Science and Environmental Education CONTENTS
About us News and Events
Community Outreach Educational Outreach
GIS Services Publications
Recycling Information Related Links

Fluoridation: In the Teeth of a Controversy

by Kristine Bradof

This article originally appeared in the July 1996 issue of the Wellspring newsletter, published by the MTU Regional Groundwater Education in Michigan (GEM) Center, now the Center for Science and Environmental Outreach at Michigan Technological University.

Fluoridation of water has been called "the single most effective public health measure to prevent tooth decay and to improve oral health over a lifetime" (American Dental Association (ADA) 1993). It is ranked with pasteurization, water purification, and immunization as "one of the four most important public health measures of our time." Fluoridation is mandatory in eight states; more than 30 countries provide fluoridated water to a total of 300,000,000 people (ADA 1993).

Yet, two of every three American communities that voted in recent years on whether or not to fluoridate their water supplies rejected the idea (Coffel 1992, Stewart 1990). Some people object to adding anything to their water. Others cite health and safety concerns voiced by critics of fluoridation, including some who are or were employees of the ADA, the U.S. Environmental Protection Agency (EPA), and the U.S. Public Health Service (Coffel 1992). Despite nearly universal support for fluoridation among health professionals and scientists, the practice is probably subject to more public controversy today than at any other time in its history.

Fluoridation’s foundations

Fluoride is present in rocks, soil, water, the atmosphere, and all foods and beverages in varying amounts. In the 1930s, a condition known as dental fluorosis was found in areas of the U.S. where fluoride occurs naturally in drinking water at concentrations higher than 2 parts per million (ppm) (Coffel 1992). Mild cases of fluorosis produce very white patches on the teeth; in severe cases, the teeth become pitted, brittle, and mottled with brownish stains. Researchers noticed, however, that people who drank water containing lower levels of fluoride had fewer cavities without developing fluorosis. Drinking water that contained natural fluoride concentrations of 1 ppm or less produced no known health problems.

In 1945, nine cities, including Grand Rapids, Michigan, began adding 1 ppm of fluoride to their drinking water in order to observe its effect on tooth decay. Ten to fifteen years later, children in those cities had 50-70 percent less tooth decay than the baseline groups not exposed to fluoride (Coffel 1992, ADA 1993). The results convinced many more communities to fluoridate their water supplies. In 1980, the Surgeon General set a goal for 95 percent of Americans on public water supplies to receive fluoridated water by 1990.

Fluoridation at fifty

Fifty years after fluoride was first added experimentally to drinking water, every dollar spent on fluoridation reduces dental bills by an estimated $80; communities spend an average of 51 cents per person per year to fluoridate their water supplies (ADA 1993). Still, the U.S. remains far short of the Surgeon General’s goal. A 1989 census found that fluoridated water is provided to only about 62 percent of the population connected to public water systems.

The 50 percent of Americans who rely on private wells also lack access to fluoridated water unless it occurs naturally. Fluoride tablets, mouth rinses, and toothpastes help prevent tooth decay but are not as cost effective or convenient as drinking-water delivery. An added problem is that low-income families often can’t afford fluoride supplements for their children.

In Michigan, more than 115,000 (37 percent) of the Upper Peninsula’s 314,000 residents are served by fluoridated public water supplies. The water in Bergland, Germfask, Garden, Ford River, and the Drummond Island Apartments contains naturally occurring fluoride at concentrations of 0.7 to 1.9 ppm (Michigan Department of Public Health 1994). That range approximates the 0.7 to 1.2 ppm established by the U.S. Public Health Service as optimum for preventing tooth decay. It is well below the 4.0 ppm Maximum Contaminant Level (MCL) standard adopted by the U.S. EPA under the Safe Drinking Water Act to protect against both skeletal and dental fluorosis. Twenty-three other communities in the U.P. choose to fluoridate their water. The smallest of these artificially fluoridated systems serves less than 500 residents on Mackinac Island; the three largest systems together serve more than 52,000 in Marquette, Sault Ste. Marie, and Escanaba.

The Public Health Code states that no Michigan community can be required to provide fluoridated water. Prior to 1978, each public water supply was required to be fluoridated unless the community opposed it by ordinance or referendum. An operator certified in limited chemical treatment must monitor artificially fluoridated water supplies, but no additional staff person is needed. If a water supply is fluoridated, a customer who wishes to remove the fluoride can install  a home reverse-osmosis or distillation system.

