December 23, 2021 | Jerry Bergman

“Settled Science” Unsettled: The Case of Fluoridated Water

Another case of scientific consensus has been undermined.
How many were put at risk by a false idea?



by Jerry Bergman, PhD

It used to be that the phrase “the science supports” was all that was required to prove a point. Unfortunately, the confidence in science has suffered a few setbacks recently, especially due to the COVID pandemic. And the claims of mainline science are being questioned in other areas as well. This website has produced several thousand articles questioning the mainline position on evolution. Other examples of what was once termed settled science are now being questioned. One new example concerns fluoridated water’s benefits for teeth.

Claim: Adding the ionized form of the element fluorine to water, called fluoridated water, was a low-cost, safe method for adults and children to strengthen teeth and reduce tooth decay. The scientific consensus, as well as public opinion, that was based on decades of dental health research was used to support this theory. New research has questioned this long-held belief in spite of the fact that widespread research

from the 1940s through to the 1970s, has pointed to fluoride as an important factor in preventing tooth decay, also known as caries. The mineral has become part of public-health lore, and has been hailed by the US Centers for Disease Control and Prevention as one of the ten greatest public-health achievements of the twentieth century. Most people who live in areas with fluoridated water on tap take the benefits for granted and view with suspicion those who question the supplementation.[1]

The history of fluoridation dates back to the early 1900’s when it was noticed that persons with stained teeth called mottling had fewer cavities than other residents. Specifically, Dr. Frederick McKay, practicing in Colorado in 1901, and Dr. J.M. Eager, an American dentist stationed in Italy, independently suspected that fluoridated water reduced dental caries.[2] McKay believed that something in the water supply could be responsible for the staining. More importantly, he also noted tooth decay was lower in areas with endemic dental staining in contrast to adjacent areas. In 1925, Ainsworth examined over 4,000 children, finding much lower tooth-decay rates in populations with the staining compared to those without. In 1931, Aluminum Company of America chemist, H.V. Churchill, analyzed water in areas where the staining was endemic and found the one common factor was elevated-fluoride water levels. The difference was 13.7 ppm (parts per million) in the towns with major levels of staining compared to 0.5 to 5.5 ppm in the areas without the staining problem. Numerous other studies found the same difference.

In 1945, Grand Rapids, Michigan became the first city in the world to artificially fluoridate the water supply. Research found the rate of dental caries in Grand Rapids was almost half of that of the nearby town of Muskegon. In 1951, five years of data were analyzed and the results were so striking that Muskegon city officials began fluoridating their city’s water supply. Soon other cities around the United States followed suit.

Indications of Fake Science Appear

The case for fluoridation of the local water supply seemed watertight until research completed during the past 50 years questioned the efficacy of massive water fluoridation because tooth decay rates

in some high-income countries with no fluoridation have declined at a pace similar to that seen in fluoridated US communities. And an increasing number of studies are indicating that fluoride — which occurs naturally in soil and therefore also in groundwater — might be a developmental neurotoxin, even at the level that the US Public Health Service has declared optimal for fluoridation.[3]

Many other examples of the same situation exist. Nations without water fluoridation, such as Denmark, experienced rates of tooth-decay declines in levels comparable to those in US communities with fluoridation.

The “If Safe for Adults, also Safe for Infants” Fallacy

One major problem was the effects of drinking fluoridated water on children, infants, and pregnant women were largely ignored. The assumption was, if it was safe for adults, it was safe for everyone else including infants and pregnant women. As a result of ignoring this important consideration and looking at new studies,

toxicologists and epidemiologists are now questioning whether even low doses of fluoride can have systemic effects, including causing a dip in IQ in children who were exposed to it in utero. The first indications of this came from studies that compared unfluoridated villages and communities with fluoridated ones (where fluoride is either naturally occurring or added to water), followed by better-controlled studies that measured fluoride in individuals.[4]

The notion that fluoride reduces cavities was not questioned; the new concern was only whether fluoridated water was safe for everyone including infants and pregnant women. Tragically, any research that questioned the efficacy of fluoridation was often “met with extreme criticism, ridicule and anger that, at times, threatened the careers of those involved.”[5]

The Theory of How Fluoridated Water Works Proven Wrong

More facts continued to undermine the fluoridation theory. As research progressed, it

became clear that the common understanding of how fluoride works was wrong. For decades, it was thought that fluoride was most effective at strengthening teeth when it was consumed, and that this would benefit a fetus exposed to fluoride during gestation. But it turns out, although fluoride is incorporated into developing teeth in utero, it is protective against dental caries only after the teeth have emerged from the gums.[6]

Thus, the theory that fluoride provides protection because it is incorporated in the enamel (an idea that I learned in medical school and taught my students for years) is now believed to be wrong.[7] New research has determined that fluoride ions are incorporated into the biofilm on the teeth known as plaque. Because fluoride is a highly electronegative anion (negative ion), when the tooth environment becomes too acidic, fluoride ions are released from the plaque which help to pull minerals from the mouth saliva to remineralize the enamel surfaces. The result is tooth decay is slowed down.[8].

