Water fluoridation is back in the spotlight as President-elect Donald Trump prepares to take office with an administration skeptical of the practice. The U.S. first began adding fluoride to water in the 1940s after studies showed exposure to it reduced rates of cavities and tooth decay. However, Robert F. Kennedy Jr., Trump's nominee for secretary of the Department of Health and Human Services (HHS), has vocally opposed fluoridation. Experts are hotly debating the health benefits and safety ahead of a proposed change.

Fluoride is a naturally occurring mineral present in soil, water, plants and food. It has been known to help oral health by preventing tooth decay and cavities, especially in children. "Countries take a range of approaches to ensure fluoride is provided to children," said CNN. "Some countries add fluoride to water, like the United States, and others add fluoride to milk or salt to keep it at recommended levels."

The U.S. first introduced fluoridated tap water in 1945 and as of 2022, approximately 72% of the country's population receives fluoridated water. It was added as a cost-effective way to improve oral health. Contrary to popular belief, the decision to fluoridate water is made at the local level and is only recommended, not mandated, by the Centers for Disease Control and Prevention (CDC). In the U.S., "more than 68 million people lack dental insurance and about one in four adults said in a survey they have avoided the dentist because of cost," said The Guardian.

Despite this, the Trump White House "will advise all U.S. water systems to remove fluoride from public water," Kennedy said on X. While the HHS secretary nominee cannot take any action against fluoridated water until he is confirmed by the Senate in 2025, "it remains unclear whether the incoming Trump administration could effectively ban water fluoridation," said Scientific American. "But at the federal level, fluoridation opponents could deploy the Safe Drinking Water Act, which regulates water contaminants nationally."

"Fluoride is the perfect example of helping people without them even having to do anything," Sreenivas Koka, the former dean of the University of Mississippi Medical Center's School of Dentistry, said to The Guardian. Aside from trace amounts of water, it has become a staple in dental products. "Several credible studies estimate that fluoridated water now reduces child and adult tooth decay by about 25%," said Scientific American.

But fluoride also "comes with potential risks, as many public health interventions do," said The New York Times. Too much can cause bone disease and tooth staining. The biggest source of the current controversy is its potential to cause cognitive problems. In August 2024, the National Toxicology Program, part of the HHS, released a report summarizing studies conducted in several countries and concluded that "drinking water containing more than 1.5 milligrams of fluoride per liter is consistently associated with lower IQs in kids," said The Guardian. The CDC's recommended limit is 0.7 milligrams per liter.

Other recently conducted studies have not shown a link between fluoride and cognition. "The contradictory results, along with the limitations of the existing studies, have fueled a contentious -- and still ongoing -- debate among experts about the potential risks," said the Times.