Warren Loeppky has been a pediatric dentist in the Canadian city of Calgary for 20 years. Over the last decade, he says, tooth decay in children he’s seen has become more common, more aggressive and more severe. Many of his young patients have so much damage that he has to work with them under general anesthesia.
“It’s always sad seeing a young child in pain,” Loeppky says. “Dental decay is very preventable. It breaks your heart to see these young kids that aren’t able to eat.”
Loeppky notes that many factors can contribute to tooth decay in children, including their diet and genetics. Still, he believes part of the problem is linked to a decision made in the halls of local government: In 2011, Calgary stopped adding fluoride to its drinking water.
“This decision of city councilors was surprising to the general public, but shocking and alarming to dentists, to pediatricians, to anesthesiologists and others in the health care field, who knew what it would mean,” says Juliet Guichon, a legal and ethics scholar at the University of Calgary who formed a group that advocated for adding fluoride back to drinking water in the city.
Several studies have shown that fluoride is a safe and effective way to prevent tooth decay. It recruits other minerals, such as calcium and phosphate, to strengthen tooth enamel and fend off acid made by bacteria. Oral health can also affect a person’s overall health.
The U.S. Centers for Disease Control and Prevention recommends that communities across the country add 0.7 milligrams of fluoride for every liter of water. It’s up to state and local governments to decide if they want to follow that recommendation. In 2022, the CDC reported that 63 percent of Americans received fluoridated water.
But that practice now is coming under new scrutiny. In March, Utah became the first state to ban fluoridation; many local governments across the country are also debating the issue. And on April 7, Department of Health and Human Services Secretary Robert F. Kennedy Jr. told news reporters that he planned to tell the CDC to stop its recommendation.
Adding fluoride to water has been contested in the United States since the practice became widespread in the mid-20th century. Opponents have historically voiced health concerns, including about tooth staining and disproven worries that fluoridated water could cause bone cancer, as well as claims that fluoridation amounts to mass medication and violates individual freedoms. More recently, people have pointed to research showing an association between fluoride and lowered IQ in children. But those findings, which have been heavily criticized, looked at fluoride concentrations much higher than those found in most Americans’ drinking water.
What happened in Calgary, as well as in Juneau, Alaska, which stopped water fluoridation in 2007, may be a cautionary tale for other municipalities. Science News spoke with researchers and other experts in both cities to understand what can happen when local governments opt to stop adding fluoride to drinking water.
Looking into the mouths of second-graders in Calgary
Lindsay McLaren says she never anticipated becoming a self-described fluoridation researcher. As a quantitative social scientist at the University of Calgary, she studies how public policies can affect the health of a population. She hadn’t given much thought to fluoridation until 2011, when the Calgary City Council decided to remove fluoride from the city’s water.
The move prompted McLaren to design a study looking at how the dental health of the city’s children fared once fluoride was removed. She recruited dental hygienists to go to schools and inspect the mouths of second-grade students. Some went to schools in Calgary and others went to schools in Edmonton, a similar city in the same province that still fluoridated its water.
In Calgary, the team surveyed 2,649 second-graders around seven years after fluoridation ended, meaning they had likely never been exposed to fluoride in their drinking water. Of those, 65 percent had tooth decay. In Edmonton, 55 percent of surveyed children had tooth decay. While those percentages may seem close, they mark a statistically significant difference that McLaren calls “quite large” on the population level.
“Compared to Edmonton kids, Calgary kids were now considerably worse as far as dental health goes,” McLaren says. Other factors, including diet and socioeconomic status, did not explain the differences between children in Edmonton and Calgary, she says.
In 2024, another study found a higher rate of tooth decay-related treatments for which a child was placed under general anesthesia in Calgary than in Edmonton. From 2018 to 2019, 32 out of every 10,000 children in Calgary were put under general anesthesia to treat tooth decay, compared with 17 for every 10,000 children in Edmonton.
The findings didn’t surprise local dentists, says Bruce Yaholnitsky, a periodontist in Calgary. “This is just obvious to us. But you need to have proper science to prove, in some cases, the obvious.”
Analyzing Medicaid claims in Juneau
Years before Calgary’s city council opted to remove fluoride from its water, members of the local government in Juneau made a similar decision.
Jennifer Meyer says she first became interested in studying the effects of lack of fluoridation in Juneau after moving there in 2015. At the time, she had two young children; a third was born in Juneau. She was surprised at how much dental work, including fillings, she noticed among many other preschool and elementary school children.
“I thought ‘Wow, what’s going on here?’ Because I could see a lot of the decay and the repairs,” Meyer says.
Juneau had stopped adding fluoride to its drinking water in 2007 after asking a six-member commission to review the evidence around fluoridation. A copy of the commission’s report obtained from Meyer, a public health researcher at the University of Alaska Anchorage, shows that two commission members opposed to fluoridation made claims about the health effects that Meyer says are “false” and “not grounded in quality investigations.”
The commission’s chair criticized anti-fluoride positions, at one point writing that part of the literature was based on “junk science.” But he ultimately recommended that the city stop fluoridation, claiming that the evidence about its safety at low concentrations was inconclusive. With the commission’s members split at 3–3, the Juneau Assembly voted to end fluoridation.
Meyer and her colleagues analyzed Medicaid dental claims records made before and after the city stopped fluoridation. They found that the average number of procedures to treat tooth decay rose in children under age 6, from 1.5 treatments per child in 2003 to 2.5 treatments per child in 2012.
The cost of these treatments in children under 6 years old, when adjusted for inflation, jumped by an average of $303 dollars per child from 2003 to 2012.
Meyer says that increased Medicaid costs for dental treatments ultimately end up being paid by taxpayers.
“When politicians decide to withhold a safe and effective public health intervention like fluoridation, they are imposing a hidden health care tax on everyone in their state or community,” Meyer says.
Continued calls to end fluoridation
Today, many opponents to fluoride in water cite a controversial systematic review released last year by the National Toxicology Program, which is nestled in HHS and evaluates the health effects of substances. That August 2024 review concluded with “moderate confidence” that water with more than 1.5 mg of fluoride per liter was associated with lowered IQ in children.
But that dose is more than double the CDC’s recommended amount. And the review authors couldn’t determine if low fluoride concentrations like those found in treated drinking water in the United States had a negative effect on children’s IQ. In addition, merely finding an association does not prove that higher levels of fluoride caused lowered IQ, the NTP notes on its website.
More broadly, Meyer says, “ending fluoridation … based on weak or misrepresented evidence is not a precaution, it’s negligence.”
Juneau remains without fluoridated water. In Calgary, though, residents voted in 2021 to bring it back. With 62 percent of voters opting to reintroduce fluoride, the margin was higher than it was in the 1989 vote that brought fluoride to Calgary in the first place. Guichon says McLaren’s study, combined with “determined advocacy,” helped bring the electorate to the polls.
“More people voted to reinstate fluoride than voted for the mayor. So that’s a success,” Meyer says. “But in America, we are entering a dark time.”
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