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If Donald Trump is elected for a second term, his presidency could threaten what is lauded as one of the most important public health triumphs of the 20th century: adding fluoride, a mineral that helps prevent tooth decay, to drinking water.

That’s because of Robert F. Kennedy Jr.THE notorious vaccine skeptic which Trump he said will play an important role in health care in his administration if elected. “On January 20, the Trump White House will advise all US water systems to remove fluoride from public water,” Kennedy said recently. wrote on X. (Trump, in an interview with NBC Newssaid Kennedy’s proposal “sounds OK”).

Adding fluoride to drinking water reduces tooth decay rates by about 25%, US Centers for Disease Control and Prevention (CDC) say. Some communities in the US have started doing this in the 1940sand today about 72% of the US population receiving water from public utilities drink fluoridated water, According to the CDC. Decisions about fluoride use are usually made at the state or local level, and at least a dozen states require large municipalities to do so, Stateline reports.

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People in countries like Australia and Canada also consume fluoride in their drinking water. A 2021 study demonstrated that children living in Calgary, a Canadian city that stopped fluoridating its water, developed significantly more cavities than children living in nearby Edmonton, which uses fluoride.

Despite fluoride’s long-standing, federally celebrated presence in US drinking water, Kennedy is not alone in opposing its use. Anti-fluoridation advocates have called for decades to remove the mineral from water sources, and a number of communities, including Portland, Oregon, Juneau, Alaska, and Wichita, Kansas, have decided against it. add fluoride to their water.

Why all the controversy over a natural mineral that has been shown to improving oral health?

Although fluoride has demonstrated benefits, namely in reducing the risk of cavities and tooth decaysome studies have also raised questions about its potential link to health problems ranging from cancer to osteoporosis. CDC maintain that there is no convincing evidence linking fluoride to “any potential adverse health effect or systemic disorder” and other major health groups including American Cancer Society and the American Dental Association (ADA), I agree it is safe. But concerns remain — particularly about the links between fluoride and cognition.

In August, the US National Toxicology Program (NTP) published a report which found with “moderate confidence” that – at concentrations more than twice the US recommended fluoride level – fluoridated water is associated with modestly lower IQ scores in children. US standards recommend fluoride levels of 0.7 milligrams per liter of water, and the NTP conclusion applies to water fluoridated at 1.5 milligrams per liter and above.

Initial drafts of the report failed to clarify the independent assessment by the National Academies of Sciences, Engineering, and Medicine, which found that the NTP authors did not adequately support their conclusions with data. Some pro-fluoride organizations, including the ADA, argues that the final version still does not provide conclusive evidence and should not lead to policy changes regarding water treatment.

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Tewodros Godebo, assistant professor at Tulane University’s Celia Scott Weatherhead School of Public Health and Tropical Medicine who studies fluoridesays studies of very high levels of fluoride exposure don’t necessarily apply to the US, where water typically contains much less of the mineral.

Still, it’s worth noting that even government scientists disagree about the safety of fluoridated water, says Christine Till, a professor at York University in Canada, whose research has shown a the link between fluoride and lower IQ scores in children. “One authority group (CDC) says it’s safe for everyone, and another US government expert group (NTP) says there are concerns about the adverse effects of fluoride intake on child development,” Till says. “At the very least, it’s time to acknowledge the evolving science.”

A federal judge in California waded into that debate earlier this year when he reigned that the US Environmental Protection Agency needs to strengthen fluoride regulations to address its potential risk to children’s cognitive development. This decision doesn’t necessarily mean that fluoride should be removed from US drinking water — the EPA can choose to approach the situation in a number of ways, including issuing a public notice about the mineral’s potential risks and benefits — but it does highlight growing scrutiny over practices. of fluoridated water, which some anti-fluoride activists argue is no longer necessary now that most people can choose to use fluoride in dental products such as toothpaste. (Till says it’s important to look at total fluoride exposure, not just exposure through drinking water, when weighing the mineral’s potential risks and benefits.)

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A 2024 Cochrane review article found that adding fluoride to drinking water may lead to slightly fewer cavities among children, but concluded that the effects of the practice are less dramatic today than they were before fluoride was widely found in toothpaste. The authors also noted that adding fluoride to drinking water may increase the number of people with dental fluorosisa mostly cosmetic condition that can leave teeth with spots, stains or white lines.

Fluoridated water, however, helps protect people who may not keep up with their oral hygiene or lack access to regular dental care, Godebo says — another factor complicating any discussion of possibly adjusting fluoride levels in U.S. water .

Despite Kennedy’s suggestion that phasing out fluoride would be a day one priority in a potential Trump administration, Godebo says “the science isn’t there” to make a change to the U.S. recommendations at this time. “It would be a huge decision,” he says. “It should take several years to reach a conclusion.”

Write to Jamie Ducharme at [email protected].