Dr. Shanna Swan: How to Safeguard Your Hormone Health & Fertility

00:00:00.000 | - Welcome to the Huberman Lab Podcast,

00:00:02.240 | where we discuss science

00:00:03.660 | and science-based tools for everyday life.

00:00:05.840 | I'm Andrew Huberman,

00:00:10.260 | and I'm a professor of neurobiology and ophthalmology

00:00:13.480 | at Stanford School of Medicine.

00:00:15.480 | My guest today is Dr. Shana Swan.

00:00:18.040 | Dr. Shana Swan is a professor of environmental medicine

00:00:21.120 | and public health at the Mount Sinai School of Medicine.

00:00:24.800 | She is a world expert in how exposure to various toxins

00:00:28.840 | and compounds in the food and environment

00:00:31.360 | impact our reproductive health.

00:00:33.680 | She focuses on how these compounds in our air,

00:00:36.520 | in our food supply, in our water supply, in cosmetics,

00:00:40.080 | even in household items,

00:00:41.760 | impact the developing fetus, children, and adults

00:00:45.900 | at the level of their reproductive biology,

00:00:48.380 | so things like testosterone and estrogen,

00:00:50.640 | and the pathways within the brain and body

00:00:52.660 | that are impacted by testosterone and estrogen,

00:00:55.680 | but also how all of those things in our environment

00:00:58.320 | and that we put into our body

00:01:00.000 | impact our health on a daily basis and our long-term health.

00:01:03.920 | So during today's discussion,

00:01:05.080 | you will learn why fertility rates

00:01:07.120 | are indeed dramatically dropping from year to year

00:01:10.320 | and have been for quite some time now.

00:01:12.960 | You'll also learn why testosterone levels are dropping,

00:01:15.680 | why sperm counts are dropping,

00:01:17.400 | why things like polycystic ovarian syndrome

00:01:19.820 | are increasing in women, and what we can do about it.

00:01:24.280 | In fact, during much of today's discussion,

00:01:26.480 | Dr. Swan emphasizes the things

00:01:28.200 | that you can do every single day,

00:01:29.800 | and that, in fact, turned out to be very simple.

00:01:32.180 | They involve certain things to do

00:01:33.840 | and certain things to avoid

00:01:35.960 | in order to limit your exposure

00:01:37.980 | to these environmental toxins and their impact.

00:01:40.980 | So by the end of today's episode,

00:01:42.920 | you will be highly informed by the world expert

00:01:45.800 | on endocrine disruptors and environmental toxins,

00:01:48.800 | and you will also be highly informed

00:01:50.880 | in terms of how you can have agency,

00:01:52.800 | how you can take control of your health

00:01:55.480 | in relation to these various compounds.

00:01:57.680 | Before we begin, I'd like to emphasize

00:01:59.580 | that this podcast is separate from my teaching

00:02:01.920 | and research roles at Stanford.

00:02:03.700 | It is, however, part of my desire and effort

00:02:05.840 | to bring zero cost to consumer information

00:02:07.800 | about science and science-related tools

00:02:09.840 | to the general public.

00:02:11.320 | In keeping with that theme,

00:02:12.400 | I'd like to thank the sponsors of today's podcast.

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00:06:45.760 | And now for my discussion with Dr. Shauna Swan.

00:06:49.300 | Dr. Shauna Swan, welcome.

00:06:51.640 | - Dr. Andrew Huberman, thank you.

00:06:54.180 | - I'm super excited for today's conversation.

00:06:57.560 | I've followed your work for a number of years.

00:07:00.160 | I've seen some of your appearances on other podcasts

00:07:04.240 | and I got to see you speak

00:07:06.980 | while we were both in Copenhagen.

00:07:09.220 | I was in the audience, you didn't know I was there,

00:07:10.820 | but incredible stuff that you've been doing

00:07:13.340 | as a researcher, as a public educator, as a writer.

00:07:16.160 | Let's kick off by just asking the basic question.

00:07:21.280 | Are there things in our environment, including our food,

00:07:27.380 | that are diminishing our reproductive and overall health?

00:07:32.020 | And if so, which are the ones that you think about?

00:07:35.560 | And perhaps if you could just mention

00:07:38.280 | a few of the more salient, maybe even shocking,

00:07:42.440 | but salient results that you've observed over the years.

00:07:45.240 | Like what was the kind of like, whoa, result or results

00:07:50.240 | that have really steered your attention

00:07:53.120 | in the last couple of decades?

00:07:55.980 | And I'll just say what we were talking about

00:07:57.840 | before we were on the microphone,

00:07:59.120 | which is that you are a skeptic.

00:08:00.440 | You are not somebody who walks out into the world

00:08:02.920 | and looks for things that could be messing up our biology,

00:08:06.420 | messing up our health, and yet you've found some.

00:08:10.240 | So if you could just share with us what you've observed

00:08:12.800 | and what you find really compelling and important

00:08:15.000 | for people to know about, we can dive in there.

00:08:17.000 | - That was a lot of questions.

00:08:18.000 | I could probably talk for a long time.

00:08:20.080 | - Feel free, I won't speak until you're done.

00:08:22.000 | - No, but I want to break it up, let's break it up.

00:08:24.400 | So I think the first question about was,

00:08:26.860 | are there forces, chemicals, agents in the environment

00:08:31.860 | that can affect our reproductive health, yes?

00:08:35.020 | Okay, so my answer to that is yes.

00:08:37.420 | I think there's no question about that.

00:08:39.800 | The question comes down to when and in whom

00:08:44.800 | and what dose and so on and so forth.

00:08:47.620 | But whether there are, let's just say broadly, things,

00:08:52.620 | yes, of course.

00:08:55.060 | The category that I focus on are man-made,

00:09:00.060 | primarily man-made chemicals.

00:09:03.500 | Although I do also include the influence of other factors,

00:09:08.500 | factors of choice, for example, sleep, exercise,

00:09:14.580 | that kind of thing, we can talk about that.

00:09:16.100 | But let's just focus here on the chemicals

00:09:18.940 | 'cause I think that's what led me to do a lot of my research

00:09:23.260 | and to write the book that I wrote.

00:09:25.980 | And so my thesis is that chemicals in the environment,

00:09:30.980 | that's a very broad class,

00:09:36.140 | so we'll have to say some chemicals in the environment

00:09:39.340 | at the right time to the right organism affect fertility.

00:09:44.340 | Okay, so, and let me just say fertility

00:09:48.500 | is one area that I focused on,

00:09:50.900 | but actually this class of chemicals

00:09:53.320 | that I'm primarily interested in

00:09:55.180 | are those that affect the body's hormones.

00:09:58.500 | So those are known as hormone-disrupting chemicals

00:10:02.140 | or endocrine-disrupting chemicals,

00:10:04.560 | hormone-altering chemicals, whatever.

00:10:07.300 | You know, there's a lot of names.

00:10:08.540 | But that helps you focus on where to look for the effects.

00:10:13.540 | 'Cause if it's hormone-altering,

00:10:15.380 | you can now have something to really ask.

00:10:17.340 | Okay, here's a chemical, does it affect a hormone?

00:10:21.880 | Which hormone, when, how?

00:10:24.900 | And then you start, that's almost, you know,

00:10:26.860 | laying out an experiment right there, right?

00:10:28.780 | So focusing in on hormone-disrupting chemicals

00:10:32.140 | I think is useful.

00:10:33.860 | - Absolutely, yeah.

00:10:35.100 | And I think much of what we'll talk about today

00:10:36.940 | probably centers on the estrogen and testosterone pathways

00:10:41.060 | as they relate to masculinization or feminization

00:10:46.460 | of the brain and body and sperm and egg quality.

00:10:51.020 | - So I'm a reproductive epidemiologist.

00:10:53.940 | I got there in an indirect path.

00:10:56.900 | I think probably my work on oral contraceptives

00:11:01.900 | led me there most directly.

00:11:04.500 | And oral contraceptives

00:11:05.860 | are endocrine-disrupting chemicals.

00:11:10.200 | - That's what they're designed to do.

00:11:11.620 | - Right, that's what they're designed to do,

00:11:13.940 | change your body's hormones, your reproductive hormones.

00:11:17.300 | So it's interesting, you know, way back when,

00:11:19.940 | when I worked on the study at Kaiser on oral contraceptives,

00:11:23.880 | which was the largest study of its kind in the world,

00:11:26.540 | actually, trying to figure out,

00:11:28.820 | were there adverse effects of oral contraceptives?

00:11:31.240 | If so, you know, for whom and when and how much and so on.

00:11:34.860 | And so that was a very great study.

00:11:36.540 | And coming forward in time,

00:11:42.740 | I, you know, I studied environmental chemicals,

00:11:46.260 | not so much pharmaceuticals for quite a while

00:11:51.260 | when I was at the California Department of Health Services.

00:11:54.680 | And then I had an aha moment.

00:11:57.920 | I was flying to Japan with my friend, John Brock,

00:12:05.840 | who's a chemist at CDC, wonderful chemist.

00:12:10.820 | And, you know, had long flights,

00:12:12.640 | we were talking about this and that.

00:12:13.480 | And he says, "Shawna, you should look at phthalates."

00:12:16.660 | And I'm going, "Why should I look at phthalates?

00:12:18.540 | I never heard of phthalates," right?

00:12:21.220 | And he said, "Well, we can now measure them at the CDC,

00:12:25.740 | and we see they're in everybody.

00:12:27.600 | They're in women of reproductive age, fact one.

00:12:30.940 | Fact two, colleagues at the NTP have shown

00:12:36.640 | something they are calling the phthalate syndrome."

00:12:41.080 | And so he explained.

00:12:42.600 | - What is NTP?

00:12:44.000 | - National Toxicology Program, sorry.

00:12:45.800 | - Thank you.

00:12:46.640 | - For using alphabet.

00:12:47.800 | - No, it's quite all right.

00:12:49.440 | - National Toxicology Program,

00:12:51.200 | a governmental, you know, research center.