Fluoride Ion Application Methods

Fluoride-ion application methods include applying it directly to the teeth by toothpaste or by ingesting fluoridated water and foods. This method results in small amounts being constantly secreted into saliva. About half of the ingested fluoride is absorbed and retained in teeth and bones, and the rest is excreted in urine. Ingesting too much fluoride causes weakened bones and joints called skeletal fluorosis.

The perception for years was a little fluoride was good, and more was better, and even more was better yet to insure that enough was present. Soon fluoridated toothpastes and other products flooded the market as did fluoridated rinses. Dentists added fluoride application varnishes and lacquers into their patients’ twice-yearly cleanings. As the topical fluoride has proven effective, dental caries around the world have consequently dropped. But finally astute observers began to ask, “Why is fluoride still being added to the water that is used to wash dishes, take a bath, water the house plants, and wash the car?”

As is true of all other element and compounds, the dose is the poison. Low enough doses, even of known poisons, are not toxic, but high enough doses of non-toxic compounds, such as water, are toxic because it adversely affects the body’s ion balance. The dangers of mercury and lead exposure are well-known. Ironically, the data from fluoride toxicity analyses levels are comparable to those used to limit the use of mercury and lead.

We know that fluoride affects ameloblasts cells. Ameloblast cells are the epithelial cells that tightly regulate, produce, and deposit tooth enamel on the teeth. Dental enamel is the hardest and most mineralized tissue in extinct and extant vertebrate species. It provides the level of durability that allows teeth to function, not only for food processing, but also as weapons and tools.[9] Because fluoride can affect ameloblast cells indicates that it can likewise affect other body cells.[10] It is critical to determine what effects it has on other cells, including inflammation and altered neurodevelopment, of both the brain and the central nervous system, especially in infants and children.

One pioneering birth cohort study of fluoride exposure during pregnancy found it was associated with significantly lower IQ scores in children aged 3 to 4 years.[11] Another longitudinal birth cohort study, involving 299 mother-child pairs in Mexico City, Mexico, found that a 1-mg/L increase in maternal urinary fluoride concentration was associated with a 6-point lower IQ score among school-aged children plus increased attention-deficit/hyperactivity disorder–like symptoms.10  Although association is not the same as causation, this study supports the recommendation that, to be on the safe side, pregnant women should not drink fluoridated water, or accept fluoride treatments. This is less a burden than it first appears, given that water fluoridation is supplied to about “66% of US residents, 38% of Canadian residents, and 3% of European residents. In fluoridated communities, fluoride from water and beverages made with tap water makes up 60% to 80% of daily fluoride intake in adolescents and adults.”[12]


The studies completed so far indicate that a real concern about fluoride water exists, at least for pregnant mothers and infants. More study will be required. Fortunately, more cohort studies are now under way to help bring clarity to the fluoride debate. These questions should have been raised and answered at least a half a century ago. The cardinal rule in health, “always be on the safe side” and “proceed with caution” was all too often ignored. This case is no exception. To fluoridate the entire water supply is both wasteful and may turn out to have deleterious health consequences. The fluoride required for healthy teeth can be easily met with fluoridated toothpaste and dental treatments.


[1] Gravitz, Lauren. The fluoride wars rage on. Nature,, 27 October 2021.

[2] Mullen, J. History of water fluoridation. British Dental Journal 199:1–4, 2005.

[3] Gravitz, L. 2021.

[4] Gravitz, L. 2021

[5] Gravitz, L. 2021.

[6] Gravitz, L. 2021.

[7] Ten Cate, M. In vitro studies on the effects of fluoride on de- and remineralization. Journal of Dental Research 69(Spec 155):614-619, p. 614, February 1990.

[8] Ten Cate, M , 2021, p. 614.

[9] Lacruz, R., et al. Dental enamel formation and implications for oral health and disease. Phycological Review 97(3):939–993, 1 July 2017.

[10] Gravitz, L, 2021.

[11] Green, R., et al. Association between maternal fluoride exposure during pregnancy and IQ scores in offspring in Canada. JAMA Pediatrics 173(10):940–948, October 2019.

[12] Green, R., 2019.

Dr. Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology for over 40 years at several colleges and universities including Bowling Green State University, Medical College of Ohio where he was a research associate in experimental pathology, and The University of Toledo. He is a graduate of the Medical College of Ohio, Wayne State University in Detroit, the University of Toledo, and Bowling Green State University. He has over 1,300 publications in 12 languages and 40 books and monographs. His books and textbooks that include chapters that he authored are in over 1,500 college libraries in 27 countries. So far over 80,000 copies of the 40 books and monographs that he has authored or co-authored are in print. For more articles by Dr Bergman, see his Author Profile.

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