Right now, it’s politically hot to spit out fluoride. Health Secretary Robert F. Kennedy Jr. has long railed against fluoride in public water supplies, claiming that it correlates to lower IQs in kids. (Research suggests that fluoride may be linked to lower IQ scores only at very high exposures.) Dozens of places in the U.S.—including Miami-Dade County, Fla., Peshtigo, Wis., and the entire state of Utah—have recently passed restrictions banning the fluoridation of public water supplies. Florida just announced plans to ban fluoride beginning July 1, 2025.

More states and localities may follow suit after the U.S. Food and Drug Administration (FDA) announced on May 13 that it is taking steps to remove ingestible fluoride supplements prescribed to children from the market. The U.S. Environmental Protection Agency (EPA) also said in April that it’s studying the health risks of fluoride, and Kennedy has signaled that the U.S. Centers for Disease Control and Prevention will stop recommending water fluoridation.

These concerns contrast with the views of most U.S. dentists and pediatricians, who advise that fluoride is safe in small doses and one of the few bright spots in the fight against cavities since its addition to water in 1945. About 1 in 4 kids have dental decay by kindergarten, with those at lower economic levels affected most.

“I am concerned about the fluoride issue,” said Dr. Mike Simpson, a Republican congressman from Idaho, to Kennedy during a May 14 congressional hearing. “I've seen the benefits, having been a practicing dentist for 22 years.”