Fluoridated drinking water has been rated as one of the top 10 public health achievements of the 20th century by the Centers for Disease Control and Prevention (CDC).
It is now being called by Robert F. Kennedy, Jr. — perhaps on track to become the head of health initiatives for the next presidential administration — as a practice that must be stopped. He recently claimed that Donald Trump would push for the removal of fluoride from drinking water on his first day in office.
Over the weekend, Trump told NBC News that he had not discussed the matter with Kennedy, saying, “But I think it’s OK. You know it’s possible.”
On Wednesday morning, Kennedy spoke to NPR, noting on Morning Edition, “We don’t need fluoride in our water. It’s a very bad way to distribute it in our systems.”
Below, a primer on fluoride in drinking water, its history of controversy, and what the science says.
What is fluoride?
Fluorine is the chemical ion of the mineral fluorine. It is present naturally in small amounts, according to the CDC, in soil, water, plants and some food sources, including plants and animals. It can also be released from volcanic emissions or as a by-product of aluminum, fertilizer and iron ore production.
Once inside the body, according to the National Institutes of Health’s Office of Dietary Supplements, approximately 80% of what is ingested is absorbed in the gastrointestinal tract, with about 50% stored in the body in adults—all but 1% deposited in bones and teeth— and the other 50% is excreted in the urine. In young children, up to 80% of absorbed fluoride is retained, as more is absorbed by bones and teeth than in adults.
Why is fluoride in drinking water?
Fluoride serves to prevent or reverse tooth decay and stimulate new bone formation, according to the NIH.
In 1945, Grand Rapids, Mich. became the first city in the world to fluoridate its drinking water. This came after a doctor’s research into fluoride and fluorosis – the discoloration of tooth enamel from an excess of fluoride – and his hunch that safe levels could serve to prevent tooth decay.
The Grand Rapids fluoridation became a 15-year project, according to the National Institute of Dental and Craniofacial Research, with researchers monitoring tooth decay rates among 30,000 schoolchildren; after 11 years, it was found that the cavity rate among Grand Rapids children born after fluoride was added to the water supply dropped more than 60%. It was considered a scientific breakthrough that could revolutionize dental care.
Since 1962, the US Public Health Service has recommended adding fluoride to tap water to reduce the risk and severity of tooth decay, according to the NIH. Currently, the CDC notes, the recommended concentration — which is not enforceable and is a decision made at a local, not federal, level — is 0.7 mg/L. The CDC says drinking fluoridated water keeps teeth strong and reduces cavities by about 25% in children and adults. (Another common source of fluoride is toothpaste, which, when you brush with it, attaches fluoride to the surface of the tooth, according to the CDC, and increases the amount of fluoride in saliva, which helps rebuild the outer layer of tooth enamel. enamel.)
Today, fluoridated municipal drinking water—including tap water and foods and beverages prepared with municipal drinking water—accounts for about 60% of fluoride intake in the U.S. By 2022, the CDC notes, more than 209 million people, or 72.3% of the US population served by public water supplies had access to water with fluoride levels that prevent tooth decay.
The chemicals used to fluoridate drinking water in the United States, according to the NSF, are fluorosilicic acid, sodium fluorosilicate, and sodium fluoride, which are byproducts of phosphate fertilizer production.
The CDC has a website that lists fluoride levels in tap water by county.
Is fluoride in drinking water safe?
Yes, says the CDC, which issued a statement on the safety and efficacy of fluoridated water earlier this year.
He noted, “The safety and benefits of fluoride are well documented and have been comprehensively reviewed by several scientific and public health organizations. US Public Health Service; UK National Institute for Health Research, Center for Reviews and Dissemination, University of York; and the National Health and Medical Research Council, Australia have all carried out scientific reviews by expert panels and concluded that community water fluoridation is a safe and effective way to promote good oral health and prevent decay. The US Community Preventive Services Task Force, based on systematic reviews of the scientific literature, issued a strong recommendation in 2001 and again in 2013 for community water fluoridation for the prevention and control of dental caries.
Why is fluoride in tap water controversial?
In his commentary posted on X on Nov. 2, Kennedy wrote, “Fluoride is an industrial waste linked to arthritis, bone fractures, bone cancer, IQ loss, neurodevelopmental disorders, and thyroid disease.”
While he may be right about his source, the CDC, in its latest statement, disputes the health risks Kennedy raises, noting that the only potential risk is fluorosis from too much fluoride over a long period of time. time.
“Expert panels composed of scientists from the United States and other countries, with expertise in various health and scientific disciplines,” he noted, “have considered the available evidence in the peer-reviewed literature and found no evidence convincing scientific evidence linking community water fluoridation to any potential negative health effects or systemic disorders, such as increased risk for cancer, Down syndrome, heart disease, osteoporosis and bone fractures, immune disorders, low intelligence, kidney disorders, Alzheimer’s disease or allergic reactions.
That’s not to say that adding fluoride to water has been without controversy all these years—starting in the late 1940s, when activists on the far right of American politics claimed that fluoridation was part of a broader conspiracy to impose a socialist or communist regime.
As recently as 2016, a Harvard Public Health article called into question the safety of fluoridated drinking water, raising the possibility of brain toxicity, based on laboratory animal studies and other studies linking it to learning, memory and cognitive deficits.
The story prompted a flurry of letters — some supportive, including from the dentist, researcher and former director of Preventive Dentistry at the University of Toronto, who worked for years on a comprehensive scientific review of fluoride toxicity. He noted, “I was trained in traditional dentistry and for many years accepted the prevailing opinion of the dental/medical establishment in Canada and the US that water fluoridation is ‘safe and effective’…was wrong.”
But many other responses were harshly critical of the article, with one from a group of dental professionals, including the dean of the Harvard School of Dental Medicine, calling for it to be retracted and offering pages of evidence of where the article went wrong.
According to the NIH, high doses of fluoride — usually from rare accidents with excessively high levels of fluoridated water or accidental ingestion of topical fluoride dental products — can result in nausea, vomiting, abdominal pain, diarrhea , periostitis and even. rarely, death. But such an acute dose, the NIH notes, “would be virtually impossible to achieve from water or toothpaste containing standard levels of added fluoride.”
Another possible result of chronic, excessive fluoride intake is skeletal fluorosis, which can lead to symptoms ranging from joint pain to osteoporosis and muscle wasting. But it is “extremely rare” in the US, the NIH notes, with no evidence that it is caused by the recommended level of fluoride in tap water.
Further, the NIH adds, while one study found an association between higher maternal urinary fluoride concentrations in pregnancy with higher rates of neurobehavioral problems in a child at age 3, another similar study did not find a such connection.
Regarding the claim that higher fluoride intake during early development is associated with lower IQ and other cognitive impairments, the NIH adds, researchers including those behind a National Academies of Sciences, Engineering and Medicine review consider the evidence as weak and methodologically flawed.
Finally, regarding fluoride and bone cancer claims, the American Cancer Society (ACS) states that many systematic reviews of the link have found “inconclusive” conclusions and “no clear link.” He notes that some of the controversy surrounding the possible link stems from an older (1990) study of lab animals that found a higher-than-expected number of osteosarcomas — a rare bone cancer — in male lab rats that drank fluoridated water.
Meanwhile, many population-based studies have looked at the possible link between water fluoride levels and cancer and “have not found a strong association with cancer,” the ACS reports.
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