Utah has become the first U.S. state to ban fluoride in public water systems after Gov. Spencer Cox signed the measure into law on Thursday. The bill, initially introduced in January, passed the state Senate on February 21 and will take effect May 7.

Governor Cox had previously expressed indifference toward the legislation, stating in an interview with ABC4 Utah that it wasn’t a bill he felt strongly about. He noted that roughly 44% of Utah’s population currently receives fluoridated water—one of the lowest rates nationwide, according to the Centers for Disease Control and Prevention. Cox explained, “You would think you’d see drastically different outcomes with half the state not getting it and half getting it. I’ve talked to a lot of dentists; we haven’t seen that. So it’s got to be a really high bar for me if we’re going to require people to be medicated by their government.”

Major health organizations, including the American Academy of Pediatrics, American Dental Association, and CDC, support fluoridation, arguing it prevents tooth decay. However, Health and Human Services Secretary Robert F. Kennedy Jr. has criticized fluoridation, associating it with conditions like bone cancer and thyroid disease, despite insufficient scientific evidence backing those claims. Kennedy further asserted before the November presidential election that, if elected, Trump would recommend removing fluoride from all public water systems.

Dr. Marty Makary, recently confirmed by the Senate to lead the FDA, also suggested in early November that fluoride in drinking water could be harmful—a claim most health experts reject. Although some studies suggest fluoride exposure could negatively affect children’s cognitive development, including a recent JAMA Pediatrics study, the authors acknowledge these studies mostly involve countries using much higher fluoride levels than the U.S.

Conversely, a recent Australian study found no connection between fluoridated water and negative cognitive outcomes, while a 2018 study linked greater availability of fluoridated water with reduced cavities among children. According to the CDC, the only documented risks of fluoridation include cosmetic concerns such as discolored tooth enamel or small holes in teeth.

Nonetheless, anti-fluoride movements have gained momentum nationwide, with over 150 towns and counties voting to remove fluoride from water systems since 2010. Lawmakers in Kentucky, Montana, and Tennessee introduced similar bills, and Florida is considering legislation this session to ban water “additives,” including fluoride.