History of Fluoridation

How did water fluoridation come to be an acceptable and largely preferred intervention? In 1901, a dentist in Colorado noted that large numbers of children in certain communities in the state had teeth with permanent, dark brown discoloration of the enamel (Figure 2) [1]. The dentist, Frederick S. McKay, began diligently investigating the disorder, which locals referred to as Colorado Brown Stain. By 1916, McKay suspected that something in the drinking water was to blame, but he was unsure of what the exact cause was [2]. 

In the late 1920s, the small town of Bauxite, Arkansas would finally yield some answers. The children of the mining town had high levels of brown stain, and residents were already sufficiently confident that water from the wells in town was to blame that they had begun work on drawing water from a river that was seven miles away [3]. Water collection surveys conducted in the area provided significant evidence to support those suspicions, as researchers noted that cases of brown stain began shortly after the wells were drilled, and that children in the area who obtained water from other sources did not have disfigured teeth.

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Aluminum Company of America (Alcoa), who owned the mining company that had built the town of Bauxite, were concerned that aluminum would be blamed for the dental issues, so they sent their chief chemist, H.V. Churchill, to investigate the matter (McNeil, 1985). Churchill conducted extensive tests, which included spectrographic examination of the water for rare elements that were not normally identified in standard tests of the era. Instead of aluminum, Churchill identified extremely high rates of fluoride in the water (13.7 mg/L)—something that McKay had never thought to test for [3]. In Churchill’s 1931 report, he also provided an analysis of water from many cities across the United States, and noted a positive relationship between high levels of fluoride and prevalence of brown stain [4]. As evidence mounted, brown stain became known as “fluorosis.” Communities with high levels of fluorosis began to change their drinking water source to lower fluoride sources, which quickly lowered levels of the dental disfigurement [3].

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Henry Trendley Dean, a researcher at what is now called the National Institutes of Health, utilized the work of McKay and Churchill to further investigate the relationship between fluoride and teeth [5]. Dean’s work not only quantitatively established a positive relationship between fluoride levels and fluorosis, but it also identified a negative relationship between fluoride levels and dental caries (i.e., cavities). Importantly, at a fluoride level of approximately 1 mg/L, Dean noted that levels of fluorosis only negligibly increased, and yet dental caries dropped substantially—a result that explained observations made decades earlier by McKay that children with brown stain often had fewer cavities [6] [7]. The natural variance of fluoride in drinking water allowed researchers to compare the health of residents in cities with high levels with the medical condition of those people living in communities with lower levels of fluoride. Even when the differences in fluoride levels were dramatic, the only adverse effects of the high fluoride that were reported were fluorosis of the teeth, and occasional, non-clinical fluorosis of bones [7].

Recognizing the potential dental benefits of water fluoridation and the seemingly minimal adverse effects at carefully controlled levels, an experiment was proposed to test the impact of artificially fluoridating the water supply for the public. The investigation began in 1945, with fluoride levels in the water in Grand Rapids, Michigan raised to 1.0 mg/L, while the nearby city of Muskegon would retain its naturally lower levels of fluoride [7]. Within six months, communities in New York and Ontario had already chosen to adopt fluoridation [6] [8]. Enthusiastic promoters of fluoridation led to many other cities soon following suit—a move that was defended against accusations of prematurity on the basis that people had long been drinking naturally fluoridated water at much higher levels than were being suggested without documented adverse effects [2]. Promising early results of the Michigan experiment and endorsement of fluoridation by the United States Public Health Service (USPHS), American Medical Association (AMA), and American Dental Association (ADA) in 1950-1951 led to even higher demand for fluoridated water [2]. Even Muskegon, which was supposed to be a control for the Michigan study, chose to adopt fluoridation in 1951 [9].

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Despite municipalities’ quick adoption of fluoridation that impacted the original experimental design, researchers were still able to eventually report fifteen years of analysis that revealed that the number of dental caries for children in Grand Rapids had dropped by half for children ages 12-14 (50-63% reduction) and 15-16 (48-50% reduction) [7]. Fluorosis rates for the children were low (10.6%), and 96% of those cases were imperceptible or mild [7]. The fluoridation in Grand Rapids and other early adoption communities were widely deemed to be successful, and by 1960, 50 million Americans were drinking artificially fluoridated water [7]. By that time, medical consensus had largely been reached on fluoridation, marking the end of significant debate about the safety of the procedure within the appropriate scientific communities [4]. Professor James M. Mather (1959) from the University of British Columbia forcefully stated such an opinion when he wrote:

[Dr. D. W. Mills] speaks of the “current controversy” concerning the fluoridation of communal water supplies. One should be clear that this is a political controversy, indeed a political football, and has no reference to any division of opinion in the medical, dental or allied professions. I don't think there has ever been a more nearly unanimous opinion as to the safety, desirability, efficacy and practicability of any health measure. Any controversy that exists is outside of the healing professions. (p.918) [10]

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A History of Misinformation

Mather’s assertion was perhaps a bit overstated, since some skepticism and resistance to fluoridation certainly did still exist within the medical community [6]. However, he was correct that controversy was far more prevalent in the political and popular arenas, with opposition and suspicion arising in those areas from fluoridation’s very beginning. For instance, in Stevens Point, Wisconsin, pro- and antifluoridation groups battled throughout 1949-1950, leading to rejection, adoption, and ultimately, overwhelming rejection of fluoride via referendum [9] [2].

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Across the nation, people opposed to fluoridation attacked it, labeling it “poison,” “forced experimentation,” and a cause of cancer, memory loss, and brittle bones [2]. The leaked, preliminary results of a University of Texas study that identified fluoridated water as a carcinogen in 1950 would go on to become widely disseminated for decades, despite USPHS researchers almost immediately identifying a critical flaw in the study—the study mice had inadvertently been given food with extremely high levels of fluoride [2]. In the 1950s and 1960s, a conspiracy theory gained popularity: Communists in the USPHS were behind the attempts to fluoridate the water supply of Americans [6] [9].