Factually! with Adam Conover - Why Is the Fertility Rate Falling? with Dr. Shanna Swan

Episode Date: April 7, 2021

There are a lot of causes of the declining global birth rate – education, freedom, and even the decline of subsistence agriculture. But what if one of the biggest factors was … plastic? Epidemiologist and author Dr. Shanna Swan joins Adam this week to break down why phthalates affect our fertility as well as our overall health. They cover her scientific research into phthalates, how they get into our systems, how they disrupt the development of reproductive organs, and what this means for the continuation of the human race. For Dr. Swan's book Count Down, as well as other books written by guests of this podcast, go to http://factuallypod.com/books. Learn more about your ad choices. Visit megaphone.fm/adchoices See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.

You know, I got to confess, I have always been a sucker for Japanese treats. I love going down a little Tokyo, heading to a convenience store, and grabbing all those brightly colored, fun-packaged boxes off of the shelf. But you know what? I don't get the chance to go down there as often as I would like to. And that is why I am so thrilled that Bokksu, a Japanese snack subscription box, chose to sponsor this episode. What's gotten me so excited about Bokksu is that these aren't just your run-of-the-mill grocery store finds. Each box comes packed with 20 unique snacks that you can only find in Japan itself.

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So if all of that sounds good, if you want a big box of delicious snacks like this for yourself, use the code factually for $15 off your first order at Bokksu.com. That's code factually for $15 off your first order on Bokksu.com. I don't know the way. I don't know what to think. I don't know what to say. Yeah, but that's alright. Yeah, that's okay. I don't know anything. Hello, welcome to Factually, I'm Adam Conover. And you know, humans have been around for a while, some hundreds of thousands of years here on planet Earth. But for most of that time, there actually weren't that many of us at all. Like, go to 10,000 BC and there are just a couple million people globally across the whole Earth. There were literally probably more giant beavers at that point than there were human beings. It takes another 9,000 years for the global population to top just 100 million and another

2,000 after that to get to 300 million people and another 800 years all the way up to the year 1800 for that population to hit a billion. But let's pause here a second. A billion people in the year 1800. That's just a little over 200 years ago. Since that time, the human population on Earth has exploded. We are talking a growth of about 8 billion people in just the last 220 years. The graph of human population growth, slow and steady for a long time, that about 200 years ago, it rockets to the sun, okay? Bitcoin has nothing on humanity.

And let's be really clear, the fastest part of the explosion is within all of our lifetimes. Like I was in high school when we hit 6 billion. I remember that happening very clearly. I remember hearing about it on the news. And now we're about to hit 8 billion. We are talking 2 billion more people breathing, eating, and shitting on this planet within my own memory. And I'm not even fucking 40 yet. Like, this is nuts.

Now, if you find hearing numbers like this worrisome, you're not alone. In fact, for most of the time of this explosion, humans have been freaking out about the explosion. The great granddad of population catastrophism was British political economist Thomas Robert Malthus. In 1798, the good old days, back when there were just one billion people on Earth, he predicted that human population growth would soon begin to outstrip the food supply and that we'd all be, you know, screwed. But it turned out his predictions were wrong in the 19th century. It just didn't happen. But the anxiety over population growth continued. Malthusian thinking, as it was called, got a big bump in the 20th century when a Stanford entomologist, that's someone who studies insects,

not necessarily humanity, published a scary sounding book in 1968 called The Population Bomb. And it argued in a familiar line of reasoning, the population growth was beginning to outstrip the food supply and that soon, meaning in the 1970s, we'd all be screwed once again. And once again, it did not happen. Now, the reason for that is that our ability to produce food started scaling up massively as well. We had something called the Green Revolution, under which massive amounts of food began to be produced by our agricultural systems for good and for ill. Our food production system, as we have talked about on this show, does have a lot of problems. But the fact is, even though we

have so many people on Earth, we actually have enough food to feed them all. It's just not distributed evenly across the population because, you know, even distribution, that's not really what capitalism is all about. But the fact is that despite the doomsaying we've been hearing for the past 200 years that our population has been exploding. The population apocalypse has not come to pass. In fact, even though the human population is still going up, human fertility is going down at another incredibly high rate. I mean, just listen to these numbers. In 1950, women had on average 4.7 children per person. But in 2017, that number was 2.4, almost half of what it was just decades previously. Now, many of the reasons for this have less to do with the food supply than with social progress.

Women today are more likely to receive an education and work outside the home than they were 50 years ago. There's also much greater access to contraception. And there's a myriad other demographic reasons why fertility is falling. But there is another reason behind it, too, that is not social. It's environmental. As my guest today will argue, certain environmental hazards, like some plastics, have led to decreases in human fertility. Sperm counts in men, for instance, are way, way down. So look, the point I'm coming to here is that this is some serious population whiplash. I mean, like if you're looking at a species in the wild, like if you're just looking at, I don't know, deer in the forest, right?

And the population increased by a factor of thousands in just a short period of time. And then you saw that species fertility drop in half. You'd say, hey, you know, I think we should study this because there is clearly some weird shit going on and potentially a problem that we're going to want to understand. Well, to that end, our guest today is one of the researchers who is at the forefront of understanding why human fertility is declining so precipitously. Her name is Dr. Shana Swan, and she's the author most recently of Countdown, how our modern world is threatening sperm counts, altering male and female reproductive development, and imperiling the future of the human race. Please welcome Dr. Shana Swan. Shana, thank you so much for being here.

