Fluoride in Drinking Water (and Our Brains)

Almost 28 years ago, I became a young, new father. Too young by a couple months, actually, since my daughter was born prematurely. During her mother’s labor, the doctors asked—or rather urged—us to allow them to administer a shot—Betamethasone—to her mother. These steroids would, they explained, reach the lungs of the fetus and mature them more quickly so that they would have more surfactant—basically, mucus—to facilitate the exchange of oxygen and carbon dioxide. That is, it would increase the chances that she would survive and be able to breathe on her own.

That’s a hard argument to deny. So, we went ahead with the shot. She did survive her five weeks in the NICU and never needed assistance in respiration. But I have always been nagged by the question of side effects. A large literature suggests that speeding the maturation of any organ system is not costless, and that stressors like steroids have long-term deleterious consequences on health and aging. In fact, the Barker Hypothesis¹ of the “developmental origins of disease” suggests that early life shocks and stressors can lay the groundwork for later life maladies such as cardiovascular disease, dementia, and so on. 

At the time, however, the neonatal pulmonologists weren’t concerned with her risk of, say, diabetes disease at age 50. They were worried about her blood oxygenation at age one day. In our efforts to minimize short-term breathing difficulties had we diminished her health span later in life?

What does this story have to do with the water fluoridation debate? It is to say that the anti-fluoridation movement, led now by Health and Human Services (HHS) Secretary Robert F. Kennedy Jr., is not (entirely) based on a crackpot conspiracy theory. It’s an example of how sometimes the often-siloed medical and public health systems adopt tunnel vision when trying to solve one goal—dental cavities, in this case—while ignoring the interconnectedness of biological systems.

Since its mid-20th-century debut in the United States, water fluoridation has been heralded as a singular triumph of preventive care. Yet, it has also been a recurring flashpoint in debates about health, risk, autonomy, and even cognitive development.

Let’s start with the basics: dental caries (i.e., cavities) remain one of the most common chronic diseases worldwide, especially among children. Before fluoridation, tooth decay was nearly universal in the US population. When Grand Rapids, Michigan became the first city to fluoridate its water supply in 1945, rates of childhood cavities plummeted by 50 to 70% within 15 years. In fact, the Centers for Disease Control and Prevention (CDC) hails water fluoridation as one of the top ten public health achievements of the 20th century. Why? Because it doesn’t require individuals to change their behavior, buy a product, or see a doctor. It literally flows from the tap, reducing tooth decay across all ages, races, and income groups. As of 2022, approximately 72% of the US population received fluoridated water.

It’s among low-income populations that fluoridation delivers the greatest benefit. Poor children are more likely to suffer from untreated tooth decay, less likely to have access to dental care, and often lack regular use of fluoride toothpaste. They are also less likely to receive fluoride varnishes or sealants, which are more common in private dental practices. For them, fluoride in drinking water may be their only consistent exposure to this protective mineral. In this sense, fluoridation is the great equalizer: a structural intervention that reduces health disparities without demanding much from the people it helps.

Despite its dental benefits, water fluoridation has endured periods of controversy. In fact, its early history in the 1940s and 1950s was marked by virulent opposition—much of it entwined with Cold War paranoia. To its early critics, fluoridation wasn’t a health intervention; it was a government plot. Opponents framed it as “forced medication” or, more colorfully, as a communist conspiracy to weaken American minds and bodies from within. The ultra-conservative John Birch Society famously decried fluoridation as “mass poisoning,” and in some quarters, the issue was taken up by right-wing activists as a symbol of creeping federal control.

Sociologically, this backlash illustrates how scientific policy decisions are never just about the science. They are embedded in cultural meanings, political ideologies, and anxieties about power. Fluoridation, in the postwar United States., became a canvas onto which citizens projected their fears about modernity, the erosion of individual liberty, and the expanding reach of the state. As Ulrich Beck² would later argue in his theory of the “risk society,” technologies that promise to reduce risk often produce new forms of uncertainty—and new forms of political conflict. Resistance to fluoridation wasn’t merely anti-scientific; it was a contest over who gets to define health, who controls the commons, and whose expertise counts in democratic life.

Yet, the conspiracy theorists were onto something: From an ethical perspective, the principle of informed consent is challenged by mass water fluoridation. Individuals cannot opt out of fluoride exposure through public water supplies, raising questions about autonomy and individual rights. Moreover, if certain subpopulations (e.g., infants, children, pregnant women) are more vulnerable to potential adverse effects, targeted policies may be necessary to protect these groups.

