Fluoridation

DEFINITION: The treatment of community water-supply systems with fluoride as a public health measure

The issue of whether it is a safe practice for communities to add fluoride to water supplies to prevent tooth decay remains controversial among some environmentalists.

Fluoridation of water supplies was first introduced in the United States in the 1940s as a preventive measure to reduce tooth decay, which was a serious and widespread problem in the early twentieth century. Since that time, many cities have taken the step of adding fluoride to their public water-supply systems, but the merits and drawbacks of have long been subjects of debate. Proponents of fluoridation note that it has dramatically reduced tooth decay in Americans, but opponents of the practice have not been entirely convinced of its effectiveness, and some are concerned about possible health risks of fluoridation. The decision to fluoridate drinking water generally rests with local governments and communities.

Fluoride is the water-soluble, ionic form of the element fluorine. It is present naturally in most water supplies at low levels, generally less than 0.2 part per million (ppm), and nearly all food contains traces of fluoride. Tea contains more fluoride than most foods, and fish and vegetables also have relatively high levels. The findings of many scientific studies suggest that water containing a of about 1 ppm fluoride, in contrast with water containing less fluoride, dramatically reduces the incidence of tooth decay.

Tooth decay occurs when acids in the mouth dissolve the protective enamel outer coating of a tooth, creating a hole, or cavity. These acids are present in food and can also be formed by that convert sugars into acids. The American diet has long included large quantities of sugar, which is a significant factor in the high incidence of tooth decay. By contrast, studies reveal that tooth decay is less common among people in primitive cultures; these findings have been attributed to these cultures’ more natural diets.

Early fluoridation studies conducted between 1930 and 1950 demonstrated that fluoridation of public water systems produced a 50 to 60 percent reduction in tooth decay and that no immediate health risks were associated with increased fluoride consumption. Consequently, many communities quickly moved to fluoridate their water, and fluoridation was endorsed by most major health organizations in the United States. By 2024, about 75 percent of US residents were living in communities with fluoridated water supplies.

Opposition to Fluoridation

Strong opposition to fluoridation began to emerge in the 1950s, as some people asserted that the possible side effects of consuming fluoride had not been adequately investigated. This concern was not unreasonable, given that high levels of ingested fluoride can be lethal. However, it is not unusual for a substance that is lethal at high concentration to be safe at low levels, as is the case with most vitamins and trace elements. Opponents of fluoridation were also concerned on moral grounds; they argued that fluoridation represents compulsory mass medication.

Since the 1960s, heated debates have arisen over the issue of fluoridation across the United States. Critics have pointed to the harmful effects of very large doses of fluoride, including bone damage, and the special risks fluoride may pose for some people, such as those with kidney disease and others who are particularly sensitive to toxic substances. Between the 1950s and the 1980s, some scientists suggested that fluoride may have a mutagenic effect—that is, it may be associated with human birth defects, including Down syndrome.

Controversial claims that fluoride can cause cancer were also raised in the 1970s, most notably by biochemist John Yiamouyiannis, who asserted that US cities with fluoridated water had higher rates of death from cancers than did cities with unfluoridated water. Fluoridation proponents were quick to discredit his work by pointing out that he had failed to take other factors into consideration, such as the levels of known environmental carcinogens. Most scientific opinion--including reports by the National Research Council, National Health Service Centre for Reviews and Dissemination (UK), and the International Agency for Research on Cancer--finds no compelling evidence of a link between cancer and fluoride.

While there is little doubt that fluoride does reduce tooth decay, the exact degree to which fluoridated water contributes to the reduction remains unanswered. It also remains unclear what, if any, side effects are associated with the ingestion of fluoride in water at the level of 1 ppm over many years. Any level, no matter how small, may not be acceptable to everyone.

Since the 1960s and 1970s, Americans’ concerns about environmental and health issues have been growing, and it has often been difficult, if not impossible, for scientists to measure—and to explain to the complete satisfaction of the public—the potential hazards posed by small amounts of chemical substances in the environment. In 1993, the National Research Council (NRC) published a report on the health effects of ingested fluoride that included information on an attempt to determine whether the Environmental Protection Agency’s maximum recommended level of 4 ppm for fluoride in drinking water should be modified. The report concluded that this level is appropriate but stated that further research may indicate a need for revision. The report also noted inconsistencies in the scientific studies of fluoride . In 2006 and 2007, the NRC reported on the detriments of excess fluoride consumption (enamel fluorosis in children aged eight and younger, risk of broken bones, and skeletal fluorosis), as well as its benefits (cavity prevention and bone mineralization).

The development of the fluoridation issue in the United States has been closely observed by other countries. Dental and medical authorities in Australia, Canada, New Zealand, and Ireland have endorsed fluoridation of water supplies, although not without considerable opposition from various groups. In Western Europe, fluoridation has been greeted less enthusiastically, and scientific opinion in some countries, such as France, Germany, and Denmark, has concluded that it is unsafe. As a result, few Europeans drink fluoridated water. In some European countries, fluoride is added to milk and salt. Naturally occurring fluoridated water is at or above optimal levels in some countries, such as Finland, Sweden, and Zimbabwe.

Bibliography

"About Community Water Fluoridation." Centers for Disease Control and Prevention, www.cdc.gov/fluoridation/about/index.html. Accessed 18 July 2024.

De Zuane, John. Handbook of Drinking Water Quality. 2d ed. New York: John Wiley & Sons, 1997.

"Fluoridation." European Union, 2010, ec.europa.eu/health/scientific‗committees/opinions‗layman/fluoridation/en/index.htm#1. Accessed 18 July 2024.

Martin, Brian. Scientific Knowledge in Controversy: The Social Dynamic of the Fluoridation Debate. Albany: State University of New York Press, 1991.

National Research Council. Health Effects of Ingested Fluoride. Washington, D.C.: National Academy Press, 1993.

Reilly, Gretchen Ann. “The Task Is a Political One: The Promotion of Fluoridation.” In Silent Victories: The History and Practice of Public Health in Twentieth-Century America, edited by John W. Ward and Christian Warren. New York: Oxford University Press, 2007.

Stewart, John Cary. Drinking Water Hazards. Hiram, Ohio: Envirographics, 1989.

"Water Fluoridation and Cancer Risk." American Cancer Society, 18 Nov. 2022, www.cancer.org/cancer/risk-prevention/chemicals/water-fluoridation-and-cancer-risk.html. Accessed 18 July 2024.

Weinstein, L. H., and A. W. Davison. Fluorides in the Environment. Cambridge, Mass.: CABI, 2004.