Welcome to Paging Dr. Gupta. Thanks for joining us. This week we're going to take a closer look at an issue that has been making a lot of headlines lately.

It makes no sense to have fluoride in our water. The evidence against fluoride is overwhelming. And I'm very, very proud of this state for being the first state to ban it. And I hope many more will come.

That was the head of the Department of Health and Human Services, Robert F. Kennedy Jr., talking about Utah, which recently became the first state in the nation to ban fluoride in public drinking water, a practice known as fluoridation. Now, typically on Tuesdays, we take your questions, but this week we're going to address a topic that's been getting a lot of questions, and that includes from our podcast producer, Sofía Sánchez.

Hey Sanjay, yes I've definitely been wondering about this topic myself, I've even been asked a few questions from my family about what exactly the concern is over fluoride. So what exactly is the concern over fluorides?

Let's start with the, basics first of all. Fluoride is a naturally occurring mineral that you can find in plants, soil, certain foods, and obviously water. It is great for strengthening our teeth and I'm going to come back to that point, but remember, fluoride can help strengthen your teeth, and that's why it's been added to toothpaste and tap water for around eight decades now. If you do the math, about 70% of Americans on community water systems, that's about 209 million people, have fluoridated drinking water in the United States, and the CDC credits fluoridate water for a 25% reduction in cavities in children. But here's the issue. There is an emerging body of science that does raise some concerns about health issues associated with fluoride.

We now have a growing body of evidence linking systemic fluoride exposure with detrimental effects on bone strength, thyroid function, and brain function, particularly when there is high exposure in early development.

This is Dr. Christine Till, a clinical neuropsychologist and professor of psychology at York University in Canada. She leads a lab that specifically investigates fluoride neurotoxicity. And what her research has found is a link between higher levels of maternal fluoride exposure during pregnancy and subsequently lower IQ scores in kids in Canada, okay? I want to repeat that. Her research found a link to higher levels in maternal fluoride exposure during the and subsequently lower IQ scores in those kids in Canada. Now, a report released last summer from the National Toxicology Program, part of the NIH, came to a similar conclusion. So you have that research in Canada, and then you have sort of validation of that research from the national institutes of health here in the United States. Now, to be fair, there is some criticism of this research. For example, like the American Dental Association, they released a statement pointing out that the research largely use data from areas outside of the United States. Why is that important? Many of those areas outside of the United States had fluoride levels that are higher than what we see typically in the United States. And I want to emphasize this point because something that I repeat often on this podcast is this idea that "the dose makes the poison." Just about anything in high enough doses can be problematic. So the dose makes the poison, you've got to pay attention to exactly how much fluoride we're talking about. It is true that exposure to too much fluorine can lead to negative side effects. I think that's what all this research is showing. Too much fluorite over the course of several years can lead to something known as skeletal fluorosis. That's a condition that causes weaker bones and joint pain. It can also lead to cosmetic problems like flecks of white on your tooth enamel, you may have seen this before. And then obviously the concerns about neurotoxicity. But the question that remains, going back to this idea that the dose makes the poison, the question that remains is, how much is too much? And where does this all leave us? What are the risks also of removing fluoride from our drinking water? We want to discuss this issue from two lenses. First of all, what is the harm? And also, what the benefit nowadays in 2025? And we'll dig into that right after the break.

All right, there goes the pager and more comments from my producer, Sofía Sánchez.

Okay, so Sanjay, if there's really research to suggest that fluoride, in large quantities of course, could be harmful, should I be worried about my drinking water? Do the risks outweigh the rewards here?

Yeah, so that's the question, Sofía, that is a fair question, and I think that's what a lot of people are wondering. Proponents of fluoridation will argue, look, it's an important tool when it comes to fighting cavities. In fact, if you look at what public health experts say about this, they will call it "one of the single most effective public health measures to prevent tooth decay overall in the nation." That's what the American Dental Association said.

Specifically, what fluoride does is it helps every time you eat something with sugars, the microorganisms that are in your mouth that are completely normal, they metabolize that sugar and they produce acids that damage your tooth. Over time, that becomes a cavity if you lose more minerals in your tooth, then you gain. And we gain minerals through our saliva. Saliva is a wonderful fluid that we have in our mouth, very important for our health, of our tissues, and our mouth, our teeth, et cetera. But many times the calcium and the phosphate and the saliva is just not enough with the diets that we have. So fluoride makes this process of minerals coming back into the tooth, which we call remineralization, much more effective. And without fluoride, really, the levels of tooth decay that we would have would be significantly higher.

