Podcast producer: Chris Robertson
So, I'm going to dive into four sobering trends in our reproductive health.
These trends are discussed in the groundbreaking book that is titled Count Down: How Our Modern World Is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperiling the Future of the Human Race. Count Down is authored by Dr. Shanna H. Swan, Ph.D. and the award-winning writer Stacey Colino.
The image above is an Amazon affiliate link.
Dr. Swan, who is the guest of this episode, is one of the world’s leading environmental and reproductive epidemiologists and a professor of environmental medicine and public health at the Icahn School of Medicine at Mount Sinai in New York City. An award-winning scientist, her work examines the impact of environmental exposures— including chemicals such as phthalates and Bisphenol A—on men’s and women’s reproductive health and the neurodevelopment of children.
In this podcast, Dr. Swan shares empowering insights that can optimize influences on reproductive health, fertility, assisted reproductive efforts, and pregnancy outcomes. For example, you will hear how decreasing your exposures to endocrine-disrupting chemicals can increase the risks in conceiving a child, miscarriage, and birth defects. These EDCs are found in common household products, like plastic food containers and cleaning products.
You will also hear how your reproductive health can reflect your current overall health and life expectancy.
This episode is another Practical Nontoxic Living podcast conversation that should help you realize that, once you are informed, you can reduce your toxic exposures through simple choices. These small detox tweaks can improve the influences on your health, fertility, assisted reproductive efforts, and pregnancy outcomes.
Dr. Swan also explains that exposure to endocrine-disrupting chemicals at vulnerable stages of human development—like the prenatal period—can impact three generations.
I don't want that finding to be so overwhelming that it paralyzes you from changes. So, please remember that just because you are exposed to something toxic or risky doesn't mean that there will necessarily be a harmful effect. We each have unique vulnerabilities, exposures, reactions, and health potential. But we should do what we can to reduce our toxic exposures and improve other non-genetic factors. First, however, we have to become informed and this podcast will help. I highly recommend Dr. Swan's book, Count Down. Everyone should read it.
Before we start, I want you to know that I'm prioritizing time to help people detox for pregnancy. The ideal time to eliminate chemicals, heavy metals, and EMFs from your home, diet, self-care, and technology is before you conceive. The earlier you start detoxing, the better. However, it's helpful to eliminate toxic exposures at any time! We should always be doing what we can.
I have been super selective about who I help 1:1 simply because the time I put into my books, speaking engagements, podcasts, articles, and workshops can help so many more people. However, I now feel like my portfolio of work is sufficient enough to help those who want a budget-friendly DIY detox.
If you would like a premium, guided detox to optimize for fertility and the best pregnancy outcome possible for you, then visit the podcast show notes for details. If you are pregnant, look forward to having children, or will be using assisted reproductive technology, then a thoughtful detox of chemicals, heavy metals, and EMFs from your home, diet, self-care, and technology will create invaluable benefits. We will co-create a plan for your new practical nontoxic lifestyle, which will be invaluable for your children. Like Dr. Swan explains in this podcast, toxic exposures can affect several generations!
Okay, now let's get to my conversation with Dr. Swan...
www.ruanliving.com/fertility-detox to learn more.
This transcript has been edited slightly to be more reader-friendly.
Sophia Ruan Gushee: [00:05:34] I've actually been a fan of yours since way before Countdown. It was only in 2007 after I became a mom that I started learning about the toxic chemicals in our everyday products. And for me, it started with BPA and plastic baby bottles. That was very upsetting to learn with a newborn. So I decided I'm going to learn everything I can about how to make healthier purchases for my daughter. And it was in that research that I started learning about your work. [00:06:02][28.0]
[00:06:03] I was so relieved by your work--reading your peer-reviewed studies. It gave me great comfort to know that somebody was studying this to try and bring more public awareness to what was happening to our environment and our children. I think it was maybe around 2009 (because I was pregnant with my second child), I went to a conference at Mount Sinai Hospital, and you were one of the panel speakers. And I went to listen to you and I was in the bathroom and you came out of a stall. And I got so excited as if you were Mick Jagger or Paul McCartney. I thought I was so excited and I thought, I have to talk to you. I have to talk to you. What am I going to say? But I'm in the bathroom. She's been in and out. But I just went up to you thinking this might be my only chance to talk to her. [00:06:58][54.5]
