In a contentious age when public health debates often resemble cultural battlegrounds, the nomination of Robert F. Kennedy Jr. as Secretary of Health and Human Services has reignited old controversies. Kennedy’s intractable opposition to vaccines, unconventional views on health interventions like hyperbaric oxygen therapy, and his advocacy for raw milk have earned him a well-deserved reputation as an unhinged, conspiracy-promoting ignoramus. His opposition to water fluoridation is more of the same but merits a discussion about this longstanding public health intervention.
Fluoridation has been lauded as one of the most effective preventive measures in modern dentistry. However, it is also a topic riddled with misinformation, passionate opposition, and even dark humor. For example, in the 1964 film “Dr. Strangelove,” loony Air Force General Jack D. Ripper asks a colleague, “Do you realize that fluoridation is the most monstrously conceived and dangerous Communist plot we’ve ever had to face?”
To understand the science and the (pseudo-) controversy surrounding fluoride in drinking water, it’s necessary to examine various aspects of the subject in some detail.
The Burden of Tooth Decay and Fluoride’s Role
An obscure medical fact is that 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, precipitating heart or respiratory problems.
Tooth decay is largely preventable, with regular oral hygiene, a diet low in sugar, and professional dental care. 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, when they metabolize sugars. When fluoride is present — whether through 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 bacterial enzymes, reducing their ability to produce harmful acids.
This dual action of fluoride has significantly reduced the global prevalence of cavities. Water fluoridation, initiated in the mid-20th century, has become one of the cornerstones of public health policy, especially in North America.
The Origins of Fluoridation
In 1901, dentist Frederick McKay observed that residents of Colorado Springs exhibited an unusual dental phenomenon: mottled, stained teeth — what we now call fluorosis — but remarkably few cavities. The cause was naturally high fluoride levels in the drinking water. By the 1940s, 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% reduction in cavities.
Other cities soon followed suit, supported by endorsements from health authorities like the World Health Organization and the American Dental Association. The latter estimates that every dollar spent on fluoridation saves 38 in dental costs, especially benefiting underprivileged populations.
The Pushback: Myths and Mistrust
From its inception, fluoridation faced opposition, often fueled by conspiracy theories and pseudoscience. Opponents labeled fluoride “rat poison” and accused governments of poisoning citizens. As exemplified by the movie dialogue quoted above, some went as far as to claim that fluoridation was a Communist plot or a ploy by the sugar industry to obscure the harms of sugar consumption.
While such arguments lack credibility, they highlight a broader issue: mistrust in authority and misinterpretation of science, intentionally or otherwise. Anti-fluoridation activists often point to fluoride’s industrial origins, noting that hydrofluorosilicic acid — the chemical used in water fluoridation — is a byproduct of fertilizer production. But context matters: 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.
The Science of Safety and Effectiveness
Water fluoridation is supported by a robust body of evidence. Numerous epidemiological studies have demonstrated significant reductions in cavities in communities with fluoridated water. However, the effect is more pronounced in populations with limited access to dental care and fluoridated toothpaste. In more affluent areas, where fluoride is ubiquitous in dental products, the incremental benefits of water fluoridation are smaller.
What about risks? Critics highlight fluorosis, a condition caused by excessive fluoride intake, which 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 naturally occurring fluoride levels — above 4 ppm — can weaken bones, but such concentrations are far above those used in public water systems.
Allegations linking fluoride to cancer, thyroid dysfunction, and neurological issues lack strong evidence. A 2006 report by the U.S. 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.
The IQ Debate
One of the most controversial claims against fluoridation is its alleged impact on intelligence. A 2019 study published in JAMA Pediatrics suggested a correlation between maternal fluoride intake during pregnancy and slightly lower IQ scores in male children. It received some media coverage, but the findings have significant limitations. 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 or lead exposure.
Do We Need to Reassess Fluoridation?
As we revisit fluoridation policies, it is essential to consider evolving science and societal changes. Widespread access to fluoridated toothpaste and professional dental care have reduced the relative importance of water fluoridation in more affluent communities. However, for underserved populations, fluoridation remains a critical public health tool.
Kennedy’s campaign to eliminate water fluoridation reflects a broader distrust in public health measures and his willingness to promulgate disinformation, undermining scientifically validated interventions.
A Measured Approach to Public Health
As Paracelsus, the father of toxicology, famously observed in the 16th Century, “The dose makes the poison.” In the case of fluoride, the evidence suggests that at recommended levels it promotes public health. However, water fluoridation exemplifies the complexity of balancing benefits and risks in public health. Its success lies in its cost-effectiveness and ability to reduce disparities in dental health. But, like any healthcare intervention, it must be scrutinized and adjusted as new evidence emerges.
A previous version of this article was published by Quillette.
Henry I. Miller, MS, MD
Henry I. Miller, MS, MD, is the Glenn Swogger Distinguished Fellow at the American Council on Science and Health. His research focuses on public policy toward science, technology, and medicine, encompassing a number of areas, including pharmaceutical development, genetic engineering, models for regulatory reform, precision medicine, and the emergence of new viral diseases. Dr. Miller served for fifteen years at the US Food and Drug Administration (FDA) in a number of posts, including as the founding director of the Office of Biotechnology.
