Most communities in the U.S. add fluoride to the tap water. It has been common practice for nearly 80 years to protect against tooth decay and cavities, and it’s considered a major achievement in public health. The Centers for Disease Control and Prevention says research shows that community water fluoridation reduces cavities by around 25%.
It has also long drawn opponents who have raised concerns about the practice, ranging from evidence-based concerns to unsubstantiated conspiracy theories. The debate heated up recently when President-elect Donald Trump picked Robert F. Kennedy Jr. to lead the Department of Health and Human Services. Kennedy is a longtime anti-vaccine activist who has also been outspoken in opposing water fluoridation, and if he’s confirmed in the role, he could influence policy.