00:12:53.280 | And their job is to look at chemicals

00:12:56.880 | and see what is the toxicity.

00:12:59.280 | So it could be reproductive, it could be carcinogenicity,

00:13:02.800 | it could be neurotoxicity, that's what they do.

00:13:06.120 | And so they had signaled out these phthalates

00:13:11.120 | as being reproductively toxic, and specifically to males,

00:13:16.320 | and specifically when exposure is in utero.

00:13:19.840 | - Pregnant mom is exposed to phthalates,

00:13:23.080 | and somehow the fetus is disrupted.

00:13:28.680 | - Yes.

00:13:29.520 | - If you don't mind, I'd like to know,

00:13:31.320 | is mom ingesting phthalates in the form of food?

00:13:34.480 | Is she inhaling phthalates?

00:13:36.120 | Are they landing on her skin?

00:13:37.720 | What are the modes of entry into the body of the mom

00:13:40.840 | that, let's just assume it goes through the placental barrier

00:13:44.200 | into the fetus and is impacting fetal development?

00:13:46.680 | - Right.

00:13:47.520 | So in those experiments, it was through food,

00:13:50.960 | but we are exposed in all those ways you mentioned.

00:13:54.640 | Every way that something can get into our body,

00:13:57.520 | phthalates get in there.

00:13:58.600 | But let's come back to that.

00:13:59.560 | Let me go to the experiment at NTP.

00:14:01.520 | So what they did at NTP, National Toxicology Program,

00:14:04.800 | they fed mother rats various doses

00:14:09.440 | of these various phthalates.

00:14:11.520 | And what they found was no changes in the females

00:14:16.520 | or not that they found at that time.

00:14:20.240 | - The female offspring?

00:14:21.240 | - Female offspring, sorry.

00:14:22.560 | But in the male offspring,

00:14:24.400 | they found that the genitals were,

00:14:28.680 | I summarize it by saying incompletely masculinized.

00:14:31.720 | So I'll explain what that is.

00:14:33.400 | So for that, I have to back up and say

00:14:36.240 | something you probably know very well,

00:14:39.020 | but I'll just explain it.

00:14:40.440 | The genital tract initially is a ridge.

00:14:43.400 | It's a single ridge.

00:14:44.600 | It's the same in males and females.

00:14:46.400 | It's not sexually dimorphic at the beginning.

00:14:48.920 | And then under the influence of testosterone,

00:14:52.280 | in a very specific window

00:14:54.040 | called the male programming window,

00:14:56.320 | in rats it stays, I think, nine to 12 of gestation.

00:14:59.960 | So a very short window.

00:15:01.240 | - To orient people, I think rat-mouse gestation

00:15:03.960 | is about 21 days or so?

00:15:05.600 | - Yeah. - Okay.

00:15:06.680 | - So for us, it'll be early first trimester.

00:15:10.960 | But that comes later.

00:15:12.280 | So at that time, if they feed their mother

00:15:17.280 | that chemical in her food,

00:15:21.600 | then her male offspring are born

00:15:24.520 | with changes in his genitals,

00:15:26.960 | or more likely to, right?

00:15:28.520 | And so what they tend to have is a smaller penis,

00:15:32.080 | less descent of the testes,

00:15:36.000 | more likely to have undescended testicles.

00:15:38.280 | There are internal changes of it.

00:15:40.880 | We didn't get into in our human study

00:15:43.960 | because we can't look there,

00:15:45.760 | but the epididymis, there are changes and so on.

00:15:48.640 | The whole genital tract is altered.

00:15:51.040 | And the most important measure for me, as it turned out,

00:15:54.920 | and for humans, and perhaps for animals,

00:15:58.560 | is something that the scientists,

00:16:02.400 | animal scientists had studied for a long time,

00:16:04.800 | for actually 90 plus years,

00:16:08.720 | but had never been studied in humans.

00:16:11.560 | And that is the distance from the anus to the genitals.

00:16:15.520 | This collection of changes in the male genitals

00:16:20.600 | was given the name, the phthalate syndrome.

00:16:22.840 | Now, you're a physician and you,

00:16:25.800 | I challenge you to think of any syndrome,

00:16:30.320 | aside from alcohol, you know,

00:16:33.120 | there, fetal alcohol syndrome, of course,

00:16:35.440 | there's a syndrome,

00:16:36.640 | but note what syndrome is attached to a chemical class.

00:16:41.640 | - Just for technical purposes,

00:16:43.880 | I'm a PhD, not a clinician,

00:16:45.360 | but I worked on neural development for many years,

00:16:48.920 | and then prior to that, some endocrine stuff,

00:16:51.040 | so I'm facile with the general terms.

00:16:54.640 | One that comes to mind would be, for instance,

00:17:00.000 | the thalidomide babies, right?

00:17:02.160 | A miscarriage, anti-miscarriage drug

00:17:04.360 | that changed limb development.

00:17:06.200 | That's a very extreme example.

00:17:08.560 | I would say for, in human normal development,

00:17:13.560 | what I'm most familiar with

00:17:16.040 | are the early organizing effects of androgens

00:17:19.880 | that convert to estrogen on external phenotype,

00:17:23.600 | which is basically nerd speak for,

00:17:26.160 | during development, the Y chromosome produces,

00:17:29.640 | it leads to the production of a number of genes

00:17:31.560 | and eventually proteins through RNA, et cetera,

00:17:33.880 | that are including testosterone and dihydrotestosterone

00:17:38.880 | that in the brain organizes the brain male

00:17:42.360 | and causes the growth of the penis

00:17:44.880 | or organizes, meaning it sets up the penis

00:17:48.320 | to then, during puberty,

00:17:49.480 | when the penis is exposed to testosterone

00:17:51.680 | and estrogen and DHT, it's a bunch of things,

00:17:54.240 | not just testosterone, the penis grows.

00:17:57.160 | So that- - And lots of other things.

00:17:58.360 | - Right, lots of other things, right?

00:17:59.640 | So the word soup that I just put forward

00:18:04.640 | is basically saying that there are a lot of things

00:18:07.880 | in development where hormones set up a potential

00:18:14.320 | to respond to other hormones later.

00:18:17.080 | It's not that testosterone grows the penis

00:18:18.880 | during development, it does that,

00:18:20.960 | but more so it establishes a potential

00:18:24.040 | for the penis to grow when exposed

00:18:25.960 | to things later during puberty.

00:18:28.240 | Do I have that right? - Right, right.

00:18:29.480 | As far as the name goes, which is the phthalate syndrome,

00:18:32.920 | there is thalidomide.

00:18:34.400 | It's not usually called the thalidomide syndrome,

00:18:36.920 | but it could be, so you're right about that,

00:18:39.800 | but it's extremely rare.

00:18:41.520 | And there's no environmentally, you know,

00:18:45.480 | chemical in the environment as opposed to a pharmaceutical

00:18:49.160 | that is given a syndrome.

00:18:50.680 | So this is very, very unique.

00:18:52.480 | And so I thought, wow, John's telling me

00:18:57.360 | this on the plane, right? (laughs)

00:18:58.960 | - Something in the environment that is basically

00:19:00.800 | having an endocrine and body disruptive effect,

00:19:04.720 | at least on par with fetal alcohol syndrome

00:19:07.600 | and thalidomide syndrome. - Right, exactly.

00:19:09.960 | Right. - Yeah.

00:19:10.800 | So when, well, at this point it was only animals, right?

00:19:14.560 | 'Cause John was telling me about the NTP study,

00:19:17.320 | which was in rats.

00:19:18.680 | And so I thought, wow, you know, I like puzzles.

00:19:23.680 | So my first question was, is this happening in humans?

00:19:28.920 | You might ask that, you know,

00:19:30.360 | as a natural thing to ask. - Great question.

00:19:32.440 | - And then I thought, how would we find out?

00:19:37.120 | And answering that question took me 10 years, okay?

00:19:42.120 | And so if you think about, okay, phthalate in the mother,

00:19:47.800 | changes in the genitals of the offspring, connect them.

00:19:54.760 | How do we do that, right?

00:19:56.520 | So we have to start with phthalates in the mother.

00:19:59.640 | How do we know that?

00:20:01.360 | Well, fortunately or not, (laughs)

00:20:05.120 | I had stored a lot of urine from pregnant women

00:20:10.120 | from a study that I was doing on sperm count.

00:20:13.720 | I just got the women's urine coincidentally, if you will.

00:20:16.840 | I thought, well, save it.

00:20:18.520 | You know, it's not expensive and not hard.

00:20:21.760 | Minus 80 degree freezers, doesn't take a lot of room.

00:20:25.360 | Put it in there.

00:20:26.200 | So I had this urine saved from pregnant women.

00:20:30.440 | And then I knew from John that we could look in the urine

00:20:35.440 | for phthalate metabolites.

00:20:38.160 | So these are products that the body forms

00:20:41.160 | when they're exposed to phthalates

00:20:43.000 | and you can measure them in urine.

00:20:45.240 | So I thought, okay, I could get that urine.

00:20:48.500 | I could look at the phthalate metabolites

00:20:50.560 | and then I'd know what the mother was exposed to.

00:20:53.100 | And based on the animal data, we have good evidence

00:20:58.080 | that it actually makes its way to the fetus.

00:21:01.100 | So then I thought, okay,

00:21:03.960 | then maybe there's a change in the babies.

00:21:08.040 | So then I had to get the babies.

00:21:09.360 | So fortunately, I had done this study on pregnant couples,

00:21:14.360 | pregnant women and their partners,

00:21:17.080 | and I was able to call them and say,

00:21:19.280 | would you come in and let us measure your baby's genitals?

00:21:23.700 | Right?

00:21:25.200 | - How willing were parents to let you do that?

00:21:27.440 | It seems--

00:21:28.280 | - They were okay.

00:21:29.100 | Most of them were okay with that.

00:21:29.940 | - Were they? - Yeah, yeah.

00:21:30.880 | Well, they trusted us.

00:21:32.000 | They had been in a study with us and we were reputable.

