What the science really says about fluoride in drinking water

Public health officials clash over conflicting studies weighing the benefits and risks of fluoride, particularly for young children. Almost everyone agrees that it is important for our dental health. The question is how much fluoride we need to protect our teeth without risking cognitive damage.

Recent analyzes suggest that high levels of fluoride may harm the brains of children and developing fetuses. Other studies have found no such evidence. And there is no evidence that fluoride harms adult cognition.

The mineral fluoride is part of the earth’s crust. It exists in all waters and in many foods. In much of the country, additional fluoride is added to public drinking water. It is also found in toothpaste and other dental products.

The decision to add fluoride to drinking water is made by local municipalities. Nearly 20 communities across the country have ended the practice and more are speaking out. Many European countries, including France and Germany, do not fluoridate drinking water.

You can find the fluoride level for certain communities on the Centers for Disease Control and Prevention website.

The benefits of fluoride

Most American public health experts and doctors strongly support adding fluoride to public drinking water to mitigate tooth decay.

Cavities are usually caused by acid destroying tooth enamel. Fluoride helps remineralize these areas, making them more resistant to rot.

In Canada, the city of Calgary stopped adding fluoride to its public water in 2011. A study published in April in the Canadian Journal of Public Health compared Calgary to Edmonton, which continued fluoridation, and found that the rate of general anesthesia for cavity-related treatments was higher in Calgary among more than 2,600 children under the age of 12 between 2010 and 2019. Children aged 5 and under had higher rates higher than older children.

“We found that 65 per cent of children under general anesthesia lived in non-fluoridated areas,” said Maryam Amin, professor and associate chair of research at the University of Alberta and lead author of the study. Calgary resumes fluoridation of its public water. .

Fluoride applied directly to the teeth via toothpaste strengthens tooth enamel and promotes remineralization. Fluoride ingested through water and food is incorporated into the developing enamel of teeth that have not yet emerged, which is why it is especially important for children during their tooth-forming years, Amin says.

Other studies found more cavities and tooth decay in Calgary and Juneau, Alaska, which ended its community water fluoridation program in 2007.

Possible risks of fluoride

A study published last year in the journal Environmental Health linked higher prenatal fluoride exposure to an increase in neurobehavioral problems, such as anxiety or emotional problems, when children reach age 3 years.

The study measured urine fluoride levels in pregnant women in Los Angeles County. It found that women whose levels were at the 75th percentile during pregnancy had children almost twice as likely to exhibit neurobehavioral problems at age 3 as those at the 25th percentile.

The National Toxicology Program evaluates chemicals that are potentially toxic to the government. In August, the organization released a study concluding with “moderate confidence” that higher levels of fluoride exposure are associated with lower IQ in children, although it is not necessarily the cause. High levels were defined as 1.5 milligrams of fluoride per liter. That’s more than twice the U.S. recommended level of 0.7 milligrams per liter.

The conclusion is based largely on research in other places outside the United States where some pregnant women, infants and children are exposed to higher levels of fluoride.

“There is very likely a much higher level of fluoride than we have in the United States that can cause neurocognitive problems during fetal and early childhood development,” says Dr. Charlotte Lewis, professor of pediatrics. at the University of Washington School. of medicine in Seattle. But there is no good evidence that fluoride levels exist in public drinking water in the United States, she says.

What to do

Parents concerned about potential risks to their children can take a few steps.

Pregnant women who want to limit their exposure to fluoride can look for bottled water labeled as deionized, purified, demineralized or distilled, without any fluoride added after the purification treatment, says Kyla Taylor, a health scientist at the National Institute of Environmental Health Sciences and co-author of the National Toxicology Program study.

Refrigerator water filters generally do not filter out fluoride. A filter requires a reverse osmosis step to remove most fluorides. You can purchase reverse osmosis filtration systems at places such as Home Depot.

The CDC recommends that children use fluoridated toothpaste starting at age 2. To avoid accidental ingestion, children under 6 years of age should use no more than a pea-sized amount of toothpaste. For pregnant women, using toothpaste containing fluoride should be safe for the fetus, says Ashley J. Malin, an assistant professor in the department of epidemiology at the University of Florida and author of the study linking the fluoride to neurobehavioral problems.

Other scientists say concerns about fluoridated water in the United States are misguided.

Lewis, a professor of pediatrics at the University of Washington, says that infants’ teeth mineralize in the jaw even when they are not yet visible. Thus, exposure to fluoride affects the final development of teeth, making them stronger and more resistant to cavities.

“Everyone benefits from fluoride at the level that we have in community water fluoridation in the United States,” she says. This includes pregnant women and infants.