PHOENIX (AP) — Robert F. Kennedy Jr., a prominent proponent of debunked public health claims over whom Donald Trump has promised to lead health initiativessaid Saturday that Trump would push to remove fluoride from drinking water on his first day in office if elected president.

Fluoride strengthens teeth and reduces cavities replacing minerals lost during normal wear and tearaccording to the U.S. Centers for Disease Control and Prevention. 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.

Kennedy the declaration was made Saturday on the social media platform X next to all kinds of claims about the health effects of fluoride.

“On January 20, the Trump White House will advise all U.S. water systems to remove fluoride from public water,” Kennedy wrote. Trump and his wife, Melania Trump, “want to make America healthy again,” he added, repeating a phrase Trump often uses and linked to Kennedy.

Trump told NBC News on Sunday that he had not yet discussed fluoride with Kennedy, “but it sounds good to me. You know it’s possible.”

The former president declined to say whether he would seek a Cabinet role for Kennedy, a job that would require Senate confirmation, but added: “He’s going to play a big role in the administration.”

When asked whether banning certain vaccines would be on the table, Trump said he would talk to Kennedy and others about it. Trump described Kennedy as “a very talented man and has strong views.”

The sudden and unexpected weekend social media post evoked the chaotic policymaking that defined Trump’s tenure in the White House, when he made policy statements on Twitter at virtually all hours. It also underscored the concerns many experts have about Kennedy, who has long promoted debunked theories on the safety of vaccines, which impact American public health.

In 1950, federal officials approved water fluoridation to prevent tooth decay, and continued to promote it even after brands of fluoride toothpaste entered the market several years later. Although fluoride can come from a number of sources, drinking water is the most important source for Americans, researchers say.

Officials reduced their 2015 recommendation for fluoride levels in drinking water to address a dental condition called fluorosis, which can stain teeth and is increasingly common in American children.

A federal agency was established in August certain “with moderate confidence” that there is a link between higher levels of fluoride exposure and lower IQ in children. The National Toxicology Program based its conclusion on studies where fluoride levels were about twice the recommended limit for drinking water.

A federal judge later cited that study order the U.S. Environmental Protection Agency to further regulate fluoride in drinking water. U.S. District Judge Edward Chen cautioned that it is not certain that the amount of fluoride typically added to water causes lower IQ in children, but he concluded that mounting research indicates an unreasonable risk that it could. He ordered the EPA to take steps to reduce that risk, but did not say what those measures should be.

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

Kennedy’s anti-vaccination organization has an ongoing lawsuit against news organizations, including The Associated Press, accusing them of violating antitrust laws by taking action to identify misinformation, including about COVID-19 and COVID-19 vaccines. Kennedy is on leave from the group but is listed as one of the attorneys in the lawsuit.

What role Kennedy could play if Trump wins on Tuesday remains unclear. Kennedy recently told NewsNation that Trump had asked him to “reorganize” agencies, including the U.S. Centers for Disease Control and Prevention, the National Institutes of Health, the Food and Drug Administration and some agencies under the Department of Agriculture.

But for now, the former independent presidential candidate has become one of Trump’s top surrogates. Trump regularly mentions that he has the support of Kennedy, a scion of a Democratic dynasty and the son of former Attorney General Robert Kennedy and nephew of President John F. Kennedy.

Kennedy traveled with Trump on Friday and spoke at his rallies in Michigan and Wisconsin.

Trump said Saturday that he told Kennedy, “You can work on food, you can work on anything you want,” except oil policy.

“He wants health, he wants women’s health, he wants men’s health, he wants children, he wants everything,” Trump added.