Thanks for inviting me. Happy to be here, Adam. So let's get into the facts about this. How do we know that fertility has gone down and how much has it gone down? So fertility, as measured by the number of children that a woman has, which is the official way of measuring it, of children that a woman has, which is the official way of measuring it, has dropped from worldwide from five children in 1960, that's five children to an average woman, right, in the world, to 2.4 at the end of 2018. So that's a drop of 50%. And that's worldwide. And we know that from looking at birth records, which are very, very good records. And why is that? What are the reasons for that decline? There must be,

I assume there's more than just one. Oh yeah. So the reasons for decline in fertility and numbers of children and other things that affect that and are reproductive, we call them reproductive outcomes. Those are all things that are in trouble right now. And so what I study is the reasons for that. So it's a big story. I've been doing it for more than 20 years. And if I had to just say broadly, I would say we can classify these as the lifestyle factors, which is the things we do in our daily lives. And then we can talk about the chemicals that we're exposed to. a bad thing. I mean, often I look around the world and I think, well, there's too many people. Maybe we don't need so many. I mean, I would like people to continue to be around, but you know, there are problems that are caused by there being a huge number of people on planet earth. Yeah. Are you alarmed by this or how do you feel about it? Well, I actually am alarmed

by it because it's a signal for lots of other things that are going wrong. And first of all, the couple that's trying to conceive and can't, which is part of the problem, and that's increasing, they're not going to see it as a good thing. And that's kind of a basic human right to be able to reproduce when you want to. human right to be able to reproduce when you want to. Secondly, the animals, I just mentioned animals around the world are also having declines in fertility and their reproductive health. And that, I think we would all agree, is not a good thing, right? And another reason it's not a good thing is that when countries get extremely low and get concerned, as we see now in Singapore and Korea and Japan, and they try to bring the number of children born up again by giving financial incentives, by, you know, encouraging them in various ways, they can't do it. This doesn't, is not, you know, they're not able to turn this around. So, I think this is a problem. And I think it's tied to, in part, people making choices to have children later, for sure. That's definitely one of the things that's happening.

But most, you know, when we look at who's having the problems, a woman of 25 is now less likely to succeed in conceiving a pregnancy than her grandmother was at 35. So it's not just an age thing. And men today have like half as many sperm as their grandfathers did. So men don't choose to have a low sperm count. So choice, you know, which people always bring up, is only part of the equation. I recognize that, of course, but it is not the answer to the problem. Well, okay.

Man, this is really a massive change that you're talking about. You're saying that it went, I just want to hear the number one more time, the decline in fertility. It went down from five in what year to what now? Five children per woman or couple in 1960 to 2.4 children per woman or couple in 2018. or couple in 2018. Wow. So less than less than half. Yes. In a number in a number of in what two generations, 60 years. Right. That is if you saw that happen in any wild population of animals, you'd be something is has really massively changed here. And you would perhaps be worried. But let's talk about first before we get into the stuff you're saying about sperm count is mind boggling.

But before we get into that, I just want to I just want to understand all of the behavioral changes and the sort of demographic changes that that also contribute to this. Because, you know, I know a lot of it is and this is me speaking as a layperson. But I know that, for instance, when folks are, you know, working in subsistence agriculture, they tend to have a lot more kids. And then when, you know, because they're sort of like making a labor force in some cases, that's been a pattern in human society. And then once you have a population become more educated and do, you know, different sort of, you know, college educations, that sort of thing, people delay when they have kids. Certainly, you know, my friends who tend to have, you know, bachelor's degrees are, you know, they're having

kids in their 30s as opposed to, you know, my grandparents who had kids when they were, you know, 20, 21. So there's all those factors. Are there other factors along those lines that are more related to modernity or, you know, changes in populations that we should also think about? Well, those are really important factors. And it is true that as a society gets more educated and the number of women in the workforce goes up, and also when a population gets more urban, you pointed to the agricultural population,

all of those things are related to lower fertility, that is number of children born to the woman. But like I said, there are many other factors as well. And some of the ones related to modernity, I would say, is the stress. It's a factor which makes it difficult to conceive. makes it difficult to conceive. And very importantly, there is the presence of hundreds, if not thousands of chemicals that have the ability to alter our hormone systems that we're exposed to every day. And this is the part of it that sounds like science fiction almost. This is why we brought you on the show was we read some of your work about this and said, hold on a second.

There are chemicals, modern chemicals that are reducing our fertility on a massive scale. There's all these other things that we talked about that are like, okay, you went to college, you decide to have kids later, or you live in the city instead of out in the country, that sort of thing. But, but this is very different because this could interfere with your ability to conceive if you want to. And so tell me more about this piece.

Yeah, so the chemicals that I'm concerned about are those that can trick our body into thinking it has enough estrogen, it has enough testosterone, or it can interfere with the transport of those. And this is critically important, and let me tell you why. So if you think about a fetus in the womb, very early, very undeveloped, and that would be maybe in the first four weeks, five weeks, then if you look at all of the organs, most of them are undeveloped or unformulated.