00:21:37.000 | - Those babies were still--

00:21:38.960 | - Young, but not newborns.

00:21:40.800 | So this was a while later.

00:21:43.000 | The babies that we actually got were on average,

00:21:45.420 | I think about a month, 12 months old.

00:21:47.640 | So not ideal maybe because the rats

00:21:50.640 | had been measured at birth.

00:21:53.000 | The rat genitals had been,

00:21:54.840 | but that's what we could do at that time.

00:21:57.480 | - Yeah, the reason I ask is there's always the potential

00:21:59.360 | for ongoing phthalate exposure to the newborn.

00:22:02.200 | - Sure, absolutely.

00:22:03.280 | - But I suppose in either case,

00:22:05.780 | you're able to draw some potential link between,

00:22:09.360 | or potentially draw a link,

00:22:10.800 | I have to be careful with my language there,

00:22:12.800 | between phthalate exposure in utero and ex utero

00:22:16.820 | and these external biomarkers.

00:22:18.480 | - I mean, given that the critical window

00:22:20.200 | is quite short and quite early,

00:22:22.560 | by the way, let me just say when the rats,

00:22:24.480 | they did a lot of work on this critical window.

00:22:26.320 | And when the rat moms were exposed before day nine,

00:22:30.220 | it did nothing.

00:22:31.280 | And when they were exposed after day 12, it did nothing.

00:22:35.320 | So it was only the exposure during,

00:22:38.520 | that critical window is very delicate.

00:22:41.440 | And it's by the way, true of the brain as well.

00:22:43.460 | So teasing out what is the critical window

00:22:46.760 | is one of the challenges that we have

00:22:48.540 | when we work with these chemicals.

00:22:50.160 | So I wasn't so much worried about exposure

00:22:53.600 | in the delivery room and in their feed

00:22:57.720 | as in the first year of life,

00:22:59.080 | because I knew that was unlikely to change these measures.

00:23:03.240 | Do other things, but maybe, but not these measures.

00:23:06.160 | So then the question became kind of what you were asking

00:23:08.680 | is what do we measure?

00:23:10.080 | What do we actually measure?

00:23:12.600 | And if you think about a newborn rat or mouse,

00:23:16.440 | their genitals are pretty small.

00:23:18.960 | And there's not, there isn't,

00:23:20.800 | it's very difficult to know exactly how that corresponds

00:23:24.280 | to the human genital system and what you see at birth,

00:23:29.280 | you know, when you spread a boy's legs, right?

00:23:33.580 | And so I got a pediatrician in Los Angeles

00:23:38.840 | who worked with me on how to make that translation

00:23:41.920 | and how to do this exam.

00:23:45.640 | And that took us quite a while

00:23:47.660 | because we really wanted to come as close as we could.

00:23:50.180 | What was clear was that the anus part of it was easy.

00:23:53.240 | You go to the center of the anus.

00:23:54.920 | So that was easy.

00:23:55.960 | Then what's the other landmark?

00:23:58.120 | What's the genital landmark?

00:23:59.680 | So it turns out there are in males too,

00:24:02.680 | and in females there are too as well.

00:24:04.800 | So, but let's just talk about males.

00:24:06.300 | So for males, the best place to measure

00:24:10.100 | and actually closest to the rat measurement

00:24:13.040 | is the place where the tissue changes,

00:24:17.000 | where the scrotum inserts.

00:24:19.600 | And that, it goes from rugator to smooth tissue.

00:24:23.400 | And that point is pretty clear, pretty easy to measure.

00:24:26.300 | The other measure, and that was the inner scrotal distance.

00:24:30.080 | And the other measurement we took

00:24:31.860 | was the anal-penile distance.

00:24:34.280 | And that was the insertion,

00:24:36.040 | the anterior insertion of the penis.

00:24:38.240 | - The part closest to the body.

00:24:40.500 | - Closest to the head, yeah.

00:24:42.080 | - Closest to the head.

00:24:42.920 | - Yeah, and that was not so obvious

00:24:46.920 | because you don't have a change in tissue there.

00:24:48.760 | So where exactly do you put your caliper?

00:24:51.580 | And we had a lot of discussion about, do you press down?

00:24:56.580 | Do you, you know, where exactly do you make that mark?

00:25:02.360 | And actually the inner scrotal is the measurement

00:25:06.600 | with the least variance

00:25:07.680 | because you can measure most precisely.

00:25:09.960 | But the anal-penile is another measurement.

00:25:12.640 | And then you can do something similar in females,

00:25:16.660 | and we did that, but that's,

00:25:18.640 | we maybe don't have to go into that now.

00:25:20.720 | So we designed this exam and we did a lot of work

00:25:25.360 | to make sure it was repeatable across examiners.

00:25:29.040 | And what we finally did was bring the mothers in,

00:25:32.520 | bring the babies in, and got three measurements.

00:25:37.520 | And then on every 10th baby,

00:25:40.860 | we got an independent examiner to get three measurements.

00:25:43.880 | So we could look at within and between examiner variation.

00:25:48.020 | You understand this is the first time

00:25:50.100 | this had been done this way in humans.

00:25:52.220 | There was a Mexican study that tried to do this,

00:25:55.780 | and I never learned very much about it.

00:25:58.340 | And I was excited that they had done this,

00:26:00.620 | but I'm not sure how it relates to this.

00:26:02.500 | So I've just mentioned that out of honesty.

00:26:04.460 | You know, there's somebody in Mexico did this,

00:26:06.680 | but to my knowledge, this is the first time

00:26:10.140 | it was used as a toxicological measure in humans.

00:26:13.880 | Right, so we did that study.

00:26:18.720 | We related those measurements to what CDC had measured

00:26:22.880 | in the urine of our women,

00:26:24.480 | collected while they were pregnant,

00:26:26.240 | and we found the phthalate syndrome.

00:26:29.920 | - Could you explain what the correlation was

00:26:33.480 | between phthalate metabolite levels, which is I believe-

00:26:37.920 | - Not by number, 'cause I don't remember it anymore,

00:26:40.660 | but there was a significant, let's just take the AGD.

00:26:45.220 | The AGD of mothers who had higher levels

00:26:48.700 | of three, the most antiandrogenic phthalates,

00:26:53.620 | I'll tell you what those are in a minute,

00:26:55.420 | had significantly shorter anogenital distance.

00:26:59.900 | And then I have to say that,

00:27:02.260 | which I haven't said and should have,

00:27:04.420 | that anogenital distance is sexually dimorphic.

00:27:06.900 | So it tends to be 50 to 100% longer in males than females.

00:27:11.840 | That makes sense if you think about

00:27:14.260 | what's going in that space.

00:27:16.060 | There's a lot of real estate in males

00:27:20.680 | between the anus and let's say the penis,

00:27:23.920 | penile insertion, much more than in females.

00:27:27.000 | So it's natural that that will be longer,

00:27:29.720 | but I began doing some work looking at other species

00:27:36.080 | and it turns out that that's true

00:27:37.760 | in all mammalian species except two.

00:27:41.720 | And one is the hyena and one is the elephant.

00:27:45.520 | So in the hyena, I'm just saying this

00:27:48.680 | 'cause you're being amused by it, you know about hyenas?

00:27:52.080 | - I do, I know more about hyena genitalia

00:27:55.040 | than I'd like to admit.

00:27:56.520 | And I can tell you why after you educate us,

00:27:59.120 | but I'll keep my explanation brief,

00:28:01.660 | but I'm very familiar with hyena genitalia.

00:28:04.760 | - So I know Stephen Glickman who works with,

00:28:09.760 | you might know him too, he works in Berkeley.

00:28:12.920 | - He was my instructor when I was a graduate student at Cal

00:28:16.800 | and I used to run in Tilden Park,

00:28:18.840 | I suppose I'll tell it now.

00:28:19.760 | And there was a colony of wild hyenas,

00:28:22.440 | but they were behind chain link.

00:28:24.800 | It's actually a favorite hike of mine

00:28:26.520 | up the Strawberry Canyon trail.

00:28:28.400 | And a good friend of mine, Brian Prendergast,

00:28:32.080 | who's now a professor at the University of Chicago,

00:28:33.920 | worked on the prairie voles

00:28:35.200 | that were also housed at that facility.

00:28:37.680 | And a fun thing to do was to go see the hyenas with Steve.

00:28:42.320 | They're brutally dangerous animals.

00:28:47.060 | And Steve has tons of stories about them.

00:28:49.960 | We should probably resist our temptation

00:28:52.360 | to spiral into that.

00:28:54.240 | Maybe sometime I'll do a little like evening chat podcast

00:28:58.520 | where I tell Steve Glickman stories,

00:29:00.260 | he's a delightful person.

00:29:01.440 | And yeah, those, let's just say this,

00:29:04.600 | the female hyenas have clitorises larger

00:29:07.160 | than some of the male hyena penises,

00:29:09.760 | and those females give birth through those clitorises,

00:29:12.600 | as we both know.

00:29:13.440 | - So you will not be surprised to know

00:29:15.960 | that the female HD is longer than the male.

00:29:19.300 | - Right, 'cause they're heavily androgenized.

00:29:21.200 | - Exactly.

00:29:22.040 | - As I recall by androstenedione.

00:29:24.440 | - Actually, I don't know that.

00:29:26.440 | - It became popular during the era of steroids

00:29:29.760 | in professional baseball because androstenedione

00:29:32.420 | was being used pretty frequently in baseball at that time.

00:29:37.420 | Anyway, we have to be, we could go down the spiral of-

00:29:40.240 | - Yeah, yeah.

00:29:41.760 | But also in terms of behavior, the female is the alpha.

00:29:45.960 | - Right.

00:29:46.800 | - Right.

00:29:47.640 | - They eat first.

00:29:48.460 | - Yes.

00:29:49.300 | - They're physically and hierarchically dominant

00:29:53.480 | in hyenas.

00:29:54.320 | - So it's really interesting, isn't it?

00:29:57.060 | That they would have a longer, more masculine

00:30:00.780 | intergenital distance.