That's Dr. Margarita Fontana. She's a dentist. She leads the University of Michigan's Global Initiatives Program in Oral and Craniofacial Health. She's one of the many medical professionals who are weighing in on this and who believe fluoridation is crucial to fighting cavities, especially in underserved communities where access to dental care is limited. There is a nuance here, emerging research finds that while fluoridations does prevent cavities It may not help nowadays as much as we originally thought. A report last fall from the Cochrane Collaboration, that's an independent group that analyzes the existing scientific body of research, they found only a slight benefit to adding fluoride to tap water. In their conclusion, fluoridation was most effective before 1975. Why is that? Because fewer children had access to dental care before that, and fluoridated toothpaste was not as commonly used. As we've improved dental care, as we've got more fluoridated toothpaste out there, the incremental benefit of fluoridating your water has gone down. These days, the report said, fluoridation may decrease tooth decay in baby teeth "slightly." Slightly was their word.

Thank you, Sanjay. I'm learning that this is complicated, but I'm still wondering how feasible is it to take fluoride out of our drinking water.

'So, that's the next question, right? And it's a question I think many public health officials and political leaders are considering right now. There has been defluoridation efforts in other countries around the world, and as we just mentioned at the top of the podcast, Utah is the first state in the nation to do that here. Now, again, about 70% of Americans are on community water systems, over 200 million people. They have fluoridated drinking water. Adding fluoride to public water systems is something that is typically up to local, city, and county governments. So for example, some communities like Portland, Oregon, they don't fluoridate their water. But that at the same time doesn't mean the federal government can't have some influence over what local governments do. Just this month, the EPA, the Environmental Protection Agency, announced that they will review scientific information on, quote, the potential health risks of fluoride in drinking water. And that's obviously something we're gonna pay close attention to. It is the EPA's role to set the limits on what is allowed in water and make recommendations under the Safe Drinking Water Act. Again, this gets back to that idea, the dose makes the poison. It's the EPA's role to the set the limit on what's allowed in the water and that goes for fluoride as well. Now, in other parts of the world, some countries have taken different steps to prevent cavities. Take Iceland, for example. The water is not fluoridated there. School children take twice-monthly fluoride rinses. In some parts of the UK, for example, schools add fluoride to milk. The good news is, across the board, I'm talking worldwide, tooth decay has decreased since the 1970s. Now, here in the United States, if you're in a city or state where there is no fluoride in the water, like Utah, which we mentioned before, it may be worth taking extra steps to take care of your and your children's oral health. You know the basic recommendations, brush your teeth with fluoridated toothpaste, fluoride toothpaste, floss daily, see a dentist at least once a year. You've heard all that. For kids, though, fluoride sealants or varnish may also be appropriate to prevent dental cavities. That's something to think about, especially in places where water is not fluoridate. Ask your dentist about this. At the end of the day, I think one thing we can all agree on is that we want to make it easier for our kids and future generations to have happy and healthy smiles, right?

So, look, whenever you think about these issues, you should ask yourselves this. What is the benefit? And we know there is a benefit, but the benefit to fluoridating water has gone down over time, as dental care has improved, as fluoridated toothpaste has become more of a thing. Second question, what is the harm? That's a little bit more complicated, but keep in mind that the dose makes the poison. Anything at too high a dose can potentially be harmful. In many countries around the world where you see this data linking potentially fluoridated water to neurotoxicity, they may have had higher levels, higher doses, if you will, of fluoride in the drinking water. Look, it's a complicated issue. There's a lot of nuance here, but we really wanted to address this, and I hope that helps you.

'Remember, we're always hoping to get a call from you. Leave us a message with your health question, 470-396-0832, and as always. Thanks for listening. I really enjoy being here. I hope you do as well. Chasing Life is a production of CNN Audio. Our podcast is produced by Eryn Mathewson, Jennifer Lai, Grace Walker, Lori Galaretta, Jesse Remedios, Sofía Sánchez, and Kyra Dahring. Andrea Kane is our medical writer. Our senior producer is Dan Bloom. Amanda Sealey is our showrunner. Dan DeZula is our technical director, and the executive producer of CNN audio is Steve Lichta. With support from Jamus Andrest, Jon Dianora, Haley Thomas, Alex Manasseri, Robert Mathers, Leni Steinhardt, Nichole Pesaru, and Lisa Namerow. Special thanks to Ben Tinker and Nadia Kounang of CNN Health, and Wendy Brundige.