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On January 7, 2011, the U.S. Department of Health and Human Services (HHS) announced plans to update the recommended optimal level for community water fluoridation to 0.7 parts per million (ppm).1 This proposed guidance from HHS will replace the current recommended range of 0.7 to 1.2 ppm for optimal fluoridation of drinking water, which was established by the U.S. Public Health Service (USPHS) in 1962 for caries prevention. The HHS guidance was developed by a panel of scientists from several federal agencies, and it is open for public comment for a 30-day period, which ends February 14, 2011. Final HHS guidance on the recommended optimal fluoride level is anticipated later this year.

Also on January 7th, the Environmental Protection Agency (EPA) reported that it will initiate review of the latest research on the maximum amount of fluoride allowed in public water systems.2 The EPA sets standards for drinking water safety, including the amount of fluoride and other regulated water contaminants that are permitted in public water systems. Under the Safe Drinking Water Act, a “contaminant” is defined as “any physical, chemical, biological, or radiological substance or matter in water.” The EPA’s planned evaluation is part of the agency’s periodic review of existing EPA standards for the maximum allowable concentration of fluoride in public drinking water, which is currently set at 4 ppm.

As an initial step, the EPA released new risk assessment reports on total fluoride exposure3 that were prompted by a 2006 report from the National Research Council (NRC),4 which recommended that the EPA update its analyses of fluoride exposure and reduce the current maximum contaminant level goal (MCLG) of 4 ppm for naturally occurring fluoride in drinking water. These assessments will provide guidance for the EPA’s evaluation of research on total fluoride exposure, and the agency’s plan to determine if the MCLG should be lowered from 4 ppm to protect public health.  

The announcements from both federal agencies were issued to balance the recognized caries-preventive benefits of community water fluoridation while reducing the potential development of enamel fluorosis, especially for children during the tooth-formation years (i.e., under 8 years of age). Enamel fluorosis is a form of hypomineralized tissue that can result in a range of visually detectable changes in the tooth enamel. The condition generally results from excess fluoride intake during critical periods of tooth development early in life, primarily from ingestion of fluoride toothpaste. 

Enamel fluorosis is considered a cosmetic condition with no known health effects, appearing primarily in very mild to mild form in the U.S., but it can cause tooth discoloration and pitting in rare, severe cases. The development of dental fluorosis has been associated with cumulative fluoride intake from multiple sources (e.g., water, food, fluoride toothpaste, other products), as well as ingestion of water with high concentrations of naturally occurring fluoride over a substantial period of time. However, only a small portion of the U.S. population (under 225,000 individuals) receive drinking water from public water systems where the natural levels of fluoride exceed the EPA’s current ceiling of 4 ppm. 

With regard to the HHS guidance, the current range for optimal water fluoridation (0.7 to 1.2 ppm) will transition to a single optimal level (0.7 ppm) for fluoride in community water systems. The HHS scientific panel determined that this level of fluoride in drinking water would be sufficient to maintain the public health benefits of caries prevention while also minimizing the incidence of enamel fluorosis, which has slowly increased over time. The following considerations were rigorously evaluated by the HHS scientific panel:

  • the strong supporting evidence on the safety and cost-effectiveness of optimally fluoridated community water for caries prevention;
  • public access to more fluoride sources than in the past, including public water supplies, fluoride toothpaste and mouthwash, topical fluoride applications in dental settings, fluoride supplements, commercial food products, and beverages and foods processed with fluoridated water;
  • maintaining the caries-preventive benefits of community water fluoridation while also reducing the potential development of enamel fluorosis, which has increased in prevalence due to greater access to more sources of fluoride; and
  • emerging research on water consumption rates by young children across U.S. climate zones, which suggests that levels of total water intake among children aged 1 to 10 are generally similar.5

As noted by the HHS scientific panel, systematic reviews on community water fluoridation have concluded that it is safe and effective in reducing caries incidence and severity.  To reduce the occurrence of enamel fluorosis, young children are encouraged to only use a small amount of toothpaste on the brush, to be supervised while brushing, and to spit out (rather than swallow) the toothpaste after brushing.  Additional information can be obtained in the ADA’s Fluoridation Facts publication.  
 
Based on a substantial body of peer-reviewed evidence, the ADA supports optimal fluoridation of community water systems as a safe and effective means of caries prevention.  For additional information about water fluoridation, visit http://www.ada.org/fluoride.aspx

Footnotes

1. Proposed HHS recommendation for fluoride concentration in drinking water for prevention of dental caries.  U.S. Department of Health and Human Services. January 7, 2011. Available at: “http://www.hhs.gov/news/press/2011pres/01/pre_pub_frn_fluoride.html”. Accessed January 18, 2011. 

2. EPA and HHS Announce New Scientific Assessments and Actions on Fluoride. U.S. Environmental Protection Agency. Available at: “ http://yosemite.epa.gov/opa/admpress.nsf/3881d73f4d4aaa0b85257359003f5348/86964af577c37ab285257811005a8417!OpenDocument”. Accessed January 18, 2011. 

3. United States Environmental Protection Agency. Fluoride Risk Assessment and Relative Source Contribution (website). Available at: “http://water.epa.gov/action/advisories/drinking/fluoride_index.cfm”. Accessed January 19, 2011.    

4. National Research Council of the National Academies. Fluoride in Drinking Water: A Scientific Review of EPA’s Standards, 2006. Available at: “http://www.nap.edu/openbook.php?record_id=11571&page=R1#”. Accessed January 18, 2011. 

5. Beltran-Aguilar ED, Barker L, Sohn W. Lack of association between daily temperature and children’s water intake in the United States — 1999–2004. Available at: “http://www.cdc.gov/fluoridation/fact_sheets/totalwaterintake.htm”. Accessed January 19, 2011. 

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Science in the News is a service by the American Dental Association (ADA) to its members 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.

Document posted January 2011