Transcription
[Music]
I'm Shanna Swan. I'm a reproductive epidemiologist, and I'm really concerned about how fast sperm counts are declining. I've been studying this for a long time, and I and my colleagues published a paper in 2017 that went viral when we concluded that sperm counts had declined over the past 50 years at the rate of one percent per year, basically been cut in half. Following that, we decided, because of the great interest in it, that we should expand that paper, bring it up to date, and so just a few weeks ago, we did that. We published the update of that paper, and now we have more studies, a longer time period, and some new results that I think we'll talk about.
So let me break those down. We added seven years of data, and that doesn't sound like much when you have almost 50 years, but it's important because it's now, and people are most concerned about what's happening now. We found two things that are really important in this new analysis: the first has to do with geography, and the other has to do with the rate of decline.
In our original paper in 2017, we searched the entire literature and got every paper that met our eligibility criteria, regardless of the location. However, there were very few papers in South America, Asia, and Africa. That meant that even though we did publish those, we were not able to say anything conclusive. There was nothing that was statistically significant about the declines in those areas because there were so few papers.
So that was a really important question for us in our re-analysis: Has that changed? The answer is yes. Since we published that paper, and since the studies that were included in that paper, there have been quite a few studies published in South America, Africa, and Asia—so many that now we can conclude, yes, among men who didn't know what their fertility was (we call those unselected men), who are by the way most representative of the general population, there was a significant decline in Asia, Africa, and South America.
Now we can say that our finding of a significant decline in sperm concentration and count is worldwide. So that was a big change from the 2017 paper. The other change from the 2017 paper was actually how fast they are declining.
We concluded in 2017 that the rate was a little over one percent per year decline. Now, when we look in recent years, particularly since the turn of the century, the rate is 2.64 percent per year. That's more than double the previous finding of 1.16 percent. That is very fast and very unusual given that this is only in the last 18 years, from 2000 to 2018, at minus 2.64 percent per year—an extremely rapid decline.
So the causes of this decline, of course, is the question on everybody's mind: What's causing it, and can we do anything about it? When we think about causes, we think first of all, could it be genetic? The answer is no, and that's because it's too fast. Genetic changes take many generations, and we're looking at a little over two generations now—human generations.
If it's not genetic, then what is it? The sort of two baskets are gene and environment, right? So that leaves us with the environment. What is the environment? Is it just chemicals in the world? Well, that's certainly an important part of it. But also, the environment, if you think of the environment for an unborn child, for example, what does that environment consist of? That environment is affected by many things that are going on in the mother's environment and in the father's environment.
Those are things like smoking. Did the father smoke right before he conceived the pregnancy? That matters. If the mother smoked when she was pregnant, that definitely matters. Did he drink a lot? Did she drink a lot? That matters. How stressed were they? How obese are they? How much exercise do they get? What kind of food do they eat? All of these things affect sperm count.
That's been published; I've published that; other people have published that. It's well known. So, those are lifestyle factors. Putting those aside, there are, if you will, the involuntary environmental factors—many of them chemical but not all chemical, by the way. Heat matters; the temperature actually matters. Noise matters, although not for sperm count, I don't think.
Then you have the chemicals. The chemicals are all over the place, right? There are chemicals in the products we bring into our house; there are also chemicals in our dust, in our air, in our water. So there are things that we can actually control to some extent by our purchases and what we allow into our house, and some things we can't control. We really can't control the chemicals in our air, right? In our air pollution, that's made up of chemicals, and what's in our water?
Well, we can do something about that, perhaps by filtering and distilling, and so on. But it's hard to keep track of them because they're just coming at us from all directions all the time. Among all those exposures, there’s a class that's particularly important for sperm decline.
So sperm are part of our reproductive system; they are germ cells produced by the reproductive system. Eggs are also in the woman. The production of those germ cells is governed by hormones; it's governed by genetic programming and then played out via the body's hormones—natural hormones. That could be testosterone, it could be progesterone, it could be estrogen, and so on.
Those sex hormones, if you will, are altered by many of these chemicals. Here are these hormones that are critical for the production of healthy sperm and eggs, and they're being interfered with all the time by these chemicals coming into our bodies through our food, our water, our breathing, our skin—every way you can think of they come into our body, and all the time they change our body's hormones.