They're not male and female, right? They don't have, they're not typically phenotypically male or female. And then at a critical moment, which is actually programmed genetically, the male testicles start producing testosterone. And because of that, there are a lot of changes that are related to that little organism being a genetic male. And if there's enough testosterone, then that organism, that fetus will develop the male typical genitals and brain and so on. Now, so the key player here is testosterone, which we know is a very, very important hormone. If there are chemicals in the mother that make their way into the fetus that can lower testosterone then that fetus is deprived

if you will of the the testosterone it needs to make this transition that make sense yeah okay so So that was shown first in animal studies, where the mother rat was fed food that contained phthalates. And then they looked at the offspring. The females were not affected by that exposure to phthalates, but the males were and the males maybe surprisingly were in a lot of ways less white call male typical and what you'd expect for a genetic male they were less of that they were closer to what you'd expect to a genetic female um and this whole syndrome that they observed in these male rats was given the name the phthalate syndrome. Say that word again? The phthalate?

Phthalate. So phthalates are chemicals in plastic that make plastic soft. We can come back to that and tell you where they are and how to find them. But basically, think plastic tubing, think rubber ducky, think shower curtain, anything soft, flexible, that's going to have phthalates in it. Do many, many other things. Everybody has it in their body. I don't know how much you have or how much I have right now. We can't know that, but we can find out. And the way we can find out is we can take a sample of our urine and we can send it to a laboratory and the laboratory will

tell us how much what we call phthalate metabolites, what the body turns the phthalates into in the urine, how much that is in there. And that's a signal for how much is circulating in our body. Right. So we're getting these chemicals that they're not present in our bodies or anything naturally. They're only present in these plastics. That's right. And how do they get into our bodies? Is it just if I hang out in my bathtub with my rubber ducky for a long time and I do that once I take my I take my bath every single night at 11 p.m. It's very hot. I got a rubber ducky in there and the chemicals leaching out of the rubber ducky and it's just it's just getting in, just going up my butthole into my body? Exactly right.

Exactly right. And it's going, wait, wait. It's going into your, through your skin. It's actually, you might be breathing in some of the particles because these are also in dust and air. And if you were going to eat something that was contaminated with phthalates, and we

should talk about because that's the most common route of exposure. The rubber duck is, you know, very appealing, but not so many people are exposed to them. But food is a really big one. So you can get it through food, you can get it through drink, you can get it through air, you can get it through dust. And those cosmetics, I don't know how many you use, personal care products, you know, aftershave lotion, you know, skin cream, all of those. Because not only do they make plastic soft and flexible, they also help hold color and odor and also make things more easily absorbed. Right. So they're put into products so that that chemical will go, you know,

that skin cream will not be there 20 minutes later. Right. You rub it into purposefully into those products. Yeah. Deliberately. Wow. That's right. And,

and you know, anything that smells a fragrance like your cologne or your laundry detergent or your room freshener or that little pine tree you hang in your car, anything that gives off a scent is going to have phthalates in it and you'll smell it. It'll get into your body through your nose. So we're just barraging these things all day long and we can't escape them. And we can't actually buy our way out of not having them because they're so pervasive. There isn't better stuff to buy. You can't just go to the store and shop a different aisle. There is better stuff to buy, but most people don't know and many people can't afford it so there's other issues around that but basically um just choosing one you know plastic product over another is not going to do it for you i mean i'll just tell you one thing you could do is don't let your

food come in contact with plastic use glass ceramic and metal and you're going to be doing yourself a big favor right there so how does in your view these chemicals then interact with uh testosterone um that you say they in some way they prevent uh when uh when a genetically male fetus is developing in the mother it somehow blocks testosterone in a way. Can you break that down for me? Well, first of all, I would just tell you the bottom line is that testosterone is lower and how it does that is there's probably several mechanisms, but one of them is that there are testosterone receptors that are, if you will, looking for testosterone. And these phthalates come in and occupy the receptor, which should be occupied by a molecule of your body's testosterone.

So then the signal given to the pituitary and so on is that there's enough testosterone already. Stop making it. is that there's enough testosterone already stopped making it. So we have this feedback loop and the amount of hormones that we have circulating is changing in response to need for the body. So if you get the signal, we're good to go on the testosterone front, don't make any more and it's locked up, then the development is impaired. So that's just one crude way of saying it, but there's many ways of interfering with these hormones. It's not just testosterone, but this is a good one to talk about because it's so clear that it

changes the development of the male typical genitals. And we know this experimentally that, that phthalates interfere with testosterone in this way. Yes. We know it in test tubes by looking at test systems, if you will, that respond to something which is called an anti androgen, which is testosterone lower. So there've been shown in you know what we call in vitro studies to be testosterone lowering to be anti-androgenic

and we know it in animal studies for many animal studies the first one i think that came out showing this was 2000 or even a little earlier um so for a long time, so 20 years, we've known that they can do this to animals. And then when I heard about this, which I did in around 2000, I thought, hmm, I wonder if that's going on in humans. Cause I also heard at the same time, and this was from a friend who told me, I should study phthalates, right?