[00:06:58] I introduced myself. I said I really admired your work. And I know this is very strange, but I just need to ask you, How do you clean your home? And I still cherish that brief moment because that is when you introduced me to the idea of steam cleaning. You said you don't really use many detergents or any, but you use steam cleaning. And I have cherished that ever since. So I was really thrilled when Countdown came out because I've been reading about the endocrine-disrupting chemicals and how it influences wildlife in humans. And it was such a scary topic to bring up as a non-scientist and a non doctor. So thank you for writing that book for my audience, who is new to how and decreeing disrupting chemicals can influence fertility and reproductive health. And the really important messages in your book, I want to start more broadly. So for those who are not interested in having children in the future, I want them to know that the findings that you share and count down are still relevant to everyone. And if you could talk more about that and how reproductive health signals other aspects of health, that would be really great. [00:08:23][84.6]
Dr. Shanna Swan: [00:08:23] Well, first of all, thanks for having me and thanks for that story. And I don't I'm sorry, I don't remember our encounter, but I hope you like a seminar at Mount Sinai. [00:08:31][8.2]
Dr. Shanna Swan: [00:08:32] So let me talk about reproductive health as the sixth vital sign. This is something that was proposed by a high level group of reproductive scientists and clinicians. And the reason is that your reproductive health does signal your later health and even your life expectancy, which is really surprising. The best data come on the male side, which is actually always the case. You know, there's much more data on the male side. We can talk about why that is. [00:09:07][34.9]
[00:09:08] But there's a study out of Denmark--and at least one out of California--which has shown that men with low sperm count have a higher risk of heart disease, and diabetes, and reproductive cancers, and perhaps other things. As a consequence, their life expectancy is reduced measurably as sperm concentration drops below 40 sperm per milliliter. [00:09:38][30.4]
[00:09:40] So that number doesn't probably mean anything to anyone. So can I tell a little bit about what that number might signify? [00:09:47][7.1]
Sophia Ruan Gushee: [00:09:48] Please do! [00:09:48][0.0]
Dr. Shanna Swan: [00:09:49] So semen quality is evaluated in four dimensions. And one has to do with numbers of sperm, one is shape, one is motion, and one is integrity. And the count part is what I've studied most and most easily studied. And that really can be talked about as concentration. And you can think of concentration of anything as their density per unit volume. For sperm, it's how many sperm in a milliliter. That's the concentration. [00:10:23][33.8]
[00:10:24] But if you blow that up and ask how many are in the whole sample that the man gives, that would be concentration times volume. That's total count. [00:10:33][9.1]
[00:10:35] So when you talk loosely about sperm count, you might be talking about count, or concentration, or total count, or density. Those terms are used--and I do use them sometimes not very carefully and interchangeably. [00:10:47][11.6]
[00:10:48] But the number 40, because it's a low number per milliliter as opposed to maybe over a thousand, which would be a count in a sample, 40 million from a millimeter is the point at which you can start to get concerned about sub-fertility. [00:11:08][20.0]
[00:11:10] So as sperm count drops below 40, goes to 30 per milliliter, 20 per milliliter, 10... ultimately to zero... the chance of getting pregnant in any month goes down. Probability per month, conception of probability, decreases when sperm concentration is below 40. [00:11:32][22.2]
[00:11:34] When it's high--whether it's 60 or 70 or 100--doesn't make a lot of difference in how quickly you can conceive. So this low count is of concern and it's also of concern for longevity. [00:11:50][15.2]
[00:11:51] So men whose counts fall below that critical 40 number show evidence in several studies of dying younger. And as you approach zero, that life expectancy gets shorter and shorter. That's kind of scary. And it's information that men should have, right? [00:12:12][21.1]
[00:12:14] You get your cholesterol checked because you know what your risks are for various kinds of cardiovascular disease. Same thing with blood pressure. Why not get your sperm count checked so that you know--whether or not you want to have a child and you might want to change your mind later and decide you do want to have a child and you'd like to know it for that reason. But aside from your ideas about conceiving, it tells you something about your overall health. [00:12:43][29.7]
[00:12:44] Now, on the female side, it's much, much more difficult because counting eggs--and by the way, your number of eggs, I'm sure most women know, decrease as you age--so the number that you have at any given age is a pretty important measure of your likelihood of conceiving. [00:13:05][20.7]
[00:13:06] But even if you don't conceive and don't want to conceive, having premature ovarian failure is a risk factor for later health problems, which has been much less studied. So I can't tell you specifics on that, but it's just something we don't put into the equation for our overall health. [00:13:23][17.6]
[00:13:24] I can't recommend that every woman have an ultrasound to have her or sonogram to have her ovaries counted. That's much too difficult and expensive, but I just point out that it is a concern for both males and females. [00:13:38][13.9]
