RFK Jr. Alleges Fluoride in Drinking Water is Harmful—Examining the Scientific Evidence

Under a Trump presidency, fluoride will be removed from America’s public water supply, according to Robert F. Kennedy Jr.

The claim comes from a post on X, shared by Kennedy on Saturday, just days before the 2024 presidential election.

“On January 20, the Trump White House will advise all U.S. water systems to remove fluoride from public water,' Kennedy wrote. 'Fluoride is an industrial waste associated with arthritis, bone fractures, bone cancer, IQ loss, neurodevelopmental disorders, and thyroid disease. President ​@realDonaldTrump and First Lady @MELANIATRUMP want to Make America Healthy Again.'

In a follow-up post, Kennedy called fluoride a 'dangerous neurotoxin.'

Water fluoridation, or adding fluoride to drinking water, is a decades-long practice in the U.S.—but Kennedy’s claims have ignited questions about the safety of fluoride in drinking water and what would happen if it were to be removed from the U.S. water supply. Here’s what you need to know.

Fluoride is a naturally occurring mineral that can help prevent tooth decay and strengthen bones. Fluoride is often found in water supplies and a variety of dental products, including toothpaste and mouth rinses, to prevent dental cavities.

Almost all water contains some naturally occurring fluoride, but usually not enough to support dental health, so local governments began adding fluoride to water systems in the 1940s. By 2020, over 72% of the total U.S. population, or about 290 million people, received fluoridated water through a community water system.

Water fluoridation is not required by law, and it’s up to state and local governments to decide whether to add fluoride to their water supplies. The U.S. Department of Health and Human Services (HHS) set the optimal fluoride concentration in drinking water at 0.7 milligrams of fluoride per liter of water. While water fluoridation typically involves the addition of fluoride, communities might actually remove fluoride if the natural level is too high.

According to the Centers for Disease Control and Prevention (CDC), drinking fluoridated water reduces cavities by about 25% in children and adults, resulting in less mouth pain, fewer fillings or teeth pulled, and fewer missed days of work and school. It’s worth noting that a Cochrane review published in October 2024 found that the benefit of community water fluoridation on tooth decay has declined since the 1970s, when fluoride toothpaste became more widely available.

Experts say this is a tricky question—research shows that health risks associated with fluoride are based on the level of exposure.

“The science of fluoride is very interesting, because fluoride in small amounts is beneficial whereas fluoride in high doses is toxic,” Athanasios Zavras, DDS, MS, DMSc, Delta Dental of Massachusetts Professor of Public Health and Community Service at Tufts University School of Medicine and chair of the school’s Department of Public Health and Community Service, told Health.

But for now, there are no confirmed health risks of fluoride at optimal levels. “There is no evidence to back up the claims that 0.7 mg/L of fluoride leads to any of the conditions mentioned,” Zavras said.

That said, fluoride has been associated with some adverse health outcomes at higher levels, according to Ashley Malin, PhD, assistant professor of epidemiology at the University of Florida College of Public Health and Health Professions.

Malin primarily studies fluoride’s effect on neurodevelopment, and there is some evidence pointing to a link between the two.

In August, a report by the National Toxicology Program found that higher levels of fluoride exposure—like drinking water with more than 1.5 mg of fluoride per liter (mg/L)—is associated with lower IQ in children.

Most of the studies included in the report were conducted in countries outside the U.S. with higher exposure levels to fluoride. But the report did find that nearly 2 million Americans have water that naturally contains at least 1.5 mg/L of fluoride—the upper limit set by the World Health Organization—and 1 million Americans have tap water naturally fluoridated at 2 mg/L and above.

The report was also cited in a lawsuit brought against the Environmental Protection Agency by a non-governmental organization and other plaintiffs. A federal court in California ruled in favor of the plaintiffs, who claimed the levels of fluoride in U.S. drinking water pose a risk to human health.

Though the court ruling didn’t conclude that the current levels of fluoride in water were dangerous to public health, the EPA must now strengthen its regulations for fluoride in drinking water due to “substantial and scientifically credible evidence establishing that fluoride poses a risk to human health.”

Opponents of the decision, like the American Academy of Pediatrics (AAP), have called into question the validity of the research highlighted in the case, specifically scrutinizing the NTP’s report on the link between fluoridated water and IQ.

