This story is from The Pulse, a weekly health and science podcast.

Find it on Apple Podcasts, Spotify, or wherever you get your podcasts.

When Bill Osmunson was in high school in 1966, he studied for a time in Europe with a group of classmates, and they had an exchange with their European professors about what was better or worse in each country.

One of the teachers brought up a point to Osmunson that made him angry.

“She said, ‘well you promote fluoride in the water.’ And I go, ‘What? That helps teeth. That’s fine. There’s nothing wrong with that’. And she said, ‘Well, we disagree with that here in Europe.’”

At the time, Osmunson thought that was crazy. But years later, he would actually go on to become a dentist — a dentist who would eventually join a small, but vocal movement pushing against fluoridation in drinking water.

“We just keep lying to ourselves that it’s safe and effective,” he said. “We’ve gotten everybody convinced that it’s safe and effective.”

The anti-fluoridation movement has been marginalized for a long time, but it’s recently gained steam for two reasons: They now have a powerful advocate in Robert F. Kennedy Jr., who was confirmed as the next secretary of the U.S. Department of Health and Human Services in the Trump administration, and a new analysis of studies linking high levels of water fluoridation and lower IQ in children has prompted a federal judge to order the Environmental Protection Agency to address potential risks of the practice.

 That’s driven many other scientists and dental practitioners to step up their efforts to defend and protect the decades-old public health strategy of fluoridating drinking water, while local communities and the public get caught in the middle of this scientific tug-of-war.

“It’s so easy to sow fear and doubt in the public,” said Scott Tomar, a dentist and oral epidemiologist. “And so difficult to reassure people that, no, we’ve looked at the best available science, the best available science continues to support that this is safe and effective.”

A turning point

Fluoride is a mineral that’s naturally found in water, food and soil. Water fluoridation is the practice of adding more fluoride to the local drinking water to reach the current standard U.S. recommended level of 0.7 milligrams per liter.

Communities started adopting the practice in 1945 after researchers discovered that fluoride, at the right levels, can help strengthen teeth enamel and lower the risk of cavities. 

It took many years for Osmunson to change his position on water fluoridation, and it started with something one of his professors said in college when he was pursuing a master’s degree in public health.

 “I want you to remember that your job is to promote policy. Your job is not to give your own opinions, but you’re to promote what you’re told to promote.”

He bristled at this idea — being part of the establishment — without being able to think through issues on his own. After becoming a dentist, he ended up working in a city in Idaho where fluoride was added to the drinking water, which Osmunson said he liked for its power to reduce cavities by about 25 percent

“I told my assistant, ‘I’m going to tell you where these people live by looking in their mouths,’” he said. “And so the next patient came in and I looked in their mouths and I would see good, strong, nice teeth, and I said, ‘This person lives in the city because they were getting fluoridation.’ Then the next patient would come in and I’d look in there and they had lots of problems and I’d go, ‘Oh, they live out in the country.’”

Osmunson said he was correct about 80 to 90% of the time.

“And what I was looking at helped convince me that fluoridation had benefit,” he said.

But over time, little by little, Osmunson started to question the safety of fluoride in the drinking water supply. He remembered taking a close look at the label on a tube of fluoride toothpaste.

“And it said, ‘Do not swallow.’ Well, that’s pretty simple,” he said. “And if you do, then contact the poison control center.’”

Osmunson knew that with anything that’s potentially poisonous, the dose is a key factor. That part started rubbing him the wrong way, because fluoride was administered and added to the drinking water by his municipality.

“They’re just shoving it down my throat, whether I like it or not, without any label, without FDA approval,” he said. “I mean, come on, there’s no dosage control. People drink different amounts of water.”

And in trying to look deeper into potential impacts of fluoride exposure, Osmunson said he came to another conclusion: the science on fluoride ingestion was not high quality.

“And so, I promoted fluoridation for 25 years. Why? Because I never looked at the science,” he said. “I just did what my profession recommended and I didn’t look at the science.”

