Editor’s note (November 14th): This story was updated after Mr Trump nominated Mr Kennedy to be his secretary of health.
Donald Trump, America’s president-elect, promised to let Robert F. Kennedy junior “go wild” with health care. Mr Kennedy, a presidential candidate who dropped out of the race in August and endorsed Mr Trump, may have just got one step closer to doing that. On November 14th Mr Trump picked him to be the secretary of health in his incoming administration (though his appointment will require confirmation by the Senate).
Mr Kennedy has vowed to “make America healthy again”. But, worryingly, he peddles many falsehoods, including the idea that childhood immunisations are linked to autism. Now he has fluoride in his sights: Mr Kennedy wants the federal government to ban the stuff from America’s water supply on the day Mr Trump is sworn in. Not all scientists dismiss Mr Kennedy’s ideas on this issue as crackpot. Should Americans take his concern about the mineral seriously?
Fluoride helps prevent tooth decay. It occurs naturally in some foods—tea, potatoes and shrimp, for example—and in some water. In 1945 Grand Rapids, in Michigan, became the first American city to add it to its drinking water. Today more than two-thirds of Americans have water with added fluoride piped into their homes.
After fluoridation began dental problems among children decreased greatly. Between 1966 and 1994 the average number of decayed, missing or filled teeth that children had by the age of 12 fell by 68%. The Centres for Disease Control and Prevention (CDC) lists fluoridating water as one of the top ten public-health achievements of the 20th century. It is particularly helpful for children with poor diets who don’t have regular dental appointments. In 2020 the Department of Health and Human Services (HHS) vowed to increase the percentage of Americans with fluoridated tap water to more than three-quarters within ten years.
But Mr Kennedy wants to pull the plug—and some scientists think there are good reasons to do so. At the very least, fluoridating water may be redundant. Some studies conducted after 1975, by which time fluoride had become a common ingredient in toothpaste, have found that fluoridated water has a very small benefit or none at all. (Others have found the opposite: that fluoridated water is significantly better for children’s dental health.) Worse, consumed in very high quantities the mineral can have harmful effects. Some of the consequences, such as dental fluorosis, which causes white spots or lines on children’s teeth, are largely cosmetic. Others are more serious: skeletal fluorosis deforms and weakens bones. But it is vanishingly rare in America—in 2004 HHS said only five such cases had ever been reported.
Mr Kennedy is more concerned that excessive fluoride consumption could lower IQ. As far-fetched as that sounds, it is something scientists are investigating. A report by the National Toxicology Programme within HHS found that high levels of fluoride exposure, at twice the legal limit, were associated with lower IQ in children. Other researchers found that even fluoride levels within the legal range were associated with that risk. And one study of American mothers found that pregnant women who drank fluoridated water were more likely to give birth to children with lower IQs.
These studies do not prove that consumption of fluoride lowers IQ; they show a correlation. More research is needed to draw firm conclusions. A federal judge in San Francisco recently ruled that the Environmental Protection Agency must review the potential risk posed by fluoridated drinking water. Mr Kennedy, by contrast, seems inclined to ban fluoride first and ask questions later. But a speedy ban will almost certainly be impossible. At present local governments decide whether to fluoridate water, an approach to governing which Republicans usually support. A federal ban would probably take years to get through the rule-making process, which would require more scientific evidence to back it up. If the government tried to hurry things along, it would increase the likelihood of legal challenges from opponents, such as the American Dental Association. Such challenges are already highly likely. The process may start on day one of a Trump administration—but banning fluoride would be like pulling teeth.
© 2025, The Economist Newspaper Limited. All rights reserved. From The Economist, published under licence. The original content can be found on www.economist.com