Fluoride Is Introduced into the U.S. Water Supply Summary

  • Last updated on November 10, 2022

Fluoride was introduced into the water-supply system of Grand Rapids, Michigan, as a test case to see if it could reduce tooth decay. The results were promising enough that widespread fluoridation soon followed, although many people expressed concern over the possible side effects of the practice.

Summary of Event

Fluoride is the water-soluble, ionic form of the element fluorine. It is present in most water supplies at low levels, generally less than 0.2 parts per million (ppm), and nearly all food contains traces of fluoride. On January 25, 1945, W. L. Harris Harris, W. L. , chief chemist of the city of Grand Rapids, supervised the first addition of fluoride to a water-supply system in the United States. Proponents of fluoridation claimed it would dramatically reduce tooth decay, which was a serious and widespread problem in the early twentieth century. Opponents of fluoridation were not entirely convinced of its effectiveness, were concerned by possible side effects, and were disturbed by the moral implications for personal rights of adding a chemical substance to an entire city’s water supply. The decision to fluoridate drinking water has generally rested with local governments and communities, and fluoridation has remained a controversial issue. Fluoride Water, fluoridation of Dental hygiene [kw]Fluoride Is Introduced into the U.S. Water Supply (Jan. 25, 1945) [kw]U.S. Water Supply, Fluoride Is Introduced into the (Jan. 25, 1945) [kw]Water Supply, Fluoride Is Introduced into the U.S. (Jan. 25, 1945) Fluoride Water, fluoridation of Dental hygiene [g]North America;Jan. 25, 1945: Fluoride Is Introduced into the U.S. Water Supply[01380] [g]United States;Jan. 25, 1945: Fluoride Is Introduced into the U.S. Water Supply[01380] [c]Health and medicine;Jan. 25, 1945: Fluoride Is Introduced into the U.S. Water Supply[01380] [c]Science and technology;Jan. 25, 1945: Fluoride Is Introduced into the U.S. Water Supply[01380] McKay, Frederick Dean, H. Trendley Yiamouyiannis, John Waldbott, George

It was Frederick McKay, a dentist in Colorado Springs, Colorado, who noticed in 1901 that many of his patients’ teeth were badly stained. Curious about the cause of this mottling, McKay concluded after three decades of study that the discolorations had no relation to race, socioeconomic level, general health, diseases, or nutrition. McKay noted that a small number of individuals living on the outskirts of the city who were not on the main water system were free from mottling. He concluded that some substance in the city’s water supply was responsible for the abnormality.

In 1931, McKay sent water samples for analysis to Harry Churchill Churchill, Harry , a chemist at the Aluminum Company of America Aluminum Company of America (Alcoa). Churchill found unusually high levels of fluoride in the water, between 2 and 13 ppm. McKay and Churchill concluded that the fluoride was responsible for the mottled teeth (a phenomenon now known as dental fluorosis). At about the same time, a group of Arizona researchers had produced mottling in the teeth of rats that were fed with high levels of fluoride, further linking the element to mottling. McKay also observed that, although unsightly, the mottled teeth of his patients seemed to be more resistant to decay. The apparent connection between fluoride and reduced decay eventually convinced H. Trendley Dean of the U.S. Public Health Service Public Health Service, U.S. (USPHS) to investigate the effects of fluoride on teeth.

In the 1930’s, Dean studied the water supplies of some 345 U.S. communities and found a low incidence of tooth decay where the fluoride levels in the community water systems were high. He also found that mottling was very minor at fluoride concentrations of 1 ppm or lower. The prospect of reducing tooth decay on a large scale by adding fluoride to community water systems became extremely appealing to many public health officials and dentists. By 1939, a proposal to elevate the fluoride levels to about 1 ppm by adding the element to water supplies was given serious consideration, and eventually several areas were selected to begin fluoridation trials.

In January, 1945, the water supply of Grand Rapids, Michigan, was fluoridated with sodium fluoride. Muskegon, a Michigan city with similar demographics, was selected as a control city in which the water remained unfluoridated. Later, cities in New York State, Illinois, and Ontario were chosen for similar studies. Although the trials were originally planned to last for ten to fifteen years, substantial reductions in tooth decay were reported in the fluoridated cities after only a few years. Proponents of fluoridation were convinced that these studies demonstrated the benefit of fluoride in reducing tooth decay and saw no need to continue the trial studies beyond a few years. Wisconsin dentist John Frisch Frisch, John and dental administrator Francis Bull Bull, Francis began an intensive lobbying campaign to convince the USPHS to support widespread fluoridation immediately. Dean preferred to wait for the completion of the fluoridation trials, but by 1950, top administrators of the USPHS overruled Dean and endorsed wide scale fluoridation.

