Dr Shanna Swan: Reproductive health is declining at 1% per year. So that doesn't sound like very much, 1% per year, 1%, that's not very much. That's what people say about climate change, right? Just one degree, well who cares? Well, we do, don't we? We care now about that one degree. And we know what it means. And the same thing is true with the 1% effect, because 1% you know, over 10 years is 10%, and over 50 years is we're cut in half. We're cut at the knees.
Dr Rupy: So you know.
Dr Shanna Swan: What do you want to know about me?
Dr Rupy: What I want to know about you. Okay. So I, I read the pod, I read the book and, I'll be honest, it's definitely one of the scariest books I've read. It's one of those things that I've been sort of aware of on the periphery, but I didn't really want to pay too much attention to because it was very, very inconvenient. But I think the prologue to the book and the dedication of the book for our children and grandchildren really did send shivers down my spine. So maybe.
Dr Shanna Swan: I don't yet. Don't yet. Um, and I'm 36. Can I ask you a personal question? I'm just going to ask you.
Dr Rupy: Go, go for it. Go.
Dr Shanna Swan: Have you ever had your sperm count tested?
Dr Rupy: I have not. I haven't.
Dr Shanna Swan: Okay, well maybe after we talk, you will do that.
Dr Rupy: Probably. After reading and listening to the book, I most likely will. Yeah, absolutely.
Dr Shanna Swan: I can tell your listeners is that this has gotten quite easy now. I can tell you, you can do it from your home, you can send in, there are companies that you can send in your sample that are reliable. And it's, it's just good information, you know, it's like you're learning something about your body and women can't do it.
Dr Rupy: Yeah, yeah, yeah.
Dr Shanna Swan: Right? You can't, you can't like send in your eggs to be checked or something.
Dr Rupy: Yeah, yeah, yeah, exactly. It's definitely weighed in our favour as a lot of things are, as I read about in the book too. Why don't we talk about about you and your background before you got interested in this subject matter because you're an epidemiologist by training, is that correct?
Dr Shanna Swan: So, yes and no. My first degree was in mathematics. My second, my second degree is in biostatistics. But my third degree is in mathematical statistics, which is also mathematics because it was probability theory. So really my, my initial training was quite theoretical. It was, you know, and, but my first job of any extent had to do with health, applying statistics in a health setting and that was working for Kaiser Division of Research and looking at the question of whether the oral contraceptive, how the oral contraceptive changed women's bodies. Pretty profound study. And it got me very interested in the subject matter beyond the statistics. You know, so we're looking at women who are putting chemicals into their body, chemicals that are hormonally active, obviously, designed to be so, and what effects did that have on their body? After working there for several years, I was kind of, you know, in the track, in the shoot to go down the road to epidemiology and public health. And that's what I did. I worked for 17 years in the Department of Health Services, California. I'm a very, if you will, socially conscious person, so I always wanted to do things that impacted people and and their well-being and so this seemed a good way to do that. And, and so I, I did that happily, sort of the first major part of my career. Um, and until I learned about endocrine disruptors. And that was through my participation in a committee of the National Academy of Sciences. And they were looking at this newly defined term, endocrine disruptors, which was, the committee was formed back in 95, I think. And so at that time, I, I didn't know what an endocrine disruptor was. Most people had never heard of this. Um, and, and then the committee was asked to consider a study that had come out of Denmark, and that study published in 92 said that sperm count had declined 50% in the prior 50 years. I don't know if you're familiar with that study. It's kind of a, it's the landmark study in this field, I would say, prior to our 2017 study, which was.
Dr Rupy: Is that the Carlson paper in 92?
