By MATTHEW BROWN and HANNAH SCHOENBAUM

SALT LAKE CITY (AP) — Utah will become the first state to ban fluoride in public drinking water, despite widespread opposition from dentists and national health organizations.

Republican Gov. Spencer Cox said he would sign legislation that bars cities and communities from deciding whether to add the mineral to their water systems.

Fluoride strengthens teeth and reduces cavities by replacing minerals lost during normal wear and tear, according to the U.S. Centers for Disease Control and Prevention. The addition of low levels of fluoride to drinking water has long been considered one of the greatest public health achievements of the last century.

Government researchers have found that community water fluoridation prevents about 25% of tooth decay.

“We’ve got tried and true evidence of the safety and efficacy of this public health initiative,” said American Dental Association President Brad Kessler, of Denver. Cavities could start emerging in children within months or years of Utah stopping fluoridation, Kessler said.

The ban comes weeks after federal health secretary Robert F. Kennedy Jr., who has expressed skepticism about water fluoridation, was sworn into office.

“It’s not a bill I care that much about,” Cox added, “but it’s a bill I will sign.”

Utah lawmakers who pushed for a ban said putting fluoride in water was too expensive. Its Republican sponsor, Rep. Stephanie Gricius, acknowledged fluoride has benefits, but said it was an issue of “individual choice” to not have it in the water.

Cox said that like many people in Utah, he grew up and raised his own children in a community that doesn’t have fluoridated water — or what he called a “natural experiment.”

“You would think you would see drastically different outcomes with half the state not getting it. We haven’t seen that,” Cox said in a weekend interview with ABC4 in Salt Lake City. “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.”

Already, some cities across the country have gotten rid of fluoride from their water, and other municipalities are considering doing the same. A few months ago, a federal judge ordered the U.S. Environmental Protection Agency to regulate fluoride in drinking water because high levels could pose a risk to kids’ intellectual development.

A Utah teenager who urged lawmakers to pass the bill described suffering a medical emergency when the fluoride pump in Sandy, Utah, malfunctioned in 2019, releasing an excessive amount of the mineral into the drinking water. The fluoride sickened hundreds of residents and led many in Utah to push for its removal.

It’s rare to find high levels of fluoridation in water, according to the National Institutes of Health. The agency said it’s “virtually impossible” to get a toxic dose of fluoride from water with standard levels of the mineral.

Kessler said the amounts of fluoride added to drinking water have been reduced over time and are below levels considered problematic.

“The science proves that it is effective at reducing cavities with little to no risk of other problems,” he said.

He added that a ban in Utah could have a domino effect with other legislatures being encouraged to follow suit with fluoride bans in their states.

Opponents warned it would disproportionately affect low-income residents who may rely on public drinking water having fluoride as their only source of preventative dental care. Low-income families may not be able to afford regular dentist visits or the fluoride tablets some people buy as a supplement in cities without fluoridation.

Fluoridation is the most cost-effective way to prevent tooth decay on a large scale, said Lorna Koci, who chairs the Utah Oral Health Coalition.

Utah in 2022 ranked 44th in the nation for the percentage of residents that receive fluoridated water, according to data from the Centers for Disease Control and Prevention. About two in five Utah residents served by community water systems received fluoridated water.

In February, the city council in Riverton, a Salt Lake City suburb, unanimously passed a resolution to remove fluoride from the city’s public water systems. Voters in Brigham City, 59 miles (95 kilometers) north of the capital city, struck down by a large margin a measure in 2023 that would have removed the mineral from its public water supply.

Out of the 484 Utah water systems that reported data to the CDC in 2024, only 66 fluoridated their water, an Associated Press analysis showed. The largest was the state’s biggest city, Salt Lake City.

Rodney Thornell, president of the Utah Dental Association, began practicing dentistry in a Salt Lake City suburb before the city added fluoride to its water. His adult patients who grew up locally continue to get lots of cavities but younger patients who grew up with fluoride in the water get fewer, he said.

“If we’re going to keep eating sugar, we need fluoride.” Thornell said, noting that Utah residents consume more than the national average of candy and sugary drinks.

Brown reported from Billings, Montana.