In addition to the USPHS, the American Dental Association and the American Medical Association also supported fluoridation of drinking water. The case studies of the late 1940’s had apparently demonstrated that fluoridation was an economical and convenient method to produce a 50 to 60 percent reduction in the tooth decay of an entire community and that there were no health risks associated with the increased fluoride consumption. Consequently, many communities quickly moved to fluoridate their water supplies in the 1950’s. Strong opposition to fluoridation soon emerged, however, as opponents claimed that the possible side effects of fluoride had been inadequately investigated. In fact, while it was initially promoting the benefits of fluoridation, the USPHS had conducted very few studies of the toxicity of water containing 1 ppm of fluoride. Later, some studies of fluoride toxicity were conducted by USPHS scientists but were criticized by opponents as being potentially biased.

Many people were concerned by the addition of fluoride to water, since it was an established fact that high levels of fluoride were lethal. Prior to fluoride’s introduction as an additive to water, compounds such as sodium fluoride were widely used in pesticides. An extraordinary accidental case of fluoride poisoning occurred in the 1940’s at an Oregon hospital, when roach powder containing fluoride was mistaken for powdered milk and was used to prepare scrambled eggs. Of the several hundred people ingesting the contaminated eggs, nearly fifty died. This and other early incidents involving fluoride poisoning were responsible for the considerable apprehension felt by many people when they learned that a pesticide ingredient was to be added to their drinking water. It is not unusual, however, for a substance that is lethal at high concentration to be safe at lower levels, as is the case with most vitamins and trace elements.

Opponents of fluoridation were also concerned on moral grounds, because fluoridation essentially represented compulsory mass medication. Fluoridation opponents argued that individuals had a right to make their own choices in health matters, and a community violated these rights when fluoride was added to its water supply. Fluoridation proponents countered such criticism by saying that it was morally correct to fluoridate water supplies, because to refrain from doing so would result in many more people suffering from needless tooth decay.


The issue of fluoridation polarized by the 1960’s; there was no middle ground, since water either was fluoridated or it was not. Controversy and heated debate surrounded the issue across the country. By the mid-1960’s, it had also become a political issue. The USPHS emphasis shifted from research to political promotion. The agency and other proponents of fluoridation continued to conduct some research, but there was little real effort to investigate possible fluoride side effects. Critics pointed to the known harmful effects of large doses of fluoride that led to bone damage (for example, skeletal fluorosis) and to the special risks posed to people with kidney disease or those who were particularly sensitive to toxic substances.

Between the 1950’s and the 1980’s, one of the leading opponents of fluoridation in the United States was the allergist George Waldbott. Waldbott documented what he believed were his patients’ adverse reactions to fluoride in water, but his conclusions were refuted by the American Academy of Allergy. Later research showed that fluoride can act as an enzyme inhibitor and may have a mutagenic effect (that is, it may be capable of causing human birth abnormalities).

Controversial claims that fluoride can cause cancer were also raised in the 1970’s, most notably by biochemist John Yiamouyiannis. Yiamouyiannis claimed that American cities with fluoridated water had greater cancer death rates than 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. The debate over the Yiamouyiannis report turned into a personal attack on the credibility and authority of those involved.

During the early years of the fluoridation debate, the USPHS was responsible for both promoting fluoridation and assessing its safety; government policy at the time did not recognize this as a conflict of interest. In later years, however, responsibility for the promotion and regulation of environmental and health programs were controlled by separate agencies. The fluoridation controversy was partly responsible for the eventual reorganization of regulatory bodies.

The development of the fluoridation issue in the United States was closely observed by other countries. Dental and medical authorities in Australia, Canada, New Zealand, and Ireland endorsed fluoridation, although not without considerable opposition. Fluoridation in Western Europe was greeted less enthusiastically, and scientific opinion in some countries, such as France, Germany, and Denmark, concluded that it was unsafe.

The decision to fluoridate community water supplies, beginning with the Grand Rapids study, created one of the greatest scientific controversies of the twentieth century. Throughout the course of the debate, proponents of fluoridation frequently claimed to have a monopoly on scientific accuracy by dismissing and discrediting studies by opponents. While there is little doubt that fluoride does reduce tooth decay, the exact degree to which fluoridated water contributes to the reduction remains unknown. Fluoride in food, salt, toothpastes, rinses, and tablets have contributed to the drastic declines in tooth decay during the twentieth century. The side effects of 1 ppm of fluoride in water ingested over many years remain unclear. Although it has been argued that any risks associated with fluoridation are small, these risks may not be acceptable to everyone.

