Regular visits to the dentist to fill cavities used to be a shared ordeal for millions of American children and adults. The reason that hasn’t been the case for late baby boomers and subsequent generations is that the fluoridation of drinking water became common starting in the late 1940s and continuing today.

So it’s right to question why Donald Trump’s nominee to head the Department of Health and Human Services, Robert F. Kennedy Jr., has placed the ending of fluoridation atop his list of first-day initiatives in his campaign against American public health.

“On January 20,” Kennedy tweeted a few days before the election, “the Trump White House will advise all U.S. water systems to remove fluoride from public water.”

The reason, he asserted, is that “fluoride is an industrial waste associated with arthritis, bone fractures, bone cancer, IQ loss, neurodevelopmental disorders, and thyroid disease.”

That’s all flatly untrue or grossly misleading. Kennedy’s screed against fluoridation is part and parcel of a policy package that has legitimate scientists warning of a public health catastrophe in the making.

Fluoridation of tap water has generated local controversies ever since it was introduced in the U.S. in 1945. But it remains fully supported by a majority of Americans and by professional organizations including the American Dental Assn. and the American Academy of Pediatrics. That suggests that the proper stance of a Health and Human Services secretary would be to voice support for the practice. Kennedy has done just the opposite.

According to the Centers for Disease Control and Prevention, fluoridation is one of the 10 great public health achievements of the 20th century, up there with vaccination, family planning and recognition of the health dangers of tobacco.

Fluoridation revolutionized dentistry, especially for children. Fluoridation of tap water was credited with reducing the incidence of tooth decay by as much as 70% when it was first introduced; by the mid-1980s, when other sources of fluoride, such as fortified toothpastes, were available, the effects of tooth decay in children were still 18% lower among those living in fluoridation communities than in those without it.

Who would benefit from the end of community fluoridation and a recrudescence of tooth decay? Dental supply companies, investors in which are rubbing their hands in glee at the prospect of more demand for their products. For example, shares of Henry Schein Inc., a distributor of specialty dental products, have risen more than 9% since RFK Jr. was named as Trump’s choice for HHS secretary.

Kennedy’s tweet about fluoridation exemplifies the anti-vaccine crowd’s method of casting doubt on established public health policies. There are two elements. One is to portray rare adverse health effects — some so rare that their very existence is questionable — as major and acute threats. The second is to downplay the beneficial effects of a policy. That leaves the public believing that the policy has only adverse effects, and that those are immediate and severe.

Tooth decay is a little-recognized public health problem, in part because fluoridation has made it rarer than it used to be. But it hasn’t disappeared. The American Academy of Pediatrics calls it “one of the most common chronic diseases in children,” and one that can have “lifelong consequences.” It disproportionately affects children who are racial minorities, come from low-income families or have special needs.

It’s not only about the occasional toothache or cavity needing filling. Tooth decay can produce “incapacitating pain,” bacterial infection that may spread throughout the body, and, of course, to the loss of a tooth. In the first part of the last century, the only remedy for decay was to pull the tooth.

As of 2012, two-thirds of Americans had access to fluoridated tap water. Thanks to fluoridation, the CDC says, “tooth loss is no longer considered inevitable, and increasingly adults in the United States are retaining most of their teeth for a lifetime.”

More baby boomers reached 60 with “a relatively intact dentition at that age than any generation in history,” the CDC says. Interestingly, that makes water fluoridation more important than ever, since it means that seniors have more teeth vulnerable to decay than before.

Communities that have ended fluoridation have seen dental illnesses soar. Since fluoride was removed from drinking water in Calgary, Alberta, Canada, in 2011, Alberta Children’s Hospital has seen dental infections requiring treatment with IV antibiotics increase by 700%, a hospital specialist told the City Council in 2019. Half of those infections were in children younger than 5.

Windsor, Ontario, Canada, voted in 2018 to resume fluoridation five years after it had ended the program, after discovering that the number of children with tooth decay or oral conditions requiring urgent care had increased by 51% in the interim.

Opponents of fluoridation have played on paranoid fears for decades, but into the 1960s, these were popularly dismissed as ravings from fringe organizations. In the 1964 film “Dr. Strangelove,” the unhinged Gen. Jack D. Ripper declares that “fluoridation is the most monstrously conceived and dangerous Communist plot we have ever had to face” — echoing the position of the John Birch Society.

