To Home Page
Fluoride and Fluoridation
Fluoride is the name given to a group of
compounds that are composed of the naturally occurring element
fluorine and one or more other elements. Fluorides are present naturally
in water and soil.
What is fluoride?
What is fluoridated water? Virtually all water contains some amount of fluoride. Water
fluoridation is the process of adding fluoride to the water supply so
that the level reaches approximately 1 part fluoride per million parts
water (ppm) or 1
milligram fluoride per liter of water (mg/L); this is the optimal
level for preventing tooth decay (1).
Why fluoridate water?In the early 1940s, scientists discovered that people who lived
where drinking water supplies had naturally occurring fluoride levels of
approximately 1.0 ppm had fewer dental caries (cavities). Many more
recent studies have supported this finding (1).
Fluoride can prevent and even reverse tooth
decay by enhancing remineralization, the process by which fluoride
“rebuilds” tooth enamel that is beginning to decay (1, 2).
When did water fluoridation begin in the
U.S.? In 1945, Grand Rapids, Michigan, adjusted the fluoride content
of its water supply to 1.0 ppm and thus became the first city to
implement community water fluoridation. By 1992, more than 60 percent of
the U.S. population served by public water systems had access to water
fluoridated at approximately 1.0 ppm, the optimal level to prevent tooth
The Centers for Disease Control and Prevention (CDC) considers
fluoridation of water one of the greatest achievements in public health
in the 20th century.
Can fluoridated water cause cancer?
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
tumors) in male rats given water high in fluoride for 2 years (3).
However, other studies in humans and in animals have not shown an
association between fluoridated water and cancer (4).
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 (4).
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 (5).
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 (5). 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 (2).
Where can people find additional
information on fluoridated water?
The CDC Web site has information on standards for and surveillance of
current fluoridated water supplies in the United States. Visit
http://www.cdc.gov and search for
The Environmental Protection Agency (EPA)
Web site has more information about drinking water and health. It
includes information about drinking water quality and standards. This
Web site is located at
http://www.epa.gov/safewater/ on the Internet.
Centers for Disease Control and Prevention.
Public Health Service report on fluoride benefits and risks. Journal
of the Americal Medical Association 1991; 266(8):1061–1067.
Centers for Disease Control and Prevention.
Achievements in public health, 1900–1999: Fluoridation of drinking water
to prevent dental caries. Morbidity and Mortality Weekly Report
Bucher JR, Hejtmancik MR, Toft JD, et al.
Results and conclusions of the National Toxicology Program’s rodent
carcinogenicity studies with sodium fluoride. International Journal
of Cancer 1991; 48(5):733–737.
Committee to Coordinate Environmental
Health and Related Programs. Review of Fluoride Benefits and Risks:
Report of the Ad Hoc Subcommittee on Fluoride. Public Health
Service, Department of Health and Human Services, 1991.
National Research Council. Carcinogenicity
of flouride. In: Subcommittee on Health Effects of Ingested Fluoride,
editor. Health Effects of Ingested Fluoride. Washington DC:
National Academy Press, 1993.
National Cancer Institute