Robert F. Kennedy Jr., dueling studies spark discussion of fluoride safety

President-elect Donald Trump’s pick for secretary of the U.S. Department of Health and Human Services wants communities to stop adding fluoride to drinking water. He’s not alone.
Neither are the high-profile medical groups that say fluoride has helped protect the dental health of children in the U.S. for many decades.
But what has long been deemed one of the country’s public health success stories is now at the heart of a national controversy, with some communities doubling down on keeping fluoridation to prevent cavities and others removing it from their water supply.
Here’s a look at why fluoride has become controversial and some of the events and research driving the discussion.
Just days before the election, Robert F. Kennedy Jr., who, if he is confirmed by the U.S. Senate, will become Health and Human Services secretary, said the Trump administration on its first day in office would recommend communities shut down their fluoridation efforts. On X, Kennedy has called fluoride “an industrial waste associated with arthritis, bone fractures, bone cancer, IQ loss, neurodevelopmental disorders and thyroid disease.” He has also referred to fluoride as a “neurotoxin.”
The Washington Post and other media noted that medical organizations responded by calling Kennedy’s assertions unfounded at the levels of fluoridation used in drinking water. But many of them have also noted that in an NBC interview, Trump said possible action against fluoridation of water “sounds OK to me … You know, it’s possible.”
Fluoride is a chemical ion of fluorine and it’s the 13th most common element in the Earth’s crust, per the Centers for Disease Control and Prevention. Almost all soil and water and many rocks contain fluoride.
It prevents cavities by combining with outer enamel tooth layers, making enamel stronger.
In 1945, Grand Rapids, Michigan, began adding fluoride to water and the rate of tooth decay among children went down. A bigger push for fluoridation to prevent cavities began in 1950. Next, toothpaste companies started adding fluoride to their products, but drinking water is still where most people get fluoride, researchers say.
The CDC notes that it doesn’t mandate water fluoridation — communities decide. But the U.S. Public Health Service has recommended adding it in small amounts to drinking water.
In 2015, amid concerns about fluorosis, which sometimes leaves discolored splotches on children’s teeth, officials reduced how much they said should be added to community water supplies. The Associated Press reported that about “2 out of 5 adolescents had tooth streaking or spottiness,” which Deputy Surgeon General Boris Lushniak described as mostly a cosmetic issue.
An estimated 75% of Americans get water that has fluoride added.
That most Americans get fluoridated water hasn’t meant it’s ever been universally accepted, however. As the AP noted, “Opponents argue its health effects aren’t completely understood and that adding it amounts to an unwanted medication.”
This summer, the National Toxicology Program, a federal agency that coordinates toxicology studies and testing related to health, released a report that said with “moderate confidence” that higher levels of fluoride lower the IQs of children. Critics of the research point out that in the research cited, fluoride levels were twice the recommended limit for drinking water.
Wrote the AP of the 324-page report, “It summarizes a review of studies conducted in Canada, China, India, Iran, Pakistan and Mexico that concludes that drinking water containing more than 1.5 milligrams of fluoride per liter is consistently associated with lower IQs in kids.” The article noted no attempt to quantify the exact IQ point loss, but said that “some of the studies reviewed in the report suggested IQ was 2 to 5 points lower in children who’d had higher exposures.”
The report had been delayed in part because an earlier draft was criticized by a committee of experts who said “the available research did not support” that draft’s conclusions, per AP.
“Since fluoride is such an important topic to the public and to public health officials, it was imperative that we made every effort to get the science right,” the program’s director, Rick Woychik, said in a statement.
The American Academy of Pediatrics responded by saying the report hadn’t caused it to change its stance on recommending fluoride be added to water to prevent dental decay. “While additional research to better understand the association and potential biologic mechanisms would be important, there’s nothing about the research that makes me concerned (about) … low levels of fluoride through use of toothpaste and drinking fluoridated water,” said Dr. Charlotte W. Lewis, a member of the organization’s Section on Oral Health.
Besides noting the report looked at levels double that in drinking water, the academy also questioned whether the program’s findings would apply widely. “The studies included for analysis were geographically heterogeneous, with different study populations. Socioeconomic, physical, familial, cultural, genetic, nutritional and environmental confounders affect IQ. It is unclear whether data on children’s IQ extracted from a variety of different studies are accurate, comparable or generalizable, according to AAP experts,” the academy’s analysis of the study reported.
Lewis said the review left out existing large population-based studies that didn’t find a link between fluoride and IQ.
As a result, the academy continues to recommend children use an “age appropriate” amount of fluoride toothpaste and drink fluoridated water. The organization said those in communities without fluoridation in water should supplement it and that dentists should apply topical fluoride to children’s teeth based on recommendations from the U.S. Preventive Services Task Force.
In a Sept. 25 statement, the American Dental Association referred to itself as “staunchly in support” of community water fluoridation at optimal levels for the purpose of preventing tooth decay.
Not everyone agrees with the dental and pediatricians group. Or, on the other side, with the government report.
Ashley Malin, a University of Florida researcher who studies how higher fluoride levels in pregnant women impact their children, said the study that was critical of fluoride in water was the most rigorous of its kind. She told the AP it makes sense for pregnant women to pay attention to and lower their fluoride intake and said policy discussions about requiring fluoride content on beverage labels might be a good idea.
She told NPR that concentrations in community water should be reduced or the practice stopped completely.