When he did review the science, Osmunson said he found the links between high levels of fluoride and damage to teeth, including fluorosis, to be credible. And worse, he became disturbed by studies linking fluoridation to cancer and lowered IQs in children.

 To him, it was enough to speak up, especially for kids.

 “Of course, I’m going to try to defend their brains,” he said. “Am I not going to speak up, knowing what I knew and not speak up to try to help parents and children?”

And that’s what Osmunson has continued to do. After practicing for 46 years, he’s now retired and lives in Washington state with his family and he remains active in efforts to stop water fluoridation.

Examining the levels of fluoride in water

“I can remember when the Public Health Service first suggested fluoridating drinking water in about 1962,” said Linda Birnbaum. “And there were people who called it a communist plot.”

Birnbaum, a toxicologist and a microbiologist, has spent much of her 40-plus career as a governmental scientist. She served as director at both the National Institute of Environmental Health Sciences and the National Toxicology Program.

Over her career, Birnbaum oversaw colleagues as they researched the effects of fluoride and water fluoridation. To her, there’s merit to studies that have shown that fluoride can be harmful to human health and development at certain levels.

But there is far less data, if any, showing harm caused by the current levels of fluoride in American drinking water, set at 0.7 milligrams per liter.

“Does inorganic fluoride have the potential to be developmentally neurotoxic? The answer is yes,” she said. “The question of, is 0.7, which is the current public health recommendation, can it be associated with IQ deficits? I think the answer is, we’re really not sure.”

To Birnbaum, that uncertainty is enough to warrant further exploration, but she said other scientists and dental experts may be less willing to explore this issue. She blamed years of how water fluoridation is taught in training programs.

“They’ve been told for the last 60 years that this is a good thing to do and it’s important. It was a belief structure,” she said. “And when you’ve been told that your whole professional career, it’s hard to change a mindset.”

But now, that mindset might have to change or at least respond to a recent ruling by California District Court Judge Edward Chen last September. After looking at the newer IQ studies, Chen determined there was enough evidence to rule that the Environmental Protection Agency must address potential risks of water fluoridation.

Addressing ‘cultural baggage’

Attorney Michael Connett of firm Siri & Glimstad, who specializes in litigation related to toxic substances, represented the plaintiffs and led arguments against the EPA in court.

“It was great to see the result, there’s no question about that,” he said. “It’s been a long time coming with a lot of hard work.”

 Part of that hard work was to change attitudes about people who’ve been opposing water fluoridation, people who’ve long been viewed as fringe, anti-science, or conspiracy theorists — the “cultural baggage.”

“A lot of people when they hear about fluoride, they immediately think of Dr. Strangelove and the crazy Colonel Ripper,” Connett said. 

The scene in question from the 1964 political satire film features General Jack Ripper explaining the “dangers” of fluoridation to Captain Mandrake.

“Do you realize that fluoridation is the most monstrously conceived and dangerous communist plot we’ve ever had to face?” Aactor Sterling Hayden asks just as bullets rip into the room.

Those sorts of depictions have made it difficult for people to take the issue seriously, Connett said, “and to really believe that there could be something wrong with this practice of water fluoridation.”

But Connett is no stranger to the issue. He first learned about it as a student at St. Lawrence University in Canton, New York, where local residents were considering removing fluoride from its drinking water in the early 2000s.

“My parents are very actively involved with environmental health issues. They had been working for decades on garbage incineration and the hazards of that. My dad’s a chemist, my mom was editing this newsletter on waste issues,” he said. “They became interested in this fluoride issue and through them, I learned about it.”

He continued to dig deeper into water fluoridation, Connett said, and became involved in the early years of the Fluoride Action Network, an advocacy organization focused on fluoride toxicity.

Group leaders hope that the recent win against the EPA means the federal agency will need to take action. But lawyers for the EPA are now in the early process of filing an appeal, which means this could turn into a drawn-out fight on a topic that many scientists argue does not warrant investigation.

Defending standard public health practice

A majority of dental experts and scientists maintain that water fluoridation is safe at the current levels, and not harmful.