After a quiescent period of several decades, fluoridization has come under renewed scrutiny in recent years—not from conspiracy theorists shouting about mind control, but from scientists and public health researchers. Namely, while fluoride’s benefits in preventing tooth decay are well-established, overexposure—particularly during early childhood when teeth are still developing—can lead to a condition known as dental fluorosis. Fluorosis is not dangerous to physical health per se, but it can have cosmetic and psychological impacts given that it causes discoloration and pitting in teeth. 

That said, the greatest concern about putting fluoride in water supplies revolves around brains, not teeth. Just as the betamethasone may help the lungs but hurt other organ systems (including the nervous system) long term, so may be the case with fluoride. In 2019, a widely cited study published in JAMA Pediatrics raised alarms by reporting that higher maternal fluoride levels during pregnancy were associated with lower IQ scores in their children ³. This was not an isolated finding. A 2024 National Toxicology Program (NTP) meta-analysis of 74 studies concluded that higher fluoride exposure was associated with modest reductions in IQ—about 1.63 points per 1 mg/L increase in urinary fluoride.⁴ The implications are unsettling, especially for parents and policymakers. Are we trading slightly stronger teeth for slightly diminished cognition – the same way I might have traded more lung surfactant in my infant daughter for unintended disease risk 50 years later?

A closer read reveals a more complicated picture. First, the majority of studies showing IQ impacts come from countries like China, India, and Iran, where fluoride levels in water are naturally much higher than the levels used in fluoridation programs in North America or Western Europe. Second, many of these studies are observational and suffer from potential confounders—nutrition, lead exposure, socioeconomic status—that aren’t always adequately controlled. Critics have also noted issues with study quality and potential publication bias. Studies on populations with lower fluoride concentrations are inconclusive due to lower statistical power. But is there any reason to suspect that the effects are not simply smaller—but real—at lower concentrations? At one time, it was thought that only drinking high amounts of alcohol was unhealthy and that moderate consumption was even beneficial. Today, we think that any alcohol is bad for you, period.

Ending fluoridation might not affect affluent families—those with private dentists, electric toothbrushes, and organic toothpaste—but it would likely increase tooth decay in the most vulnerable populations. And as any economist or sociologist will tell you, oral health isn’t trivial: it’s tied to employability, social stigma, and even cardiovascular disease. But the same is true for cognitive functioning—especially in an information economy that offers high returns to human capital.

So, perhaps the question is not whether fluoridation “works,” but what its success reveals about the limits of the public health imagination. Like the neonatologists who saved my daughter’s lungs but may have altered her long-term physiology, fluoride’s champions achieved their narrow goal brilliantly: fewer cavities, less pain, more smiles. Yet, in pursuing that single metric, we may have neglected the organism as a whole — not just the human body, but the social body.

This myopia is baked into the very architecture of modern medicine. Disciplines are siloed; success is measured in discrete endpoints — caries reduced, lungs inflated, tumors shrunk — rather than in holistic well-being or lifespan quality. The result is a pattern of one-step-forward, one-step-sideways interventions: we solve the problem we can measure, while sowing the seeds of new ones that fall outside our immediate purview. In that sense, fluoridation is less an anomaly than a parable of progress itself — a reminder that every technological fix carries its own unexamined externalities.

To be clear, none of this means that we should definitely abandon fluoridation or prenatal steroids or any other intervention that demonstrably saves lives or prevents suffering. It means we must widen the frame through which we judge them. What if public health metrics included measures of neurological, developmental, or even ecological ripple effects decades down the line? What if the same rigor we devote to proving efficacy were applied to mapping unintended consequences across systems?

The paradox, then, is not that science makes mistakes — it always will — but that its institutional incentives reward precision at the expense of perspective. The question is whether we can cultivate a form of science humble enough to acknowledge its blind spots before they become crises. Fluoride in the water may have made our teeth stronger, but the true measure of collective health is whether it can make our thinking stronger too.

In this sense, the fluoridation debate belongs squarely within Ulrich Beck’s risk society ²: a world in which the very tools that once protected us from nature’s dangers now generate their own manufactured risks. Each intervention—whether chemical, pharmaceutical, or technological—solves yesterday’s problem while creating tomorrow’s uncertainty. The sociological challenge is to move beyond the illusion that health can be engineered one variable at a time. The biological and the social are coiled together, and the costs of ignoring that entanglement accumulate quietly until they surface as the next crisis. To see that pattern clearly—and to act on it—may be the truest form of prevention we have

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