Sophia Ruan Gushee: [00:13:39] So I was going to get into this later. But this seems like a great time to talk about the fact that sperm count that's low can maybe increase if certain environmental factors improve. And so I'm wondering for those listeners who are looking forward to having children, maybe they've been struggling to conceive, it sounds like it would be a really good idea as soon as someone gets engaged to have the male get the sperm count measured because then the man can change environmental factors that can improve the likelihood of the sperm count improving. And of course, the sooner they make the changes, the better. But does that sound like a good idea? [00:14:23][44.9]
Dr. Shanna Swan: [00:14:24] Yes, and I would actually make a couple of recommendations in that regard. [00:14:28][3.5]
[00:14:29] One is to consider his environmental exposures, which I'll talk about in a minute, but also to consider his lifestyle. Because their contributions to impaired reproductive success come on many, many fronts: some of them might be genetic, can't do anything about those, some of them might have come from your mother's exposure or even your father's exposure just before you were conceived. You can't do anything about those. However, you can do things about your current exposure. So let me give you two examples. [00:15:07][38.2]
[00:15:08] One, just to tell you very dramatically that there's been several studies of pesticide workers, people who actually apply pesticides in one of those. This was something that was put on pineapples in Hawaii and in Israel called [Diepraam Chloro Propane] and men who use that discovered because when their wives talked about their families, they were saying they were all having trouble getting pregnant. And so they looked into this and it turned out that these men that were using this pesticide had zero sperm. [00:15:38][29.8]
[00:15:41] When they discovered that, they stopped using this chemical, and within four to six months, depending on the individual, their sperm count had returned. [00:15:51][10.2]
[00:15:52] So that's a very good example of a complete wipeout of sperm and a nearly complete recovery. And there have been many examples of that. That's a high dose. And you're not going to get those high doses in your environment from environmental chemicals. You're going to get low doses. The problem is that you're going to get many, many, many of these from tons of sources, which we'll talk about. [00:16:15][22.8]
[00:16:16] Before I go into that, I'd like to just tell you another example. So this is of a man who went to a sperm bank, and he was a regular donor in a sperm bank, supplemented his income. He was young, was student. He had good sperm and he regularly went. And then one day he was told that his sperm was no longer of acceptable quality--there's very high quality for sperm in a sperm bank. [00:16:38][22.8]
[00:16:39] And so they talked to him. They counseled him and they said, well, what have you changed? Because your sperm count is strange. [00:16:45][5.7]
[00:16:45] Well, he thought about this. He said, I have a new girlfriend and she smokes. And actually, I started a job, and it's really stressful so I have less time for exercise. So there you have smoking, lack of exercise, stress...all contributing factors to low sperm count. Others might be that maybe he drank too much as a result of the stress and so on. [00:17:17][31.8]
[00:17:18] So there are these changes that people can make in their daily lives, which will improve their sperm count. He made those changes, came back, and was accepted as a sperm donor again. So it's definitely possible. [00:17:33][15.6]
[00:17:34] So that's one of the reasons I say that people men should actually get to know their sperm count, because, first of all, it's a marker for later health. And it may be something that he'll want to use in the future. [00:17:47][13.2]
[00:17:48] By the way, if his sperm is good, he may want to bank it. Because as he goes through life and is maturing, his sper will decrease in quality--very slowly since aging is not nearly as severe in men as in women, but it does decrease. But he'll also be exposed to continuous impacts that could alter his chromosomes, that could alter her sperm, that could impinge on his later fertility. So banking semen sample, if you can afford it, is something to consider. And many women actually consider that also (banking eggs for future use). [00:18:28][40.0]
Sophia Ruan Gushee: [00:18:29] That's fascinating. I have three daughters and I have often thought that when they are older, I will encourage them to freeze their eggs. Ever thought about the male banking, their sperm? But that's really helpful. From what I understand, you're born with a certain number of ovaries and you can't really change that. So it's so interesting that for men, their sperm is so responsive. [00:18:55][25.9]
Dr. Shanna Swan: [00:18:57] Yeah, you're born with a fixed number of eggs. You don't mean ovaries, you mean. [00:19:00][2.9]
Sophia Ruan Gushee: [00:19:00] Oh, yes, that's right. [00:19:02][1.7]
Dr. Shanna Swan: [00:19:04] You're born with actually millions of eggs, but that decreases rapidly and actually decreases from early pregnancy until birth... it's already decreasing and then it continues to decrease. [00:19:15][10.4]
