Science is ever-evolving. When new information comes out, it is protocol to test it rigorously and check every assumption along the way. But what happens when the public takes a single new data point as gospel?

In the last few years, there has been a sharp increase in skepticism about the health effects of putting fluoride in public drinking water. Fluoride, a natural mineral, helps to prevent tooth decay by strengthening and rebuilding weakened tooth enamel. It was introduced into public water systems in the U.S. in 1945, and by 2020  72.7% of the U.S. population on a community water source were3 receiving fluopridated water..

For as long as it’s been in water systems, there have been studies on its effects, with the vast majority finding it beneficial to include.

But Robert F. Kennedy Jr., President Donald Trump’s new Secretary of Health and Human Services, has led the latest charge against water fluoridation. In a social media post before Trump took office, RFK Jr. said “the Trump White House will advise all U.S. water systems to remove fluoride from public water.” His concerns include higher risks for cancer and lower cognitive function in children, amongst a host of other health issues.

Americans are increasingly uneasy about fluoride, some are beginning to weigh the health benefits far lighter than the fear of perceived unknown effects. Utah has taken the lead, with a bill heading for Governor Spencer Cox’s desk that would make the state the first to ban fluoride in public water.

Analysis

There are myriad studies on the health effects of water fluoridation. On the cancer front, in 2011 California found that “fluoride and its salts have not been clearly shown to cause cancer.” The Dana Farber Cancer Institute also says that “overwhelming research shows that there is no reason to believe that fluoride, when used in an approved manner, causes any disease, including cancer,” while the National Cancer Institute concurs.

The worries about cognitive functioning in children, however, stem from a recent study by the National Toxicology Program that found higher levels of fluoride exposure (more than 1.5 milligrams of fluoride per liter) associated with lower IQ in children. This appears to have helped motivate a September 25th decision by a federal judge in California ordering the EPA to strengthen regulations for fluoride in drinking water.

Both of these have asterisks. The study explicitly states that “there was insufficient data to determine if the low fluoride level of 0.7 mg/L currently recommended for U.S. community water supplies has a negative effect on children’s IQ” and also found no evidence of adverse effects on adult cognition. In the judge’s case, he stressed he was not concluding with certainty that fluoridated water endangered public health.

It should be noted that there is evidence that fluoride levels above 1.5 mg/L are known to increase health risks such as bone fractures, thyroid disease, and nervous system damage. But that concentration is over double of both what is optimal for preventing tooth decay and what the vast majority of water systems have, at 0.7 mg/L.

All of these uncertainties have given momentum for RFK Jr. and the Trump administration to crack down on water fluoridation. However, the decision about if a water system receives fluoride is up to state and local governments, as the federal government can only make recommendations. But the EPA can set and regulate the maximum level of fluoridation in water systems, which could provide an avenue for the Trump-appointed head of the agency, Lee Zeldin, to affect local policy.

Utah’s bill would be the most sweeping fluoride legislation to be passed if it’s signed; but it wouldn’t be the first place to ban fluoride. Lakeland, Florida, on March 3 unanimously voted to stop adding fluoride to its drinking water, and joins a growing list of over 170 American communities that have ended the practice since 2010.

Despite the long and safe history of fluoride’s use in drinking water, it seems that water fluoridation is having a similar moment to vaccinations. A new data point has emerged, casting doubt on the safety of the practice. But that new point is just one drop in an ocean of evidence supporting the usage of fluoride in water systems.

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