And I think, why should they study phthalates? I had never heard of them. And so, you know, he told me they're in everybody. They're in pregnant women. And in their laboratory, a pregnant rat exposed develops this cluster of outcomes that has been called the phthalate syndrome. So I thought, well, I could check

that out in a human population, right? And so I began the work of doing that, which took me close to 20 years because I did it, you know, not just once and did it really carefully, especially the second time and showed that measured levels of these phthalates in a pregnant woman's urine were measurably related to the development of her son's genitals. Wow. And you did this. What kind of study is this? Are you looking at a large population of people? Or just tell me a little bit about your method and the place that you occupy in the scientific community looking at these issues. Sure. So I'm an epidemiologist and we study people. Right. But I also think of myself as a human toxicologist because I try to translate animal toxicology to humans. And so what to do this, we have to get humans who will talk to us and give us urine samples and allow us to, for example, measure their babies or maybe give us semen samples, which is another study we can talk about. is another study we can talk about. And so what we do is we go to a university setting or some other setting where pregnant women come in for care. And we ask them whether they would agree

to participate in a study. And if they sign a consent and they understand all the risks and so on, which are not great in this case. Then they're enrolled in the study. We ask them lots of questions over the course of their pregnancy. And we get their medical records to see if there are medical problems. And then we ask them for samples. And the simplest sample to get are urine samples. They're very easy. So you collect urine, you freeze it, you know, standard protocol. And

then when the time comes, you can send it off to a lab to be analyzed. We also get blood, we draw blood. That's harder. And we don't do that as often because that's, you know, a little more difficult for people. Other studies might look at other samples like breast milk or you name it, all kinds of fluids tell us of what's going on in the body. And then we follow those women. And then we got in our second study samples in each trimester, questionnaires in each trimester. And then when the baby's born, then we have another job, which is examining the baby. born, then we have another job, which is examining the baby. So let me just ask this about phthalates, because, you know, in my view, there are so many concerns that people have about plastics, about other objects in their environment. And a lot of it is very pseudoscientific. You know, a lot of

people have, oh, you should never use a microwave. You should, you know, furniture off gassing and things like that. And some of it is some of it is true. Some of it is fear based. Some of it's in between. Sure. And so it's one of those areas that to me is very hard to parse. But it sounds like to you from hearing you talk about it, this is relatively well established at this point. There is a connection between these plastics and between these hormones.

Yes, that's correct. And I share your concern. Certainly not every, you know, anxiety that somebody has about a chemical should be, you know, something that worries us. But I think, for example, phthalate in reproductive health has been studied for more than 20 years by many, many people around the world, publications, peer-reviewed, and it's not really disputable now, I think. It's really a well-established body. And by the way, let me just say, to do this work and to get this level of proof that we have now cost millions and millions of dollars. Each of those pregnancy cohort studies that I described cost $5 million. And, you know, then there's the animal studies and all that. time and so i'd like to just say if the government had some control over these chemicals before had some testing of these chemicals before they were put into our products it would save us a lot of

grief because and money and time because um you know we would have some knowledge of them but we're blind to this you and i don't know the levels of chemicals in our bodies right now. We could, but we don't. And we don't know where they're coming from. And we don't know what they're doing. So we're kind of like guinea pigs, you know, or animals in a big experiment. And I didn't agree to this experiment and I don't think you did either. So I think people should be concerned about being exposed about their consent. Yeah, we have a we have a fundamentally reactive regulatory regime. That's how it works in America is is you make a product. And then after scientists have proven through great effort and strain that nicotine or not nicotine, but that cigarettes cause cancer and that asbestos causes disease and death as well. Those things are finally regulated against. But in the meantime,

you still got a whole bunch of houses full of asbestos. Absolutely. And, you know, that's a different conversation, how we could ameliorate that. No, no, I don't think it is actually. It's exactly the same conversation because the same thing that happened and i'm glad you brought this up the same thing that happened with cigarettes and with asbestos and is you know is happening with these chemicals now they're they're put into commerce without testing and then that when test results come out the the response of the industries involved is to belittle them and to say they're not conclusive and we need more evidence and so on and so forth. And there's a whole industry of sowing doubt in

the science of these products that we have to fight against. So I think it's exactly the same story. Okay. Yeah. I meant, you know, there's an even, like how we might reform our entire regulatory apparatus to like stop these problems before they start would be such a huge project. But the comparison between these chemicals and, you know, cigarettes is absolutely an apt one. And it's one that I hadn't thought about before. It's fascinating. So let's come back to when, you know, you say women who had a higher count of phthalates had lower testosterone or their children had lower testosterone in fetal or in babyhood. I didn't say that.

Let me just say they had changes, measurable changes in their genitals. The testosterone is another story. It comes later. Yeah. Yeah. So they did have lower testosterone in utero, but we didn't measure that because you can't measure what's going on in utero. However, in the uterus, right, in the womb.

But in fact, we had measurements, which I can talk about with you if you want, which reflect how much testosterone there was in the womb. So we had an indirect measure through these measurements of the children. I see. So, so yeah, break that down a little bit more for me and then connect that to fertility. How does that then result in the fertility changes that we've seen? So, so to do that, I have to talk about something which is not maybe very comfortable, excuse me, not very well known. And that is something called the anageneral distance. Have you heard of that?

I have not heard of it. And don't worry, we have no standards and practices on this podcast. You can talk about any matter you wish. Right. No, no, no. I just I just wondered if you had heard of it. So this is a distance and it's the distance from the anus to the genitals. Okay. Now, then you have to worry about where in the genitals you're going to measure.

Exactly. That's exactly what it is. It's the tank length. That's right. Okay? Or you might say the gooch or the brundle, right? Yes. So that's what, yes, right?