00:30:02.280 | Elephants, we won't go into now,

00:30:03.760 | but they're kind of midway in many things.

00:30:06.540 | So including, they're about equal intergenital distance

00:30:10.260 | in males and females.

00:30:11.540 | Other than that, humans and other species,

00:30:15.640 | male intergenital distance is 50 to 100% longer.

00:30:18.880 | However, so three phthalates, diethylhexyl phthalate, DEHP,

00:30:25.300 | dibutyl phthalate, DBP, and butylbenzyl phthalate, BBZP,

00:30:30.300 | are the most antiandrogenic testosterone-lowering phthalates.

00:30:36.860 | And those are the ones that were associated

00:30:40.860 | with a shorter intergenital distance in males.

00:30:45.340 | - In human males.

00:30:46.660 | - Human males and animal.

00:30:49.060 | So we replicated that animal study in humans.

00:30:54.040 | And then, because you know this is how it is in science,

00:30:57.100 | I had to do it all again, right?

00:30:58.740 | So I started a whole new study,

00:31:02.220 | and that study is still going on.

00:31:07.100 | The children are still being followed.

00:31:09.060 | I think we started in 2012.

00:31:12.900 | The first paper on intergenital distance came out in 2005,

00:31:18.660 | had a pretty big impact.

00:31:21.860 | - So these are studies where you're looking

00:31:25.080 | at the intergenital distance in relatively newborn humans,

00:31:30.080 | then tracking that distance.

00:31:32.680 | - No, that's a different, tracking is another study.

00:31:35.080 | This is just two studies

00:31:36.760 | on demonstrating the Thaller syndrome in human males.

00:31:41.760 | So the first one I described,

00:31:43.560 | the second one the replication,

00:31:45.120 | and the second one is the one that's going on still.

00:31:47.720 | So, and what it does to their reproductive function,

00:31:52.100 | we don't know, the kids are only 12 years old now.

00:31:53.980 | So we would like to know that, and we will know that.

00:31:58.060 | Okay, but I have another answer for you about that.

00:32:01.420 | So we started the second study,

00:32:03.740 | and the second study, which is called TIDES,

00:32:06.660 | which is the Infant Development Environment Study.

00:32:10.220 | By the way, these are both in four cities

00:32:11.820 | in the United States.

00:32:13.940 | And there we did it right.

00:32:18.680 | So we got the urine in the first, early urine,

00:32:23.200 | 'cause we knew that could be important.

00:32:24.480 | We didn't have that option in the first one.

00:32:26.560 | Remember, those urine samples were accidental.

00:32:28.760 | We got them when we could, right?

00:32:30.640 | And we got repeated urines, one in each trimester,

00:32:34.700 | to look at the effects in different trimesters.

00:32:37.600 | And then we examined the babies at birth,

00:32:40.140 | which is what the rats,

00:32:42.040 | so we came much closer to replicating the rodent study.

00:32:46.780 | And we saw it again.

00:32:48.260 | - I'd like to take a quick break,

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00:34:20.940 | - More phthalate exposure equates

00:34:23.460 | to shorter anal genital distance in males.

00:34:27.620 | It was approaching the distribution in females.

00:34:31.380 | It sounds like the distributions

00:34:34.460 | moved more closely together.

00:34:35.660 | - Yes, yes. - Right.

00:34:37.460 | - Although it wasn't the females that moved.

00:34:39.180 | - Sorry, the male distribution-

00:34:41.180 | - Became more like the female.

00:34:42.260 | - Became more- - Right, feminized.

00:34:44.100 | - I could say feminized, but more female-like in its-

00:34:46.340 | - And they, but these boys also had smaller penises,

00:34:49.280 | less descent of the testes, smaller scrotums.

00:34:53.580 | So they were smaller, you know,

00:34:55.380 | everything was in their genital areas.

00:34:57.340 | - All the secondary sex characteristics

00:34:59.420 | of puberty in males, Adam's apple, facial hair growth,

00:35:03.500 | thickening of the vocal cords,

00:35:04.580 | therefore lowering the voice, et cetera,

00:35:06.540 | are those all later activating effects of hormones

00:35:11.060 | or are there precursors to those that are present in males?

00:35:15.820 | Because in mice, as I recall,

00:35:18.540 | like I couldn't tell you,

00:35:23.700 | like we call it in the laboratory,

00:35:25.160 | people always chuckle at this,

00:35:26.060 | but it's like sexing the animals when you, you know,

00:35:29.420 | look to determine if it's a male or female.

00:35:31.020 | When they're really young,

00:35:32.340 | you have to like look carefully at first, right?

00:35:34.820 | And then you get pretty good at it.

00:35:37.020 | As they get older, it gets easier.

00:35:38.700 | But when the mice are, you know,

00:35:43.220 | feet down, back up, you know,

00:35:45.220 | you can't really, you can't really tell.

00:35:47.660 | You can't really tell.

00:35:49.500 | As the mice get older,

00:35:50.340 | their testicles become visible in the males from,

00:35:52.940 | even from above.

00:35:54.260 | But, you know, as far as I know,

00:35:55.900 | there aren't really external markers.

00:35:57.260 | So you may have found the one truly external biomarker

00:36:00.940 | of maleness.

00:36:02.060 | And, and so I do want to say one thing about females,

00:36:06.100 | 'cause then that'll lead me to my conclusion

00:36:08.240 | about the role of this measure.

00:36:11.420 | So if the mother is exposed

00:36:16.340 | to more testosterone than expected,

00:36:19.720 | you might expect that her female offspring

00:36:25.380 | would have a more male in a genital distance.

00:36:27.900 | - Is that the case?

00:36:28.820 | - Yes.

00:36:29.820 | - So it's a bi-directional effect.

00:36:30.940 | - Yes.

00:36:31.820 | - Can we also presume that if the mother either secretes

00:36:34.820 | or is exposed to more androgen,

00:36:36.900 | then the males can become hyper male?

00:36:39.620 | - No.

00:36:40.460 | We'd never, I don't know what that would be.

00:36:42.020 | We never saw anything that would be hyper male.

00:36:44.780 | So the yes I said to you was the result of a study

00:36:51.220 | where we looked at the girls born to women with PCOS.

00:36:56.620 | So women with PCOS, as you know,

00:36:58.780 | have excess testosterone.

00:37:00.420 | - Polycystic ovarian syndrome.

00:37:02.900 | We've talked about it a little bit before in the podcast.

00:37:06.340 | It's associated with, my understanding is it's associated

00:37:10.420 | with elevated levels of androgens.

00:37:12.780 | - That's right.

00:37:14.700 | And these women often have facial hair and you know.

00:37:18.260 | - Not just the moms, but the people,

00:37:20.620 | the women with PCOS have elevated androgens.

00:37:24.460 | - Yes.

00:37:25.300 | - Not just, we're not talking about pregnant moms.

00:37:27.260 | - Exactly.

00:37:29.100 | And so in our study, Population,

00:37:31.380 | we did a search for women who had diagnosis of PCOS

00:37:35.140 | and took that as a marker of higher testosterone exposure

00:37:38.380 | and then looked at the girls.

00:37:39.740 | And yes, those girls had a longer quote,

00:37:42.940 | more masculine intergenital distance.

00:37:45.180 | - What age group were you looking at?

00:37:46.980 | - In the infants, in the infants.

00:37:49.020 | Oh, the PCOS was at pregnancy.

00:37:53.420 | At the time they were pregnant.

00:37:54.540 | - So presumably people between their like,

00:37:56.980 | somewhere in their twenties out to their forties.

00:37:58.620 | - Yeah, yeah.

00:37:59.460 | - So adult human females who have PCOS tend to,

00:38:04.460 | we know they have higher levels of androgens,

00:38:07.140 | but they also have more male like in a genital distance.

00:38:11.540 | - They do not, their daughters do.

00:38:13.380 | - Their daughters do.

00:38:14.380 | Thank you for that clarification.

00:38:15.900 | - Their daughters, and so put this together,

00:38:20.000 | this measure is a look inside the womb.

00:38:26.700 | At the androgen level that the fetus is exposed to

00:38:30.020 | at that time, which is amazing

00:38:32.700 | because you can't go in there without disturbing,

00:38:36.500 | you know, you can't.

00:38:37.700 | And so this is very early first trimester,

00:38:42.180 | you can't even get, you know, fluid and so on.

00:38:44.840 | So this tells you, this is like a readout

00:38:48.300 | of what was in, you know, in the fluid at the time.

00:38:53.700 | So then your next question was,

00:38:58.700 | what does this mean for later fertility?

00:39:03.300 | Yes?

00:39:04.140 | - Yeah, what is the impact of this early androgen exposure

00:39:08.500 | to female offspring, or let's just say reduction

00:39:13.500 | in functional androgen exposure to male offspring?

00:39:18.480 | The reason I'm using these, you know, loop-de-loop languages

00:39:21.820 | as you probably know, but for the audience,

00:39:24.420 | not trying to complicate things here,

00:39:25.860 | but a lot of the masculinizing effects of hormones

00:39:29.740 | in fetal development is actually testosterone

00:39:32.500 | that's converted into estrogen.

00:39:33.980 | So it can get pretty tricky.

00:39:35.340 | - Right.

00:39:36.180 | - And, but maybe for sake of simplicity today,

00:39:39.420 | we'll just stick with androgen effects on masculinization

00:39:43.620 | with the understanding that some of those effects

00:39:46.660 | are the consequence of testosterone

00:39:48.820 | being converted into estrogen.

00:39:50.380 | - Right.

00:39:51.220 | - And that people form such strong associations falsely

00:39:54.340 | that, you know, testosterone is male, maleness,

00:39:57.500 | and that's not true, and estrogen is femaleness,

00:40:00.720 | and they both, and it just gets really murky.

00:40:02.700 | But for the time being,

00:40:04.540 | you identified an external biomarker of fetal androgen,

00:40:11.740 | AKA masculinization via the mother.

00:40:16.660 | - That's right.

