With a new law, signed by Gov. Spencer Cox on March 27, Utah has become the first U.S. state to ban the addition of fluoride to public drinking water, The New York Times reported. The law will go into effect on May 7, 2025.

This new legislation arrives as fluoride faces increased scrutiny. Since 1945, this mineral has been widely added to U.S. drinking water to prevent cavities. While the safety of water fluoridation has been debated since the 1940s, recent years have seen heightened concerns.

Most concerns with adding fluoride to public drinking water revolve around potential cognitive effects in children. A recent review of studies suggested a link between high levels of prenatal or childhood fluoride exposure and lower IQ scores in children.

However, Scott Tomar, M.D., a public health dentist and oral epidemiologist at the University of Illinois Chicago, told The Times that levels associated with cognitive problems are twice as high as those typically encountered through community water fluoridation.

The bill does not specifically mention any health concerns relating to fluoridation, according to The Times. Gov. Cox has previously claimed the oral health benefits of water fluoridation have been insubstantial in Utah, adding that in 2022, about half of Utah residents had fluoridated public drinking water and half did not, but there were no drastically different outcomes between the two groups.

That claim, however, runs counter to published research, according to The Times. Studies suggest that fluoridation improves oral health. In a systematic review of 20 studies published in 2007, researchers found a 27% decline in cavities associated with water fluoridation among adults. Furthermore, a 2018 study revealed that water fluoridation led to a 30% reduction among children.

Tomar voiced his concern that the Utah law, along with other potential bans, may result in a rise in oral health issues nationwide, particularly in underserved communities.

“The benefits of community water fluoridation are most pronounced in low-income communities—communities that often have the least access to dental care and to other sources of fluoride,” Tomar said. Fluoride bans, he added, are “misguided on a number of levels.”

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