Sophia Ruan Gushee: [00:19:15] When my husband and I were first trying to conceive, we couldn't conceive for the first year. And when we found out it was actually an issue on his side, I was so relieved and I realized it never occurred to me it could be on the male side. And your book helps shed light on how much influence the male side has. And there's so much we can do. That's what's empowering. Whereas with females, I'm sure there's a lot we can do, but it seems a little more restricted in terms of egg count. But like you said earlier, it hasn't been studied as much before. [00:19:50][34.5]
[00:19:50] Before we dive into the fertility trends that you found and other details in fertility. I wanted to touch upon how animal studies are relevant to humans because I often hear from people. Yeah, but those are animal studies. They aren't relevant to us. We're not like mice. What would you say to someone who feels that way? [00:20:10][19.8]
Dr. Shanna Swan: [00:20:11] I think that animal studies are absolutely critical for understanding human studies. Here's the reason. As humans, we can't ever be subjects in an experiment or we shouldn't be without our permission. And there's very few things that a researcher is allowed to experiment on. When I say experiment, I mean giving a dose of a chemical, giving a certain exposure, a stressor. You can't do that, or only a very limited way, certainly not for environmental chemicals. You can't administer those to a pregnant woman. [00:20:47][36.1]
[00:20:48] And so you can't actually draw from a single human study or even a bunch of human studies causation. Because for causation, what you really need, the ideal study in an animal studies, you have randomized assignment of exposure, blind exposure... I'm sure you're familiar with this. These are set up for a clinical trial. So if you're testing the safety of a drug, you'll use a clinical trial. [00:21:14][26.2]
[00:21:16] By the way, those are tested in animals first also, but is far less critical to have that animal back for human study when we can't assign exposure. Here's the problem. Maybe I am more heavily exposed to phthalates because there's other things that affect my fertility, that drive my exposure to phthalates. You see what I mean? So maybe I am very stressed anyway, and I intend to use a lot more personal care products and makeup and take less good care of myself because of my stress. That's a far-fetched example. But just to say that, in humans, we can't ever separate the exposure from other risk factors because we don't randomize. Does that make sense? It's kind of technical... [00:22:06][50.2]
Sophia Ruan Gushee: [00:22:07] Right, because science needs to study one exposure at a time. Correct? And in real life, we can't do that. [00:22:14][6.4]
Dr. Shanna Swan: [00:22:14] Right, exactly. So what we can do with it and if we find an animal model-- and that's really important--that is, an animal that has the same basic biological setup so that when we see a change in the animal, we can look for it in the human, and it will mean the same thing in the human as it did in the animal... So if you have the animal model, as we did for reproductive development in the rat or the mouse, then you can assign the exposure, say, to the rat, look at the offspring, see the effects, and then look for it in the humans. Then if you see the same thing you say, it's much more likely to be causal because in the rat, it was causal. There was nothing else changed. [00:23:02][48.0]
Sophia Ruan Gushee: [00:23:03] So if it was causal in the rat, it would be causal in humans? [00:23:07][3.7]
Dr. Shanna Swan: [00:23:07] Yes. If it was a good model of human reproduction or human physiology. Yes. Yes. And without that animal experiment, all you can say is that you have an association. But once you have the animal model and, by the way, let me go back one step further. What you would really like, in addition, is some if you're looking at chemicals, you would like to have to understand the chemical structure and how it impacts the system you're looking at. For example, when we looked at phthalates, we know that certain phthalates, lower testosterone, you can see that in a test tube. Before you look at the animal, then you look at the animal, you see the same thing. Then you look at humans and you see the same thing. [00:23:52][44.5]
[00:23:52] Then when you have the complete sweep of what we call test-tube or in vitro studies, then you have animal studies, and you have human studies. then you have replication of human studies, which is the next step you need. You can't do it just once. It could be a chance finding. [00:24:10][17.5]
[00:24:11] When you have that whole sweep of the science on a single exposure-outcome relationship--like phthalates and lower testosterone, which I can talk about--it's probably causal because we've checked all the boxes along the way. [00:24:28][17.6]
Sophia Ruan Gushee: [00:24:29] So please share. What has the science found? What have your studies found about our reproductive health? [00:24:36][7.6]
Dr. Shanna Swan: [00:24:37] First of all, I'll talk about sperm count and concentration, which I started to talk about. This was something I got interested in in the 90s, actually. A paper came out in 1992. It said sperm count had declined 50% in 50 years. Huge, huge change: 50% drop in half over 50 years, 1% per year. That means in 10 years you'd expect another 10 percent drop. And in a generation, 25 years, 25% drop. So, I just want to impress on everybody that--even though you say 1% per year, that doesn't sound like much--if you multiply it across a generation, it's a lot. [00:25:20][43.4]