What chemicals are those? Those are chemicals in plastics, but not only in plastics. Plastics are big players because the products in them, like phthalates and bisphenol, are essential to the structure of the plastic. For example, if you look at a soft water bottle and a hard water bottle, you could contrast them. The soft water bottle is soft because it has certain phthalates in it—that's a hard nasty word, but there it is.
Those are chemicals that lower our body's testosterone. I mean, that’s big, isn't it? Men don't want to have their testosterone lowered if they can help it. And yet they're drinking from these soft water bottles and putting things on their face and on their skin that contain these phthalates. This does measurably lower their testosterone.
And when the mother is carrying a fetus and she's drinking from that soft water bottle or putting cosmetics on her face or perhaps getting these through scents, perfumes, wall fresheners, or air fresheners plugged into the wall, she's lowering her testosterone. That might not matter so much for her, but it matters a lot for her unborn child, particularly her unborn son.
Back to the man with a soft water bottle: If he chooses the hard water bottle, then he's going to expose himself to bisphenols—that's BPA; people know that as BPA—or its bad cousins, BPF and BPS, which have been substituted so the manufacturers can say this bottle doesn't contain BPA. The result is that in a factory in China that studied men making bisphenol A, there were more complaints of erectile dysfunction.
So in a way, this is a hard choice: the hard water bottle or erectile dysfunction? So those are just two examples. Pesticides have been known and shown for just a long time now to reduce sperm count, even to zero, in adult men.
The good news is that if the man stops using that pesticide, his sperm count in about three months will recover. On the other hand, if the mother is exposed to these chemicals that alter her hormones while she's pregnant, the son is affected—he will not recover.
So there are quite different impacts of what the mother experiences and passes on to her son versus what the father experiences and passes on to his son or daughter, by the way, because women are affected as well. What you do as an adult—you have some control over that.
When people ask me what they can do, I can only tell them things that will change their adult exposure. I can't, of course, tell them how to change their prenatal exposure. But if they're pregnant or thinking of getting pregnant, they can think about changing their offspring's exposure.
So it's something we should worry about for ourselves and also for our offspring—and by the way, also for our grandchildren because it is passed on. Perhaps the area that's most sensitive to these stimuli when the fetus is in utero is a small area, which is really amazing because it tells us what the mother was exposed to and what the fetus was exposed to in utero.
That's a black box; there's no way to know what's going on in the womb by direct measurement, but this indirect signal tells us how much testosterone that little guy experienced while he was in utero. The amazing thing is that it also tells us how he'll function as an adult.
How can that be? Well, it turns out that the distance from the anus to the genitals, which is called the anogenital distance, is much smaller in females than in males—I should say genetic females and males. It’s about 50 to 100 percent bigger in a genetic male than a genetic female.
That makes sense if you think about what it actually measures. It's a distance that includes all the paraphernalia between the anus and the top of the genitals, or the scrotum. There's a lot in there for males—much more than for females—because in females, the organs are internal, but for males, they're external, and that's why they take up more space.
In almost every mammal—there are some exceptions—but in every mammal, we have this phenomenon that the male distance called the anogenital distance or the taint, or the gooch, or the grundle on the street. I'll just call it AGD. The AGD, as I said, is a marker of how much testosterone there was in utero. The more testosterone, the bigger the distance.
If there isn't enough testosterone, or if it comes at the wrong time—because your whole growth and development is timed and programmed genetically—so if the signal, the cue, comes, okay testosterone start doing your job at this time in development, but if it's in the wings and not getting the cue, it's not going to happen.
Then that genetic male will have an AGD that is less than it should be. He'll be more feminized, so there are consequences. It turns out that if a young man has a shorter than expected AGD for his body size, then he'll have a lower sperm count and he'll be more likely to be infertile.
So this is undoubtedly part of the picture of declining sperm count and declining fertility, by the way, which has declined at the same rate as sperm count—about one percent per year. So what can do that? The chemicals we talked about, particularly the phthalates.
Here's the whole picture: there's the male fetus developing around the first couple weeks of the first trimester. The genetic signal is for the testicles to develop and start making testosterone, and here comes this foreign influence from phthalates telling the body, "Well, you don't need to make as much testosterone; we got it covered." They occupy the spaces, the receptors that the testosterone—the androgen receptors—sit in, saying, "Okay, we're good here; you don't need to make any more."
