Donald Chi was surprised to hear fluoride had become a presidential issue.
“It’s really rare for someone who has influence at the federal level to take a stand on an issue that directly affects oral health,” said Chi, an associate dean for research in the school of dentistry at the University of Washington.
Chi said that fluoride has been a staple of oral medicine for roughly eighty years, since the U.S. added the mineral to the country’s water supply with the goal of reducing the incidence of tooth cavities and decay.
Studies suggest the intervention was greatly successful at protecting Americans’ teeth. Water fluoridation was credited with a 65% reduction in cavities, and in 1999, the Centers for Disease Control and Prevention declared water fluoridation as one of the greatest public health interventions of the 20th century.
But Chi worries that may be about to change.
President-elect Donald Trump nominated Robert F. Kennedy Jr. to head the U.S. Department of Health and Human Services.
RFK Jr. has espoused a number of unfounded claims this election cycle, including that Wi-Fi causes cancer and vaccines cause autism. He also repeatedly said that he is concerned about the fluoride in America’s water supply system, thrusting the natural mineral into the spotlight and reviving some of the conspiracy theories and misinformation that’s surrounded it for years.
However, not all of RFK Jr.’s statements regarding fluoride are unfounded. Recent studies have found a potential association between high fluoride exposure and behavioral impacts in young children.
While most scientists say more research is needed to confirm a link between fluoride and negative health outcomes, others believe there is enough evidence to begin considering policy changes.
An important intervention
Fluoride is a naturally occurring mineral that is found in many foods including shrimp, coffee and tea. But it has also been the subject of conspiracy theories since the start of its use in public drinking systems, including a fear in the 1960s that fluoride was part of a communist plot.
A low dose of fluoride has been added to public water systems in the U.S. and Canada since the 1940s to help protect against cavities. Today, roughly 200 million Americans receive fluoridated water from a community water system, according to the U.S. Centers for Disease Control and Prevention.
The intervention, which costs just $1 to $2 per capita, has dramatically reduced cavities in children and adults, according to the CDC. That saves the U.S. nearly $6.5 billion every year from direct and indirect dental costs.
“Evidence is really that if you want to prevent decay and have our modern diets that are very rich in carbs and hidden sugars –– and not so hidden sugars –– we really need some fluoride around [teeth] to be able to prevent disease,” said Margherita Fontana, a professor in the School of Dentistry at the University of Michigan.
So, what happens if you stop fluoridating the water?
People who brush their teeth with fluoride toothpaste twice a day and avoid foods high in carbs and sugar may not see a big difference.
But that’s not the case for everyone, especially those who have difficulty brushing their teeth, said James Dickinson, professor of community health sciences at the University of Calgary in Canada.
In 2011, the city council of Calgary voted to stop fluoridating its water. The result: The number of cavity-related dental treatments for every 10,000 children under the age of five increased from 22 in 2014 to 45 in 2019, according to one study.
Dickinson said while some research has suggested the impact of ending fluoride in water might be lessened because of the ubiquity of fluoride toothpaste, the city still saw a clear uptick in cases.
“It’s not as big as it was in the days when fluoride in the water was the only way that people got fluoridation, but it does make a difference,” he said.
Calgary is expected to reinstate public water fluoridation in 2025.
Some studies suggest risk
The evidence surrounding the benefits of water fluoridation abounds, but there are some studies that suggest risks.
Earlier this year, the National Toxicology Program –– an agency within the Department of Health and Human Services –– released findings from an eight-year review of studies mostly outside the U.S. The review expressed “moderate confidence” that fluoride exposure could be associated with lower IQ in children. But it noted those findings were for exposure levels more than double what is recommended for U.S. drinking water systems.
The American Academy of Pediatrics pushed back against that review,questioning its validity. But the review was enough to sway a federal judge in California earlier this year into ruling that the Environmental Protection Agency needed to strengthen fluoride regulations against the “unreasonable risk” posed to health.
Other studies abroad have also found an association between prenatal fluoride exposure and both behavioral health problems and lower IQ scores among young children. Those findings have been divisive among public health experts, with most agreeing that more research is needed before making changes to public policy.
Still, researchers behind these studies wonder whether the potential tradeoffs of fluoridated water are worth it.
“The concentration needs to be reduced in community water, or that the practice needs to be ended altogether,” Ashley Malin, assistant professor of epidemiology at the University of Florida, said.
Malin worked on a study in Los Angeles that looked at fluoride exposure in pregnant women. The study used urine samples to assess total fluoride exposure –– not just from drinking water.
The study found an association between prenatal fluoride exposure and negative behavioral health effects in children.
“It doesn’t necessarily mean that it was causal, but it is consistent with numerous other studies published in North America that do show an association of higher prenatal fluoride exposure with poor neurodevelopmental outcomes,” she said.
Malin points to a recent Cochrane review of the benefits of community water fluoridation, also released this year, which found “the benefits of fluoride in water supplies may be smaller than they were before the widespread addition of fluoride to toothpaste.”
“Whose decision should that be, to be able to decide how many IQ points is worth how many teeth or fractions of teeth? I think it is more of a bioethical issue as well,” Malin said.
Lisa Fotios/Pexels. Community water systems adjust for naturally existing fluoride levels in the water –– scaling up or down to hit the recommended level: roughly 0.7 parts per million. That 0.7 parts per million level avoids a common side effect of fluoride at high levels: fluorosis, which is a cosmetic discoloration of teeth in young children. But that level is also protective against cavities, something that is especially important given diets rich in sugars and carbs.
‘Science is cumulative’
Experts in favor of maintaining water fluoridation say more research is needed to better understand any potential negative associations, but worry about the politicization of the issue and the risk of prematurely losing an effective public health intervention.
“Rarely is one study going to definitively tell us all the answers we need to make a decision,” Chi with the School of Dentistry at the University of Washington said. “Science is cumulative.”
On Malin’s Los Angeles study, Chi said he wonders what biological mechanism would allow fluoride to impact behavioral health, and doesn’t see a clear answer.
“I don’t think we should completely discount it, meaning that additional studies are needed,” he said. “And if we can start to replicate these findings across different populations, different geographies, I think that’s when we can start saying, ‘You know what? Maybe there needs to be a policy change.’”
Chi said oral health fell across the country over the pandemic as many people stayed home and fell out of their routines. He said water fluoridation is still critical in areas where the rates of tooth decay are high.
More broadly, Chi said he sees a shifting role for scientists and health experts explaining their findings to the general public.
“The old healthcare 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.”
