Fluoride — long hailed as one of the greatest public health achievements of the 20th century — was able to be removed from public water systems under the influence of an adviser to President-elect Donald Trump, Robert F. Kennedy Jr.

Kennedy – who has no training in medicine or dentistry – called fluoride on the social media platform X “an industrial waste linked to arthritis, bone fractures, bone cancer, IQ loss and other problems.”

“I think fluoride is on the way out,” Kennedy said Wednesday on MSNBC. “The quicker it goes out, the better.”

Whether fluoride is added to the water supply is decided and funded by local jurisdictions, not the federal government. Still, Kennedy said that if it were tapped, he would educate communities about fluoridated water.

Dentists who care about children’s oral health say ending fluoridated drinking water would be harmful.

“It won’t happen immediately, but as children continue to grow and develop, they will have increased rates of tooth decay,” said Dr. Meg Lochary, a pediatric dentist in Waxhaw, North Carolina, an area that recently decided against adding fluoride to water systems. “At some point we will see an increase in tooth decay.”

According to the Centers for Disease Control and Prevention, fluoride exposure from community water supplies is particularly important for families who lack dental care.

While an estimated 75% of Americans have fluoridated drinking water, hundreds of U.S. communities are increasingly opting out of water fluoridation.

Caught in the middle are parents trying to understand the very different views on added fluoride. Is it good? Is it bad? Let’s break it down.

What are the benefits of fluoride?

The mouth is teeming with bacteria that produce acid in saliva. These acids weaken teeth and lead to tooth decay. Fluoride delivers a one-two punch to this process by reducing acid and strengthening enamel, the protective outer layer of the tooth.

The phenomenon was discovered among residents of Colorado Springs, Colorado, in the early 1900s. Caries was almost non-existent in the population. The only explanation for this was their drinking water, which was naturally high in fluoride, leached from the local rocks and soils.

Grand Rapids, Michigan, became the first community in the world to add fluoride to its water supply in 1945. Within a decade, tooth decay among young children in the city fell by 60%. Other public water systems followed.

Major health groups, including the American Dental Association, the American Academy of Pediatrics and the CDC, soon supported the use of fluoridated water. All cite studies showing it reduces tooth decay by 25%.

Tooth decay prevention is a major public health coup, experts say. Uncontrolled tooth decay can lead to infections, tooth loss and painful abscesses.

Are there risks from fluoride?

Despite decades of studies and real-world evidence of its benefits, fluoride continues to face scrutiny.

To date, there is no convincing evidence that fluoridated water leads to the effects mentioned by Kennedy, including loss of intelligence.

“There is no evidence that fluoride has lowered children’s IQs,” said Dr. David Margolius, Cleveland public health director.

However, there are a few small studies worth mentioning.

Research published in May suggests that fluoride exposure during pregnancy may be linked to neurobehavioral problems in children. However, the study’s authors said the results make it premature to stop adding the cavity-fighting mineral to drinking water.

A 2019 study published in JAMA Pediatrics found that IQs were slightly lower in 3- and 4-year-old children whose mothers had higher levels of fluoride in their urine during pregnancy.

While the researchers said it might be time to put a pause on water fluoridation, they didn’t say the mineral should be removed from water supplies.

In September, a federal judge in California ruled that the U.S. Environmental Protection Agency should tighten regulations on water fluoridation, even though he could not determine with certainty that fluoridated water poses a threat to public health.

What should parents do?

Experts claim there is no credible evidence that fluoride has lowered children’s IQs.

With science in mind, parents should be able to ask questions about what their children are consuming, Dr. Richard Besser, former acting CDC director and current president of the Robert Wood Johnson Foundation.

“Every parent should feel very comfortable asking their child’s doctor, ‘How should I manage fluoride to protect my child’s teeth?'” Besser said. “These are reasonable questions, but to say that fluoride has no value contradicts the science and the evidence.”