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

Republican Gov. Spencer Cox signed legislation Thursday barring cities and communities from deciding whether to add the mineral to their water systems.

Florida, Ohio and South Carolina are considering similar measures, while in New Hampshire, North Dakota and Tennessee, lawmakers have rejected them. A bill in Kentucky to make fluoridation optional stalled in the state Senate.

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

Cavities are the most common chronic childhood disease, the ADA noted. 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.

“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,” the association’s president, Denver dentist Brett Kessler, said in a statement.

Is fluoride unhealthful? Some lawmakers say it is

The ban, effective May 7, brings into the mainstream concerns over fluoridation that for decades were considered fringe opinions.

It comes weeks after water fluoridation skeptic Robert F. Kennedy Jr. was sworn in as U.S. health secretary. Kennedy said in November that the administration of then-presidential candidate Donald Trump would advise water systems nationwide to remove fluoride.

Cox, who grew up and raised his own children in a community without fluoridated water, compared it recently to being medicated by the government. Utah lawmakers also said the ban was a matter of personal health choice and that putting fluoride in water is too expensive.

Florida’s surgeon general last year recommended against community water fluoridation because of what he called its “neuropsychiatric risk.” That guidance came after 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.

Federal officials determined last year “with moderate confidence” that there was a link between higher levels of fluoride exposure and lower IQ in kids. But the National Toxicology Program based its conclusion on studies involving fluoride levels at about twice the recommended limit for drinking water. The amounts of fluoride that can be added to water based on federal guidelines are below levels considered problematic, Kessler said.

It’s nearly impossible to get a toxic dose of fluoride in water, the NIH says

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 used by dentists’ offices or supplements inappropriately given to children. The agency says it’s “virtually impossible” to get a toxic dose from fluoride that’s added to water or toothpaste at standard levels.

However, communities sometimes exceed the recommended levels because fluoride occurs naturally at higher levels in certain water sources. In 2011, officials reported that 2 in 5 U.S. adolescents had at least mild tooth streaking or spottiness because of too much fluoride.

Since 2015, federal health officials have recommended a fluoridation level of 0.7 milligrams per liter of water. For five decades before that, the recommended upper range was 1.2 milligrams per liter. The World Health Organization has set a safe limit for fluoride in drinking water of 1.5 milligrams per liter.

Fluoride is considered one of the greatest health achievements in 100 years

The addition of low levels of fluoride to drinking water has long been considered one of the greatest public health achievements of the past century: one of the most cost-effective ways to prevent tooth decay on a large scale.

In 1950, federal officials endorsed water fluoridation to prevent tooth decay, and they continued to promote it even after fluoride toothpaste brands hit the market several years later. More than 200 million people in the U.S., or almost two-thirds of the population, receive fluoridated public water.

Fluoride in drinking water can reduce cavities by at least 25% for all age groups, according to the Utah Dental Association. Opponents of the Utah legislation to limit fluoridation warn it will have a disproportionately negative effect on low-income residents who may rely on fluoridated water as their only source of preventative dental care.

It’s a matter of personal choice, Utah’s bill sponsor says

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 that in the state’s biggest municipality, Salt Lake City.

Utah in 2022 ranked 44th in the nation for the percentage of residents that receive fluoridated water, according to the CDC data.

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Brown reported from Billings, Montana. Gruver reported from Cheyenne, Wyoming.