[00:25:22] So this study had claimed that, and it was so big that I and others were skeptical. I didn't actually believe that at first, and I had the time and the luxury to actually look in detail in that and see whether other factors, of the kind we were talking about, because this wasn't an animal study--this was humans--maybe something else was going on. Maybe later on in the study period, men were fatter, or exercising less, or smoking more, drinking more, and more stress, and all these things that could matter. or maybe count counting sperm changed in a way that could have produced a trend. And so on and so forth. [00:26:00][38.1]
[00:26:00] So I spent six months reanalyzing all the studies that had gone into that finding and very surprisingly found that the results were unchanged. Disappointing in a way, but also pretty exciting because that said that, wow, this is probably really happening. And exciting in the sense that now I had a really interesting and important research question, which I have been following ever since. So that was the start. [00:26:36][35.2]
[00:26:38] I published my findings in 1997--in 1992, the first ones; 1997, then I published another study which was bigger of a similar kind in 2002. [00:26:47][9.1]
[00:26:48] Then I met a colleague at a meeting and he said, you know, that '92 study by Carlson, we should update that. We should look at that again because it's been quite a while. [00:27:00][11.3]
[00:27:02] So we decided to do that. And he got money to come to Mount Sinai and to spend a year with me. His name is [Hagai Levine]. He came from Israel. And we carried out the largest, most complete, most rigorous study of sperm count trend ever done. [00:27:20][18.4]
[00:27:21] It took us two years and 7 colleagues, and that was published in 2017. [00:27:27][5.7]
[00:27:29] What's so interesting is that the result in that study, which was based on 185 studies as opposed to the original based on 61 studies--so much bigger, broader... had conclusions that were very consistent with the '92 study. [00:27:30][0.1]
[00:27:30] It really seems to be happening: sperm count seems to be declining. When we looked at the decline in more recent years... that 2017 paper actually covered 40 years. If you look at the last 30 years, the last 20 years, why would we do that? We would like to see it getting better as we get closer to our time. And it didn't. The slope stayed the same [00:27:30][0.3]
Sophia Ruan Gushee: [00:28:26] The sperm was collected from worldwide, right? Not just in the US? [00:28:30][4.4]
Dr. Shanna Swan: [00:28:31] That's correct. Partially. So, yes. [00:28:35][3.9]
[00:28:35] We sought all studies in English languages, English language studies, because we couldn't handle all these translations; and they had to be published in peer-reviewed literature. [00:28:49][13.9]
[00:28:50] When we looked at those studies, they broke down into studies which we call Western, which were North America, Europe. Australia, New Zealand. That's the group we called Western. [00:29:04][14.2]
[00:29:05] All other countries combined had very few studies, not enough to draw a conclusion. Now, that was 10 years ago. Well, soon going to be 10 years that we did that analysis. And we're updating that now. But I don't know what that's going to show. And we're getting more information from non-Western countries. [00:29:27][21.8]
[00:29:28] Anecdotally, when we hear from isolated papers, or you look at the fertility in, for example, Asian countries, it's extremely low. We'll come to that later. Fertility and sperm count are not the same thing. [00:29:44][15.3]
[00:29:45] So let me just leave this initial sperm count study and remind people what the numbers are. Our starting point was 1973. That was the first sample collection in this big study that we published in 2017. So 1973. At that point, the count was very high. It was 99 million per milliliter. That's a very hefty sperm concentration. [00:30:15][30.4]
[00:30:17] The last year in the study period was 2011 (last sample collected in 2011) that median sperm count was only 47. [00:30:29][12.4]
[00:30:33] Wow. [00:30:33][0.0]
[00:30:34] 99 to 47 is 52% drop in 39 years--faster now than 1% per year. Originally, it had been 1%, now it's faster than 1%. [00:30:47][12.5]
[00:30:51] So here we are in 2021, ten years later. If that slope has continued--and I don't know that--we would now be at a median for Western countries (By the way, these are men who were not known to be fathers. They're are called unselected men), we would be at 37 million per milliliter. That is, in the range that life expectancy is shortened, and in the range that it becomes more and more difficult to have a child. And my prediction is that that is where we are now, or that we are at least close to 40, close to that cutoff. [00:31:33][42.2]
Sophia Ruan Gushee: [00:31:35] Based on the data available now, it's expected that sperm count will go to zero by 2045, is that right? [00:31:43][8.2]
Dr. Shanna Swan: [00:31:43] No, no, that's actually something that the press says. But it's not. [00:31:49][6.1]
[00:31:51] It's because I was asked. When would this extended line hit the zero axis? [00:31:59][8.4]
[00:32:01] You can certainly do that mathematically, but does it make sense? Not really, and here's why. [00:32:08][6.3]
[00:32:09] You have to know just a little bit of statistics. These are medians. What's a median? It's the center of the distribution. [00:32:16][6.5]
[00:32:17] So if you have a median age of 45, that means half the people at the population are under 45 and have are over 45. [00:32:25][8.1]