And it's interesting that it comes up in science now when it's been on the street for so long. It's also been in science animal laboratories for a long time, right? So the first study I found that measured this and talked about how it was nearly twice as long in males than females when dated to 1912. This is not new, but it hadn't been measured in humans. So I went to this animal

study that was used to define the phthalate syndrome. And the key thing, in addition to smaller penises, smaller testicles, less testicular descent, and other changes, the most dramatic thing was this taint length. It was shorter when the mother had been exposed to certain phthalates. Measurably. Significantly shorter, okay? So, that's what I wanted to measure in humans. But there was no, like, standard protocol for measuring this. So I had to take the animal studies, see what did they look at, and try to translate it to humans, right?

And so that's what I did. And so when the babies came into to you know our clinic to be examined we measured how the width of the penis at the base okay and the length of the then the taint length i'm going to use that because i love that you know and we saw you know we felt where were the testicles and there's a way to run your finger down and you feel where it is does it go into the scrotum then they're descended but if you can't feel them down in the scrotum they're undescended or partially descended and so that's a defect as well um so we did this to the to boys. And what we found, I told you that when the mother had higher levels of certain phthalates, they had shorter taint length, smaller penile width,

smaller penis size, and more likely to have underscinded testicles. So that's not sperm count. So how do we get there? Okay. So that was the next problem. Okay. So these are babies. They don't produce sperm. For that, we have to wait for adolescence. And then human subjects approval means we have to wait till they're 21. Okay. So nobody had any AGD measurements on boys at birth who were 21. So first of all, I'll tell you in animal studies, that taint length is yours for life. Meaning that if you tend to be small at birth, you tend to be small your whole life. The actual length will increase as you get bigger, of course, just as your hands and feet do. But, you know, if you're born, if you have small hands at birth, you're probably going to have small hands when you're an adult, right? And it's the same thing

with your taint length. All right. So, if we accept that, then we can say, okay, an adult man, we could look at his taint length and we could say, is that related to a sperm count? Mm-hmm. I mean, you might not ask that question, but I did. As an epidemiologist, you might. Yeah. Yeah. Right? And so what I did was, how would I do that?

Well, I'd have to get men to come in and let me or someone measure their taint length, measure their taints, blurs or their taint, and also measured their sperm count. So we did that. This is, this is quite a day at the lab for these subjects.

Yeah. We got young men who went to the University of Rochester and we paid them 75 bucks. And they said, and this was... Fair enough. Yeah.

This was more than 10 years ago. So 75 bucks was a fair amount of money. 10 years ago, when I was in my 20s, I would have taken 75 bucks to get my taint measured and give a sperm sample. Sure thing.

Right? Yeah. Yeah. So they did. And normally I do that alone at home in my room. So I'm happy to get some money for it. Right. That's right.

But for 75 bucks, you could do it in the laboratory and let somebody on our staff measure that. So that's what we did. our staff measure that. So that's what we did. And we found that when the taint was shorter in these guys, they had a lower sperm count. And the longer the taint, the higher the sperm count. So that's what the model predicts, right? Because it predicts that when you disrupt things in early pregnancy related to general development, you're going to mess everything up. Sperm count is related to fertility for, I think, intuitive reasons. I would imagine that that lower sperm count, you have a lower chance to conceive. Is that correct? Yeah, up to a point. So if you have a good sperm count, which would be, you know, 60 million per milliliter, 50 million per milliliter, that sounds a lot, right? And 50 million, you know, milliliter, small, that's how concentrations are, you know, summarized, then that's a good number. And whether you have 50 or 60 or 70 or 100 doesn't make a lot of difference.

You've got a lot. When you go to the short end, then it matters more and more. So at about 40, you're kind of at the point where it starts to matter. And below 40, it gets harder and harder to conceive a pregnancy. That is, to put it technically the the chance that you conceive in any month goes down okay so that's how it's related to fertility and and men who have zero sperm are totally infertile infertile men who have a few sperm could conceive a pregnancy, but it would take a long time. This is another thing.

Yeah, if you're at the lowest end of the curve, it becomes vanishingly less and less likely. And so the effect of this, of more phthalates in conception in general in utero and women across the country and the world would mean you just are ending up pushing the entire population of men down the curve a little bit. So you end up with more on that very low on that very low threshold. Am I sort of understanding it right? Absolutely. Absolutely. And I'm actually impressed. How will you summarize that? Are you sure you've never studied statistics? I never I never studied statistics. I'm just a dilettante who understands a little bit about a lot of things. And that's why I host this show, because then I can talk to people like you. I have a bachelor's in philosophy. I do my best to keep up.

Got it. So really, I really appreciate you walking us through the chain of how the experimentation and the studies worked, because I can see how there is you've drawn a link all the way from phthalates at the beginning of, you know, in the mother's body during pregnancy, all the way to a drop in fertility. That's really, really fascinating. We got to take a really quick break, but I want to ask you about the implications of this. Please do before we go to. Yeah. I just want to, I just want to say I made the link not to fertility, but to sperm count, which is not the same thing. However, another study in California, Stanford, another researcher looked at men at an infertility

clinic and he measured their antigenal distance, their chain, and he looked at it in relation to sperm count, which we also did, but he also looked at whether they had ever had a child. Some men in infertility clinics have had children, so those men are not infertile. And he found that the infertile men not only had, you know, a shorter taint if, you know, because they were related to their infertility, but also related to the sperm count. So they have a double whammy. Low sperm count decreases it and being infertile decreases it. And they're not quite the same thing. Got it. Well, I want to find out more about the implications of this on a broader scale, but we got to take a really quick break.