Also this year, a Cochrane review of fluoridation concluded that the benefits may be less now that fluoride is generally added to toothpaste. Cochrane is a nonprofit, international network with headquarters in the U.K. that’s part of the U.K. National Council for Voluntary Organizations. “Cochrane produces systematic reviews, published in the Cochrane Library, to help people make informed health decisions,” per its website.
In response to the Cochrane piece, the American Dental Association in October issued a statement reaffirming its endorsement of community water fluoridation “at optimal levels to help prevent tooth decay.” It said that recent reviews don’t present “new or significant findings on the subject.”
The statement noted that fluoridated water was accessible to communities regardless of their socioeconomics and added that the CDC has said water fluoridation and fluoridated toothpaste work together to help prevent tooth decay, doing a better job than “either one alone.”
Lorna Koci, who chairs the Utah Oral Health Coalition, is outspoken in support of fluoride.
“In stated amounts, we are very favorable and have studies that show the benefit of that from an oral health perspective,” she told the Deseret News. “We have information that shows what has happened in cities where they have removed the water fluoridation.” That, she added, is “a noticeable increase in decay.”
The coalition itself has a position statement on fluoridation that reads: “Dental caries (tooth decay) is the most common chronic disease of childhood and dental caries incidence for adults exceeds that of children. Community water fluoridation is a safe, beneficial, cost-effective, and socially equitable public health measure for preventing dental caries in children and adults. As such, the Utah Oral Health Coalition supports the optimal fluoridation of water systems throughout the state of Utah.”
Experts who favor maintaining water fluoridation agree that more research is needed to better understand possible negative associations, but they worry about the politicization of the issue and the risk of losing what’s long been considered an effective public health intervention.
“Rarely is one study going to definitively tell us all the answers we need to make a decision,” Donald Chi, associate dean of research at the University of Washington dentistry school, said. “Science is cumulative.”
The National Toxicology Program study was cited by U.S. District Judge Edward Chen, who said in a ruling this year in California that while it’s not clear that there’s a problem with the levels of fluoridation in U.S. drinking water, that is a question that needs to be addressed.
He told the Environmental Protection Agency to lower the risk, though he did not specify how the agency should do that. The judge ordered the EPA to study the effects of fluoridated water and tighten its regulations as appropriate.
The EPA has for years reported that levels of fluoridation above 4 mg/L could contribute to skeletal fluorosis, which can weaken bones and increase stiffness and pain.
The Centers for Disease Control and Prevention fluoride page notes that the U.S. Public Health Service recommends that fluoride be added to drinking water. The recommendation, it says, “is science-based guidance on the optimal level of fluoride in community water supplies.” That optimal amount is for 0.7 mg/L as the concentration that “maximizes fluoride’s oral health benefits while minimizing potential harms, such as dental fluorosis.”
The CDC reports that in 2013, the Community Preventive Services Task Force reaffirmed and updated the recommendations for fluoridation of water that it first made in 2001.
The public health agency acknowledges the need to limit how much fluoride young children get, but has long supported adding it to water. It recommends not using fluoridated toothpaste in children younger than 2 unless a dentist suggests doing so. And children ages 2-6 should have only a pea-sized amount of toothpaste. They also should avoid fluoride mouthwash.
Among the worries that critics cite are how fluoride impacts developing fetuses and babies who may get fluoridated water in their baby formula.
KFF Health News quoted David Bellinger, a Harvard Medical School neurology professor and professor in Harvard School of Public Health’s Environmental Health Department. He said the calculation of benefit and risk would be different depending on the amount of fluoride and whether typical exposure levels lead to the concerning conditions or if that only happens when exposure levels are higher.
“In toxicology, ‘the dose makes the poison’ is a long-standing principle,” he said. “So a general statement that fluoride is associated with diseases X, Y and Z is not very helpful unless the dose that might be responsible is specified.”
Chi told the NPR reporters he believes that scientists and health experts will have to change how they explain findings to the public.
“The old health care model was very paternalistic, meaning that providers would tell patients what to do and largely patients would go and do it,” he said. “I think health providers, public health officials, those working with patients, you really have to know your stuff. I think it’s really important to create a space with patients to have these conversations.”
Cities, like experts, appear to be divided on the issue. And some of them are taking steps related to their positions on the topic.
NPR’s WFYI in Indianapolis reported that in 2011, the city council in Calgary, Canada, voted to stop fluoridating water, a move it’s expected to reverse in 2025. “The number of cavity-related dental treatments for every 10,000 children under the age of 5 increased from 22 in 2014 to 45 in 2019, according to one study.
In another example, Lebanon, Oregon, voters on Election Day narrowly approved removing fluoride from the water supply, as The Washington Post reported. The state already had one of the lowest water fluoridation rates in the country, the Post noted.
In Winter Haven, Florida, last week, the city commission voted 3-2 to stop adding fluoride to drinking water “as soon as reasonably practical thereafter,” as WFLA-TV reported. The story noted that Mayor Pro Tem Brian Yates suggested that some of the approximately $48,000 the city would save could be donated to charities that provide dental health services and products.
Some cities have simply not added fluoride, including Portland, Oregon, where voters said no. On the opposite side, Sheridan, Wyoming, recently started adding fluoride.
Buffalo’s WIVB4.com said that New York city plans to keep fluoridating its water regardless of Kennedy’s recommendations.