Fluoride has a controversial history. So, what is fluoride, and should we worry about potential risks?
Fluoride is a naturally occurring element that has been added to drinking water in some areas of the United States since the 1940s.
This element is endorsed by the American Dental Association, the American Academy of Pediatrics, and the Canadian Dental Association for its effectiveness in preventing tooth decay.
The Centers for Disease Control and Prevention (CDC) lists the addition of fluoride to water – adjusting fluoride levels in municipal water supplies – as one of the top 10 public health achievements.
However, fluoride has a controversial history. So, what is fluoride, and should we worry about potential risks?
What is Fluoride?
Fluoride is a natural element found in soil, rocks, and water.
“All water sources contain a certain amount of fluoride” – Steven Levy, Professor of Preventive and Community Dentistry at the University of Iowa, states. It can even be found in tea.
Consuming foods that contain refined carbohydrates – such as bread, yogurt, or fruit – allows bacteria to produce acid that demineralizes the surface of teeth, creating tiny cavities.
“Fluoride helps accelerate and enhance the remineralization process, which is why most people never get cavities” – he adds.
Some countries, including the United States, the United Kingdom, Spain, and Brazil, have local jurisdictions that add fluoride to water to prevent tooth decay. Germany has been adding fluoride to salt since 1991.
“All water sources contain a certain amount of fluoride.”
Fluoride Supplementation in Water
In the early 1900s, researchers discovered that individuals in areas with naturally high fluoride levels in their drinking water were more likely to suffer from dental fluorosis. This condition often affects children “exposed to” excessive fluoride while their teeth are still developing.
Dental fluorosis is a condition characterized by “mottled enamel” – according to John Morris, a senior lecturer in dental public health at the University of Birmingham in the UK.
Cheryline Pezzullo, a Professor at the New York University College of Dentistry, explains that this condition causes teeth to have white spots or streaks.
However, individuals with fluorosis also tend to have significantly lower rates of tooth decay due to the naturally low fluoride content in their water.
American scientists concluded that, at concentrations of about one part per million, fluoride in water provides protection against tooth decay without causing fluorosis. Today, the recommended concentration in the U.S. is 0.7 parts per million, as people also “absorb” fluoride from toothpaste and mouthwash.
Safe Dosage
Fluoride is a natural component of bones.
“No vertebrate animals – humans or other animals – lack fluoride in their bones” – Howard Pollick, a dental scientist at the University of California, San Francisco, states. Long-term exposure to fluoride at concentrations above four parts per million can lead to skeletal fluorosis, weakening bones.
This figure significantly exceeds the World Health Organization (WHO) recommendation of 1.5 milligrams per liter, as well as the recommendation of the U.S. Public Health Service of 0.7 milligrams.
Morris mentions that the “sufficient” amount to develop skeletal fluorosis might come from “drinking a lot of tea or “ingesting” multiple tubes of toothpaste every day.” Any substance can be toxic at high concentrations – even water. Pollick adds, “The issue is not the substance, but the dosage.”
Concerns About Fluoride
People have been concerned about fluoride ever since it was first added to water. Some oppose it due to fears of fluoride gas being lethal, while proponents worry that people will now rely solely on fluoride in water and neglect brushing their teeth – Pollick says.
There are also concerns about the cancer risk. A 1990 study showed an increase in bone tumors in mice when given “high” concentrations of fluoride.
However, a report from the Public Health Service, based on more than 50 population studies, found no “detectable cancer risk for humans” at low fluoride concentrations.
(Source: The New York Times/National Geographic).
Recently, there has been a debate regarding the link between fluoride exposure and children’s IQ (intelligence quotient). A 2021 study correlated high fluoride exposure with lower IQ in boys, while a 2023 meta-analysis found no connection.
A report from the National Toxicology Program has “moderate confidence” that fluoride levels above the WHO recommendation may impact children’s IQ.
Preventing Tooth Decay
While the rate of tooth decay has decreased, it remains “one of the most common chronic diseases, and remember that [tooth decay] is entirely preventable in children” – Morris states. He emphasizes that tooth decay affects children’s learning, diet, and overall development.
After the city of Calgary in Canada removed fluoride from its water, the situation of tooth decay among children worsened.
For those who do not have easy access to or cannot afford dental care, tooth decay is a significant “burden”.
Pezzullo notes: “Tooth decay can lead to infections and pain, and those infections can spread to other parts of the body.”
Levy adds that adding fluoride to water is a cost-effective preventive method. “All you have to do is drink water.”
The Controversy Surrounding Fluoride
Fluoride can be a contentious topic, particularly in the United States. Some in the 1950s claimed it was a “conspiracy” to poison America, while many others argued it was a way for the sugar industry to sell more sweets.
There has been strong backlash against fluoride since the first adjustments of its concentration in water. Morris states: “I think discussing adding something to the water is quite a sensitive issue for some people.”
“People feel it infringes on personal freedom” – Pezzullo adds.
Morris mentions that other public health decisions – such as vaccine issues and seatbelt laws – have also faced similar opposition. “The development of clean drinking water in the 19th century was also quite controversial.”
He states: “We should not dismantle [public health programs] based on the opinions of a minority.”
Pollick agrees, stating: “Overall, the scientific community has a consensus in supporting the appropriate and sensible use of fluoride.”