[00:32:26] So if you have a median sperm count of zero, that means half the men would have a negative sperm count. You can't have a negative sperm count, right? Impossible. So that number zero, that zero line is never going to be hit by a median. [00:32:44][18.1]
[00:32:45] It can be headed by an individual man, for sure, or groups of men, as happened with the pesticide workers? They have zero but for half of the population to have zero, highly unlikely. [00:32:59][13.7]
[00:32:59] So I think what's going to happen is that curb is going to slow down and become closer and closer to zero if we don't do something about it. But it's unlikely that the median will reach zero. Does that make sense? [00:33:16][16.7]
Sophia Ruan Gushee: [00:33:17] Yes. What age group was studied? I assume they included young men in their 20s. [00:33:22][4.9]
Dr. Shanna Swan: [00:33:24] Actually, these data on the sperm count and Western men that I've been talking about from 99 to 47, those were actually young men, predominantly. And the reason is that in order to get in that group of unselected men, they have to not be aware of their fertility. They had to never have tried to father a child, had never conceived a child. So that tends to be younger men who haven't had that experience at least once. And so, yes, many of them are college students. They were in Europe going for military exams to be screened for the military, which of course, we don't do. But, yeah, that's that's who they were. And so, yes, they are younger man. This is relevant to younger men as well as older men. [00:34:09][45.3]
Sophia Ruan Gushee: [00:34:11] Earlier you said fertility and sperm count are not the same thing. Would you explain that? [00:34:16][5.1]
Dr. Shanna Swan: [00:34:16] Sure. So first, the obvious fact that it takes two people to conceive the child. So the health of the woman and the health of the man are intimately involved with that. [00:34:27][10.7]
[00:34:28] The fertility rate technically used by demographers is the number of children that are born to a woman or a couple. And so it's even in its definition, a couple enterprise. And while decreasing sperm count is certainly one of the drivers of decreasing fertility. It's certainly not the only one. [00:34:50][22.3]
[00:34:50] But what's interesting is that I told you those figures on sperm count in Western men. But if you look at the data from the World Bank, which anyone can do by going on WorldBankFertilityData, a very nice website, you can see how fertility has declined over the past nearly 50 years. [00:35:08][18.0]
[00:35:09] So on that interactive graphic, you see that in 1960 there were five children born per woman or couple worldwide. That was the average. [00:35:20][11.1]
[00:35:21] And if you go down to the most recent year, which I think is 2019, that's down to 2.4. Now, that's a drop of 50% and that's about 1% per year, just like sperm count. [00:35:33][12.5]
[00:35:34] However, there's a critical number there, too, just like 40 was the critical number for sperm count, two is the critical number for fertility. 2.1, actually, to get technical. So 2.1 Is the number of children on average that a woman has to have--a couple has to have--to replace themselves. [00:35:53][18.9]
[00:35:56] So Western countries, most of them are not replacing themselves in many countries. And in particular I could name Singapore, Korea, Japan, the fertility rates are extremely low. And I think in Korea, Singapore, they're actually hit one point zero. Which is the lowest ever recorded in the history of recording these data. [00:36:24][28.7]
[00:36:25] What is causing this? [00:36:26][0.7]
[00:36:26] It's certainly not just sperm count because that's only one part of the equation. And the other part of the equation is that couples and women are deciding to have their children later and women's ability to conceive drops quickly as she ages past 35. Men not so quickly. But they do have a decrease in fertility. [00:36:46][19.8]
[00:36:47] And this is associated with a lot of positive things like urbanization and education and contraception, availability and choice for women and so on, which are all good things. However, there are not going to explain all of it because these decreases are also seen in young women. And if it was merely a matter of delaying childbearing, you would only see it in older women. [00:37:10][23.1]
[00:37:10] Now, in a Danish study showed a woman of 25 today has lower fertility than her grandmother did at 35. And the other thing to think about when we think about this fertility decline is to go back to the rest of the species in the world who we're also losing fertility at a terrible rate to the extent that many are now endangered, and threatened, and even extinct, and they did not choose to have their children later. And I believe that they teach us about the impacts of our environment because they share our environment. The chemicals that we're exposed to are found everywhere in every organism that's been examined, whether it's at the North Pole or anywhere. There's nowhere in the world that chemicals do not go and particularly the chemicals which we haven't yet talked about, which are the chemicals that have altered the body's hormones, which are the ones that most concerns me. [00:38:04][53.6]
Sophia Ruan Gushee: [00:38:04] So why don't we dive into that and decline disrupting chemicals, especially phthalates, which I think you specialized in? [00:38:11][6.8]