00:40:17.640 | - Got it.

00:40:18.880 | - So then we asked the question you've asked,

00:40:23.320 | and many people asked, who cares?

00:40:26.200 | Why would we worry about a boy

00:40:31.800 | having a slightly smaller anogenital distance?

00:40:35.360 | - Well, I can tell you, there are many boys

00:40:36.560 | that are probably worried about it right now.

00:40:38.180 | - Right, right.

00:40:39.020 | (both laughing)

00:40:40.040 | - They've probably got the ruler

00:40:40.880 | and the calipers out right now, which is, you know.

00:40:43.900 | - But I'm gonna answer that question.

00:40:46.200 | - Right.

00:40:47.800 | So I told you that our kids are too young.

00:40:50.720 | They're not producing sperm right now, right?

00:40:53.280 | So we had to go to an adult population, right?

00:40:58.000 | And so we went to a population of college students

00:41:02.140 | in Rochester, New York.

00:41:03.600 | And what we did there was make an assumption,

00:41:09.600 | which is based on animal data.

00:41:12.840 | It's true in animals.

00:41:13.880 | We've been following the animal path here all along.

00:41:15.840 | So in the animals, my colleague, Earl Gray,

00:41:19.360 | who did these studies.

00:41:20.880 | - His name is Earl Gray?

00:41:22.000 | - Yeah.

00:41:22.840 | - That's cool.

00:41:23.660 | - He said AGD is forever.

00:41:28.960 | - Anogenital distance is forever.

00:41:31.520 | - Now what that means is it's not like

00:41:33.700 | your anogenital distance today

00:41:35.480 | is what it was when you were born.

00:41:36.760 | Of course, you're a bigger person,

00:41:38.400 | but that means adjusted for body size, right?

00:41:41.320 | So if you assume that AGD is forever,

00:41:43.560 | if you're born with a short for your size AGD,

00:41:47.520 | then when you're 20, you'll have a short for your size AGD.

00:41:51.400 | Okay?

00:41:52.320 | Can we assume that?

00:41:53.360 | Okay.

00:41:54.200 | So if we assume that,

00:41:55.640 | then if we get these college students to come in

00:41:59.660 | and we can measure their anogenital distance,

00:42:01.920 | we're getting a reflection

00:42:04.000 | of what it was when they were born.

00:42:06.400 | Okay?

00:42:07.240 | And then we can get their sperm count.

00:42:09.440 | And then we can see if they're related.

00:42:13.280 | And that's what we did.

00:42:15.120 | So we got this population of volunteers,

00:42:19.080 | paid them $75.

00:42:20.440 | And one of the guys said,

00:42:21.880 | "For 75 bucks, you can do anything."

00:42:24.080 | (laughing)

00:42:25.680 | And so what we did was

00:42:26.760 | we measured their anogenital distance,

00:42:29.320 | and then we got them to give a semen sample

00:42:32.760 | and complete a questionnaire and things you do in a study.

00:42:36.260 | - We'll link to that study,

00:42:37.320 | but I have a couple of questions

00:42:38.400 | about the controls in that study,

00:42:40.240 | just for sake of people understanding

00:42:41.800 | how a study like this would be done.

00:42:44.040 | I don't expect you to recall all the details,

00:42:46.880 | but you're adjusting for body size and body weight,

00:42:50.440 | height, weight.

00:42:51.800 | What are the factors that would scale here

00:42:53.960 | that would allow you to normalize?

00:42:55.800 | In other words, what you're trying to do

00:42:58.120 | is backtrack to what it likely was at infancy.

00:43:01.040 | - No, we didn't actually try to go back.

00:43:03.480 | Let me just tell you what the results were.

00:43:06.040 | In this group of men,

00:43:08.300 | if they had a longer anogenital distance,

00:43:12.220 | they had a higher sperm count.

00:43:13.720 | - Got it, so you were correlating those two measures.

00:43:17.180 | - Right, and then if we wanted to say something about,

00:43:20.940 | we didn't try to say anything

00:43:22.060 | about how it was when they were born.

00:43:23.380 | We just said, "Okay, we'll take that assumption

00:43:26.580 | "that this reflects their early AGD."

00:43:29.820 | If we wanna say something about early AGD and sperm count.

00:43:34.100 | So it's easy to say AGD is related to sperm count

00:43:37.580 | because we measured that, we saw that.

00:43:39.740 | A correlation, that's published.

00:43:42.140 | Okay, if we wanna say their early AGD at birth

00:43:46.180 | and their sperm count,

00:43:47.300 | that's a leap of faith in some sense

00:43:50.100 | because we don't have their early.

00:43:52.740 | For these guys in Rochester,

00:43:54.220 | we didn't measure their AGD at birth.

00:43:56.620 | - Were there any conditions of being a participant

00:43:59.140 | in the study such as refraining from alcohol,

00:44:02.060 | cannabis, et cetera, in the 90 days prior,

00:44:04.280 | 90 days being the duration of a spermatogenesis?

00:44:08.360 | - Yeah, I don't remember that.

00:44:09.280 | - These are college students,

00:44:10.160 | so presumably some of them are drinking, okay.

00:44:12.680 | But in the end, it was a robust link.

00:44:16.780 | - And then Mike Eisenberg, who you might know at Stanford.

00:44:19.600 | - Yeah, my colleague at Stanford.

00:44:20.440 | He's been on this podcast.

00:44:21.600 | - Yeah, good, good.

00:44:23.080 | So he's a colleague of mine too.

00:44:24.480 | And he looked at men in a fertility clinic

00:44:29.480 | and those who had born children

00:44:31.640 | and those who had not born children.

00:44:33.820 | And the men who had born children

00:44:35.520 | had a longer in a general distance

00:44:37.840 | than men who had never born a child.

00:44:39.580 | - Never born, but were trying.

00:44:41.080 | - Yes. - Right.

00:44:42.400 | These were not people who opted out.

00:44:44.200 | - Right, exactly.

00:44:45.400 | - These were people who were having challenges

00:44:47.940 | with fertility versus success with fertility.

00:44:50.960 | - And by the way, you know,

00:44:52.760 | the question of how you measure AGD in an adult man

00:44:56.280 | is a different question

00:44:57.360 | than how you measure it in a newborn.

00:44:59.680 | And we did a lot of work on that.

00:45:01.140 | And Mike will help with that too.

00:45:02.920 | So it sounds like, oh, and may I ask,

00:45:06.040 | were the sperm counts that were on the,

00:45:08.640 | let's just say the lower, like the lower quartile,

00:45:13.640 | were the quote unquote lower sperm counts

00:45:17.240 | like functionally lower?

00:45:18.720 | 'Cause I always wonder about this.

00:45:19.920 | Like it's come up in a number of discussions

00:45:22.120 | like with Robert Sapolsky, with Mike Eisenberg.

00:45:24.200 | And now I'm asking you,

00:45:25.360 | and when we hear that sperm counts are going down,

00:45:28.280 | are they going down to the point

00:45:29.480 | where fertility is impacted?

00:45:31.720 | That's really one of the, I think, functional questions.

00:45:35.360 | - So I'm gonna, let's lay aside the question of AGD, right?

00:45:40.200 | That's really interesting,

00:45:42.200 | but let's talk about sperm count.

00:45:44.000 | Okay, so there's a beautiful study

00:45:50.480 | among pregnancy planners out of Denmark

00:45:56.480 | quite a long time ago.

00:45:59.680 | And in that study, what they did was take couples

00:46:04.160 | that were trying to conceive that had never,

00:46:08.480 | or not recently, I can't remember,

00:46:09.880 | used oral contraceptives.

00:46:11.920 | And then they saw what the sperm count was

00:46:16.080 | and how long it took them to conceive, right?

00:46:18.480 | Time to pregnancy in relation to, so.

00:46:21.320 | And what they showed is a really interesting curve,

00:46:25.160 | which has never been corrected to my knowledge.

00:46:28.440 | It's what I use and what I think people use,

00:46:31.120 | which is that if you, I wish I could draw it here,

00:46:33.920 | I wish I had a black, you should have a board,

00:46:35.360 | a whiteboard. (laughs)

00:46:36.200 | - The problem is a lot of people are listening,

00:46:37.320 | but maybe we can talk people through it.

00:46:39.680 | - Yeah, yeah. - Sorry.

00:46:40.680 | - So just think about a curve

00:46:43.160 | where you go all the way down to zero,

00:46:45.120 | that would be no sperm.

00:46:46.920 | And then as the probability of conceiving is zero,

00:46:52.800 | so you're looking at sperm count along the X-axis

00:46:56.600 | and months to conception.

00:46:59.440 | And what you see is that if you have no sperm,

00:47:03.680 | you don't have no conception.

00:47:04.840 | If you go up to around 40, 45, there's a steep increase.

00:47:09.400 | So the more sperm you have-

00:47:11.040 | - 40, 45 million?

00:47:13.400 | - Million per milliliter.

00:47:14.520 | - And this is million per milliliter,

00:47:16.960 | so just pure concentration, not number of motile sperm.

00:47:19.600 | This is just how many sperm?

00:47:21.000 | We're not talking about quality.

00:47:22.000 | We're just talking about number.

00:47:22.840 | - No, no, no, just the number.

00:47:23.800 | And when you have 45 to 50 million per milliliter

00:47:27.280 | and below, it matters a lot what your sperm count is.

00:47:31.840 | I mean, people say it doesn't matter.

00:47:33.440 | Yeah, if you get in this range

00:47:35.400 | where the probability of conception

00:47:36.880 | is dropping off really rapidly, it matters a lot.

00:47:40.560 | And then around 45 to 50, it starts to level off.

00:47:44.520 | And then after that, certainly after 100, probably 75,

00:47:49.080 | it doesn't matter at all.

00:47:50.680 | - So 100 million sperm per milliliter of semen.

00:47:55.680 | - Yes.

00:47:57.400 | So can you see this?

00:47:58.720 | Okay, so when people say,

00:48:01.200 | "Does sperm count matter for fertility?"