We'll be right back with more Shauna Swan. Okay, so we're back with Shauna Swan. So we've been talking about how phthalates in our environment are linked to a drop in fertility. How much of the drop we've seen in fertility over the last 60 years, can we say is the result of these chemicals? Because we've talked about the other reasons as well, just changes in the way that we live, changes in education, all these other sorts of things.

People choosing to have less children, people having less children for sociological reasons. Do you have any sense of how much is due to these chemicals, though? No, we don't know that. And that's really the sixty four thousand dollar question. And I'm not even sure how we would go about studying that. But on an individual basis, I know that an individual man or woman can make it more likely that they conceive a pregnancy or have better sperm count by cleaning up their act. And there's one example in our book of a man who goes to a sperm bank. He's a donor, a regular donor. He has a very good semen quality. And then one day

he doesn't, you know, and they ask him to clean up his act and they tell him various things to do. And he does that and he comes back and he's good to go. So things you're exposed to as an adult, you can change. And so it's important to know what those things are. And by the way, it's important for men, I think, to know what their sperm count is. Most men have no idea. They just figure they're good to go when they need it. But here's the kicker. It turns out that having a low sperm count is actually bad for your health throughout your life, not just about having babies. That's surprising. So men with low sperm count have more heart disease, more diabetes, more cancers, particularly reproductive cancers, and they die younger. Wow. But wait, could, could that be, you know, could the causation be reversed? Like if, you

know, could men who are prone to heart disease simply have lower sperm count because they're otherwise less healthy? I have no idea. I'm just, you know, I have to ask the question. I'm sure, I'm sure that there, that there could be some of that going on. However, what I think is going on and what animal studies suggest is that when you disrupt one system early in pregnancy, remember the phthalates disrupting things, and knocking down testosterone or maybe increasing estrogen as other chemicals do, you are changing the balance of systems throughout the body and things that affect the heart and things that affect the thyroid and things that affect the immune system and so on and on and on. So you can't disrupt one system in isolation. It's going to have repercussions for your whole body's health.

And this can end, you know, lead to ending up with, you know, earlier death. And that's what the studies are showing. So I think, you know, some people say this should be the sixth vital sign. It's really an important signal for your overall health. And you can learn about it by getting a checkup at a, you know, fertility clinic or an andrologist. Women do that. They go for OBGYN checks every year, but men never do.

Yeah, that's really funny because I know you said andrologist and I know the word gynecologist. I don't know the word. You're the first person I've ever heard say the word andrologist. Yeah. Which is obviously the obverse of gynecologist.

Male sexual function, right? Yeah yeah yeah yeah i don't i don't know my sperm count i've never never thought to had it measured and perhaps i mean i'm not planning on having children and i so i was like why would i why would i care but perhaps it's worth finding out um but your book is uh is called countdown and it's about, you know, you're raising the alarm about phthalates and about these about other other chemicals, I imagine, that are contributing to this decline. So clearly you you feel that this is of great concern. Again, I'm trying to get a sense of of how concerned we should be, given, again, that I think there are certainly other factors for fertility. So when you're talking about the human race as a whole and our fertility, what concerns you so much about these chemicals? So I'm just going to read you the title of the book.

Please do. And that'll convey my concern. How our modern world is threatening sperm counts, altering male and female reproductive development, and imperiling the future of the human race. That's pretty big. Tell me about that piece, about the future of the human race, because I think we've talked a lot about the other two.

What's your concern about our future? So my concern about our future is that if you extend the line that we drew in our 2017 paper showing that sperm count had declined 50 percent more than 50 percent you know in in 40 years um wait really it's declined 50 percent in 40 years yes more than 50 percent in 40 years i can tell you the exact numbers if you want but if you extend that line it's a decreasing line we drew a straight line and several people said to me um what happens if you keep going? When does it hit zero? Now, as a statistician, which I am, I'm reluctant to do that. But you can say hypothetically, if it were to continue, which I don't think it will for a number of reasons we can discuss, but it's definitely going down. All of our data show that the slope that we showed is not slowing down. It's not like

if you look 40 years, 30 years, 20 years, it gets better and better. No, we don't see that. So if you extended it in 2045, it reaches zero. That means that our best prediction, given the available data, which is all you can ever do, is that by 2045, half the men in the world, is that by 2045, half the men in the world, at least half the men in Western countries, where the data are strongest, will have no sperm. Wow. Half the men. And the other half will be low.

There'll be a lot of them near that 40 that I told you was not good to get close to if you wanted to conceive a pregnancy. So can they have children? Yes. There are many very sophisticated methods of assisted reproduction that can deal with problems on both the male and female side, and people can seek that. I think what's going to happen and what is happening, that more and more children are being born by assisted reproduction. By the way, that is happening along with the lowering in sperm count. And so that's one reason, that's one prediction I have.

I don't know how the technology will develop, you know, how easy, whether it'll become easier to have babies in this way rather than in, if you will, the old-fashioned way. But if we look at other species around the world, everyone knows that the number of species are in decline or endangered, threatened, or extinct. So it's not unheard of that failures in reproductive health drive species to extinction. Wow. You are really raising the prospect of human extinction as a result of this. I'm raising the prospect in the hope that people will take this seriously and begin to take action. But this is a real threat. I mean, what you're describing,

you said it sounded science fictional, and this is the piece where I'm not saying it sounds science fictional to discredit it. I'm saying literally I've read science fiction novels with this premise that say, in the future, humanity will mostly be infertile. There's that film Children of Men in which humanity is mysteriously infertile. There's that film Children of Men in which humanity is mysteriously infertile

for an unknown reason. This is like a common premise when we're thinking about the future and you are raising it as a real possibility. Yes. Now, if you would ask me, do I predict this? Do I think this is what's going to happen?

