RFK Jr. wants to stop putting fluoride in drinking water. Here's what scientists say

On day one of Donald Trump's presidency, Robert F. Kennedy Jr. says he'll be advising Trump to take fluoride out of public water. The former independent presidential hopeful — and prominent proponent of debunked public health claims — has been told he'll be put in charge of health initiatives in the new Trump administration. He's described fluoride as "industrial waste." 

Here's what scientists say, and what we know about fluoride in drinking water in Canada.

What is fluoride?

Fluoride is a naturally occurring mineral, released from rocks into the soil, water and air.

It's commonly used in dentistry to strengthen tooth enamel and prevent cavities.

In many parts of the world, including Canada, public health authorities or local governments add it to the drinking water supply to help prevent tooth decay in the community.

Major public health bodies around the world, including the World Health Organization and the Public Health Agency of Canada (PHAC) support the practice. PHAC says fluoridation is associated with an approximate 25 per cent reduction in tooth decay in children and adults. In the U.S., the Centers for Disease Control and Prevention named it one of the great public health achievements of the 20th century.

In Canada, 38.8 per cent of the population has access to fluoridated water, according to PHAC. Access varies across provinces and territories, based on several factors like cost, infrastructure and community concerns.

But some have questioned the practice: from a debunked conspiracy theory of a communist plot in the 1950s, to whether fluoridation is effective enough to justify the costs.

Many of the concerns — including those raised by Kennedy during the run-up to the U.S. election — are not based on good science, says Gerry Uswak, the director of the dental therapy program at the University of Saskatchewan.

"People who are non-scientists are interpreting scientific data and making policy decisions based on emotion, not on objectivity," he said.

What are the risks?

Ingesting too much fluoride over a long period of time can lead to skeletal fluorosis, a bone disease that can cause bone pain and deformities. The condition is extremely rare in Canada, because health authorities adjust fluoride levels in water to keep it safe.

Another mild risk for children according to Health Canada is dental fluorosis. Children who ingest more fluoride than recommended (such as by swallowing toothpaste) can develop white spots on the surface of their teeth, but there are no other symptoms or harms associated with this condition.

Aaron Burry, the CEO of the Canadian Dental Association, says he's open to changing his recommendation on water fluoridation if the science warrants it. But right now, he isn't convinced the risk outweighs the benefits.

"We review all of the research that comes out every year. And to date, we haven't seen something that … is a cause for concern," he said.

Is there an impact on young brains? 

Some scientists have recently studied a possible link between fluoride and intelligence in children.

A 2019 study published in JAMA Pediatrics suggests an association between lower IQ scores among Canadian children aged three to four years and the level of fluoride their mothers consumed while pregnant. The study did not establish causation — other factors could be at play beside the fluoride — and its methods and conclusions were also widely criticized at the time.

"That doesn't mean that fluoride during pregnancy definitely has no effect on IQ — just that it's far from clear that it's even the main explanation for these relatively small IQ differences," said Kevin McConway, emeritus professor of applied statistics at the Open University in the U.K.

When it was published, the journal editor explained his decision to publish the article, noting the importance of examining any possible link between fluoride exposure and cognitive development.

The Public Health Agency of Canada says fluoridation is a cost-effective and equitable way to prevent tooth decay for everyone in the community — even those who can't access dental care easily. (chanchai plongern/Shutterstock)

"Scientific inquiry is an iterative process," wrote Dr. Dimitri Christakis in the editor's note.

"It is rare that a single study provides definitive evidence."

Christine Till, one of the authors of the study, and a professor of psychology at York University, says there's not enough evidence of a link at lower levels of exposure — like those currently recommended for drinking water in the U.S. and Canada.

"We don't have as many studies in that area. We need more studies and [to] replicate," Till said.

Another report published this summer by the U.S. National Toxicology Program also looked at the impact of all sources of fluoride exposure, like food, water or toothpaste, on pregnant women, infants and children. It suggests high levels of exposure — 1.5 milligrams per litre —  are associated with lower IQ in children. That's more than double the recommended water concentration in Canada, which is 0.7 milligrams per litre.

A recent review of high-quality studies on the subject — published by Cochrane, an international network of health professionals that examines health research — suggests that while fluoride in water leads to less tooth decay among children, the benefits may be smaller than before fluoride was also added to most toothpastes.

It's no surprise, says Burry. He says water fluoridation is "one tool in the whole overall toolkit" in ensuring dental health among Canadians.

Uswak says those who can't afford to see a dentist stand to suffer the most without fluoridation.

"Those people in society that face the most access-to-care barriers are the people that benefit most from community water fluoridation."