00:48:03.960 | Yes, it matters a lot if it's low,

00:48:06.840 | and no, it doesn't matter at all if it's high.

00:48:10.600 | So we just have too many sperm.

00:48:13.000 | I mean, I don't, but humans, you know.

00:48:15.880 | - So nature runs a probability game, overproduced sperm.

00:48:19.520 | - Right.

00:48:20.600 | - Some of those will be high quality,

00:48:21.840 | some will be low quality. - Exactly.

00:48:22.880 | - Depending on their age, that is when they were generated.

00:48:26.280 | - Or their conditions, you know.

00:48:27.520 | - Or their conditions, how much heat exposure, et cetera.

00:48:29.960 | So nature runs a probability game.

00:48:31.600 | - That's right.

00:48:32.440 | - Hoping that the best quality sperm

00:48:36.360 | will fertilize the egg.

00:48:39.160 | - Right.

00:48:40.480 | - So below 45,000, excuse me, below 45 million.

00:48:45.480 | - Million per milliliter.

00:48:46.560 | - Below 45 million sperm per milliliter of semen,

00:48:50.320 | the sperm count really matters.

00:48:51.800 | It drops off precipitously.

00:48:53.360 | - That's right.

00:48:54.200 | - Once you get up to 75, 100 million per milliliter of sperm,

00:48:58.480 | then- - It's all good.

00:48:59.840 | You're good to go.

00:49:00.680 | - Right, and sperm counts range anywhere from,

00:49:04.920 | you know, it could be low eight, nine,

00:49:07.640 | 10 million per milliliter in the very low situation.

00:49:10.400 | - It could be zero.

00:49:11.240 | - It could be zero in some people, right?

00:49:12.560 | All the way up to 400 million.

00:49:15.080 | There's a huge range.

00:49:16.160 | - That's right.

00:49:17.000 | - And that's a function of age,

00:49:17.920 | it's a function of genetics,

00:49:19.080 | it's a function of presumably phthalate exposure, right?

00:49:22.880 | - Yeah.

00:49:24.080 | - I'd like to take a quick break

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00:51:11.160 | We were on to the fact that sperm counts are dropping.

00:51:13.480 | There's a relationship to anogenital distance,

00:51:15.560 | and there's a relationship between anogenital distance

00:51:17.840 | and phthalate exposure.

00:51:19.480 | And then I asked the question,

00:51:21.720 | you know, okay, we're hearing about sperm counts dropping,

00:51:24.200 | but is it functionally relevant?

00:51:26.360 | Is that one of the reasons why fertility is dropping?

00:51:29.760 | And we've also got the female side

00:51:31.120 | where we've got women with elevated androgens.

00:51:34.920 | So we can talk about that a little bit later.

00:51:36.440 | But, and then of course we have the socio,

00:51:40.160 | the sociobiology piece where people are opting out,

00:51:45.160 | or it's also economics in some cases,

00:51:49.400 | opting out of having kids.

00:51:51.400 | - Right, so let's go back to sperm count,

00:51:53.320 | 'cause we haven't really talked about that.

00:51:55.120 | It's a kind of a different path.

00:51:57.160 | And my introduction into phthalates

00:51:59.320 | was not through sperm count, right?

00:52:01.920 | It was through this question of my colleague asking me,

00:52:04.800 | you know, you should look at this, I'm challenged.

00:52:06.520 | And I looked at it,

00:52:07.360 | and that was really, really interesting journey

00:52:09.880 | that I went on, okay?

00:52:11.080 | So that, but there was a separate for a while journey

00:52:15.920 | that I was on, and that started in the late 1990s

00:52:20.040 | when I was asked to join a committee

00:52:24.240 | of the National Academy of Sciences.

00:52:26.280 | And that committee was assembled to look at the question

00:52:32.520 | of whether hormonally active chemicals,

00:52:36.600 | endocrine disrupting chemicals in the environment

00:52:39.800 | posed a threat to human health.

00:52:41.560 | Because at that time, it was like,

00:52:44.520 | well, yeah, we hear about this, but should we care, right?

00:52:48.160 | And so that committee wanted to consider a study

00:52:53.160 | that had come out of Denmark a few years earlier,

00:52:58.440 | which claimed that sperm count

00:53:01.080 | had dropped 50% in 50 years.

00:53:04.000 | - Wow, that's a huge drop.

00:53:07.480 | - That's what, we're seeing worse than that,

00:53:09.320 | by the way, now, so, okay.

00:53:11.800 | They said to me, I was the only statistician on the panel,

00:53:14.840 | would you look at this and see if we need to consider this

00:53:18.040 | in our deliberations?

00:53:20.480 | And as I mentioned, I'm skeptical, and I looked at it,

00:53:24.160 | and I thought, eh, I don't think so.

00:53:27.440 | That was my initial reaction.

00:53:28.880 | And that was because, first of all,

00:53:32.080 | I didn't know who had written this.

00:53:33.840 | I just saw it in a journal, and it was not very big

00:53:37.800 | and not very many figures, not very much data.

00:53:41.600 | And I thought of it, and I thought,

00:53:43.240 | that's a big claim for a little paper, you know?

00:53:47.560 | But I'll look at it, 'cause it's important.

00:53:51.360 | And so what I did then was to think about all the factors

00:53:56.360 | that we epidemiologists call confounders,

00:54:01.160 | things that might have caused that decline

00:54:04.620 | if it wasn't real biologically, right?

00:54:08.220 | And so we could think of some of them together.

00:54:11.480 | You know, maybe the method of counting sperm had changed

00:54:15.320 | so that later methods counted fewer sperm

00:54:18.340 | in the same sample.

00:54:19.640 | That's certainly possible, right?

00:54:21.660 | But it turned out that wasn't the case,

00:54:24.600 | 'cause they actually had all used the same method.

00:54:27.900 | And maybe the men had changed, so maybe there's,

00:54:31.420 | you can't get a sperm count at random.

00:54:33.460 | You have to get somebody to volunteer, right?

00:54:36.020 | So who were these men?

00:54:37.100 | Were they very different, you know,

00:54:38.940 | in the early part of the study,

00:54:40.140 | in the late part of the study,

00:54:41.080 | in a way that maybe in the late part of the study,

00:54:43.500 | there were men with lower sperm count,

00:54:45.780 | and they were more concerned, you know?

00:54:47.740 | Maybe they were more obese.

00:54:51.460 | That's pretty plausible.

00:54:52.620 | Obesity is related to sperm count, fertility.

00:54:56.680 | And maybe they smoked more, and maybe,

00:55:00.060 | and so on and so forth, right?

00:55:01.660 | So what I did was to get the 61 studies,

00:55:06.660 | go through them, and try to extract information

00:55:10.820 | on all the factors that could explain the decline.

00:55:13.960 | So I created a multivariable model and ran that model.

00:55:19.760 | And to my astonishment, when I was done,

00:55:25.980 | the slope of the decline was exactly the same

00:55:30.420 | to the first decimal place.

00:55:32.080 | It had not explained anything.

00:55:37.140 | I was like, "Oh my God, this looks like it might be real."

00:55:42.140 | - And for those listening, what Dr. Swan is describing

00:55:44.940 | is being the excellent scientist that she is,

00:55:48.500 | she went and looked for all the things

00:55:50.620 | that could impact the result that were not related

00:55:54.680 | to what the main conclusion seemed to be,

00:55:58.120 | which is that sperm counts were going down over time, right?

00:56:02.000 | And this is really important because I think

00:56:05.620 | what we're talking about here in parallel

00:56:07.180 | to the main conversation is how to do really great science,

00:56:10.140 | especially in human populations that are out there living.

00:56:14.620 | Some of these men probably smoke some cannabis.

00:56:17.820 | I'm not saying that reduces sperm count.

00:56:19.180 | It might reduce sperm motility, however.

00:56:21.820 | We covered that in the podcast.

00:56:23.060 | Now that all the cannabis folks go,

00:56:24.540 | well, so-and-so got so-and-so pregnant

00:56:27.620 | when they were doing a lot of weed.

00:56:29.240 | And I always say, okay,

00:56:30.080 | well, there are a number of other factors, right?

00:56:32.740 | But alcohol, there's frequency of ejaculation, right?

00:56:37.120 | The requirement to abstain for 48 to 72 hours

00:56:41.280 | to up to five days prior, et cetera.

00:56:44.020 | All these factors that men may or may not faithfully report,

00:56:48.480 | but you assume that if some are telling the truth

00:56:50.880 | and some aren't, that there's an equal distribution of that.

00:56:53.220 | So all the different things, right?

00:56:55.500 | This is so very different than looking at, for instance,

00:56:58.520 | ovarian reserve, like the number of eggs,

00:57:03.220 | where you use ultrasound and you use AMH levels.

00:57:05.960 | And sure, things can impact that,

00:57:08.620 | but it's a little different

00:57:10.140 | than when we're taking sperm counts.

00:57:12.860 | So thank you for doing the studies so carefully

00:57:15.220 | and for repeating them so many times.

00:57:17.280 | I mean, many of the studies that you've done

00:57:18.740 | are you've done follow-up on the sperm count studies

00:57:23.740 | across multiple years.

00:57:25.220 | As you said, the first study was in 1992,

00:57:27.620 | then you did one in 2017, then there was one again,

00:57:29.820 | and there was an update I noticed online.

00:57:31.700 | So you are extremely thorough,

00:57:34.500 | and it probably reflects your early training

00:57:37.820 | in math and statistics and probability theory.

00:57:40.740 | You're not somebody to just kind of go in and go,

00:57:42.660 | oh yeah, like in these people

00:57:43.740 | that eat a few too much of this,

00:57:45.140 | then there's a little bit less of that.

00:57:47.180 | So I just wanted, if today's discussion feels like

00:57:49.740 | we're really, we're lathing through this,

00:57:54.220 | that's intentional.

