Is fluoride in your Idaho water? What to know as Utah and RFK Jr. fight it
In 2010, a small city nestled between the Rocky Mountains and Lake Pend Oreille in North Idaho voted to stop adding fluoride to its municipal water system. The decision came after over a dozen residents bemoaned the practice at a public meeting, blaming fluoride for bone deficiencies, cancer and Alzheimer’s disease.
Carrie Logan didn’t believe that the arguments the Sandpoint City Council heard against fluoridation were grounded in science. Logan was one of two council members who voted against repealing the city’s fluoridation law. Afterward, she said the vote marked “a sad day” for the citizens of Sandpoint, the Bonner County Daily Bee reported.
Idaho has had the biggest decline in fluoridation of any state since 2000, according to data from the U.S. Centers for Disease Control and Prevention. That’s even though Idaho played a role in the discovery of fluoridation.
Yet hundreds of thousands of Idahoans still get fluoride from their drinking water. That fluoride is drawing increasing attention as Robert F. Kennedy Jr., President Donald Trump’s secretary of health and human services, pushes to stop the federal government from encouraging its use in water supplies despite generations of research supporting its benefits to dental health in controlled amounts.
Only one public-serving water system in the state still adds fluoride to its drinking water, according to the Idaho Department of Environmental Quality: the Mountain Home Air Force Base. That’s because a U.S. Department of Defense policy adopted in 2011 directs all military bases that own or operate their own water systems to provide fluoridated water to help “improve and sustain” the health of military personnel.
Boiseans served by Veolia, a private water company, normally get a small amount of naturally occurring fluoride in their water, below the recommended concentration for dental health benefits.
An estimated 31% of Idahoans served by public and private water providers drink fluoridated water, according to the CDC. Nearly all of that fluoridation is naturally occurring. But most communities in the state have neither naturally occurring nor added fluoride in their public water systems, in contrast with about 70% of Americans who do drink from a fluoridated water supply.
Idaho ranked No. 48 in the nation in the percentage of population served by water systems with fluoridated water as of 2022. Public opinion has played a role.
“We’re noticing that more questions are being asked about fluoride,” Dr. Brooke Fukuoka, president-elect of the Idaho State Dental Association, told the Idaho Statesman in an interview.
Resurging opposition to fluoridation — the practice of adding fluoride to public water systems at safe levels to prevent tooth decay — has been a nuisance for dentists, researchers and public health experts. The American Dental Association credits fluoridation with a 25% reduction in cavities, a statistic that it says several decades of research and experience supports. The U.S. Centers for Disease Control and Prevention once called fluoridation one of the country’s 10 great public health achievements of the 20th century, along with vaccination and recognizing tobacco use as a health hazard.
But a key member of the Trump administration is arguing otherwise.
Fluoride skepticism rises
Health and Human Services Secretary Robert F. Kennedy Jr. wrote on social media that the new administration will advise all U.S. water systems that serve the public to remove fluoride. He said the mineral “is an industrial waste” and repeated claims that it increases the risk of bone cancer, even though his department’s National Cancer Institute says decades of research have turned up no credible evidence to support that.
Dr. Donald Chi, a pediatric dentist, professor of oral health and associate dean for research in the School of Dentistry at the University of Washington, has studied the impacts of water fluoridation on oral health and people’s attitudes, concerns and beliefs about the practice. He said Kennedy’s comments about fluoride are “preposterous.”
But such statements are enough to influence people who may have been on the fence about it, he said.
“He’s spouting off all these untruths about water fluoridation, and that’s something that, when I’m seeing patients on Monday morning in clinic, I have to be ready to talk to parents about,” Chi told the Statesman by phone. “It affects us with fluoride just like it affects physicians with vaccines.”
Kennedy’s rhetoric, backed by Trump, could sway communities around the country to revisit decades-old fluoridation programs. Legislation banning fluoride in public drinking water in neighboring Utah — the first state to enact such a ban — took effect Wednesday, despite opposition from many dentists and health experts. Kennedy applauded the decision.
Though some states have laws that require large water systems to provide fluoridated water, the decision is often up to local municipalities.
The Idaho State Dental Association says it is “deeply concerned” about the impact that government recommendations to stop fluoridation could have on the oral health of children and adults. It joined a letter signed by 250 leading health organizations urging the federal government to affirm the safety and efficacy of community water fluoridation.
“Community water fluoridation remains the only way to ensure that all people — especially those at greatest risk for dental disease with the fewest resources to maintain their oral health — can receive its cavity-preventing benefits,” the association said in a statement.
How does it work?
Chi said fluoridation was born from an observation.
In the early 1900s, a young dental school graduate who moved to Colorado Springs, Colorado, to open a practice noticed that the vast majority of locally born residents had brown stains on their teeth, with splotches sometimes as dark as chocolate. The mystery was dubbed Colorado Brown Stain.
The dentist took it upon himself to investigate. He went on to make two critical discoveries with the help of a renowned dental researcher.
First, they found that the mottled enamel resulted from developmental imperfections in children’s teeth. Residents whose permanent teeth had calcified without developing the stains did not risk having their teeth turn brown, according to the CDC. Second, they found that teeth with Colorado Brown Stain were inexplicably resistant to decay.
In 1923, the dentist trekked across the Rocky Mountains to Oakley, a small town in southern Idaho, to meet with parents who had noticed the peculiar brown stains on their children’s teeth, the CDC says.