Since the 1960’s and 1970’s, concerns over environmental and health issues have grown, and it has often been difficult for the scientific community completely to resolve the potential hazard associated with small amounts of chemical substances in the environment. Only about 50 percent of U.S. communities have elected to adopt fluoridation. In 1993, the National Research Council published a report on the health effects of ingested fluoride and attempted to determine if the maximum EPA recommended level of 4 ppm for fluoride in drinking water should be modified. The report concluded that this level was appropriate but that further research might indicate a need for revision. The report also found inconsistencies in the scientific studies of fluoride toxicity and recommended further research in this area.

The fluoridation issue demonstrated how scientific debate can be influenced by political and social policies and pressures. Neither proponents nor opponents of the fluoridation issue have been consistently objective in the analysis of their scientific findings. Only unbiased scientific research can adequately attempt to measure the potential toxicity of low levels of fluoridated water. For more than half a century, the scientific community has been unable to reach a consensus on the toxicity of fluoridated water. Fluoride Water, fluoridation of Dental hygiene

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Bryson, Christopher. The Fluoride Deception. New York: Seven Stories Press, 2004. The most compelling and best-researched of the muckraking attacks on water fluoridation. Argues that fluoridation was essentially a public relations stunt by the government and industry that ignored deleterious health effects of fluoride. Bibliographic references and index.
  • citation-type="booksimple"

    xlink:type="simple">Ekstran, Jan, Ole Fejerskov, and Leon M. Silverstone, eds. Fluoride in Dentistry. Chicago: Year Book Medical, 1988. Although some chapters are technical, several sections provide useful, easy-to-read information. Chapter 1 provides a comprehensive account of fluoride in the environment. Chapter 8 examines fluoride toxicity. Chapter 10 provides a summary of fluoridation issues, including a historical perspective and the benefits and risks of fluoridation.
  • citation-type="booksimple"

    xlink:type="simple">Estupiñán-Day, Saskia. Promoting Oral Health: The Use of Salt Fluoridation to Prevent Dental Caries. Washington, D.C.: Pan American Health Organization, 2005. Scientific study of the effects upon tooth decay of adding sodium fluoride to drinking water. Bibliographic references.
  • citation-type="booksimple"

    xlink:type="simple">Hileman, Bette. “Fluoridation of Water.” Chemistry and Engineering News 66 (August 1, 1988): 26-42. The author consulted both opponents and supporters of fluoridation when she wrote this article. Scientific evidence and arguments against fluoridation, which generally have received little attention in science and medical journals, are presented here in a nontechnical format.
  • citation-type="booksimple"

    xlink:type="simple">McClure, Frank J. Water Fluoridation: The Search and the Victory. Bethesda, Md.: National Institute of Dental Research, 1970. Provides an account of notable events that led to fluoridation as a vital public health measure early in the fluoridation debate.
  • citation-type="booksimple"

    xlink:type="simple">McNeil, Donald. The Fight for Fluoridation. New York: Oxford University Press, 1957. An early account covering the decade after the first experimental trial in Grand Rapids. Presents both sides of the issue impartially.
  • citation-type="booksimple"

    xlink:type="simple">Martin, Brian. Scientific Knowledge in Controversy: The Social Dynamic of the Fluoridation Debate. Albany: State University of New York Press, 1991. The author presents a contemporary view of the debate, giving more credibility to fluoridation opponents than most earlier works. The chapter by Edward Groth provides an authoritative account of the debate, with a new perspective on the role of fluoridation opponents.
  • citation-type="booksimple"

    xlink:type="simple">National Research Council Committee on Toxicology. Health Effects of Ingested Fluoride. Washington, D.C.: National Academy Press, 1993. Reports the findings of the National Research Council’s Committee on Toxicology on the possible health effects of fluoride, which recommended more research to resolve the question. Provides a good summary of scientific studies on fluoride toxicity.
  • citation-type="booksimple"

    xlink:type="simple">Shaw, James H., ed. Fluoridation as a Public Health Measure. Washington, D.C.: American Association for the Advancement of Science, 1954. The author provides early evidence for supporting the use of fluoridation to reduce tooth decay on a wide scale.

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