00:57:55.300 | And it's important for people to hear

00:57:58.020 | these kinds of claims are not the sort of thing

00:58:00.180 | that you could, people would make them all over the board,

00:58:03.340 | but work like this needs to be done

00:58:05.300 | with an extremely meticulous eye

00:58:08.660 | and consideration of all the variables.

00:58:10.300 | - Well, good scientific method, yeah.

00:58:12.180 | - Yeah, and I would say,

00:58:13.060 | especially with human epidemiological work,

00:58:15.860 | because of the number of potential confounding variables.

00:58:19.220 | - So when I saw that,

00:58:22.020 | and actually did another study to select my own studies

00:58:26.940 | and not accept her 61 studies that had been published,

00:58:29.700 | that Elizabeth Carlson had published.

00:58:33.020 | So new studies, came up to more recent times,

00:58:36.180 | went back further, did it again,

00:58:38.580 | found exactly the same thing.

00:58:39.980 | Okay, so there were three looks at that,

00:58:42.580 | and I thought, okay, I'm gonna accept this now.

00:58:44.840 | This is, sperm count is declining.

00:58:47.040 | And why?

00:58:50.900 | That turned to the why.

00:58:52.380 | Okay, because up and down now,

00:58:53.940 | we hadn't said anything about why.

00:58:55.220 | We just said, is it doing that?

00:58:57.220 | Yes, okay, now we believe it is declining, why?

00:59:01.620 | And so then I thought quite a lot and talked to people

00:59:04.740 | and ruled out genetics because it was too fast.

00:59:07.580 | It's two generations, it's too fast.

00:59:10.140 | 50 years, two generations.

00:59:11.660 | So if it's not genetics, then it's environment.

00:59:14.620 | And so what is it about the environment that could do this?

00:59:19.020 | So I asked, okay, in the environment,

00:59:23.880 | there could be things that are making sperm decline.

00:59:28.500 | So if you think about how you might look at that,

00:59:32.300 | you might design the study that I designed next,

00:59:34.340 | which was another study.

00:59:36.280 | And by the way, this preceded the AGD.

00:59:40.340 | So we had four cities in the United States

00:59:42.880 | that we picked with different environments.

00:59:45.020 | And then we got men to come in

00:59:47.380 | and we used the same equipment at each place.

00:59:51.680 | We used the same method of selecting the men.

00:59:55.620 | The technicians were trained centrally at UC Davis.

00:59:59.700 | We had very good quality control,

01:00:01.300 | so samples were sent around every quarter

01:00:03.960 | to make sure that everybody was measuring things

01:00:06.020 | the same way.

01:00:07.700 | We didn't want drift, right?

01:00:09.860 | And then we got their urine.

01:00:12.940 | And that's how I had those urine samples.

01:00:14.820 | So if you wanted to do this study

01:00:17.180 | and you wanted to get a representative sample of men,

01:00:19.820 | where would you go?

01:00:22.740 | Because I can't ask a guy in the street

01:00:25.300 | to give me a semen sample right now.

01:00:27.340 | It's not something you'd get very, you know.

01:00:29.860 | So I thought, how can I get a representative sample

01:00:33.740 | and which would teach me something

01:00:36.140 | about a larger population called the parent population?

01:00:39.060 | So here's a sample, it should represent the parent.

01:00:41.240 | So how do I ensure that?

01:00:43.340 | And what I decided was to sample partners of pregnant women

01:00:47.780 | because pregnant women all come to medical care, almost all.

01:00:52.460 | And if their partners will give a semen sample,

01:00:55.580 | then we have a representative sample

01:00:57.940 | and we know what we're looking at.

01:00:59.300 | So that's what we did.

01:01:00.500 | So this is the semen study

01:01:03.140 | is the study of partners of pregnant women.

01:01:06.660 | And of course, they'll have slightly higher semen quality

01:01:10.000 | 'cause they got their partner pregnant.

01:01:11.460 | But, and so we had their urine, we had their blood

01:01:16.460 | and we looked at their semen quality

01:01:22.580 | and then we decided to look at pesticides.

01:01:26.380 | And the reason we look at pesticides

01:01:28.300 | was because there was a lot of gradation

01:01:32.100 | across our four centers and pesticide use.

01:01:34.860 | And what we found was really extraordinary

01:01:38.800 | that men who were living in Central Missouri,

01:01:41.300 | where I was living at the time,

01:01:43.580 | who were in the middle of a agricultural belt

01:01:47.020 | where there was spraying all the time

01:01:48.860 | for soybeans and so on.

01:01:50.880 | Those men had half as many moving sperm

01:01:56.660 | as men in Minneapolis.

01:01:58.460 | - Whoa.

01:02:00.580 | - Whoa, huge, right?

01:02:04.540 | And then we went one step further and within Missouri,

01:02:09.580 | we looked at a sample of men

01:02:11.620 | who had very high sperm parameters

01:02:15.180 | and very low sperm parameters

01:02:16.980 | and showed that five pesticides were significantly higher

01:02:21.100 | in the men with the low sperm parameters.

01:02:23.660 | That include motility, morphology, all the parameters.

01:02:26.660 | - So these are pesticides

01:02:27.700 | that are being sprayed in the air on crops.

01:02:29.580 | You mentioned soybeans, what other types of crops?

01:02:32.660 | - I don't know.

01:02:33.660 | - Okay.

01:02:34.500 | - I don't remember.

01:02:35.820 | - So plant and fruit crops, presumably.

01:02:38.620 | - Yeah, whatever they were growing

01:02:40.780 | in Columbia, Missouri at that time.

01:02:42.740 | - And just to make sure I understand,

01:02:46.420 | it's not that the men eat--

01:02:47.260 | - Soybeans, corn and soybeans.

01:02:48.540 | - Corn and soybeans.

01:02:49.380 | But we're not talking about eating corn and soybeans.

01:02:51.660 | We're talking about living in an area

01:02:53.300 | where pesticides are being used

01:02:55.580 | by, is it still called dust crop?

01:02:58.640 | - Yeah, we didn't go into how they got these.

01:03:01.000 | We just looked in their urine and there were the metabolites.

01:03:03.740 | The metabolites don't get in their urine

01:03:05.740 | unless they were exposed.

01:03:07.140 | - Exposed through the air or exposed

01:03:08.780 | by eating corn and soybeans?

01:03:09.620 | - Don't know.

01:03:10.460 | - We don't know.

01:03:11.280 | - We don't know.

01:03:12.120 | - Okay.

01:03:12.960 | - We don't know.

01:03:13.780 | But this was not a particularly,

01:03:15.340 | you know, we didn't sample farmers only

01:03:17.660 | or anything like that.

01:03:18.500 | So whoever came into the,

01:03:20.900 | you remember how we got these men?

01:03:22.460 | Their wives were pregnant.

01:03:23.780 | They were having prenatal care

01:03:25.360 | at the University of Missouri.

01:03:27.260 | So that's where we got them.

01:03:28.420 | Whoever happened to come in to the prenatal clinic

01:03:31.260 | and agreed to be in our study,

01:03:33.060 | their, the male, you know, urine,

01:03:36.420 | male's urine was measured for these pesticides.

01:03:39.360 | - I'm sure a number of people,

01:03:40.820 | including myself are wondering,

01:03:42.840 | in what other products are these five pesticides present?

01:03:48.980 | Are these commonly used pesticides

01:03:53.180 | or is it something about-

01:03:54.620 | - They're called the triazine pesticides.

01:03:57.060 | Atrazine was the most widely used

01:03:59.180 | and it's a huge use around the world.

01:04:02.380 | I mean, it's highly, you know,

01:04:04.380 | one of the most, the largest commercial pesticides.

01:04:07.780 | So these were very big players in the pesticide field.

01:04:11.340 | - A relevant theme there would be,

01:04:14.020 | maybe we could take a moment and talk about atrazine

01:04:16.420 | and its effect on male sexual behavior in amphibia.

01:04:21.180 | And we'll come back to the sperm studies

01:04:24.540 | because when I was a graduate student at UC Berkeley,

01:04:28.240 | I had the wonderful experience of taking a course

01:04:30.260 | from the now, I think you mentioned he's a dean.

01:04:33.740 | There are multiple deans on campuses.

01:04:35.060 | Tyrone Hayes is a wonderful researcher

01:04:37.140 | who established a link through his research

01:04:41.220 | between atrazine exposure

01:04:43.980 | and male sexual behavior of amphibia.

01:04:48.980 | Could you elaborate on that result?

01:04:52.300 | - Yeah, so Tyrone first caught frogs in the wild

01:04:58.460 | in environments that were more or less exposed to atrazine

01:05:02.140 | and showed effects on development and sexual behavior.

01:05:05.840 | Then he, in his lab, he actually exposed them.

01:05:08.860 | So he knew exactly who was exposed and how much.

01:05:12.260 | And he showed that the,

01:05:15.100 | and I can't tell you what percent or what, you know,

01:05:17.900 | but a significant number of frogs exposed

01:05:21.220 | to this pesticide atrazine

01:05:23.740 | chose to mate with other male frogs.

01:05:27.320 | - Tried to mate with other male frogs,

01:05:29.020 | presumably unsuccessfully.

01:05:30.260 | - Well, they mounted them.

01:05:32.100 | He has photos of the males mounting males.

01:05:35.700 | - And so presumably this is a neural change that occurred,

01:05:40.260 | neuroendocrine change, but ultimately neural

01:05:42.740 | since mounting behavior is controlled by,

01:05:45.100 | actually we now know the hypothalamic nuclei

01:05:48.740 | that control this.

01:05:49.580 | David Anderson, who's been on this podcast,

01:05:51.060 | has people in his laboratory that,

01:05:53.060 | including a former graduate student of mine,

01:05:55.760 | working on this specific issue of what the circuitry is.

01:06:00.760 | That's a remarkable result.

01:06:06.740 | It's been kind of, you know,

01:06:10.000 | used and misused out there in the media

01:06:13.160 | and in popular culture.

