Scientific Reviews: Assessing the Weight of the Evidence 

Reviews of scientific literature are an important resource to judge the safety of community water fluoridation. Scientific reviews are helpful because they—

• Consider evidence from published studies on a subject.
• Use carefully-designed methods to critically examine scientific evidence.
• Use national and international panels of experts in various health and scientific disciplines. This includes experts that may come from fields outside of oral health; such as, medicine, biophysics, chemistry, toxicological pathology, and epidemiology.
• Judge the quality of individual studies and summarize the strength of the entire body of evidence.
• Identify and summarize research gaps and make recommendations for further research.

Scientific and pubic health organizations have conducted scientific reviews about fluoridation during the past two decades. These reviews provide compelling evidence that community water fluoridation is a safe and effective method for reducing tooth decay across all ages.

United States Public Health Service Review of Fluoride: Benefits and Risks, 1991
This report provides a comprehensive review and evaluation of the public health benefits and risks of fluoride from drinking water and other sources.

Institute of Medicine Dietary Reference Guidelines, 1997*
These guidelines describe the dietary reference intakes for specific nutrients known to be beneficial to health including fluoride.

National Research Council

The National Research Council (NRC) released its current report, Fluoride in Drinking Water: A Scientific Review of EPA’s Standard, on March 22, 2006. The NRC's previous report, entitled Health Effects of Ingested Fluoride*, was issued in 1993. It examined the possible toxic effects of ingested fluoride and concluded—

• Fluoride at recommended concentrations is not likely to produce a number of unwanted health effects that had been claimed by opponents of water fluoridation.
• The maximum contaminant level (MCL) set by the Environmental Protection Agency (EPA) at 4 mg/L was an appropriate interim standard, even though fluoride at this level might cause moderate or even severe dental fluorosis in a small percentage of the population.

Australian Government

Australia's National Health and Medical Research Council (NHMRC) conducted a systematic review published in 2007, that considered recent evidence relating to the efficacy and safety of fluoride interventions, with an emphasis on widespread public health initiatives. The report, A Systematic Review of the Efficacy and Safety of Fluoridation, primarily addressed the caries-reducing benefits and associated health risks of providing fluoride systemically. The council found that—

• Community water fluoridation is beneficial for reducing dental caries (tooth decay).
• Water fluoridation at optimal levels does not affect the risk of bone fractures.
• There is no clear association between water fluoridation and overall cancer incidence or mortality.
• The reviewed studies do not suggest an increased risk of adverse health effects at optimal fluoridation levels.

NHMRC is Australia's main agency for supporting health and medical research; developing health advice for the Australian community, health professionals, and governments; and providing advice on ethical behavior in health care and conduct for health and medical research.

University of York

A systematic review of public water fluoridation* was released in 2000 by the National Health Service (NHS) Centre for Reviews and Dissemination, University of York, United Kingdom. This looked at the evidence of positive and negative effects for community water fluoridation. They identified five objectives and evaluated the studies relating to each objective. Based on the best available research they found that—

• Community water fluoridation reduces tooth decay.
• Fluoridation is still effective even with the use of many other sources of fluoride.
• There is no clear association between fluoridation and bone fractures or cancer.
• There appears to be no difference between benefits from natural and artificial fluoridation.
• There is an association between the water fluoride concentration and the occurrence of enamel fluorosis.
• No clear evidence of other potential negative health effects were found.

Additional systematic reviews on the benefits of water fluoridation may be viewed on the Benefits page.

* Links to non-Federal organizations are provided solely as a service to our users. Links do not constitute an endorsement of any organization by CDC or the Federal Government, and none should be inferred. The CDC is not responsible for the content of the individual organization Web pages found at this link.

Date last reviewed: December 9, 2008
Date last updated: December 10, 2008
Content source: Division of Oral Health, National Center for Chronic Disease Prevention and Health Promotion