So then the body says, "Okay, I won't make any more," and then the AGD can stop growing. The boy will be under-masculinized, and that also affects the germ cells that will go on to become sperm when he's a young man, and so they are impaired by this as well.
When he goes on to be in his 20s or whatever, trying to have a child in his 30s, he won't do as well; his sperm count will be lower, and he won't be able to do the job. So that's the story.
If we continue exposing ourselves to chemicals and we continue on this path that we're currently on, where does this all lead? Boy, there are so many consequences. Mark, in terms of reproductive development, it’s going to be harder to conceive a child. We know that's going on now because more couples are going to a clinic, saying, "We're not getting pregnant; can you help us?"
There are various ways that medicine can help; fortunately, that field is developing rapidly, and there's a lot of very good things that can be done. I want to point out one study that’s not very new, actually. I think it was from 2008, and it showed that boys born to couples that had gone through assisted reproduction actually themselves have lower sperm counts.
So it doesn't reboot totally; it doesn't reset the system totally, but it does allow you to have a child, so that's great. There are also consequences to the brain, and we can talk about that if you want.
There are also consequences to overall health because men with low sperm counts die younger, so that's kind of dramatic. Sperm count tells us something not just about the ability to conceive, but it also tells us something about longevity, which is pretty important.
Another consequence is that we are having fewer children in the world. That's what it means for the fertility rate to go down, and in some ways, that's good. Some people say that's good. We can talk about that.
But the predictions by good demographers are that the population will continue to increase, as it's increasing, until perhaps in the years that vary with a demographer—from 2024 to 2050—and it will go down and never come back. The consequences of that are that we'll have many fewer young people to support the older people.
The old population pyramid, which had a strong, big base of newborns and young children supporting a very small peak of very old people, was actually an actual physical pyramid. You could draw it that way, but now if you look at the population pyramids in, say, Japan, they're totally messed up. The bottom is very small, and the top is very big because people are living longer.
Japan has, I think, the longest life expectancy and one of the lowest fertility rates, so it's been inverted. What that means for society is huge, huge. Because you don't have the people to generate the products and the income that's needed for that society, you don't have the people to support, say, Medicare in this country, and you just don't have the people to support the older people.
This is a social problem that's growing, and particularly the Asian countries are aware of it and trying to do something about it. But the problem is, even though they offer economic incentives to people to have more children, it's not working.
Why is it not working? Well, fertility rates go down in countries in which women are educated, okay? As women become more educated, they enter the workforce, the couples have a larger income base, and they don't want to go back. Why do they want to go back to a very poor economic situation with lots of kids that they have to support, to being much more comfortable having jobs out in the world where women are respected, and so on and so forth?
It's an indication of social change and social growth to have fewer children, and that's the trend. People will not go back—women particularly will not go back to staying home and taking care of five kids.
This was the most popular question or comment on the last video. People said, "Oh, the population is going to collapse; this is a good thing!" Is there any reason why this isn't a good thing and why we should be concerned about it?
There are several reasons why we should be concerned about population decline. The first, let me just say, is that population is made up of people, and a basic human right I feel many people have is the ability to reproduce. These external forces, chemicals, and so on are limiting that right—limiting our right to choose to have children when we want to and the way we want to.
So that's one way that it's a bad thing. Another thing to point out is that some people say, "Well, this is a matter of choice; people shouldn't have kids if they don't want them." That's true, but I'm saying people should be able to have kids if they want them.
If you look at other species that have become endangered, if not worse, in the environment today, you see many, many smaller litters, smaller population sizes, and these animals are not choosing this. It's not because they have contraception available; it's not because they want to have a bigger income.
It's obvious that something is affecting them, and they are exposed to the same chemicals we are. If we want to know what's going on, I would say look at the animals, because we're a part of that.
The other thing is that, as I have said, if you shift the population so that there are not enough children available to take care of the older people—which is what is happening—then this is a very big social problem and a burden economically. How do you support the population? How do you maintain production if there are few people in those middle years that will be producing?
I would say if we want to look at where things are most severe, it’s probably Asia and East Asia, and in countries like South Korea. In South Korea, the fertility rate is below one child per couple; it's actually, I think, 0.89 now, which is historically low.