Dr Shanna Swan: Exactly. Exactly. Right. So the committee asked me whether they should consider that study, as a statistician, what did I think of it? And to be honest, I was not convinced. For a number of reasons. One is they didn't seem to consider the possibility that changing methods or changing populations could have produced this decline. In other words, they didn't consider things we call biases and confounders that might have produced an artificial decline, which was actually not temporal but due to other changes, right? So I had the opportunity to look into this and I committed six months to doing that and that's what I did. And so over the next six months, I got all the 61 studies that had gone into that and I selected from them all the factors that could possibly explain the decline. So how the sample was tested, how men were recruited, what their ages were, whether they smoked, whether they were obese, and whether it was an occupational study, was it, you know, and so on and so forth. And I and two colleagues at the Health Department put this in a large model, not yet called a meta-analysis, by the way. This is a reanalysis of a, I don't know what to call the Carlson paper, certainly not a meta-analysis, but it was, it's a prototype of a meta-analysis. It was before meta-analysis was defined really, right?
Dr Rupy: Right, okay.
Dr Shanna Swan: Yeah, and, and so we ran this model really not knowing what we would find and to our surprise, nothing changed. It was exactly what Carlson had published. The slope to the first decimal place was the same. So this was a, this was my first wake-up call that there was a problem with declining sperm count. So let me stop there and that kind of gives you that back history and then we can go, go forward.
Dr Rupy: Sure, yeah. So that was sort of the first warning sign that there was a genuine decline that needed to be investigated further. And I guess the next 20 years of your career has been spent trying to figure out why, what the evidence is, what could be causing this. And your paper, I mean, you've done multiple publications, but the one in 2017 really caused these like incredible shock headlines. I think I remember reading something from the BBC about, you know, who's killing our sperm, like, you know, the human race is going to be extinct in the next 50 years. You know, you're responsible for that, right? Or you and your colleagues.
Dr Shanna Swan: Yeah, yeah, we did our best to get attention to that. But unlike the book, by the way, which we worked pretty hard to get distributed and noticed, that 2017 paper, we didn't do anything. That was just pick up by the media. We never had even a press conference. But the, there's, I don't know if you're familiar with Altmetrics, it's a, it's a metric system that looks at the how many times a paper is accessioned and referenced and so on and so forth. And of all the papers published in 2017 in the world, ours was the 26th.
Dr Rupy: Wow.
Dr Shanna Swan: So, you know, you can almost say it was the, certainly one of the top papers for the whole year. So, so it was big. And one of the consequences was that an agent called me, a literary agent. And she said, would you like to write a book about this? Again, my first reaction was negative because first of all, you've written books, so you know what's involved. I didn't know what I was getting into actually. But, um, here's what I thought. Look, I've written about this for 20 years, right? I've spoken about this to countless audiences, all scientific or possibly governmental. Um, very few to the general public. But I've certainly spoken about it. I've written about it. I've written over 200 papers. So, haven't I kind of done this? And she convinced me that the reach would be different. The megaphone, if you will, would be different. And as something you know as a podcaster and an author, you know, you do reach a different audience than a scientific audience. So you and I share a lot because we're both in some sense academicians and we're both in the health field and we both have both reached out to the public in a untraditional way, I would say for academicians and also the academic route. So, so you understand what I'm talking about. So it's a way to, um, go beyond the, well, certainly the ivory tower, that's kind of a cliche, but the, you know, the limited, um, range of your voice in an academic setting. Um, and I must say, I'm learning more and more that through social media and through talking to people who are understand how to impact people through social media, that, and particularly today, people are not necessarily convinced by science. It's a, that's a hard thing for me as a scientist to say. Would you agree?
Dr Rupy: I, I would agree. Um, I think science has a bit of a branding problem and a communication problem as well because whilst your study can be the most robust and, um, the, the, the best peer-reviewed and the top ranked, you know, in all tricks and and other sort of means of of getting the the literature out there to scientific colleagues, it wouldn't touch the average person on the street and that's generally who you need to try and influence if you want to enact change. And that's why, you know, I commend you writing the book because it's, it's for the lay audience who actually need to know this more than anyone.
Dr Shanna Swan: Right. And I have to say that my agent's suggestion that I get a writer, someone to write with me, and that I was so lucky to find Stacy Colino, um, because it's her, it's really her voice. So, have you ever written collaboratively? I don't know if you've done that.
