SALT LAKE CITY — Utah has become the first state to ban fluoride in public drinking water, over opposition from dentists and national health organizations who warn the move will lead to medical problems and disproportionately affect low-income communities.

Republican Gov. Spencer Cox signed legislation Thursday 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.

Utah lawmakers who pushed for a ban said putting fluoride in water was too expensive. Cox, who grew up and raised his own children in a community without fluoridated water, compared it recently to being “medicated” by the government.

The ban, which is effective May 7, comes weeks after U.S. Health Secretary Robert F. Kennedy Jr., who has expressed skepticism about water fluoridation, was sworn into office.

The American Dental Association sharply criticized Cox and Utah lawmakers, saying the ban showed “wanton disregard for the oral health and well-being of their constituents.”

The group said that cavities are the most common chronic childhood disease.

“As a father and a dentist, it is disheartening to see that a proven, public health policy, which exists for the greater good of an entire community’s oral health, has been dismantled based on distorted pseudoscience,” said the association’s president, Denver dentist Brett Kessler.

Lawmakers in states including Ohio, South Carolina and Florida also have made proposals to restrict local governments or water system operators from adding fluoride to water.

Proposed restrictions on fluoridation in New Hampshire, Tennessee and North Dakota were rejected. A measure in Kentucky to make fluoridation optional stalled in the state Senate.

Fluoridation is considered the most cost-effective way to prevent tooth decay on a large scale. More than 200 million people in the U.S., or almost two-thirds of the population, receive fluoridated water through community water. 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.

But 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 the intellectual development of children.

The president of the American Dental Association, Brett Kessler, has said the amounts of fluoride added to drinking water are below levels considered problematic.

The National Institutes of Health says very high doses of fluoride that can cause sickness are typically the result of rare accidents, such as the unintentional swallowing of fluoride use by dentists’ offices or supplements inappropriately given to children. The agency says it’s “virtually impossible” to get a toxic dose that could cause systemic health problems from fluoride that’s added to water or toothpaste at standard levels.

Opponents warn the ban will 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.

The sponsor of the Utah legislation, Republican Rep. Stephanie Gricius, acknowledged fluoride has benefits, but said it was an issue of “individual choice” to not have it in the water.

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

Utah in 2022 ranked 44th in the nation for the percentage of residents that receive fluoridated water, according to the data from the Centers for Disease Control and Prevention.