More than half of Californians and nearly 75% of U.S. residents live in communities where fluoride has been added to drinking water to prevent tooth decay, an intervention hailed by the U.S. Centers for Disease Control as one of the interventions of the 20th century. greatest achievements in public health.

Yet if Donald Trump were elected to a second term, water systems would be immediately asked to end the practice, according to his supporter Robert F. Kennedy Jr.

“On January 20, the Trump White House will advise all U.S. water systems to eliminate fluoride from public water,” Kennedy said. posted Saturday on the social media platform

Kennedy described the mineral, found naturally in all freshwater supplies, as an “industrial waste” associated with various health risks.

Sunday, Trump told NBC News that he had not discussed the fluoride proposal with Kennedy, “but it seems OK to me.” Reached for comment Monday, a campaign spokesperson told the Times that while Trump “has received a variety of policy ideas, he is focused on Tuesday’s election.”

Kennedy’s statement follows a September ruling by a federal judge in California that could have major effects on the long-standing public health intervention, but that several dentists and pediatricians say is based on a reading erroneous from the available science.

In his X post, Kennedy tagged Michael Connett, the lead attorney representing the plaintiff in that lawsuit, the advocacy group Food & Water Watch.

In late September, U.S. District Judge Edward Chen ordered the U.S. Environmental Protection Agency to take unspecified new steps to regulate fluoride in drinking water.

In his decision, Chen quoted a literature review by the United States National Toxicology Program that found associations between exposure to high levels of fluoride and lower IQ levels in children.

Although he could not “conclude with certainty that fluoridated water is harmful to public health,” Chen wrote, he nonetheless determined that it posed an “unreasonable risk” of harm. Its decision does not specify exactly what the EPA should do about it.

The American Dental Association. and the American Academy of Pediatrics published a joint declaration concern after the decision, saying there were major limitations in the study Chen quoted. The groups pointed out that the study found associations of low IQ only at fluoride concentrations more than double those of the current recommendation of 0.7 milligrams per liter.

“There is nothing in the current decision that changes my confidence in the safety of optimally fluoridated water in the United States,” Dr. Charlotte W. Lewis, a member of the Section of the AAP on oral health. “Water fluoridation is a public health policy based on solid evidence. »

In California, a scientifically shaky skepticism about fluoridated water has existed for almost as long as these substances have been coming out of taps.

In 1952, San Francisco and Antioch became the first communities in California to supplement natural levels of fluoride in their drinking water, after a series of studies showed that the mineral made tooth enamel stronger and more resistant to acid. In a decade, cavities on the permanent teeth of 6-year-old children have decreased by 84%.

The United States Public Health Service recommended in 1962 a fluoridation level of 0.7 to 1.2 mg per liter in the drinking water supply. (In 2015, the service revised It is recommendation at 0.7 mg per liter — an ideal level that maximizes dental health benefits while reducing the risk of tooth discoloration associated with excessive fluoride exposure.)

Yet as the number of California communities voting to fluoridate their water increased, so did complaints from skeptics who supported debunked theories about the link between fluoride and cancer, AIDS and other illnesses, according to a report. history by Ernest Newburn, professor of oral biology at UC San Francisco.

Despite California’s early leadership in water fluoridation, it now ranks 39th among U.S. states in percentage of population covered by fluoridated water systems, with 57.5% of residents living in covered communities, according to the United Health Foundation. (Kentucky tops the rankings with 99.9% coverage.)

An exploration study published this year found associations between prenatal fluoride exposure and increased risk of neurobehavioral problems at age 3 in a cohort of 229 children from the Los Angeles area.

The American Dental Assn., the American Academy of Pediatrics and others have pushed back on the study, citing concerns about the methods used to assess both children’s IQ and maternal fluoride levels.

“It is irresponsible for the authors, based on this study, to suggest that recommendations be changed on the beneficial use of fluoride to prevent dental problems,” said Howard Pollick, a professor at the school of medicine Dental from UC San Francisco. shortly after the study was published.

A larger study published last year, followed more than 2,000 children in Australia for five years and found no association between prenatal fluoride exposure and behavioral development problems.

Trump and Kennedy have said publicly that Kennedy, a longtime anti-vaccine activist, would likely play a leading health policy role in a second Trump administration.

“I’m going to let it run wild on health. I’m going to let him run wild with the food. I’m going to let him run wild with the meds. Trump told his supporters during a rally at Madison Square Garden last month.

The Associated Press contributed to this report.