Dr Rupy: I haven't written collaboratively. I've written my all my own work, but um, I, I guess sort of my experience is slightly different because I've come at writing through the sort of route of of being a general practitioner. So I have conversations with people all day, every day where I explain the side effects of medications, the implications if they don't change their lifestyle, trying to, you know, debunk myths and that kind of stuff to someone who doesn't come from a scientific background. So I think my writing sort of kind of flowed out of that and and also through the podcast medium as well, whereas I think if you've come from core academia where you're used to, you know, conversing with your esteemed colleagues, it's a very different endeavour to go into sort of public writing.
Dr Shanna Swan: Right. So, so Stacy and I together crafted this and and it was very much a team effort and she would say, well, tell me the science about this question. You know, and then I'd talk about it and she'd take notes and then she said, I think I can use that. And then she would rewrite it and send it back to me. And then we would, you know, and that that was the process. And I highly commend it to anybody who, you know, hasn't had your experience of of talking to people on the street, if you will. Um, and it was certainly what, you know, taught me a lot how to talk to to people. And now since the book came out, I have to tell you, Rupy, I have been talking to people three, four, five, six times a day since February.
Dr Rupy: Wow.
Dr Shanna Swan: It's absolutely extraordinary. The interest and and and and then on, um, you know, Instagram live or, you know, chats or, you know, open discussions where people can jump in. They're so engaged, they're so interested that it really makes me feel like this is the way we have to get our health messages out. This is this is what this is the way.
Dr Rupy: No, I think I, I agree. All scientists should should be taught about communication skills because there's no point just sitting in a lab or, you know, conversing with colleagues unless that science is actually going to have an impact on the real world. So, you know, yeah, I think more people need to do what you're doing. How how are you enjoying the kind of social media world? Are you finding it largely positive or?
Dr Shanna Swan: I, I have to confess that I have a helper.
Dr Rupy: Okay.
Dr Shanna Swan: Okay. And, um, that's Emily Copeland and she is, um, a buffer for me. So, you know, there may be stuff that I wouldn't like to see. I think maybe. Um, not too much, I think. But, but, um, she is like stands between and she sends me things. She said, would you like to, you know, um, support this? Do you want to make a comment on this? Do you want, so she helps me, uh, you know, deal with that. I'm learning, but it's not a space that I'm, you know, familiar with. So, I'm gradually learning. How about you? Do you like it?
Dr Rupy: I, I, I do like it. I've been, I've been in it now for over five years. I'm sort of used to the platforms. It's very easy to get social media fatigue, which is why it's probably nice and important to have a buffer, uh, because you can spread yourself too thin. Um, but, you know, my favourite medium is definitely podcasting because you can have a much more nuanced conversation. And I guess Instagram Live also gives you that opportunity as well because this is a very complicated topic as we're as we're going to get into it. You know, um, the thoughts that we won't have the ability to reproduce naturally much longer is very contentious and it's scary, frankly. Um, why don't we talk about that? So, so what is the, the 1% effect? You've mentioned this in the book. What, what is, what is that exactly for the listener?
Dr Shanna Swan: So, when I, when I saw the, um, first of all, the rate of decline of sperm count from our 2017 study, um, just to go over the numbers, the samples were collected between 2011, 20, sorry, 1973 and 2011, right? 39 years. Say 40 years. Um, and in that time, sperm median, mean, sorry, mean sperm count, um, dropped from, um, well, it dropped 52%. So that's 52%. 50%. Cut in half, basically. And, and that's about 1% per year, right?
Dr Rupy: Yeah, yeah.
Dr Shanna Swan: 50, 50% in 40 years, just a little. Okay. So that's the rate at which it's going down. And then, and we'll go back to what that number refers to, by the way, it's not the whole world. Okay. So then if we go to fertility data, which anybody can do, you, I recommend it to you, you go, just put in Google World Bank fertility data. You get a very nice interactive map. And that map tells you the number of children born per woman or couple. And you can query it by year, by time, and so on. And what you see is that that number dropped between 1960 and 2019 by 50%, which is again, 1% per year. And by the way, that is actually true pretty much everywhere. You know, people have this image that, well, in the poorer countries, um, where people have a lot of children, fertility is not declining. That is not true. If you go into that map and you put in any, say, African country, you'll see the decline is actually steeper there.
