COMMUNITY WATER FLUORIDATION

Community water fluoridation is the process of adjusting the concentration of fluoride that occurs naturally in a community's water supply to a level that is best for preventing dental decay. A key word in this definition is "adjusting" because all water supplies contain some fluoride; fluoridation merely adjusts the natural amount to a level that results in a minimal amount of dental decay.

Many epidemiologic surveys conducted in the late 1930s and early 1940s showed that children who lived in communities with optimal levels of fluoride occurring naturally in their drinking water had about 50 percent to 65 percent fewer decayed teeth than did children who lived in communities with negligible concentrations of fluoride. These studies showed that about one part fluoride to one million parts of water (1 ppm) produced maximal protection against dental decay and only minimal amounts of dental fluorosis, a cosmetic condition of teeth that may occur from the chronic ingestion of excessive fluoride during the period when permanent teeth are forming. In January 1945, Grand Rapids, Michigan, became the first city in the world to adjust the fluoride concentration in its municipal water supply. Recommended concentrations for community water fluoridation in the U.S. range from 0.7 ppm in hot climates where people consume more water to 1.2 ppm in cold climates where less water is consumed.

Fluoride works to prevent dental decay in several ways: When ingested, it is incorporated into developing teeth, making them more resistant, after they erupt, to acids that are produced by bacteria when sugars are consumed; when applied to teeth directly, fluoride produces many antibacterial effects and fosters the repair (remineralization) of enamel that has been demineralized by bacterial acids. More than one of these mechanisms of fluoride action may operate simultaneously.

Most recent estimates indicate that 145 million persons or 56 percent of the U.S. population live in approximately 10,000 communities with sufficient concentrations of fluoride in their drinking water. The population with fluoridated water as a percentage of those who live in areas with central water supplies is approximately 62 percent. At least 40 countries practice controlled water fluoridation. Large segments of populations are covered in Australia, Brazil, Chile, Ireland, Malaysia, New Zealand, and Singapore. Community water fluoridation has attributes that make it an ideal public health disease-preventive method. It is inexpensive and eminently safe. It benefits children and adults for a lifetime if consumption continues. Costs of dental treatment are reduced. It is socially equitable because everyone in a community benefits and no individual effort or direct action is required by those who will benefit.

Opponents of fluoridation are a small, heterogeneous group who cannot easily be categorized by any single characteristic. They include right-wing extremists, misguided environmentalists, some chiropractors, persons concerned with the costs of fluoridation, food faddists, antiscience "naturalists," and those who believe strongly in individual rights. Vocal opponents to fluoridation have attempted to link various adverse health effects with fluoridation. Claims that fluoride is harmful have been amply reviewed by international, national, state, and local authorities. Many committees or commissions of experts in medicine, epidemiology, pathology, pharmacology, and toxicology have reaffirmed the safety of community water fluoridation.

Herschel S. Horowitz

(see also: Caries Prevention )

Bibliography

Horowitz, H. S. (1996). "The Effectiveness of Community Water Fluoridation in the United States." Journal of Public Health Dentistry 56 (5):253–258.

Newbrun, E. and Horowitz, H. (1999). "Why We Have Not Changed Our Minds about the Safety and Efficacy of Water Fluoridation." Perspectives in Biology and Medicine 42 (4):526–543.

Ripa, L. W. (1993). "A Half-century of Community Water Fluoridation in the United States: Review and Commentary." Journal of Public Health Dentistry 53:17–44.

U.S. Department of Health and Human Services (1991). Review of Fluoride—Benefits and Risks. Report of ad hoc Subcommittee, Committee to Coordinate Environmental Health and Related Programs. Washington, DC: Government Printing Office.