I would say no. I think we is what's going to happen? I would say no. I think we can do amazing things to turn trends around. I mean, you know, put the lander on Mars and think about the vaccine production this year, which was incredible. Never predicted that it would be that fast and so on. So as a species, we're really resourceful and we're very smart. And, you know, if we channel our energy in part, you know, of course, we need a lot of energy for these other crises we're facing. But if we channel part of that into producing safer chemicals and regulating chemicals properly, I believe we can really change this. And actually, a researcher in Washington State showed that in three generations,

you could turn this around. Wow. In rats. But the problems happened in two generations. Yes. We've got to go a little faster. We've got to go a little faster. Yes.

Yes. Okay. But those rats don't have access to assisted reproduction. I do want to ask. I think it's easy to make this case sound too frightening. I want to make sure that that we don't because there's still a decline in fertility. There's some piece of the decline that is not due to a scary reason and is to some degree natural given the way human civilization has progressed. That people simply choose, again, to have less children. When we look at that number going down per woman from five to less than two and a half, not all of that is bad or scary. There's maybe there's some amount of

lowered fertility that we as a species should be comfortable with, but there's also a certain level at which we should want to reverse. Is that, do you feel that way? I do. And I, what I feel is that when couples want to have a child, they should have the capacity to do that. I'm not saying that more and more people should want that, but it's, you know, it's a basic human right that you should be able to have a child if you want that. And the babies have a right to be born without something that's going to threaten their later health. So it's not just about conceiving the child. It's also carrying it to term and it's having a healthy baby and a baby that will go on to be able to

produce their own children. Because don't forget the germ cells that are inside the child when it's in utero are also being exposed. So that child's children will be exposed to the mother, grandmother's exposure. You see that? It's like a Russian dolls, nest of Russian dolls. Yeah. Yeah. And I just want to touch on this subject and this might be entirely outside of your interest or, or expertise, but you know, the way that we talk about testosterone in our society is, is often really, you know, bound up with ideas of, you know, to put it frankly, toxic masculinity. And, and, you know, it's often used as a, there's a pseudoscientific folk understanding of testosterone that's often used, you know, to make men feel bad about themselves or to, you know what I mean?

Like, oh, that guy, that guy's low T or like that kind of thing. And I do worry about, you know, a narrative of, oh, you know, men are becoming feminized is like a very, very old sort of reactionary story that's been told for decades and decades. And I do wonder how the hard research that you have interacts with that. Is there anything in there that that strikes you as as uncomfortable or i'm just curious how you feel about that piece of it yeah that's a really touchy difficult subject um but i will say first of all that the decrease in testosterone lowering libido which is what you're you're talking about right um happens both in men and women. And this has been shown in studies, in our study, our own study, when women had higher levels of phthalates, they reported more sexual dissatisfaction.

And a study in China among workers showed more erectile dysfunction and so on. So there is a definite connection between these chemicals and sexual function and desire, which is, you know, is shown, is scientific. However, the question of whether these chemicals are going to produce more gay men or more lesbians or, you know, more people on the spectrum or more people seeking to transition, you know, that is a very, very difficult and very fraught topic. And all I can say is that, you know, we can't get any animal evidence for the desire to change our sex because we can't ask animals what body they wish they'd been born into.

Right. So we can't go there, I think, with our science. It is true that animals can be produced in the laboratory and in the wild with what we call disorders of sexual development. laboratory and in the wild with what we call disorders of sexual development. So animals with ovaries and testes in the same individual produced by pesticides, no question. Fish, same thing. And animals that males that want to mate with males, attempt to mate with males and so on. This can be produced in the laboratory. So I think there's evidence there and there's a scientific question there. But when we go to the other part of the question,

which is gender choice, that is very difficult to answer scientifically. Yeah, I think there's a way in which, and we'll move off of this, but I think there's a way in which our social conversation around gender, gender roles, masculinity, femininity, all these things, there's a lot of folks who want to bring science into it in an inappropriate way, when we're really having a

social conversation about those things. And they want to say, oh, men are wimpy now, or men are feminized, and that sort of thing. And that, to me, oh, men are wimpy now or men are feminized and that sort of thing. And that to me strikes me as totally separate and an inappropriate place to bring science in when what you're talking about is biology and issues that, you know, we should be concerned about for our own health and that we should, in my view, I think we should sort of build a firewall between those things. I just want to bring it up because so often you hear people with social agendas misusing science in order to justify their social agenda. And I don't think we should do that. And I wanted to say it. I agree. I agree. And I'm glad you brought it up. It's important. Well, so let's talk about what we should do. First of all, let's talk about what what we should do. First of all, let's talk about what the average individual can do.

If you are say, you know, say that someone who's thinking of conceiving or perhaps is is pregnant. Are there consequences of your research that you feel should affect their behavior that they might want to know? affect their behavior that they might want to know. Absolutely. Absolutely. And I mentioned one simple, you know, you know, make a plastic free kitchen if you can. There's other food related things. I'll mention a few of them. But I just want to say in our book, Countdown, you know, we have several chapters devoted to the question of what you as an individual and we as a society can do. So I can't possibly go into them all there. Of course. I encourage people to read the book.