Dr Rupy: Wow.
Dr Shanna Swan: So, um, so anyway, 1% per year fertility decline. Um, and then if you look at a very important driver, I feel of this, which is testosterone. There are fewer studies, but there are a number of studies that have looked at testosterone pretty carefully over time, and those studies demonstrate a decline in adult male testosterone of about 1% per year. And then if you turn to the woman and look at the miscarriage rate, again, no meta-analysis, much fewer data. However, where it's available, and we talk about that in detail in the book, where it's available, um, it's going up at about 1% per year. And then there are other related factors such as testicular cancer, male genital birth defects, premature ovarian failure, um, erectile dysfunction increasing in young men and so on. So if you look at how fast these things are changing, they're all, there's nothing that's going like five times as fast or half as fast. They're all in the same, I would say, order of magnitude. And so what I say overall summarizing this is that reproductive health is declining at 1% per year. So that doesn't sound like very much, 1% per year, 1%, that's not very much. That's what people say about climate change, right? Just one degree, well who cares? Well, we do, don't we? We care now about that one degree. And we know what it means. And the same thing is true with the 1% effect, because 1% you know, over 10 years is 10%, and over 50 years is we're cut in half. We're cut at the knees, right?
Dr Rupy: Yeah.
Dr Shanna Swan: And, and, and, so yeah, that's the 1% effect.
Dr Rupy: Wow. Okay. So 1% a year. So, so just to clarify, when it comes to the prevalence of miscarriages, that's increasing as well over the same time period by about 1% a year. Okay. Wow. All right. So by the time, so I, I qualified as a doctor over 12 years ago. I went to medical school over 15 years ago. So in that time period, miscarriages have increased by 1% per year over that, over that time period. So when I started, the prevalence of miscarriage would have been much lower, considerably lower than what it is today when I see people.
Dr Shanna Swan: Now, Rupy, there's a, there's a qualifier here for miscarriage. As you know as a clinician, miscarriage is a little bit of a tricky endpoint, right? What is a miscarriage? You know, so do you require that the woman had a, um, you know, clinically diagnosed pregnancy that she then lost, that number will be lower than if you have self-reported miscarriage or you have women coming in saying, I had a late bleed and I think I had a miscarriage. And it's much less than the really best studies, one of which I did, which is you get urine every day, you test it for HCG, HCG goes up, the woman's pregnant, HCG goes down, she's had a loss. Okay, are you familiar with those studies?
Dr Rupy: Yeah, yeah, I know I haven't looked at those studies myself, but I'm familiar with the terminology.
Dr Shanna Swan: So it's called early pregnancy loss, non-clinical loss, sub-clinical loss. And those occur much, much more frequently, like 30, 35% of all pregnancies end without a woman knowing about it. So, um, that's, it makes it really tricky when you look at these trends. It's not like sperm count where you have measured levels by methods that have remained constant. Miscarriage is much trickier, right?
Dr Rupy: Yeah, that is trickier.
Dr Shanna Swan: And so I just pointing that out that the quality of the data, um, testosterone levels pretty, pretty stable, you know, I mean, pretty easy to measure in a stable way, methods remaining stable. So you can say these have gone up. So whenever we talk about trends, we have to talk about how are we determining that and in whom, right?
Dr Rupy: Yeah, yeah, yeah.
Dr Shanna Swan: So who's going to come and report, you know, a lot of entire populations would never maybe notice that they've missed a period or that they won't participate in these studies. So we have, you know, there's a lot of epidemiological questions here. But I think I'm speaking broad in broad brush, if you will, 1%.
Dr Rupy: Yeah, yeah, yeah. I think that's a really important qualifier for that. Um, but everything else, I mean, it sounds, uh, again, very scary because if you extrapolate that, then that's where you get the genuine fear that we would lose the ability to reprocreate. Is this something that we see in animals, in other species as well?