“There is nothing about the current decision that changes my confidence in the safety of optimally fluoridated water in the U.S.,” Charlotte W. Lewis, MD, MPH, FAAP, a member of the AAP Section on Oral Health, said in a statement. “Water fluoridation is a public health policy based on a solid foundation of evidence. When new research is published, health experts scrutinize it to make sure it meets high standards for public safety.”

One established concern for exposure to high levels of fluoride in young children is dental fluorosis—too much fluoride while teeth are growing can cause teeth discoloration, including white flecks, spots, or lines.

In the U.S., cases of dental fluorosis are mostly mild and cosmetic, meaning it does not affect tooth function and is not painful. Children are no longer at risk of dental fluorosis around age 8, when the enamel of permanent teeth is fully formed.

In his post on X, Kennedy also linked fluoride in drinking water to poor bone and joint health—namely bone fractures, bone cancer, and arthritis—as well as thyroid disease.

While high levels of fluoride can weaken bones—in serious cases causing a condition known as skeletal fluorosis—bone cancer has yet to be confidently linked to fluoride exposure. A review from the National Research Council expressed concern over bone cancer risk based on preliminary research and animal studies, but Malin said there have not been rigorous U.S.-based studies on low exposure.

There has been some research that found a link between fluoride exposure and increased risk of bone fracture, Malin said. Most of the studies tested higher levels of fluoride, but a recent Swedish study showed that fluoride exposure at similar levels to the U.S. was associated with an increased risk of major osteoporotic and hip fracture among postmenopausal Swedish women.

As for arthritis, overall, studies of fluoride’s association with increased risk of arthritis have not drawn strong conclusions. One study of residents of Tongyu County in China found that excessive exposure to fluoridated water may increase osteoarthritis risk, but only at levels above the recommended 0.7 mg/L.

Thyroid disease has yet to be strongly connected to fluoride exposure as well. Malin said the association is plausible, and a Canadian study found an increased risk of hypothyroidism in pregnant women with low levels of fluoride exposure from drinking water, but more rigorous studies in the U.S. are needed.

The National Sanitation Foundation has approved three chemicals for drinking water fluoridation: hydrofluosilicic acid, sodium fluorosilicate, and sodium fluoride. “These can be byproducts of phosphate fertilizer production,” Malin said, perhaps explaining what Kennedy meant when he called fluoride “industrial waste.”

Two of these fluoride additives have been found to contain heavy metals, Malin said. A 2014 study found arsenic, lead, and aluminum in hydrofluorosilicic acid, and aluminum and barium in sodium fluoride, noting that all of the tested samples contained a “surprising amount of aluminum.”

The study only used a few samples, but Malin also warned that these two chemicals can have a harmful effect when combined with disinfecting agents like chlorine found in plumbing pipes.

“When combined, disinfecting agents can leach lead from lead-bearing plumbing into the community drinking water, and that can increase lead exposure,” Malin said. “Oftentimes, people think that it’s medical grade fluoride, or similar to the naturally occurring fluoride, but these chemicals are, from my perspective, quite different.”

The most important and immediate impact would be a significant increase in dental cavities, especially among children.

“Water fluoridation is often referred to as a ‘public health miracle’ because it helps so many across all socioeconomic groups avoid the devastating effects of dental disease,” Zavras said. “Groups that consume high levels of carbohydrates will bear the burden of such increase disproportionately.”

However, Malin said there is evidence suggesting that water fluoridation is no longer essential for preventing tooth decay, with fluoride toothpaste being widely accessible. “It seems that the demonstrated benefit has declined over the years,” Malin added. “There’s more evidence in support of the topical application.”

Fluoride recommendations have been altered before. The HHS initially set the optimal range of water fluoridation at 0.7 to 1.2 mg/L. In 2015, the agency updated its recommendation to the current optimal concentration of 0.7 mg/L due to the increasing amounts of fluoride in food that is processed with fluoridated water. “We need to remember that community drinking water isn’t the only source of fluoride exposure,” Malin added.

Whether Kennedy is in charge of American health initiatives or not, the EPA will have to address the health risks of water fluoridation per the federal court ruling.

“I think it makes sense to further regulate the chemical to mitigate the risk,” Malin said. “Whether that means reducing the concentration or eliminating it from the water supply altogether remains to be determined.”