Dr. Shanna Swan on How Plastics in Food are Affecting Our Hormone Levels

When did all this come to light? When did people start understanding the negative consequences of plastics in your food? Well, they came to understand it first in animals, because that's the way science works. You know, first you do animal studies and then you try to replicate them in humans, right? So, in around 2000, they did some experiments where they fed a rat food contaminated with phthalates. And then they looked to see how the offspring developed, right? And what they saw was that the males were born different than the females and different from unexposed males. Do you want me to tell you how different? Yes, please. So, this will really interest you, I think. What happened is... So, let's go back. So, before the phthalates, you know, early in pregnancy, the genitals are just a single ridge. Same in males and females. Undifferentiated. Okay? And then, at a certain time, and in mice and rats, it's 15 to 18 days of gestation, the testicles start making testosterone. And then that gives the signal to produce the male typical genitals. So, if they don't have the testosterone, there will be ovaries, and if there is testosterone, there'll be testicles, and so on and so forth, right? And that migration requires testosterone at exactly the right time and the right amount. That's very delicately programmed, okay? So, if that happens, if everything goes well, then the penis will develop, it'll have a certain size, and then there's something which is very key to my research, which is something you might know by the name of the taint. That taint, or we call it anogenital distance... Yeah, it's not a real... It's not really a technical term, is it? But anogenital distances. Yes. That's hilarious, listening to a PhD, saying taint. Right. Well, I'm saying that because I'm talking to a lot of people who might not know. The area known as the... Okay. Yes. Known on the street as the taint, right? Yes, the streets. And or the gooch or the grundle, or the... The gooch. I've never... Yes, I've known as the gooch. You know about the gooch? Yeah, I just saw someone the other day that didn't know what a taint was, and they were like, oh, you mean the gooch. I've never heard of the gooch. Yeah. I thought the gooch was like a baseball player. Well, it could be that also, but... Isn't there a guy named... Maybe he's named after... Sorry. And also ABC. Have you heard ABC? ABC? No, I have not heard that. How's that one go? Asphalt connector. Oh, the asphalt connector. Okay. But enough for a woman. Yes, you can measure... Yeah, it's not called... But you can't call it an ABC. It's not called the ABC for a woman. Okay. Sorry. So here you got this distance, and it's been measured in animals for like 100 years. And what they used it for was first to just sex the animal. So the litter is born. There's a lot of little pups. They want to separate the males and the females because they're going to do different things with them. And they just hold them up by the tail and they look. And the reason you can do this is because in the male, it's much longer. It's 50 to 100% longer. Now, this is... Stop and think about this. There's nothing else in the body that's that different between males and females in terms of size. Organs, yes. No. Our heights don't differ by 50 to 100%. Our weight's nothing, nothing. It's this is it. This is the mark. Is that in all animals? It's almost all mammals. Really? The hyenas are a little different. We could tell you that. Yeah, I know about those. You know about those, yeah. I have a whole bit about them. Yeah. So, the females are masculineized, so they have a longer AGD, right? But most, for most mammals, it's this way. Okay, including humans. So here's this little pup that's born and he's... If he's unexposed, he'll have a good, you know, standard penal size and AGD and he won't have any malformations of his penis and so on. You know, he'll be normal. But if his mother was exposed to phthalates, everything can go south. And what happens is the penis is smaller and the AGD is smaller and the scrotum is smaller and the testes are maybe not descended. In other words, it didn't finish the process. It was arrested, if you will. So we say that that pup is incompletely masculinized. Now the amount of phthalates that get into the pup system in utero, is that the same... Is it possible to achieve those levels in the modern world with human beings? Absolutely. It is. And I'm going to tell you what I did to show that. I showed that. Wow. So when I heard this story, I was flying on a plane to Japan to go to a conference. I was with a friend who was a chemist for the Centers for Disease Control and he said, Shana, you should study phthalates. And I'm going, why? I'd never heard of them. Why phthalates? And he said, well, we have been measuring them at the CDC and they're in everybody. They're in pregnant women. And this group of scientists in the National Toxicology Program has shown that they altered the development of the male newborn. And they called that the phthalate syndrome. That's what it's called. That collection of changes that come about after the mother has phthalates is called the phthalate syndrome. So I thought, well, does that happen in humans? Same question you asked, right? So how would you answer that question? Then I'll tell you what I did. How would I... You would hope that you're not running experiments like you're running them on animals. Right. Are you measuring the blood of the people that are having children that have issues like with development, development of issues in the way the children look when they're born? Is that what you're doing? It's really close. So phthalates have the property that they dissolve in water, water soluble. And so they go into the urine. So for this class of chemicals, if you want to know how much is in your body and my body, we've got to