Dr Shanna Swan: Yes. So, um, we haven't talked about causes of these changes. But let me just fast forward and say it is the opinion of me and others working in the field that we are exposed to chemicals that are playing a large role in this, and non-human species are exposed to these same chemicals because they're in the environment. And we see in many of these species declines in many of the same endpoints that we see. So we see, um, for example, alligators with smaller litter sizes. We see alligators, by the way, with smaller genitals, which we also see in humans. We'll talk about that later, I think. We see, um, frogs with, um, disturbances of their genital organs, which is related to their pesticides. And we see endangerment, right? And in some species, extinction. So there's, there's no question that, um, chemicals play a role in non-human species and in my opinion, in humans as well for these declines.
Dr Rupy: When it comes to, we'll talk about the, the chemical, the array of different chemicals that could be responsible for this effect that we're seeing, this phenomena. Um, do we know the proportion to what it might be related to what we've done to the environment versus the other lifestyle factors, i.e. diet, smoking, obesity, uh, foods that we've now developed a taste for versus what we would have traditionally been eating?
Dr Shanna Swan: That's, um, it's really hard to separate those out. Okay. I would say that lifestyle factors, as you've described, are definitely important. And I would say that probably in adults, they are the most important drivers. So, however, I don't think they're the most important drivers in our lifetime because I think what's happening, which is most influential, is what the foetus is exposed to in utero. And there, both sides of the equation, if you will, are important. Let me give you one piece of data which comes from two Danish studies. If you, or three actually. So smoking, lifestyle factor, okay. So in this Danish study, mothers who smoked while they were pregnant had sons who had a 40% reduction in sperm count as adults. Now, how could that be? They're smoking and this is a little creature in their body. There's no sperm, there's not even perhaps genital organs. Well, that smoking affects the germ cells, right? The spermatogonia that will go on to later produce the sperm that the man has when he's an adult. And if those are adversely impacted by smoking, that's damage that is irreversible. So he will have this reduction probably not fixable, unless there's some magic bullet, you know, now in science, biology, we're getting a lot of magic bullets, right? The vaccines and CRISPR and so on. Who knows, but I can't say there won't ever be, but I don't know now of anything that could fix that. However, if the man smokes, so he wasn't exposed prenatally, he takes up smoking as an adult, his sperm count is also reduced, but it's much less of a reduction, 20% versus 40%, and if he stops smoking, he recovers. So they're quite different impacts. The good news is, if you're doing something to your body that's impairing your reproductive function, you can actually turn that around. And that's really positive for people. And and that's one of the reasons I suggest to men that they get their sperm tested because maybe before they want to try to have a child and it's not great, well, they can look into these things. Are they binge drinking occasionally? Are they smoking? Are they exposed to, you know, ambient cigarette smoke? Are they stressed? Can they reduce their stress? Can they change their diet? We can talk about all those things. But there are definitely things that people can do to improve their reproductive function when the exposure occurs as an adult. However, if it occurs in utero, as I said, there's nothing that I know of that can be done about it.
Dr Rupy: Right.
Dr Shanna Swan: So, so, and by the way, it's not just smoking in utero, it could be exposure to these endocrine disrupting chemicals we're going to talk about. It could be diet, it could be stress. There's all these things that also affect reproductive function and and development in utero.
Dr Rupy: Yeah. So the exposure in utero derived from those studies is a lot more important than the lifestyle factors given that the exposure is the same in this case, cigarette smoking, let's say. Um, and one is reversible, one is not reversible at this point in time. Um, do we know about the effect of, let's take cigarette smoking in this example, uh, on female fertility if the child was female and and female smoking?
Dr Shanna Swan: Yes. Um, so we know, um, that smoking affects risk of miscarriage, it affects the risk of becoming pregnant, um, time to pregnancy. Um, it affects, um, probably, although I don't have those data in my head right now, probably the success of an ART procedure. That's another thing we haven't talked about, but all of these chemicals affect success of ART, artificial reproductive technology. So in vitro, ICSI, and for, there's a really elegant study which has been going on for quite a while at Harvard. It's called the Earth study. And in that study, they, um, and you might want to talk to the person who runs that. His name is Russ Hauser. He's a clinician.
