The Dose Makes the Poison: Clarifying the Record on Fluoride

Despite water fluoridation being widely regarded as one of the greatest public health achievements of the 20th century, Robert F. Kennedy Jr. (RFK Jr.), President-elect Donald Trump’s nominee for HHS secretary, is pushing to remove fluoride from drinking water. Florida surgeon general Joseph Ladapo, MD (R), is now echoing RFK Jr.’s concerns and advising Florida communities against adding fluoride to public water systems. He is calling it “public health malpractice.” Meanwhile, other states and communities have initiated conversations about whether they should still mandate the practice.

This is not the first time RFK Jr. and Ladapo have called into question proven public health measures. I’d like to clarify the record on fluoride and underscore an important point: removing fluoride from public water will have health consequences, especially for vulnerable communities.

What Is Fluoride?

Fluoride is a naturally occurring mineral found in groundwater, various water sources, and certain plants. Since 1945, federal officials have recommended adding very low levels of fluoride to public water, and as of 2022, 63% of the U.S. population received fluoridated water.

Why Do We Fluoridate Water?

Bacteria in the mouth that serve to break down food also create acids that degrade the enamel on the surface of the teeth. Fluoride strengthens teeth and prevents cavities by countering the acid damage caused by the bacteria. Water fluoridation reduces tooth decay by about 25% in children and adults, and has a greater benefit (66% decrease) in children who have fluoride exposure before they develop their teeth. Fluoride also prevents other downstream dental complications like infections and abscesses that can lead to heart disease and other chronic health problems.

The Dose Makes the Poison

As with any other health intervention, the benefits of fluoridation must outweigh the risks. It’s important to remember that many substances that are healthy and beneficial when taken in smaller doses could cause harm at higher doses. Aside from fluoride in water, there are many other common examples of mineral fortification in the U.S. diet such as iodine in salt, iron in flour, folic acid and B12 in breakfast cereals, and calcium, iron, zinc, and selenium in dairy products. All these minerals, including fluoride, have health benefits at the dose that is added, while minimizing potential risks.

The current recommended fluoride level for public water is 0.7 mg/L. This is equivalent to about three drops of water in a 55-gallon barrel. As with any substance, fluoride can have side effects when exposure occurs at higher-than-recommended doses. Excess intake usually occurs where community groundwater contains naturally high levels of fluoride. Excess fluoride exposure in community groundwater has been associated with dental fluorosis or crippling skeletal fluorosis, which can lead to chronic bone, tendon, and ligament issues, as well as bone deformities.

A systematic literature review published earlier this year by the National Toxicology Program (NTP) found “with moderate confidence” that fluoride exposure levels in water greater than 1.5 mg/L are associated with lower IQ in children. This study received significant media attention and re-introduced people to potential safety risks of fluoride. In a historic ruling in September, a federal judge ordered the Environmental Protection Agency to further regulate fluoride in drinking water. Meanwhile, RFK Jr. has emphasized the link between excess fluoride and youth IQ to support his anti-fluoridation campaign.

But it is very important to note that the NTP systematic review considered fluoride at levels greater than double the amount recommended for U.S. public water supplies. Several meta-analyses of studies that examined fluoride exposure at or below the recommended dose have not shown any association between fluoride and lower IQ in children.

Additionally, there have been studies in communities like Juneau, Alaska and Calgary, Canada that stopped fluoridating their water supplies and subsequently saw the prevalence of dental caries in children increase.

Fluoride in Water Promotes Health Equity

Profound disparities in oral health exist for some population subgroups, such as the poor, older adults, and many members of racial and ethnic minority groups. According to multiple national surveys, children in low-income families were twice as likely to have decay in their primary (baby) teeth as children from families with high incomes. Access to professional dentistry and/or fluoride-enriched toothpaste or mouth rinse may not be available to vulnerable groups or those living in poverty.

Water fluoridation is the most cost-effective and accessible way to provide fluoride community-wide. The CDC reports that every $1 spent on fluoridation nets a community average of $32 per person per year by avoiding treatment for dental cavities. In a city the size of Chicago (2.7 million population), that is a return on investment of approximately $85 million per year. A majority of the U.S. population gets water from a fluoridated public source, which ensures over 200 million Americans reap the benefits of fluoridation, regardless of their income, health status, or age.

The Benefits Outweigh the Risks

A large body of data amassed over nearly 80 years shows that fluoride is cost-effective, safe at the recommended levels, and effective at preventing tooth decay, which can lead to other downstream chronic health problems. Safety concerns about fluoride have been demonstrated only with excess exposure. As always, the dose makes the poison, and the benefits of adding the small, recommended amount of fluoride to public water supplies have been shown to far outweigh any risks at the community level. The challenge ahead will be quieting the disinformation and encouraging continued use of a proven public health measure.

Katrine Wallace, PhD, is an epidemiologist and adjunct assistant professor in the Division of Epidemiology and Biostatistics & Division of Community Health Sciences in the School of Public Health at the University of Illinois Chicago.