Dr. Shanna Swan: [00:38:12] Right. So we've talked about lifestyle and that's good and that's important. But those are fixable things. The chemicals--and particularly the endocrine disrupting chemicals--we have much less control over. But we do have some talk about ways we can alter our exposures. [00:38:25][13.3]
[00:38:26] Why endocrine disrupting chemicals? What are they, first of all? And why am I interested in them? [00:38:31][4.7]
[00:38:31] So these are chemicals that the body confuses, if you will, with its natural endogenous hormones. So they can take the place of testosterone, or an estrogen, or possibly a thyroid hormone. They can occupy a receptor meant for your body's own hormone, they can influence the transport, they can influence the function of our bodies, hormones. So they interfere with hormones. So they're endocrine-disrupting, that's hormone interfering, I guess you could say. [00:39:03][31.8]
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[00:39:03] I like to call them hormone highjackers because they sneak in and unknown undetected and just hijack our hormone systems. [00:39:12][8.3]
[00:39:13] Now, I'm particularly interested in phthalates, as you mentioned, because phthalates have the ability to do that with respect to testosterone. And testosterone is really critical for the development of the genital tract, which is so critical for reproductive function. And I'm a reproductive epidemiologist, so it's a natural for me to study phthalates, and I've done that for about 20 years. [00:39:35][22.6]
Sophia Ruan Gushee: [00:39:36] Would you talk about how quickly can the body flush out phthalates, or BPA, some of these endocrine-disrupting chemicals? Because they can be pretty quick. So if we cut our exposure, then it can reduce our body burden of them. [00:39:51][14.4]
Dr. Shanna Swan: [00:39:51] Yeah, so that's actually one of the good news stories in this bigger story: these chemicals, which are called non-persistent, are water soluble. And because they're water-soluble, they enter the bloodstream, and then the urine, are excreted in the urine very quickly. The Half-Life for many hours is four hours and for the females. So that's the good news. [00:40:15][24.0]
[00:40:15] The bad news is that the exposure is pretty continuous. [00:40:19][3.8]
[00:40:21] So let's maybe talk about where they come from. They're in our food--that's probably the major source of exposure to phthalates and bisphenos. [00:40:28][7.1]
[00:40:28] By the way, phthalates and bisphenols...I don't want to evil twins, but phthalates make plastic soft and flexible. And the bisphenols--like BPA--make plastic hard. [00:40:39][11.0]
[00:40:40] And phthalates are anti-androgens--testosterone lowering; whereas the bisphenols or BPA are estrogenic. So they're somewhat different in their action and they are different in the products that they're in, and they're different in their function within the plastic. [00:40:56][16.0]
[00:40:56] But both are found in foods. In phthalates, we know they can be introduced in food processing--whenever the food goes through tubes, soft, flexible tubing--food goes through them. Particularly if it's warm, the phthalates leave the plastic. It's not chemically bound to the plastic. So the phthalates go into the food, maybe that food goes into a jar of spaghetti sauce, or maybe it goes into milk that you get in your milk container, and then it goes into our body. The bisphenols are used also for foods, particularly the lining of tin cans. So there are liners and they can also be used in pizza boxes and also surprisingly found in cash register receipts. [00:41:39][42.5]
[00:41:40] There are coatings. There are other dangerous coatings which come under the name of perfluorinated compounds. And those are things like Teflon nonstick-ware or rainwater. That is water repellent or paper. That's oil repellent. You might see that in pizza boxes. So coatings and repellents are really something to try to avoid. [00:42:02][21.7]
[00:42:08] But one thing you can do is if you can afford it, and if you can find it, is to buy unprocessed food. That is the actual food: the carrot, the head of lettuce, ... Whatever it is. Just by that, take it home, cook it, eat it on a nonstick pan, don't introduce plastic into the process, then you will not get any of these chemicals from your food. This is possible. It's difficult. It's particularly difficult, by the way, for people of lower incomes because very many don't have unprocessed food in their local grocery store, and they might not have the time to go through this effort. [00:42:45][37.1]
[00:42:46] Also, eating organic is a step toward keeping out phthalates because phthalates are added to pesticides. [00:42:51][5.5]
[00:42:52] But also pesticides have the ability, as we saw from that example I gave, of lowering sperm count. So pesticides are not a good thing in our food. So eating organic is another recommendation. [00:43:04][12.2]
[00:43:06] So we can take a lot of steps and it's good they're leaving quickly. But we should be aware that [00:43:11][5.8]
Sophia Ruan Gushee: [00:43:12] There's so many, aren't there? Like a thousand? It's estimated there are a thousand. [00:43:16][3.9]
Dr. Shanna Swan: [00:43:17] Maybe, maybe. I mean, the CDC measures over one hundred chemicals in their monitoring project. They have a monitoring project that, well, they used to know is everything is slowed down. But every two years they used to measure a sample, representative sample of the United States, measure these chemicals in people's bodies--up to 100 hundred they were measuring. But they can't physically measure thousands. [00:43:41][23.7]