Dr Rupy: Okay. Yeah.
Dr Shanna Swan: Yeah. Um, and and what they do is they measure the body burden of the man and the woman at the time they come in for assisted reproduction. And then they link the exposure that they measure in the urine and blood to the success of the procedure.
Dr Rupy: Ah, interesting.
Dr Shanna Swan: And they've published quite a bit on this showing that what you have in your body. So, so another sort of take home here is that if a couple is going to go through these procedures, it really would behoove them to get tested, to find out what their body burdens are, to talk to people about how to lessen those, right? To get counselling on that, and then improve their chances of succeeding. This is a expensive and difficult and painful sometimes procedure that people, you know, want to maximize their chances. So, you know, that's a really good take home there. So there's a lot of intervention points. One I haven't talked about is that the father. So the father, um, you know, but your listeners might not know or remember that sperm are being produced all the time. And it takes about 70 days to produce a sperm. So in that 70 days that's prior to ejaculation, right? Um, the man is smoking, that's going to affect that sperm. The man is binge drinking, the man is exposed to phthalates, the man is exposed to BPA, whatever, he is adversely affecting that sperm and that sperm will have an effect on the foetus. Now, I told you about the mother smoking during pregnancy and the son's sperm count. It's also true that if the man smokes in that window, his son has a 40% lower sperm count.
Dr Rupy: So it's comparable to the effect.
Dr Shanna Swan: Right. Right. Okay. So, you know, there's a lot of care that has to be taken, you know, and if you, and a lot of couples, you know, they're not sure when they're going to conceive. 50% of pregnancies are unplanned. So, if you think you could be getting pregnant, either not using contraception, you know, or whatever, then you've got to kind of have in your back of your mind, okay, any day now I could get pregnant and what I'm doing right now in terms of my lifestyle and in terms of chemicals I'm letting into my body could affect my foetus. And by the way, that foetus's offspring.
Dr Rupy: All right, okay, yeah, yeah.
Dr Shanna Swan: Right? Because, for example, you're carrying a boy, that boy has inside him those germ cells that will produce the next generation's sperm. They are also being exposed. So, you know, that's why the book is dedicated to our children and grandchildren. Maybe we should have said great grandchildren, although we haven't had any yet. Because, um, um, Pat Hunt has shown at the University of Washington, wonderful study in animals, you know, how, what she did, this is what she did, elegant study. Take a rat, I think she used mice, take a mouse, expose it to an estrogenic compound, then that rat's or mouse's offspring is again exposed to the estrogenic compound, and the grandchild, and she sees a cumulative effect. It just gets worse and worse, reproductive function declines. And that I think is what's happening to us. That's why sperm count continues to drop. That's why it doesn't reset each generation.
Dr Rupy: Yeah, I think, you know, the theme certainly that I got, um, the impression I got from the first part of the book is about how this is an equal, uh, responsibility. And I think historically, it's been the, uh, the onus has been on the female partner to, um, to, you know, sort out fertility issues. And just to underscore, you know, that 70-day period for men in particular, but also their lifestyle factors up to that point, certainly have an effect on fertility. We've talked about that on a previous podcast episode with a good friend of mine actually, about optimizing fertility using lifestyle up to that point. Um, I think we should probably define what we mean by endocrine disrupting chemicals. Um, because we've referred to them quite a few times to this point. What, what is the, what is the definition of them?
Dr Shanna Swan: Yeah. So, um, an endocrine disrupting chemical is a chemical, usually but not exclusively man-made, which can masquerade as one of the body's many, actually up to 100 hormones. We don't know all the hormones that are imitated by chemicals, but we know of many. So, for example, um, if your body is looking out for a molecule of testosterone, it might have a receptor for that molecule. It's open, it's waiting for that testosterone. And then you are exposed to a phthalate, we can talk about what that is, but they're plasticizers that make, for example, bottles soft. And, um, and then that goes into your body and into your bloodstream, and then that receptor is sitting there waiting for your body's own testosterone, and this phthalate look alike, mimic, if you will, takes its place, and then the body says, okay, I'm good to go. I don't need to make any more of that.
