Longtime research has found that adding fluoride to U.S. drinking water is a safe way to boost children’s oral health. Since 2015, the recommended level in the U.S. has been 0.7 milligrams per liter. Public health organizations, including the American Dental Association, the American Academy of Pediatrics and the Centers for Disease Control and Prevention, support the practice.
Recent studies, however, have shown possible links between fluoride and bone problems and children’s IQs, particularly when fluoride is above the U.S. recommended levels.
“There is evidence that fluoride exposure has been associated with the diseases [and] disorders that RFK listed but with caveats,” said Ashley Malin, who is an assistant professor in the University of Florida’s Epidemiology Department and has studied fluoride’s effects in pregnant women.
Malin referred to studies showing that higher fluoride exposure, particularly during pregnancy, is associated with reduced child IQ and that prenatal exposure is also linked to decreased intellectual functioning and executive function. For high exposure in pregnancy, the studies showed symptoms associated with other neurobehavioral issues, such as attention-deficit/hyperactivity disorder.
However, many of these studies took place in countries other than the U.S. and looked at fluoride in drinking water at sometimes twice the United States’ recommended level. Also, some of the other ailments that Kennedy listed, such as an association with bone cancer, have less robust evidence and need more study.
“Aside from fluoride’s impacts on neurodevelopment, I think that there is more that we don’t know about health effects of low-level fluoride exposure than what we do know, particularly for adult health outcomes,” Malin said.
David Bellinger, a Harvard Medical School neurology professor and professor in Harvard School of Public Health’s Environmental Health Department, said the risk-benefit calculation of added fluoride differs depending on whether typical fluoride exposure levels cause health problems or if problems occur only when recommended levels are exceeded.
“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.”
PolitiFact contacted Kennedy through his Children’s Health Defense organization but received no reply. The organization sued PolitiFact and Meta related to a 2020 fact check. A federal court dismissed that lawsuit. The dismissal was upheld on appeal, and the case is pending a possible appeal to the U.S. Supreme Court.
What is fluoride, and what are its benefits?
Fluoride is a mineral naturally occurring in soil, water and some foods that helps prevent tooth decay and cavities. It strengthens tooth enamel that acid from bacteria, plaque and sugar can wear away.
Water fluoridation has been happening in the U.S. since 1945.
The federal Public Health Service first recommended fluoridation of tap water in 1962, but the decision still lies with states and municipalities. Around 72% of the U.S. population or about 209 million people, had access to fluoridated water in 2022, the CDC reported. Fluoride also has been added to oral care products such as toothpaste and mouth rinse.
In 2015, U.S. health officials lowered the recommended amount of fluoride in drinking water to 0.7 milligrams per liter, saying a higher level was less necessary given other sources of fluoride and that the lowered amount would still help protect teeth without staining them.
Pediatric dentists note that applying fluoride with toothpaste and rinses is beneficial, but small amounts circulating in the body via water consumption help younger children who still have their baby teeth because it can benefit the development of permanent teeth.
The American Dental Association said studies have shown that fluoride in community water systems prevents at least 25% of tooth decay in children and adults and that “for more than 75 years, the best scientific evidence has consistently shown that fluoridation is safe and effective.”
The association said on its website: “It’s similar to fortifying other foods and beverages — for example, fortifying salt with iodine, milk with vitamin D, orange juice with calcium, and bread with folic acid.”
According to the CDC, health experts and scientists from the U.S. and other countries have so far “not found convincing scientific evidence linking community water fluoridation with any potential adverse health effect or systemic disorder such as an increased risk for cancer, Down syndrome, heart disease, osteoporosis and bone fracture, immune disorders, low intelligence, renal disorders, Alzheimer’s disease, or allergic reactions.”
The agency said risks of water fluoridation are limited to dental fluorosis, which can alter dental enamel and cause white flecks, spots, lines or brown stains on the teeth when too much fluoride is consumed.
Do Studies Show Fluoride Posing Any Other Risks?
Some studies have said that excess fluoride exposure, often at higher levels than the recommended U.S. limit, can harm infants and young children’s developing brains and that higher levels of fluoride exposure during pregnancy were associated with declines in children’s IQs.
A study published in May that Malin led with the University of Southern California and Indiana University researchers suggested that fluoride exposure during pregnancy was linked to an increased risk of childhood neurobehavioral problems and said more studies were “urgently needed to understand and mitigate the impacts in the entire U.S. population.”
Experts noted prenatal fluoride exposure is most strongly linked to children’s IQ loss and said the timing of fluoride consumption might need to be considered when making recommendations.
A federal review of dozens of studies published in August by the Department of Health and Human Services’ National Toxicology Program concluded that higher levels of fluoride exposure were linked to lower IQs in children. However, the report was based primarily on studies in countries such as Canada, China, India, Iran, Mexico and Pakistan and involved fluoride levels at or above 1.5 milligrams per liter, twice the recommended U.S. limit. The authors said more research is needed to understand whether lower exposure has any adverse effects.
In the report, researchers said they found no evidence that fluoride exposure adversely affected adult cognition.
Bellinger, of Harvard, pointed to the review as an example of how the amount of fluoride matters. He noted how researchers concluded that a very small percentage of people in the U.S. are exposed to levels that correlate with IQ loss.
“Second, the fact that there are now multiple pathways of exposure to fluoride besides fluoridated water (toothpaste and other dental products, etc.) makes it really difficult to attribute a particular adverse effect to the fluoride added to the water,” he wrote via email. “It is the cumulative exposure from all sources that contribute to any adverse health effects.”
In September, a federal judge ordered the Environmental Protection Agency to further regulate fluoride in drinking water because of the potential risk that higher levels could affect children’s intellectual development.
U.S. District Judge Edward Chen wrote that the court’s finding didn’t “conclude with certainty that fluoridated water is injurious to public health,” saying it’s unclear whether the amount of fluoride typically added to water is causing children’s IQs to drop. However, he wrote that there was enough risk to warrant investigation and that the EPA must act to further regulate it. The ruling did not specify what actions the agency should take, and the EPA is reviewing the decision.
After the ruling, the American Association of Pediatrics issued a statement that fluoride in drinking water is safe for children and said the policy is based on a robust foundation of evidence.
Besides dental fluorosis, experts say that fluoride exposure over many years above the U.S. recommended amount can cause skeletal fluorosis, a rare condition that causes weaker bones, stiffness and joint pain. Although the Public Health Service recommends a fluoride concentration of 0.7 milligrams per liter for community water systems, the EPA, under the Safe Drinking Water Act, sets enforceable standards for drinking water quality. Currently, to prevent skeletal fluorosis, the EPA requires that water systems not exceed 4 milligrams of fluoride per liter of water.
Malin said she and her research team are investigating a potential link between fluoride and bone fractures. She said that although several studies have found high fluoride exposure associated with increased risk of bone fractures, and some have linked fluoride with thyroid disease, rigorous, U.S.-based studies haven’t been done.
The CDC concluded that recent research found no link between cancer risk and high levels of fluoride in drinking water.
The American Cancer Society reviewed a possible link between water fluoridation and cancer risk. An organization spokesperson pointed PolitiFact to its review and said it has no data showing a definitive answer.