The anti-fluoridation camp has long claimed that the process “increased the risk for cancer, Down syndrome, heart disease, osteoporosis and bone fracture, acquired immunodeficiency syndrome, low intelligence, Alzheimer disease, allergic reactions, and other health conditions,” the CDC noted in 1999. “No credible evidence supports an association between fluoridation and any of these conditions,” the agency stated.

More recently, critics object that fluoridation “is being imposed on them by the states and as an infringement on their freedom of choice,” the National Research Council reported in 2006 — similar to the elevation of individual “freedoms” over communal interests that animates the anti-vaccine movement.

The anti-fluoridation camp scored a legal victory in September, when federal Judge Edward M. Chen of San Francisco, an Obama appointee, ordered the Environmental Protection Agency to review its safety standard for fluoridation in tap water. Chen concluded not that “fluoridated water is injurious to public health” but that “there is unreasonable risk of such injury,” triggering a legal mandate that the EPA take a closer look.

Chen’s findings were heavily based on a government study with a checkered research history. More on that shortly. Despite the limitations of his order, it may well be taken as a validation of suspicions about fluoridation.

What of RFK Jr.’s roster of adverse health effects? Let’s take them one by one. To begin, although fluoride can be a byproduct of industrial processes, it’s also a mineral naturally present in soil, groundwater, plants and food.

Arthritis? The National Research Council’s 2006 analysis of government fluoride standards identified “no indications” in the existing scientific literature implying “that fluoride had a causal relationship with … rheumatoid arthritis.”

Bone fractures? The 2006 analysis determined that the leading evidence for fluoride’s effect on bone strength pointed to lifetime exposure to fluoride at concentrations at or exceeding 4 milligrams per liter, which is more than five times the concentration in fluoridated tap water. The effect was found chiefly in people prone to concentrating fluoride in their bones, such as those with kidney disease.

Bone cancer? The main source of this claim appears to be a 15-year study led by the Harvard School of Dental Medicine, published in 2006 in the journal Cancer Causes and Controls.

In the same issue of the journal, however, two Harvard experts cast doubt on the study, noting that the original researchers were unable to replicate their findings when they repeated their study with new subjects. The results, they said, “do not suggest an overall association between fluoride and osteosarcoma” (that is, bone cancer).

Evidence of “thyroid disease,” as Kennedy tweeted, is similarly inconclusive, especially at the approved levels of fluoride in tap water.

That brings us to Chen’s ruling in the San Francisco lawsuit. His findings relied heavily on a monograph by the National Toxicology Program first published in 2019. The paper initially concluded that “fluoride is presumed to be a cognitive neurodevelopmental hazard to humans,” based on findings that children exposed to high concentrations of fluoride showed lower IQs than others.

The survey focused on the effect of water with more than 1.5 milligrams of fluoride per liter, more than twice the approved level in the United States. It acknowledged that it had only “moderate confidence” that such concentrations could result in lower IQs, and stated that it had “insufficient data” to determine that the 0.7 mg/liter concentration in fluoridated tap water affects IQ.

There were lots of problems with the National Toxicology Program’s monograph. Two peer reviews by the National Academies of Sciences, Engineering, and Medicine essentially ripped it apart, rejecting it both times. The program “had not adequately supported its conclusions,” the peer reviewers wrote.

The monograph lacked a “rigorous statistical review.” The reviewers recommended that the program “make it clear that the monograph cannot be used to draw any conclusions regarding low fluoride exposure concentrations … typically associated with drinking-water fluoridation.” Among other changes in the final monograph published this summer, the program removed references to a “neurodevelopmental hazard to humans.”

Critics also pointed out the inherent problems with treating IQ as an all-purpose measure of intelligence, since it’s well-known that IQ can be affected by “socioeconomic, physical, familial, cultural, genetic, nutritional, and environmental factors,” the American Academy of Pediatrics observes.

Kennedy’s mindset is curious: He has promoted treatment of COVID-19 with ivermectin and hydroxychloroquine, which have been proven to be useless for the purpose, but he campaigns against fluoridation, which has demonstrated a health benefit over nearly eight decades. Is this any way to run a public health agency such as the HHS?