Dr Rupy: Right.
Dr Shanna Swan: Very simplistically, what it does is it, um, they're imposters. They're imposters that, um, come in very silently, very sneakily, you know, we don't know what's in our bodies and I can tell you if we measured our urine right now, we, you and I both would have many, many hormones, mimics in our body.
Dr Rupy: Yeah, I mean, you're living, you're in New York at the moment. I'm in the centre of London, so it's, uh, highly likely.
Dr Shanna Swan: Right, right, right. But they've also been found in the Arctic Circle in the bodies of animals, and they've also been found very deep in the ocean, even to the bottom of the Mariana's trench. So there is nowhere on earth that they don't go. I'll just tell you that. Nowhere on earth that they don't go. Okay. So anyway, so, so these are, one way to think about them is hormone mimics. I think that's a simple way to think about them. Um, the name is kind of complicated, endocrine disrupting chemicals. Endocrine means hormone. The endocrine system, endocrinology and so on. So, um, most people don't think about their endocrine system, but they might think about their hormones. Certainly many think about their testosterone. Um, and, and women think about their hormones of pregnancy, of a menstrual cycle. So, so I think people are familiar with hormone. And, and one really simple way to think about endocrine disruption is to think about the oral contraceptive. It's not, it's not an environmental chemical unless it's dumped into the water, by the way. So it is through our urine. But, um, these are things we take specifically to disrupt our hormones. That's why we take them, right? So, um, you know, the sort of proof that we, you know, we use these, we know these and, but what we didn't know for a long time, um, well, really not, I think, clearly until about 2000, um, a little earlier, I think our stolen future, which is an excellent book that I recommend to you and your listeners, um, told a lot, you know, the start of the story, the history of the story. And, and, um, and then about 2000, we started measuring them in everybody's bodies and, you know, being able to quantify it and do these studies. So, um, yeah, so they're everywhere and they're, they come in many forms. Um, and those have to do with the function of the chemical, how it's used, what it does, you know, in terms of its, um, use to society, if you will. It's nice to have a hard water bottle, right? You need BPA for that. Or BPF or BPS. It's nice to have, um, soft, flexible tubing, for example, you know, in the hospital, it's used all over the hospital. And patients are all the time getting phthalates through these tubes, by the way, just including newborn babies. Um, and, um, so, yes, it's nice to have it, they have a function and they also can convey harm. So we have to balance, we have to balance the pluses and minuses. I'll give you a very example of that. So I, I said they're in the hospital, um, they're in tubing, they're in IV tubing, they're in dialysis tubing, they're in NICU tubing and so on. All right. So hospitals have started to take them out, which is great, remove phthalates from your hospital tubing. It's a fantastic, important campaign. However, it turns out that blood bags, blood bags can't take out phthalates. And you know why?
Dr Rupy: Why is that?
Dr Shanna Swan: It prolongs the life and it prevents coagulation. So they've not found yet a substitute. And that's what I mean about risk and balance. You know, if you really need this chemical, which you certainly do in a blood bag, you have to take the balance it, you know, and say, okay, we're giving this exposure, but we're providing this absolutely life-saving, you know what I mean? So, so I think I wouldn't universally say, take it all out. I think you have to look at the function, how it's used, whether it's needed for that function, whether there's a substitute which would perform as well, which is not hormonally active. And that's the work we have cut out for us now.
Dr Rupy: You, you mentioned a term, body burden at the start. Um, and I'm, I'm guessing that's referring to the concentration of chemicals that we can measure in the urine, let's say. Um, and I'm guessing that your body burden only gets to a critical level when you're having multiple exposures of all these different chemicals from various parts. So, skipping forward a little bit, but I'm assuming there's a way to reduce said body burden with some pragmatic decisions to make that you can do at an individual level as well as a societal level.
Dr Shanna Swan: Yeah. And, um, by the way, you can measure those things in your urine if they're water soluble.
Dr Rupy: Right. Okay.