Researchers like Scott Tomar point to decades of studies and data showing that fluoride continues to prevent and protect against cavities, even if increased sugar consumption has cut into some of those successes.

Tomar said there’s no conclusive evidence that water fluoridation at standard levels in the U.S. negatively impacts health or development. 

Tomar, professor and associate dean for prevention and public health sciences at the University of Illinois Chicago College of Dentistry, has previously worked as an oral health epidemiologist at the CDC.

He’s taken a critical look at studies like the latest ones linking fluoride and lower IQ, which were included in a larger systematic review of existing science on the issue.

“The levels that we’re talking about in the United States, 0.7 milligrams per liter, are less than one half of the lowest level that they even looked at,” Tomar said of the studies. “The bottom line is, there’s no evidence from that systematic review that there’s any association between the levels used in fluoridated water and any impact on IQ.”

Tomar echoes comments and criticisms made by other scientists and experts affiliated with major dental and medical organizations like the American Dental Association and the American Academy of Pediatrics. They say many of these studies were poorly designed, contain errors and were seriously flawed in ways that invalidate the findings.  

But the studies, and the subsequent news headlines like “Fluoride Linked To Lower IQ,” have created doubt among the public, and not just limited to the fluoride in water.

“I’m hearing from all of my colleagues in dentistry that a not insignificant percentage of their patients no longer want topical fluoride on their child when they go in for their checkup visits, they’re looking for non-fluoride toothpaste,” he said.

The conflicting study outcomes and public debate is making it harder and harder for public health leaders to cut through the noise, Tomar said.

Helen Hawkey said she’s seeing the fallout in her daily work. She’s the executive director of the Pennsylvania Coalition for Oral Health, which supports communities in maintaining or starting water fluoridation.

“It just takes one person to say, ‘Oh, I read that fluoride lowers IQ and so we can’t have fluoride in our water, so let’s take it out,’” Hawkey said.

Since 2010, the coalition has helped towns and cities that have struggled with the costs of fluoridation or had trouble locating a supplier for the mineral. But Hawkey said their biggest challenge is battling misinformation about water fluoridation, which can lead to a rollback, or communities stopping fluoridation. 

“Water boards, they’re not scientists, they’re not researchers. They’re usually everyday folks from the community and they want to do what’s right for their community,” she said. “When there’s a rollback, our first step is always to find out what the reasoning is.”

Sometimes, Hawkey said that involves acknowledging what people are reading and seeing in the news headlines and helping them put it into context.

“Yes, too much fluoride is bad, just like too much water is bad or too much caffeine is bad. But we still drink our coffee every morning,” she said. “That’s the part we want people to understand, is that the levels we want to be used in Pennsylvania are super helpful and just so important.” 

Hawkey and others who do oral public health work are used to dealing with criticism and challenges to data and research. But in this moment, she said it feels more intense, especially with politicians interested in reducing or banning water fluoridation.

“Just in the last four months, we had a community that was voting on a rollback and the justification they gave in the newspaper was that, ‘Hey, the federal government’s going to stop doing this anyway, so we may as well do it now,’” Hawkey said. “And we’re like, wait a minute, wait a minute, wait a minute, nothing even happened yet.”

Changing water fluoridation – inevitable or futile?

Change can be hard, especially when there’s so much disagreement on if that change is actually needed.

But for anti-fluoridation advocate and retired dentist Bill Osmunson, he said this is an important moment when discussion could get more attention, and could perhaps no longer be viewed as “fringe.”

Taking the stance he has taken has not been easy.

 “It comes with a serious cost,” he said. “When you go out on a limb, you’re out on a limb.”

Osmunson said he knew there would be some pushback, but often underestimated the stress of fighting for this issue.  

“Did I know it would become so intense on my part? No,” he said. “I don’t think I would have the stomach problems, the acid problems in my stomach. I think I could sleep better if I was just retired.”

But Osmunson said he’s not done fighting, even when there are no guarantees that anything will change regarding water fluoridation any time soon.