That means that the average couple, who should produce 2.1 children to maintain the status quo (two people, two children, 0.1 for loss), is now at 0.89. This is much the same for much of East Asia, and it's just not sustainable. There are many social phenomena that are seen in Japan right now that are alarming and reflect that.
For example, the phenomenon of "rent-a-family." You can rent a family member for an occasion if you don't want to go alone to an event. If you want to be seen with a child or with a wife, you can rent a family member—shocking, isn't it?
There’s also a phenomenon in Japan of women marrying themselves, and this goes hand in hand with a decline in libido, which is associated with a decline in testosterone. We found, by the way, that in our studies, we asked women about their sexual satisfaction. Those who had higher levels of phthalates in their body had less sexual satisfaction.
The number of times that couples have sex has decreased; there's a whole literature on that now. The decline in testosterone is essential for libido, and declining testosterone, which is happening worldwide, has consequences not only for population size but also for population satisfaction. Both of those are going down—is that shocking?
That is really shocking, and I'm wondering, is this all by accident? Are all these things that are affecting our libido, testosterone, and sperm count just kind of a side effect of incompetence? Did we just not know? Or do you think that there's any deliberate attempt to lower the population?
Oh, I don't think it's deliberate. I don't think it's deliberate, no. I think that foreign—I don't know about ignorance because, you know, people have been pointing this out. I think it's economic. I think that people who are manufacturing plastics, pesticides, and flame retardants and so on have businesses. People want these products because they're seen as modern and part of everyday life and necessary for our survival—it's kind of an addiction.
Manufacturers are happy to supply the drugs, if you will. We're a society now that is, I would say, addicted to these products—these endocrine-disrupting products—and that addiction is being exploited.
By the way, the stock, the feedstock for these chemicals is fuel, and the production of fuels—coal and so on—those byproducts are what's used for making these phthalates and bisphenols. The companies that you know, around 1950, when production started taking off, they had to think about what to do with the byproducts, and they put them into our everyday household products.
That way, they could capitalize on both ends: make the fuels and then make money off of the byproducts. That’s worked for a long time until people started noticing that it wasn't good for society.
Are people becoming aware, and do you think through awareness, we're going to just demand change by saying, "Hey, we don't want these anymore," or do you think we need regulation?
I definitely don't think that people will just become aware and stop using things. I think we're creatures of habit. And let's face it: These products are nice, they're useful, and we're dependent on them.
It’s going to be—we're going to have to find safer alternatives to make these products. We're not going to stop asking for a disposable water bottle or something to line our frying pan so food doesn't stick. We're still going to want that, right?
We just have to find ways to do it more safely, and that takes a lot of work and money and regulation because why should people stop making products that sell very well for possibly better products that they might be able to sell to people? That’s not a good business model, so unless they're forced to do that, they're not going to change.
When we talk about the possible connection between endocrine disruption and the LGBTQ spectrum, I like to start by segregating and separating the issues. There’s a condition called disorders of sexual development (DSD). There’s a medical code for that, and that can be fused labia, that can be a micropenis, that can be ovaries and testes in the same individual.
Those disorders are, by the way, usually not considered on the spectrum, but I just want to start there. Those disorders can be caused by endocrine-disrupting chemicals, and a great example is the frogs that Tyrone produces by exposing them to atrazine, which is a pesticide. He also finds them in the wild near fields that were sprayed with atrazine.
Okay, so there’s no question that those changes can be caused. Let’s move to the next category, which is the question of choice of sexual partner: the sex of your partner, partner choice, and homosexuality.
That can be caused by environmental chemicals, and again, the best example is these frogs that are homosexual. Tyrone has lots of photos of male frogs mating with other male frogs. The Museum of Sex in New York has a whole floor devoted to homosexuality in non-human animals.
Some of those will be naturally occurring, and some may be influenced by environmental chemicals; we don't know, but it's certainly a phenomenon. The third category, if you will, is the question of gender choice and gender dysphoria, and this is much, much more difficult because we can't look to animal models.
This is a condition of how you view yourself. How do you feel? Do you feel you're in the wrong body? Do you feel that you should have been born a male when you're a genetic female? There's no way to ask an animal that, right? You can't ask your dog, "Do you think you would…" No, you can't do that, right?
The closest, again, I talked to Tyrone Hayes about this, and I said, "What do you think?" He said, "I don't know, but I can tell you that in the homosexual frogs that we produced by exposing them to atrazine, some of the males prefer to be a top and some prefer to be a bottom."
