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Overview
On March 22, 2006, the National Academies’ National Research
Council (NRC) released a new
report  that
evaluates the U.S. Environmental Protection Agency (EPA) standards
for maximum levels of naturally occurring fluoride in drinking
water. The report received national media coverage,1–5 and it
will be reviewed by the EPA to determine if changes are necessary
to the agency’s
standards for maximum fluoride levels in
public drinking water.
The National Research Council’s report reviews toxicologic,
epidemiologic, and exposure data relating to naturally occurring
fluoride in drinking water. The report also presents information
on fluoride content in other sources (e.g., food, beverages
and dental products). The EPA requested the NRC review as
a routine, periodic examination of the agency's existing
standards for the maximum allowable concentration of fluoride
in drinking water. The NRC was asked to examine whether the
amount of naturally occurring fluoride currently allowed
in drinking water poses a health risk. In particular, this
report focused on the maximum contaminant level goal (MCLG),
which is currently set at 4 parts per million or ppm (equivalent
to 4 milligrams of fluoride per liter of water) for naturally
occurring fluoride in drinking water.
In the report, the NRC evaluated the rate and severity of
enamel fluorosis and noted that while 10 percent of children in
communities with water fluoride levels at or near 4 ppm exhibited
severe dental fluorosis, at 2 ppm severe dental fluorosis
was basically eliminated. Those concentrations are significantly
higher than the optimal fluoride levels (0.7 to 1.2 ppm)
established by the U.S. Public Health Service more than 40
years ago for caries prevention. The NRC report also examined
other possible adverse health effects associated with high
levels of naturally occurring fluoride (e.g., musculoskeletal
and endocrine effects, genotoxicity, carcinogenicity, reproductive
and developmental effects, neurotoxicity and neurobehavioral
effects).
Although the report states that more research is necessary,
it did confirm the previously accepted conclusions that high
concentrations of naturally occurring fluoride are a risk
factor for dental fluorosis and may place some individuals
at increased risk for bone fractures and possibly skeletal
fluorosis. On the basis of its review, the NRC committee
recommended that the current MCLG for naturally occurring
fluoride in drinking water (4 ppm) should be lowered.
Fluoride ions come from the element fluorine, an abundant
natural element found in soil and water sources, including
the earth’s crust and oceans. Small amounts of fluoride
are present in all water sources. In the United States, the
natural level of fluoride in ground water varies from low
concentrations (less than 1 ppm) to over 4 ppm. Public water
systems in the United States are monitored by the EPA, which
requires that community water systems not exceed fluoride
levels of 4 ppm. A small segment of the U.S. population,
estimated to be approximately 200,000 people, are on public
water systems where the natural levels of fluoride are above
the EPA’s current ceiling of 4 ppm. Today, over 160
million people in the United States receive their drinking
water from optimally fluoridated water supplies.
Most importantly, the NRC report did not evaluate the safety
or effectiveness of community water fluoridation, the well-established
process of adding fluoride to public water supplies to reach
optimal levels (between 0.7–1.2 parts per million)
for protection against tooth decay.
Based on the substantial body of peer-reviewed evidence, the
ADA supports community water fluoridation within the optimum
range of 0.7 to 1.2 ppm as a safe and effective means of
caries prevention. For additional information about fluoride,
water fluoridation and the new report from the National Research
Council, visit www.ada.org/goto/fluoride.
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Footnotes
1 Leary WE. Panel Urges Lowering of Allowable Fluoride. The
New York Times, March 22, 2006.
2 Weise E. Report Raises Flag on Fluoride. USA Today,
March 23, 2006. Available at: http://www.usatoday.com/news/health/2006-03-22-fluoride-water_x.htm .
3 Cone M. Scientists Sound Warning on High Natural Fluoride
Levels. Los Angeles Times, March 23, 2006. Available
at: http://www.latimes.com/news/nationworld/nation/
la-na-fluoride23mar23,1,7628952.story?coll=la-headlines-nation .
4 Sink Your Cavity-Riddled Teeth Into This One (editorial).
The Oregonian, March 25, 2006. Available at: http://www.oregonlive.com/search/index.ssf?/
base/editorial/114324813030940.xml?oregonian?ede&coll=7 .
5 Deardorff J. Researchers Pour Dose of Worry in Fluoridated
Water. Chicago Tribune, April 2, 2006. Available
at: http://www.chicagotribune.com/features/health/chi-0604010266apr02,1,5942967.story .
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A-Z Topic: Fluoride & Fluoridation
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Science in the News is a service by the American Dental Association (ADA) to present current information about science topics in the news. The ADA is a professional association of dentists committed to the public's oral health, ethics, science and professional advancement; leading a unified profession through initiatives in advocacy, education, research and the development of standards. As a science-based organization, the ADA's evaluation of the scientific evidence may change as more information becomes available. Your thoughts would be greatly appreciated.
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