Meryl Horn (Senior Producer, PhD)
speaker
109 appearances
3 recordings
2 series
first heard Dec 2024
last heard May 2025
Meryl Horn (Senior Producer, PhD)’s voice in public audio — every appearance, attributed to the second.
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Appearances
Yeah, so that's what Ashley started looking into herself.
I was like, huh. And so she decided to do her own research on this. She wanted to find out if being exposed to fluoride in the womb could affect brain development.
So she got involved in this big study in California. Here's how it worked. So they started following a couple hundred pregnant people and they were taking pee samples from them. And this way they could look at how much fluoride was in their pee. And that kind of roughly maps out to how much fluoride you're taking in.
But by the way, this isn't just looking at like fluoride from the water, because we actually do get fluoride from a bunch of different sources. Something like 60% of it comes from the water, but we also get it from, you know, stuff like black tea apparently has a lot of fluoride in it. Pesticides can have it. Or if we swallow little bits of fluoridated toothpaste...
So, yeah, the researchers here are looking at kind of like overall fluoride exposure. Okay. And then they followed up with these moms three years later. So by now their kids are three. And they had them fill out a survey about their kids where they asked them about all sorts of stuff.
Like people will say like, oh, my kid has temper tantrums like all the time or like, oh, that's really rare. It's like that kind of a thing.
So, yeah, they're, like, casting a wide net here to see if people who had more fluoride in their bodies when they were pregnant went on to have kids with more of any kind of, like, neural behavioral issue when they were 3.
So Ashley was working from home looking at her data on her laptop when she saw the results.
They did have more temper tantrums. They had more anxiety and symptoms linked to autism.
Well, it wasn't like every kid who had some fluoride in the water got anxiety. Right. But what she did is she kind of took the kids who were kind of near the bottom end of getting exposed to fluoride and compared them to the kids who are more towards the higher end of fluoride exposure. And here's what she saw.
Yeah, it's funny. I thought that you would be way more like surprised and alarmed at this study. Like that's how I felt when I saw this. There was like a turning point for me where I was like, what? Like fluoride might actually be doing something bad here? Yeah.
Okay, so I found eight studies altogether that basically did what Ashley did. So they looked at prenatal fluoride exposure.
Yeah, yeah. And then they followed their kids and looked for behavioral issues or sometimes lower IQ. So, okay, so out of those eight studies, six of them found bad stuff. And two of them didn't find anything bad. So six out of eight studies did find some sort of, like, negative effect on the brain from prenatal exposure to fluoride.
But the thing is, that's all just one group of studies. So other scientists tackle this in a completely different way. And they'll zoom in on water fluoridation specifically and ask, if you grew up with fluoridated water, do you have a lower IQ later in life? Right. And a lot of those studies don't find any differences.
I mean, it could be these other sources, yeah. It could be, like... that maybe it's not the fluoride in the water. It could be they're all drinking a lot of black tea or something.
It could also be the difference in when the kids are getting exposed because a lot of the studies finding effects, they're looking at kids who are exposed in utero and their fetuses, and a lot of the ones that aren't are looking after they were born. Another thing that we haven't talked about yet here is that we don't really know what the mechanism would be yet. There are some ideas, but...
Researchers aren't really like coalescing around one thing that is happening.
In general, IQs have been going up in places like the U.S.
And even one researcher who thinks that there is something here estimated that the difference between growing up in a community with fluoridated water and not is only the difference of two and a half IQ points. So that feels like not that big a deal.
Well, I live in New York City and we do have fluoridated water here. Right. But, like, I haven't stopped drinking it. Like, I'm not worried about it for my brain or my kids' brains. Like, I just don't think the evidence is there yet. But I do think that if I were pregnant, like... If I had known all this when I was pregnant, then I would have avoided drinking fluoridated water then. Really?
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