The parents told him that the stains started appearing shortly after the town built a communal water pipeline to a warm spring about 5 miles away. The dentist found nothing suspicious about the water but advised town leaders to abandon the pipeline and use another nearby spring instead. Within a few years, children in Oakley were growing secondary teeth without any brown stains, according to the CDC.
The so-called mottled enamel is now known as fluorosis.
“What they realized is that there could be some oral health benefits by adding fluoride to water, but at a certain level,” Chi said. “You don’t want people to have this brown stain even if it prevents cavities. So there were a lot of lab studies to try to figure out the right amount of fluoride to add so that you wouldn’t get these defects on the teeth. What they realized pretty quickly was that the people living in areas where the water was optimally fluoridated had these benefits where they didn’t have cavities, and they didn’t have the brown staining.”
Several decades of data now show that fluoride is safe and effective at decreasing dental decay by strengthening the enamel of our teeth, he said.
Where is it?
Despite Veolia’s low levels, Idaho overall has among the highest levels of naturally fluoridated water in the country, according to a graphic from The Washington Post that used CDC data to show nationwide fluoride levels.
Tyler Fortunati, drinking water bureau chief at the DEQ, said there are varying concentrations around the state. Idaho’s levels are higher because of the abundance of hot groundwater bubbling under the surface. Some of the highest levels are just south of Boise along the Snake River, he said.
Fluoride, like salt, is a naturally occurring element. It’s in our soil, rocks and water. It’s released into the environment when water dissolves rocks or soil that contain it.
“Areas that have geothermal activity tend to have higher levels of fluoride in the groundwater,” Fortunati told the Statesman. “The fluoride will leach out of the surrounding bedrock formations and become part of the drinking water’s chemical makeup.”
Only one municipality in Idaho, the Bruneau Water and Sewer District in Owyhee County, has levels so high that it’s required to remove naturally occurring fluoride from its drinking water, according to Fortunati.
Other areas have little to none. Those public water systems could add it, but it would entail another treatment process, ongoing maintenance and increased costs, a type of effort that most public water systems in the state would avoid, if they can help it, Fortunati said.
Madeline Wyatt, a spokesperson for Veolia, the water company that serves nearly 250,000 people in Boise, about two-thirds of Eagle, a small portion of Meridian and parts of unincorporated Ada County, said Veolia does not add fluoride to its drinking water system, and neither did its predecessors: Boise Water, United Water and Suez.
She said no municipality has ever asked it to.
“In our memory, no one has ever discussed or approached us about adding fluoride to our water,” Wyatt said.
Melissa Stoner, a spokesperson for Boise’s Public Works Department, confirmed that the city has not had a conversation with Veolia about adding fluoride to its water system. But Stoner said the city often gets questions from residents about whether the supply is fluoridated.
What is the optimal level?
The U.S. Environmental Protection Agency’s drinking water standard is 4 milligrams per liter of fluoride, a guideline that the agency plans to reconsider at the direction of Kennedy, according to an April news release. That’s the maximum amount allowed in public-serving water systems to protect against fluorosis, the EPA says.
Kennedy’s department recommends a level of 0.7 milligrams per liter of fluoride in drinking water to prevent tooth decay and promote good oral health. Fukuoka, the president-elect of the Idaho State Dental Association, calls that the sweet spot.
“This is the level that prevents tooth decay and promotes good oral health,” the CDC says on its website.
Still, levels up to 1.5 are determined to be safe by the World Health Organization. The average concentration of fluoride in Veolia’s system is 0.4 milligrams per liter, according to Wyatt.
Fukuoka said the controversy over fluoridation was sparked by a small number of studies that cite negative outcomes based on levels of the mineral that far exceed federal guidelines. The most important factor is the dose, she said.
“All of those studies are looking at places where the indigenous fluoride is just astronomically higher than what is recommended,” Fukuoka said. “If you do it right, it’s safe and healthy.”
Fluoride levels around the state
The Idaho State Dental Association told the Statesman that it supports efforts to achieve and maintain community water fluoride concentrations of 0.7 milligrams per liter of fluoride.
But few public-serving water systems in Idaho meet that concentration.
Nampa’s water system has 0.3 milligrams per liter of fluoride, and so does Caldwell’s. Twin Falls’ has 0.5 and Idaho Falls has 0.4, while Pocatello and Coeur d’Alene have none, according to the CDC’s website. Moscow has among the highest, at 0.9, which is above the recommended amount but well below the level determined to be safe. The Bruneau Water and Sewer District, which has to remove some because it has too much, maintains about 1.1 in its system.
Fluoridation levels that fall below the recommended concentration likely won’t budge unless citizens advocate for it, Chi said.
He said he rarely encountered fluoride hesitancy early in his career as a pediatric dentist. But about 15 years ago, as the internet became more accessible, parents started coming in with more questions.
He led a study published in 2023 that interviewed dozens of fluoride-hesitant parents to understand why they were on the fence about it. The overwhelming takeaway was that the parents simply loved their children and wanted to make the best decisions they could for them, he said.
“They’re not conspiracy theorists,” Chi said. “Our interview data do not support that at all. And as much as I’d like to blame an individual for landing us in this situation, this is also part of our job. I’m a dentist, and I have to be ready to have a conversation that can help parents make the best decisions they can for themselves and their children.”
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