Dr Shanna Swan: Right? You can measure them in your serum if they're fat soluble, or in your fat if they're persistent. That's much harder to get a fat sample than a urine sample, right? So, so looking at levels in fat is pretty tricky, but you can pretty easily get serum and you can very easily get urine. So yeah, in terms of reducing your body burdens, um, I recommend to you a book called Slow Death by Rubber Duck.
Dr Rupy: It sounds, uh, uplifting.
Dr Shanna Swan: So these are, slow death by rubber duck was written by two Canadian environmentalists. And what they did was they said, we're going to see how much this, these chemicals matter for us. And they set up this experiment on themselves. And what they did was they created a little lab in one of their homes, and there was a room that they got squeaky clean. And how might you do that? Well, you would remove any plastic from it, you would remove, certainly no air fresheners, which contain phthalate exposure, you want to have nothing covering the furniture or the floor that could have flame retardants in it, and so on and so forth. So they, they cleaned up their environment, and then they cleaned up what they took in their bodies. So the foods they ate were organic, and they were not wrapped in plastic, and they were not heated in plastic, and and so on. And they were not in tin cans, and they were not in, you know, so they went through all these ways that things could come into their bodies. And they measured their body burden, that is the levels of these chemicals, total levels of these chemicals in their body before they started the experiment, after the experiment, and then they reloaded and did it again. And so what they showed is that, yes, you can lower your body burden. And they did it and they showed it. So I, I think that's pretty convincing. Uh, not everyone can do everything, but, um, it can encourage people to to start and to try and to reduce.
Dr Rupy: Yeah. There are some pragmatic decisions that you can make. I, I guess, um, was it reduced by a significant amount? And do we, do we know what the threshold is, uh, such that we can see, oh, we don't.
Dr Shanna Swan: No.
Dr Rupy: You're shaking your head.
Dr Shanna Swan: Thresholds are really tricky for these chemicals. Um, but, but let me say, there were some, for example, diethyl phthalate, um, was one that went down a lot. And diethyl phthalate is a phthalate that's, uh, contained in anything fragranced.
Dr Rupy: Okay, so this is phthalate spelled P T H A L A T E S. Okay, P T H A, right.
Dr Shanna Swan: So, anything with a fragrance, you know, whether it's a room freshener, you hang it in your car, you put it in your on your skin through personal care products, you in your laundry soap, you know, you're going to get a lot of phthalates. So, you know, we asked women in our studies, you know, I do study pregnant women and we ask them a lot of questions of what they're, how what they're doing. We asked them what products they put on their body and were they fragranced. And the women that use fragrance products had much higher levels of several phthalates, dibutyl phthalate, diethyl phthalate. So, um, those are the things that were easiest to knock down in this experiment of of Rick's. So, what's really surprising, I don't know how much endocrinology you studied in your medical practice, but.
Dr Rupy: Uh, basic, but I understand about negative feedback and all that kind of jazz.
Dr Shanna Swan: You know, in the endocrine system, the endocrine system is tuned to to be sensitive to extremely low doses, right? Very, very small changes in hormones can have big effects. And it's unlike a lot of other, um, agents coming into our bodies or influences, this very low dose effect. And so we think now through a series of many, many studies that there is no threshold. You know, for example, lead, lead and lead poisoning and IQ, no threshold. Um, so, definitely we want to reduce these things, definitely we can't completely eliminate them, and we can just do the best we can. But there's no level at which there's not going to be, maybe not measurable change, maybe some small change that doesn't matter that our body adapts to, but, and besides no threshold, there's this mixture question. So, as a physician, if you're prescribing a drug to a patient, a new drug, you'll probably say, what else are you taking, right? And you ask that because all of the medications that this patient is taking have to be considered together. There could be bad interactions, there could be, right? So, um, the same thing is true of these chemicals. And because we're exposed to so many different ones, CDC measures over 100 in their random samples of tracking, you know, tracking samples. Um, and they're mostly in everybody. So, right now, you've probably got 100 endocrine disrupting chemicals in your body. At some level, maybe not doing any harm, maybe doing harm. So, if you just study one of them at a time, you're not getting the full impact, just like you wouldn't for a medication.
