Water Fluoridation: The Science and the Myths
Water fluoridation is a scientifically validated public health measure. Robert F. Kennedy Jr.’s campaign to eliminate it is unjustified scaremongering.
Tooth decay is the second most common physical malady, behind only the common cold. Cavities in teeth are more than just a cosmetic nuisance; they can lead to significant health complications, including infections that may enter the bloodstream and precipitate heart or respiratory problems.
Tooth decay is preventable. Regular oral hygiene and professional dental care are critical. Yet, another intervention has proved revolutionary: fluoride. Tooth enamel, which is primarily composed of hydroxyapatite, is vulnerable to acid produced by oral bacteria, such as Streptococcus mutans, which metabolise sugars. When fluoride is present—whether in water, toothpaste, or topical treatments—it transforms hydroxyapatite into fluoroapatite, a more acid-resistant compound that is less prone to cavity formation. Fluoride also inhibits the ability of bacterial enzymes to produce harmful acids. These dual effects have significantly reduced the global prevalence of cavities. Water fluoridation, initiated in the mid-20th century, has become a cornerstone of public health policy in many developed countries.
In 1901, dentist Frederick McKay observed that residents of Colorado Springs had mottled, stained teeth—due to what we now call fluorosis—but remarkably few cavities. The cause was naturally high fluoride levels in the drinking water. By the 1950s, studies confirmed that communities with fluoride concentrations above 1 part per million (ppm) had significantly lower rates of tooth decay. Thus, in 1945, Grand Rapids, Michigan, became the first city to adjust its water fluoride concentration to optimal levels. The results were dramatic—a 50–65 percent reduction in cavities. Other cities soon followed suit, supported by endorsements from authorities like the World Health Organization and the Centers for Disease Control and Prevention. The latter estimates that every dollar spent on fluoridation saves $38 in dental costs, which especially benefits poor people.
From its inception, however, fluoridation has faced opposition. Opponents have called it “rat poison” and accused governments of using it to poison their citizens. Some even claimed that the introduction of fluoridation was a Communist plot, or a ploy by the sugar industry to obscure the harms of sugar consumption. More recent anti-fluoridation activists often point to fluoride’s industrial origins, noting that hydrofluorosilicic acid—the chemical used in water fluoridation—is a byproduct of fertiliser production. But repurposing industrial byproducts into safe, beneficial uses is common. For instance, iodine, another public health supplementation success story, was once a waste product of seaweed processing.
Water fluoridation is supported by a robust body of evidence. Numerous epidemiological studies have demonstrated significant reductions in cavities in communities with fluoridated water. The effect is most pronounced in populations with limited access to dental care, especially if they choose not to use fluoridated toothpaste. In more affluent areas, and when fluoride toothpaste is used, the incremental benefits of water fluoridation are smaller.
What about risks? Fluorosis, a condition caused by excessive fluoride intake, can result in white stains or, in severe cases, brown discoloration of teeth. While this is a cosmetic issue, it underscores the importance of maintaining fluoride levels within recommended limits (0.7–1.2 ppm in drinking water). In rare cases, excessive natural fluoride levels—above 4 ppm—can weaken bones, but such concentrations are far higher than those used in public water systems.
Allegations linking fluoride to cancer, thyroid dysfunction, and neurological issues lack strong evidence. A 2006 report by the US National Research Council recommended lowering the maximum allowable fluoride concentration in drinking water to 2 ppm—not because of new health concerns but to prevent severe fluorosis in areas with naturally high fluoride levels.
One of the most controversial claims is that fluoridation impacts intelligence. A 2019 study in JAMA Pediatrics suggested a correlation between maternal fluoride intake during pregnancy and slightly lower IQ scores in male children. However, the study relied on estimates of fluoride consumption and failed to account for critical variables like maternal IQ and environmental pollutants. Moreover, subsequent analyses have challenged its conclusions, suggesting that if an effect exists, it is minor and likely insignificant compared to other prenatal risks, such as tobacco smoke, lead exposure, and, indeed, maternal dental caries.
As Paracelsus, the father of toxicology, famously said, “The dose makes the poison.” In the case of fluoride, the evidence suggests that at recommended levels it promotes public health, especially if people choose not to use fluoride toothpaste. Like any intervention, it must be scrutinised and adjusted as new evidence emerges. Such new evidence is so far lacking.