[00:43:42] There are many analogs, by the way. So Bisphenol A is one of the class of bisphenols. There could also be bisphenol F, or bisphenol S, and increasingly these are shown to have the same harms as bisphenol A. [00:43:57][15.5]
[00:43:57] There's other chemicals that are substituted for phthalates as well. [00:44:01][3.8]
[00:44:02] This is very confusing to consumers because if you buy it, you bought a bottle that said bisphenol A free right. You're careful to do that. But at that time, probably there weren't these bisphenol alternatives. But now a woman who would buy that bisphenol A free bottle--marked that way--might well get other bisphenols in there, which can do the same harm as bisphenol A. It's kindof deceptive. [00:44:25][23.6]
Sophia Ruan Gushee: [00:44:26] Yeah. So I know we just have a few minutes left and I'm just dying to ask you about how you think and disrupting chemicals may affect assisted reproductive technologies like IVF. And if you could also quickly comment on how they influence miscarriage. I know you've said some really eye opening statistics on miscarriage, and erectile dysfunction, and other things. [00:44:52][25.9]
Dr. Shanna Swan: [00:44:57] First, let me say that sperm count going down and fertility going down are only two examples of trends in the reproductive function that are deteriorating at about the same rate, 1% per year. And that includes miscarriage rates going up, testicular cancer rates going up, male genital defects going up. We have testosterone levels going down so that younger and younger men are asking for testosterone replacement therapy, and that's accompanied by erectile dysfunction going up. [00:45:29][32.1]
[00:45:30] So pretty much any reproductive parameter you look at, you're going to see in the last...data aren't available for the old 50 years, of course, for most of these... But where we have data, we do see declines. And there at a comparable rate to the declines, we've been talking about 1% per year. So what we have to do is recognize this problem. [00:45:54][24.2]
[00:45:55] I'm not going to talk about specific cause of miscarriage rates, by the way. I mean, we do I've done studies on endocrine disruptors influencing miscarriage rates, and we know that they can do that: they do it both for early miscarriage, repeated miscarriage and the primary miscarriage are all affected. [00:46:14][18.7]
[00:46:15] And we know that these chemicals interfere with the assisted reproduction. A beautiful study, if you want to look into this, is conducted at Harvard, it's ongoing, and I take couples coming in for assisted reproduction. They get the man and the woman to give a urine and a blood sample, and then they measure the chemicals in those samples and then they see how does the procedure turn out. [00:46:39][24.0]
[00:46:40] So it turns out that number of chemicals--and it's different chemicals have different / closer links to different outcomes--but in general, you can say higher levels of endocrine-disrupting chemicals in the samples of the couple at the time they start to procedures are related to the success of that procedure, whether it be the number of eggs retrieved, or quality of the embryo, or successive implantation, or ultimately the birth of a live healthy baby. All of those things can be impacted by what they start out within their systems. [00:47:14][34.6]
[00:47:15] So definitely if people are thinking about assisted reproduction--and more and more are--try to avoid exposure to endocrine-disrupting chemicals and read Countdown because in our book we give a lot of examples of how to do that: things you can cut out of your lives, or activities that you should do that will improve your reproductive health. Do that before. It takes 60 to 70 days to make a sperm. And that sperm can be harmed by exposures in that period prior to conception in a way that affects the fetus if you get that far. [00:47:51][36.2]
[00:47:52] And by the way, changes to the fetus caused by endocrine-disrupting chemicals are permanent. So we talked about how a man could improve his sperm count by stopping smoking. But he can't do anything about his sperm count being decreased because of his mother's or his father smoking. That's for life. [00:48:10][17.8]
[00:48:11] So young men and women, if you are going to have a child, this is a huge responsibility for you. And it's not just even for your child because your child has within their body, the germ cell for the next generation. And so you are affecting at least three generations by your exposure. So bear this responsibility and own up to it, and try to decrease the risks for all these generations. [00:48:38][27.3]
Sophia Ruan Gushee: [00:48:39] Thank you. I love what you do. It's so important. [00:48:41][2.3]
Dr. Shanna Swan: [00:48:42] Thank you so much, Sophia. I'm happy to be here. And I'm so glad you're interested in the science. And I hope more people will get interested and talk about it and share it. And by the way, you can use #CountMeIn if you want to lend support to the book Countdown. [00:48:57][14.9]
Sophia Ruan Gushee: [00:48:59] Thank you so much. Take care. Bye bye. [00:49:01][2.7]
Sophia Ruan Gushee: [00:49:02] Thanks for listening. Please subscribe to the practical Nontoxic Living podcast and if you'd like to support it, then please like it and share it until next time.
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