measure the urine. Other chemicals like flame returns, we would look in the blood. So it depends what the chemical is. But the right idea, look inside the body. Okay. Then rather than looking at kids with problems, what I did was I just took a whole population of pregnant women and I got their urine, measured their phthalates, got their kids, measured their kids. So then I had the problem of what to measure in the kids because nobody had made this translation from an animal genital development system to a human. And so that was kind of a challenge, figuring out how to do that. But we did that. And we developed this system for this exam for measuring all these things that you measure in a rat, we measured it in our children. And then we showed, and this was big news when it came out, that the mother's phthalates did alter the genitals of the boys. So that was the first evidence. That was 2005. And then we published some more in 2008. And then we, fortunately, I got money to do it all again. NIH doesn't like to pay for replication. It's very expensive. These things are $5 million a study, by the way. Well, it seems like it's very important though. Yeah. So they gave it to me. They gave my money to do it again. So the second time I did it better because I really knew what I was looking for. And I got urine actually in three points in pregnancy. And I measured the kids exactly when they're born. So everything was much more precise. And I found it again. So now there's no question. I don't think anyone questions that at least this class of chemicals, which we know lower testosterone, alter the development of these boys. And then I asked, well, what does that have to do with sperm count? Because actually for a long time, we haven't talked yet about sperm count. But I've been studying, tracing what's happening with sperm count. I'll tell you the history of that in a minute. But so then I thought, well, is this related to sperm count? Well, these are babies. They don't have a sperm count. But in rats, it looked like the AGD was permanent. So if you had a short, just like if you have a small hand, your stature is certain, you set it at birth, right? So the AGD, if you're born small, and my friend Earl Gray, who was a toxicologist, said AGD is forever. We don't know that for sure about humans, by the way, because we haven't had the 20 years yet. But if you believe that, then a sensible thing to do was to take a group of adult men who could give you a sperm count and measure their AGD, right? And then you could see whether those with a shorter AGD had a lower sperm count. And then you would have one pretty solid piece of evidence that chemicals in the environment lower sperm count. Are you with me? Yes, ma'am. Okay. So I did that study too. So I got students in Rochester, New York to volunteer for 75 bucks to participate. And they gave us a semen sample, and they gave us opportunity to measure them, also a questionnaire. How does one measure kids' taints? Do they just bend over and you bust out a ruler? I happen to bring you something to show you. I noticed you had this measuring device. Jamie's volunteered to let you measure his taint, by the way. That's why I have some pants on. So this is not for a baby. This is for our Rochester young men's study. And it looks kind of fierce, but we had the points taken down in the... Yeah, I used one of those to measure pool cue tips. There you go. All right. So you know all about it. Yeah. Turn it on. You want 13 millimeters. But only for pool cue tips. So look, I also brought you a little diagram so you can see where we measure. But we can't show this. So the calipers are in millimeters or in inches or both? Both. You can, yeah. Yeah. And so what you... Oh boy, you got a diagram with a taint. Is there any chart online I could look up? Like a... How about I just hold this up? Yeah. All right. Can we have a selfie with you and me in that picture? Yes ma'am. Of course. Okay. All right. So what I wanted to... So when I published this, the headlines were size matters, but it's not what you think. Right. Right? Yeah. And so I got all these people asking me, what should it be? What's good enough? What's big enough? So I did this translation from the millimeters for you. So here it is, the two inches is the median. Okay? Okay. And in this population. And here's the kicker. If it was less than two, men who had less than two inches were seven times more likely to have a sperm count in the subfertile range. I can tell you what that is. As men who had an AGD longer than two inches. Wow. Seven times. It certainly is related to sperm count. And then another study in California showed that infertile men in an infertility clinic versus men who had born a child had smaller taint length. When did this stuff start getting into our food supply? Has that been estimated? So the growth of these chemicals tracks with the growth of the petrochemical industry because they're made from petrochemical byproducts. Okay? So if you look at a curve of the growth, it starts around the 1950. So back in 1950, you have people loving science, jumping on the science bandwagon. There's this better living through chemistry that everyone's talking about. And everybody is just wanting everything made of plastic. It's the new craze. It's the new... And it just took off. It went faster than a straight line, exponentially up. So somewhere in there, it started having an effect. But we're not sure, but I did look at the decline in sperm count over time. So we could look at that as an indication that this is not the only thing that's affecting sperm count, by the way, these phthalates. But that's one where I feel I can say this with confidence because I measured those babies and I did it. I did the science and I did it again and other people have done it. And so it's, I believe it's solid. And that's just one example of the many chemicals that can affect our hormone system.