Fluoridated drinking water has been hailed as one of the Top 10 public health achievements of the 20th century by the Centers for Disease Control and Prevention (CDC).

Now he is called by Robert F. Kennedy, Jr.– perhaps poised to become responsible for health initiatives for the new presidential administration – as a practice that should end. He recently stated that Donald Trump would push to eliminate fluoride from drinking water on his first day in office.

This weekend, Trump told NBC News he had not discussed the matter with Kennedy, saying, “but it seems OK to me.” You know it’s possible.

On Wednesday morning, Kennedy spoke with NPR, noting on the morning edition“We don’t need fluoride in our water. This is a very bad way to introduce it into our systems.

Below, a look at fluoride in drinking water, its controversial history, and what the science says.

What is fluoride?

Fluoride is the chemical ion of the mineral fluorine. It is naturally present in trace amounts, depending on CDCin soil, water, plants and some food sources, including plants and animals. It can also be released through volcanic emissions or as a byproduct of the manufacturing of aluminum, fertilizers and iron ore.

Once inside the body, depending on the Office of Dietary Supplements of the National Institutes of Healthapproximately 80% of what is ingested is absorbed into the gastrointestinal respiratory tract, of which approximately 50% is retained in the body of adults (all but 1% is stored in bones and teeth) and the remaining 50% is excreted in urine. In young children, up to 80% of absorbed fluoride is retained, as more is absorbed through bones and teeth than in adults.

Why is there fluoride in drinking water?

Fluoride is used to prevent or reverse tooth decay and stimulate new bone formation, according to the NIH.

In 1945, Grand Rapids, Michigan. became the first city around the world to fluoridate their drinking water. This followed one doctor’s research into fluoride and fluorosis (the discoloration of tooth enamel due to excess fluoride) and his intuition that safe levels could serve to prevent tooth decay.

Grand Rapids fluoridation has become a 15-year project, according to the National Institute of Dental and Craniofacial Researchwith researchers monitoring the rate of tooth decay in 30,000 schoolchildren; after 11 years, it was found that the rate of cavities among Grand Rapids children born after fluoride was added to the water supply had dropped by more than 60 percent. This discovery was considered a scientific breakthrough that could revolutionize dental care.

Since 1962, the U.S. 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 notesthe recommended concentration, which is not enforceable and is a decision made at the local and 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, sticks the fluoride to the tooth surface, according to at the CDCand increases the amount of fluoride in saliva, which helps rebuild the outer layer of enamel.)

Today, fluoridated municipal drinking water, including tap water and foods and beverages prepared with municipal drinking water, accounts for approximately 60% of fluoride intakes in the United States. In 2022, notes the CDCMore than 209 million people, or 72.3% of the U.S. population served by a public water supply, have had access to water with fluoride levels that prevent tooth decay.

Chemicals used to fluoridate drinking water in the United States, according to the NSFare fluorosilicic acid, sodium fluorosilicate and sodium fluoride, which are byproducts of the manufacture of phosphate fertilizer.

The CDC has a Web page which lists fluoride levels in tap water by county.

Is fluoride in drinking water safe?

Yes, says the CDC, which published a declaration on the safety and effectiveness of fluoridated water earlier this year.

He noted: “The safety and benefits of fluoride are well documented and have been reviewed extensively by several scientific and public health organizations. The United States Public Health Service; the UK National Institute for Health Research, Center for Reviews and Dissemination, University of York; and the National Health and Medical Research Council of Australia have all conducted scientific reviews by expert panels and concluded that community water fluoridation is a safe and effective way to promote good oral health -dental and prevent cavities. THE US Task Force on Community Preventive Servicesbased on systematic analyzes of the scientific literature, issued a strong recommendation in 2001, and again in 2013, in favor of community water fluoridation for the prevention and control of dental caries.

Why is fluoride in tap water controversial?

In his comment posted at X on November 2Kennedy wrote: “Fluoride is an industrial waste associated with arthritis, bone fractures, bone cancer, IQ loss, neurodevelopmental disorders, and thyroid disease. »

Although it may be correct about its source, the CDC in its recent statement disputes the health risks cited by Kennedy, noting that the only potential risk is fluorosis due to excess fluoride over a long period of time. period of time.

“Expert panels composed of scientists from the United States and other countries, with expertise in various health and scientific disciplines,” he noted, “reviewed the evidence available in the peer-reviewed literature and did not find convincing scientific evidence linking community water fluoridation to community water fluoridation. any potential adverse health effects or systemic disorders such as increased risk of cancer, Down syndrome, heart disease, osteoporosis and bone fracture, immune disorders, low intelligence, kidney disorders, disease Alzheimer’s or allergic reactions.

That’s not to say that adding fluoride to water hasn’t been controversial for all these years — since the late 1940s, when far-right activists in U.S. politics claimed that fluoridation was part of a larger plot to impose a socialist or communist regime.

More recently, in 2016, a Harvard Public Health Article questioned the safety of fluoridated drinking water, raising possibilities of brain toxicity, based on studies in laboratory animals and other studies linking it to learning, memory and cognitive deficits .

The story sparked an avalanche of letters, some supportive, including from the dentist, researcher and former chair of the department of preventive dentistry at the University of Toronto, who worked for years on a research project. full scientific review fluoride toxicity. He note“I was trained in traditional dentistry and for many years accepted the prevailing view of the dental/medical establishment in Canada and the United States that water fluoridation is “safe and effective” …I was wrong.

But many other responses were harshly critical of the article, like a from a group of dental professionals, including the dean of the Harvard School of Dental Medicine, calling for its reversal and providing pages of evidence explaining where the article had gone wrong.

According to at the NIHHigh doses of fluoride – usually due to rare accidents related to excessively high levels of fluoridated water or accidental ingestion of fluoridated dental products intended for topical use – can cause nausea, vomiting, abdominal pain, diarrhea, periostitis and, rarely, even death. But such an acute dose, the NIH notes, “would be virtually impossible to obtain with 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’s “extremely rare” in the United States, the NIH notes, with no evidence that it’s due to the recommended level of fluoride in tap water.

Additionally, adds the NIH, while one study found an association between a mother’s higher urinary fluoride concentration during pregnancy and higher rates of neurobehavioral problems in a child at age 3, another similar study does not found no such association.

Regarding the claim that higher fluoride intakes during early development are associated with lower IQ and other cognitive impairments, the NIH adds, researchers, including those behind a study of the National Academies of Sciences, Engineering, and Medicine, consider the evidence weak and methodologically flawed.

Finally, regarding the fluoride and bone cancer claims, the American Cancer Society (ACS) points out that many systematic studies of this link have yielded “inadequate” conclusions and “no clear association.” He notes that part of the controversy over the possible link stems from an old (1990) study in laboratory animals that found a higher than expected number of osteosarcomas – a rare bone cancer – in rats from male lab drinking fluoridated water.

Meanwhile, numerous population-based studies have examined the potential link between water fluoride levels and cancer and “have not found a strong link to cancer,” the ACS reports.

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This story was originally featured on Fortune.com