Fluoridation foes’ shaky case

Fluoridation has been opposed for allegedly contributing to cancer, birth defects including Down’s syndrome, Alzheimer’s disease, weakened immune systems, arteriosclerosis and heart disease, breakdown of collagen and risk of skeletal fractures, interference with enzyme activity and DNA repair/synthesis in the body, allergic reactions, kidney damage, and AIDS (Stewart 1990). Although the causes of these health problems are difficult to pinpoint, their links to fluoride either don’t stand up to closer examination of the evidence or are associated only with exposure levels many times higher than the EPA MCL of 4 ppm (ADA 1993).

For example, pathologist John Yiamouyiannis, a prominent fluoridation opponent, coauthored "a controversial epidemiologic report in 1977 that claimed a yearly excess of 10,000 human cancer deaths due to U.S. water fluoridation" (Cowen 1990). The National Cancer Institute and other investigators who reviewed the report found that well-known risk factors were ignored when excess cancer deaths were assessed. Re-analysis of the data using standard procedures to correct for these cancer risk factors showed no increased cancer related to fluoridation (ADA 1993).

At the urging of Yiamouyiannis and other fluoridation skeptics, Congress ordered a study of fluoride toxicity in animals. The researchers and a review panel of nongovernmental scientists found a weak, "equivocal" link between fluoride and bone cancer in male rats. Of 80 male rats given water with a fluoride content 80 times the recommended drinking water level, three developed cancer (Cowen 1990). One rat of 50 that drank water containing 45 ppm fluoride developed cancer. No cancer appeared in 100 male rats given water containing either 11 ppm fluoride or fluoride-free water. Similar tests in female rats and both sexes of mice also produced no cancer.

Critics question the motives of some fluoridation supporters. Yiamouyiannis says in Garbage magazine, "Early on, the ADA made a mistake and endorsed fluoridation of the public water supply. If they turned around now they could be destroyed financially, and they could be destroyed by a face-saving problem" (Coffel 1992). The same article claims that early research on and promotion of fluoridation was funded by aluminum- and phosphate-fertilizer industries, which then were fighting legal and public-relations battles over fluoride-containing wastes they produced. By the time the Public Health Service, the American Medical Association, and the ADA had endorsed fluoridation of water supplies in the early 1950’s, "the fervor to fluoridate was such that scientific debate over its effectiveness or potential health threats became impossible: Funding for research evaporated, along with any interest on the part of professional journals."

The MCL was raised from 2 ppm to 4 ppm during the past decade, largely at the urging of communities with water that naturally contains more than 2 ppm fluoride. Some groups, such as the Natural Resources Defense Council (1986), question the raising of the MCL because some fluorosis may occur at concentrations of 2-4 ppm. Another concern about fluoridation that research has yet to resolve is whether fluoride in toothpaste or rinses may be harmful to people who also drink fluoridated water.

Science on the side of fluoride

A 1993 ADA publication, Fluoridation Facts, lists 67 national and international health, service, consumer, and professional organizations that have endorsed fluoridation, some for as long as 45 years. They include the ADA, the American Medical Association, the American Public Health Association, the World Health Organization, the National Cancer Institute, the Mayo Clinic, the American Academy of Pediatrics, the National Academy of Sciences, the U.S. Environmental Protection Agency, the Consumer Federation of America, and the U.S. Junior Chamber of Commerce. Fluoridation Facts cites 238 references, largely from peer-reviewed medical and dental journals or agency reports, in its question-and-answer discussion of benefits, safety, public policy, and cost effectiveness of fluoridation. The evidence presented shows "that consumption of fluoride in community water supplies at the level recommended for optimal dental health has no harmful effect in humans."

Possible long-term harm from exposure to low levels of any substance is difficult to disprove. Still, fluoridation of water has been under scientific scrutiny for 50 years, and few critics dispute its value in preventing dental decay. In Antigo, Wisconsin, for example, officials suspended the town's ten-year-old fluoridation program in 1960, then reinstated it five years later after local children’s dental health declined significantly (ADA 1993). Other communites have had similar experiences. For the benefits gained, especially for young children, the relative costs and risks of fluoridation appear to be low.

References:

American Dental Association 1993. Fluoridation Facts, 29 pp.

Coffel, S. 1992. The great fluoride fight. Garbage May/June 1992, pp. 32-37.

Cowen, R. 1990. Panel finds fluoride-cancer link ‘equivocal.’ Science News vol. 137, p. 278, May 5, 1990.

Michigan Department of Public Health. 1994. Upper Peninsula Type I public water fluoridation, 1990 census. November 28, 1994.

Natural Resources Defense Council. 1986. New and pending cases: Drinking water fluoridation. NRDC Newsline, vol. 4, no. 1, February/March 1986.

Stewart, J.C. 1990. Drinking Water Hazards: How to Know if There Are Toxic Chemicals in Your Water and What to Do if There Are. Hiram, OH: Envirographics. 323 pp.