That's the closest we can come to an animal expressing their preference. I certainly wouldn't say that's the same situation at all, but I'm just saying that's a little hint that maybe there's something there.
Other than that, I don't think we have any way to know. We could study this, and we will study this, I'm sure—I won’t probably, but other people will—where you can take chemical exposure in the woman's body before she gave birth, follow those children until they're teenagers or 20 or 30 years old, and ask them.
That study has not been done, and that is an absolutely critical study to answer this question because without asking people, you're not going to answer this question. So I have to say, I just don't know.
But I do want to say that this usually precedes somebody saying, "Well, do you think the increase in gender dysphoria is due to environmental chemicals?" I would question the increase. Certainly, there is more reported. Certainly, there is more medical attention to it. It’s in the political arena, and it wasn’t before, but that’s happened for many things.
When I was growing up, nobody would consider talking about being born in the wrong body. It was just not in the public consciousness; individuals might have thought that, but they would not have said it.
So we're sort of hamstrung in a way. We can't turn to animal data; we don't have a good historical record, so we're really starting our investigation now—and we’ll know more in another generation, but not now.
That was a fantastic answer, and really, thank you. That was probably the most informative I don't know I've ever gotten. By the way, this is such a delicate topic, you know, because the problem is that if you ask, "Do environmental chemicals cause homosexuality or gender dysphoria?" you're saying, in a way, those are negatives—those are illnesses, those are problems—whereas people who are on the spectrum very often will say, "No, it's not a problem; it's fine. I love it; I'm happy to be here."
So you have to be very careful in talking about this—not to medicalize it and not to characterize it as a defect. By the way, this is also the reaction of some families with Down syndrome, and also people with ASD who would say, "This is how I am, and I have a lot of good things out of this."
I don’t want to say, "Was this caused by this problem or this problem?" You see, just the asking of the question has political implications, so be careful.
I think it’s always nice to end a video with a positive note. If people do want to have kids one day, if you're talking to a group of college kids, and one day they want to have a family, what would you tell them?
I would tell a group of college kids who want to have a family that they should think about what they're allowing into their bodies, even right now, in terms of the kind of food, the kind of drink, the kind of air, and the kind of products they use, the cosmetics they use—mostly just to be aware that it all matters.
They might not want to change, but they could say, "Okay, I understand this skin cream contains phthalates, and those go into my body, and they might affect my testosterone level." But that's okay; I really like this skin cream—fine, fine—just be aware.
I think more people can be aware of chemicals that we're totally blind to, the better off we'll be. Then I would say men should bank a semen sample—why not? It's not difficult; it’s not particularly expensive. Now you can do it in your home; there are companies that allow you to do it at home and mail in a sample. I don’t think it's going to get better in the short term, although I hope it will get better in the long term.
But if you want to conceive a child in the next, say, 10 years, why not have a sample that's probably okay? By the same measure, I would say that every man should have his sperm tested, and if it's not great quality, then he can think about what to do to improve that in terms of his lifestyle, his exposures, and so on.
There are ways to be active that way. A woman cannot have her eggs tested because they're hidden; they're not available, so that’s unfortunate. But if she's concerned, she can be checked for various conditions, like, you know, are her fallopian tubes open, and so on and so forth.
Do a little homework ahead of time, not the doctor’s, and say, "If I want to get pregnant now, would I be able to? Do you see any barriers that I could take care of?"
And then, like I say, be aware of chemicals that are sneaking into our body against our will and try to keep them away. Unfortunately, reproduction is not very much talked about or studied. People are embarrassed to talk about their problems having a child; women are embarrassed particularly because they feel it’s their fault.
They take a lot of blame on themselves if they have a miscarriage or can’t get pregnant. If you look at research agendas all the way up to the NIH, reproduction is not there; it’s just not there.
There's cancer; there's birth defects; there's diabetes, and there’s neurology, but reproduction is a poor stepchild. I think that's one reason why we know relatively little about it, and I think the more we can recognize this as a societal problem and put more resources there, the better off we'll be.
So I've really enjoyed making this episode of After Skool. I hope you did too, and I hope you’ll want to learn more, and you can do that by reading our book, Countdown: How Our Modern World is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperiling the Future of the Human Race.
Thank you.
[Music]
Thank you.
[Music]