian Drinking Water Guidelines specify a target for fluoridation of between 0.7 and 1.0 mg/L. The lower end of the range is recommended where the climate is hot and people drink more water.3 In Western Australia fluoridation of drinking water is controlled by the Fluoridation of Public Water Supplies Act 1966.7
The International Agency for the Research of Cancer (IARC) evaluated the safety of fluoride in drinking water in 1982 and reviewed the evidence in 1987. IARC concluded that fluoride is not classifiable as to its carcinogenicity to humans. This means that there is not enough evidence to say that fluoride either does or does not cause cancer. Studies published since the IARC review have not shown a clear or consistent link between fluoridation of drinking water and increased incidence of cancer.2
In 2007, Australian National Health and Medical Research (NHMRC) published a report explaining the systematic research review conducted of 5,418 citations. After reviewing each study individually 77 citations were deemed to be of good quality.11 From these articles the NHMRC were able to recommend the continuation of fluoridating the water supply.11
There have been many independent studies into a causal link between water fluoridation and osteosarcoma (cancer of the bone). Many anti fluoridation websites quote the study by the American National Toxicology which was able to find a causal link between fluoridation of water and osteosarcomas in male rats when given water with high doses of fluoride.8 Though a link was found in the first study, no replicated study has been able to show the same link.
In response, the American National Cancer Institute conducted its own research into osteosarcoma (a form of bone cancer) incidence over time. The studies found age specific and sex specific increases in osteosarcoma over time in fluoridated areas in contrast to non-fluoridated areas.9 Further analysis of the data revealed that increases in osteosarcoma in these populations did not coincide with the timing of fluoridation of the water supply. It was concluded that there was no consistent evidence for an association between fluoridation and osteosarcoma.9-10
Fluoridation is considered by many to be a major public health success. The addition of fluoride to drinking water has led to a significant reduction in dental carries. There is no consistent evidence of fluoride from drinking water increasing cancer risk. At very high doses - much higher than in drinking water - fluoride can have some adverse health effects on teeth and bones.
- Centers for Disease Control and Prevention (CDC), Recommendations for using fluoride to prevent and control dental caries in the United States. MMWR, 2001. 50 (RR-14).
- Fawell, J., et al., Fluoride in drinking-water. 2006, World Health Organization, London, England.
- Australian Dental Association (ADA). Fluoride and your dental health, Dental health information [cited 23 March 2008]; Available from: http://www.ada.org.au/app_cmslib/media/umlib/documents/public/consumer_info/ dental%20health%20tips/fluoride%20and%20your%20dental%20health.pdf.
- Centers for Disease Control and Prevention (CDC), Ten Great Public Health Achievements - United States, 1900-1999. MMWR, 1999. 48(12).
- Centers for Disease Control and Prevention (CDC), Fluoridation of Drinking Water to Prevent Dental Caries. MMWR, 1999. 48(41).
- Armfield, J.M., The extent of water fluoridation coverage in Australia. Aust N Z J Public Health, 2006. 30(6): p. 581-2.
- Fluoridation of Public Water Supplies Act. 1966: Western Australia.
- National Toxicology Program. Toxicology and carcinogenesis of sodium fluoride in F344/N rats and B6C3F1 mice. Technical Report Series 393, NIH Publication No. 90-2848, 1990.
- Review of fluoride: benefits and risks. Report of the ad hoc subcommittee of fluoride of the committee to coordinate environmental health and related programs. Public Health Service, Department of Health and Human Services, 1991.
- Parnell, C, Whelton, H & O'Mullane, D, Water Fluoridation. Ireland European Archives of Paediatric Dentistry.10 (3). 2009
- National Health and Medical Research. A systematic review of the efficacy and safety of fluoridation, Part A: review methodology and results. Australian Government. ISBN: 1864964219. 2007