And we also have resources like websites to go to to look for, you know, discussions of specific exposures. But so I think the first thing that people can do is to recognize that what they do and what they bring into their house and what they put into their bodies and what they put onto their skin can affect their health. And if they are pregnant or planning to get pregnant, can affect the health of that pregnancy. So just recognizing that this is important is a really big step because most people don't. Yeah. Right. You wouldn't have before we talk, right? So it's not on the agenda. And I think there's a lot of reasons for that, but I think that's, let's get the conversation going. Let's talk about it. Let's not make it embarrassing. Don't be afraid to talk about, you know, sperm counts and women not be afraid to say, well, yeah, I did miscarry. And there's just, this is all a

very loaded, you know, minefield to go into for a lot of people. So I think, you know, that's a really big first step. And then in terms of actually things they can do, I mentioned the plastics in the home. I think food is really, really important. And I just want to mention that these tips are, I love them and I think it's important that people know about them, but they do have this, if you will, social justice component to it. You know, foods that are pesticide free are going to be more expensive. Unprocessed food, having the luxury to eat unprocessed food, it takes time, takes money. You have to have access nearby to buy the foods, you know, to buy the cleaner products. It takes money. And it also takes the kind of education that makes you ask the question, where can I find a safer product? You know, you've got to have a certain level of education.

So I'm just saying not everybody has the whole, the same access to this information. And one of the things we can do is broaden access to this information so that everyone, access to this information so that everyone, you know, can, can use it to have a healthier life. So yeah, I think that's what I want to say about that. But you also, those are wonderful tips. I think the last piece is really important because something that I hit a lot in my work on this show is that there are many, many problems that are so big that we cannot shop our way out of them, that we cannot tell people just buy better stuff, A, because a lot of people are not able to buy better stuff, and B, because there is often not enough better stuff to buy.

And so, you know, we create this situation where people are endlessly stressed about, oh God, what do I buy at the CVS so that my baby doesn't come out weird or whatever. When they get, we are driven into this state of anxiety about our consumer choices where everything seems like a mistake. When the fact is, that is not where our energy should be directed. Our energy should be directed to reforming our supply chains,

our regulatory systems, and those things that are determining what gets on the shelves in the first place so that we and everybody else don't have to obsess over our choices. And in fact, we have simply better things available to us. So what can we do in that world in order to, what can the government be doing? What can our elected representatives be doing? What can companies be doing in order to, what can the government be doing? What can our elected representatives be doing? What can companies be doing in order to solve this problem? Yeah, so you mentioned when we started our conversation that we're exposed and chemicals are put into commerce

without our, you know, being tested properly. And that's true. But there is an alternative, which is the REACH proposal, which is in place now in Europe. And that is the model where chemicals have to be proven to be safe by the manufacturer before they're given permission to be put into products. Really? That's how they do it in Europe? Yeah. And, you know, there are, I'll give you an example. that's how they do it in europe yeah and you know there are i'll give you an example there are 11 somebody said 13 chemicals that are banned from our personal care products in this country

and there are about 1100 that are banned in the eu wow so there is a better way and it's right there there's an example of it we can do that and by the way chemicals that are manufactured here can't be sold there if they contain those over 1 000 products so you know it's we can learn from our neighbors if you will, across the pond, better ways to do this. And what we have to do is not only regulate properly, but we have to produce the products that we want and love and, you know, in our lives out of chemicals that don't have these damaging properties that are not hormonally active. And by the way, we haven't talked about low dose effects, but many of these chemicals exert their, you know, harm at very, very low doses, which people say, oh, the dose is so low, it can't be doing anything. And that's actually not correct.

So, you know, getting rid of chemicals that have these very powerful, you know, effects at low doses is something that we have to to regulate um and then the you know hundreds if not thousands of chemicals that are in commerce right now never tested never tested because they were already in commerce when the laws went in and people said oh these have been around a long time they're good to go just let's keep selling them right That's a lot of what our exposures are. Wow. Well, what, yeah, tell me what research you feel needs to be done on this topic and what research are you most excited about going forward? I'm excited about the research that's exploring chemical alternatives because I think that's where the answer is going to be. If we had affordable chemical alternatives to our

phthalates and our phenols and our flame retardants and our, you know, all these chemicals that are burdening our life with, you know, these risks, then I think we could make this change much faster. So I think we need to support those companies that are developing these alternatives. And then, of course, we need to support the regulation of them properly. Yeah. Yeah. I absolutely agree because it, I mean, really the way you're putting it is the future of humanity depends on it to some extent. Absolutely.

Absolutely. Wow. Well, thank you so much, Dr. Swan, for being here to talk to us about it. This has been fascinating. It's been really a pleasure talking to you, Adam, and hope we can do it again another time. Well, thank you once again to Dr. Shana Swan

for coming on the show. If you'd like to check out her book, Countdown, a reminder once again that you can get her book and every book from a guest on this show at factuallypod.com slash books. That's factuallypod.com slash books. And if you buy there, you'll be supporting not just this show, but your local bookstore as well. I want to thank our producers, Kimmy Lucas and Sam Rodman, our engineer, Andrew Carson, Andrew WK for our theme song. The fine folks at Falcon Northwest for building me the incredible custom gaming PC that I recorded this very episode on. You can find me on the internet at AdamConover.net or at Adam Conover wherever you get your social media. Thank you so much for listening. We'll see you next week on Factually. That was a HeadGum Podcast.