01:06:15.000 | But if nothing else,

01:06:15.960 | it suggests that the organization of the neural circuits

01:06:19.240 | and neuroendocrine pathways that control sexual,

01:06:24.920 | I don't want to say partner because it is mating thing.

01:06:27.840 | Frogs aren't monogamous,

01:06:28.920 | but sexual preference are significantly impacted

01:06:33.920 | by this atrazine.

01:06:37.320 | - Yes.

01:06:38.160 | And it suggests that there are other

01:06:40.560 | environmental chemicals can as well.

01:06:43.100 | And I don't know if we'll have time to go there,

01:06:45.720 | but I did work on neurodevelopmental outcomes

01:06:50.720 | in relation to prenatal phthalate exposure.

01:06:53.640 | And so I think the overarching idea here

01:06:58.400 | is that the brain, like the genitals, is sexually dimorphic.

01:07:03.400 | And there's many people, by the way,

01:07:05.160 | who will take offense at that.

01:07:07.120 | - Really? - Yeah.

01:07:08.200 | - I think there's, I mean,

01:07:09.200 | going back to the work of Frank Beach

01:07:11.540 | in the psychology department at UC Berkeley.

01:07:13.720 | - I know.

01:07:14.740 | - Showed this in beagles.

01:07:16.280 | It's been shown in pretty much every species,

01:07:19.420 | but it's not a better, worse.

01:07:20.640 | I think this is what people need to hear.

01:07:21.760 | Like dimorphic does not mean better, worse.

01:07:23.480 | It means different. - Right, right.

01:07:25.160 | And that there, and there are, for example,

01:07:28.480 | advantages to spatial reasoning in a male,

01:07:32.920 | which are related to testosterone, right?

01:07:38.800 | You know that.

01:07:39.640 | - I mean, I think there, yeah.

01:07:40.840 | I mean, my understanding of this literature,

01:07:42.520 | and I'm not an expert in this particular aspect,

01:07:45.020 | which is the behavioral phenotypes,

01:07:47.360 | but like the medial preoptic area of the hypothalamus

01:07:51.000 | is known to be sexually dimorphic,

01:07:52.360 | dependent on testosterone converted into estrogen

01:07:55.200 | during development, et cetera, et cetera.

01:07:56.920 | And there's just so much evidence of this.

01:07:59.220 | How it links to behaviors is can,

01:08:03.360 | I think can be reasonably placed

01:08:05.040 | into ethologically relevant,

01:08:08.040 | evolutionarily logical arguments

01:08:13.080 | when talking about rodents or beagles

01:08:14.960 | or even rhesus macaque monkeys.

01:08:18.340 | I think where people get a bit inflamed

01:08:22.200 | is when people try and take the sexual dimorphisms

01:08:25.400 | that have been observed in animal brains

01:08:27.880 | or in even in human brains

01:08:29.360 | and tack those to specific abilities or lesser abilities.

01:08:34.120 | I think that's when people sort of go, wait a second,

01:08:36.160 | like I have much better sense of direction than my husband.

01:08:38.640 | And you go, well, yeah, like, you know,

01:08:40.360 | and then you go, well, well, does that mean

01:08:41.900 | that she has higher testosterone than him?

01:08:43.400 | And then maybe, and then, and pretty soon you're,

01:08:45.840 | you're in almost a no man's land,

01:08:49.320 | a no person's land of confounding variables, right?

01:08:54.320 | But I really appreciate that you raised this

01:08:56.440 | and also that you said it and I didn't

01:08:57.900 | because I feel safer that way.

01:08:59.480 | - But look, there is a very simple,

01:09:03.080 | outdated questionnaire and it's play behavior.

01:09:07.840 | It's called the PSAI.

01:09:09.200 | It's been used for years.

01:09:10.760 | Have you heard?

01:09:12.080 | - Rough and tumble play.

01:09:13.200 | - Yes, yes.

01:09:14.600 | And there are 24 questions on there

01:09:17.240 | and they are sexually dimorphic, I guess you could say.

01:09:21.600 | My child likes to play with dolls.

01:09:24.920 | My child likes to play dress up.

01:09:26.320 | My child likes to play rough and tumble, et cetera.

01:09:30.280 | And we gave that questionnaire to our population

01:09:34.840 | and looked at the answers that the mothers gave,

01:09:40.580 | both in our population, by the way,

01:09:41.940 | and a Swedish population of a colleague there,

01:09:44.960 | Carl Bornahag and Gustav Bornahag.

01:09:49.380 | And what we found, higher phthalate levels,

01:09:54.380 | these anti-androgenic phthalates were associated

01:09:59.800 | with less masculine male typical play in our male boys.

01:10:04.800 | So-

01:10:07.720 | - This is phthalate exposure to the mom.

01:10:11.360 | - Baby is born in the young human child.

01:10:15.080 | - Yeah, I think it was four years of age.

01:10:17.200 | - Four years of age, less rough and tumble type play

01:10:21.120 | among the boys whose mothers were exposed to more phthalates

01:10:24.080 | during a critical period of development.

01:10:26.600 | - Now you can see that's a politically loaded issue now.

01:10:30.420 | - Well, I think we're,

01:10:33.760 | I mean, let's have some fun with this

01:10:36.280 | in the scientific sense.

01:10:39.720 | The notion of dimorphism is,

01:10:41.820 | okay, male and female brains are different, right?

01:10:44.160 | And male, female defined in those,

01:10:46.160 | almost all those studies as presence of a Y chromosome.

01:10:48.720 | And then people say, well, there's X, Y, Y,

01:10:50.840 | and then there's X, X, Y, okay.

01:10:52.200 | But most of the time you're talking about X, X chromosome

01:10:54.720 | or X, Y chromosomes at birth.

01:10:56.840 | Forget everything else for the moment.

01:10:58.900 | These are always distributions.

01:11:02.640 | This is what I think people need to know.

01:11:04.060 | We're not talking about, these are not,

01:11:05.800 | this is not two hills of data separated by a valley.

01:11:10.800 | These are overlapping distributions, right?

01:11:13.560 | So you get males with a "female-like distribution",

01:11:16.400 | you get females with a "male-like distribution".

01:11:19.320 | And I think as long as we acknowledge that,

01:11:22.760 | then we're just talking statistics.

01:11:24.840 | We're not placing any cultural

01:11:27.800 | or any value on it really whatsoever.

01:11:31.200 | - Right, but if you could make the analog

01:11:33.800 | to the intergenital distance,

01:11:35.200 | it's kind of similar, you know,

01:11:36.560 | you have the same exposure, phthalate exposure,

01:11:38.360 | you have something changed statistically.

01:11:40.580 | We don't see huge differences in the boys' genitals.

01:11:44.200 | And we don't see huge, I don't, we know,

01:11:48.320 | these kids have not been scanned,

01:11:49.520 | so we don't know how their brains look.

01:11:50.920 | But based on their answers, we don't see huge differences.

01:11:54.520 | We see tendencies.

01:11:55.560 | We see they are more likely,

01:11:58.520 | if they had been exposed to these phthalates,

01:12:01.280 | to want to play dress up and have tea parties.

01:12:04.320 | More likely, doesn't mean that they're all going to,

01:12:07.040 | but that's the direction and so on.

01:12:09.920 | So I think we have to just think about

01:12:11.240 | more likely, not absolute, yeah.

01:12:13.400 | - And of course there are also the sociobiological variables,

01:12:18.100 | such as if a young boy has a sibling that's a sister,

01:12:23.100 | there's more likely to be dresses around, right?

01:12:26.400 | She's gonna, if he has two older brothers,

01:12:28.880 | there might be more rough and tumble play

01:12:30.120 | happening in the house.

01:12:30.960 | And I have some friends that are women

01:12:32.960 | who have older brothers, and those women are,

01:12:35.760 | some of them roll jujitsu or do,

01:12:39.200 | and I know some women who are only children

01:12:41.920 | who do martial arts and fight, right?

01:12:45.480 | So I think that none of this is deterministic, as we know.

01:12:50.480 | - But let me just add,

01:12:51.400 | we did control for the sex of the sibling, older sibling,

01:12:54.880 | and we also asked about the parents' attitude

01:12:58.200 | just towards same-sex play.

01:13:00.840 | So what would, how would you feel if your child,

01:13:03.920 | your male child played with dolls?

01:13:06.280 | Would you be discouraging?

01:13:08.040 | Would you encourage?

01:13:09.240 | 'Cause it has a lot to do with what's in the house.

01:13:11.920 | You know, if you say, "Did your child play with dolls?"

01:13:13.760 | Well, what if there were no dolls?

01:13:15.200 | - This is super interesting to me.

01:13:16.400 | I don't wanna reveal too much, but I grew up,

01:13:19.000 | just because it's not, it's just an N of one,

01:13:21.000 | but I grew up in a household where I have a sister,

01:13:24.200 | but then after a certain age,

01:13:26.120 | I received very strong messages

01:13:28.000 | about what sorts of play were gender appropriate.

01:13:33.000 | And I think I also just naturally defaulted to,

01:13:36.960 | there were a bunch of boys that lived in my neighborhood.

01:13:39.260 | They had older sisters,

01:13:40.360 | so all the sisters hung out together.

01:13:41.920 | It's kind of interesting,

01:13:42.760 | and all the younger brothers pretty much hung out together,

01:13:45.120 | and the guys that weren't, didn't have siblings

01:13:47.240 | or had brothers who were siblings.

01:13:48.640 | So there was a really strong divergence,

01:13:50.480 | but I grew up in the, that was in the '70s and early '80s

01:13:53.000 | when things were, let's just say,

01:13:54.640 | culture was more dimorphic then, clearly.

01:13:57.680 | I mean, there were television shows like "All in the Family,"

01:13:59.840 | which the entire basis of the show

01:14:01.240 | was the wife going back to work

01:14:03.000 | and the husband being confused about it.

01:14:04.240 | I mean, nowadays people will go like, "What? That's wild."

01:14:07.400 | I have to ask, because I know people are wondering,

01:14:10.120 | and I'm wondering,

01:14:11.320 | what are some non-pesticide sources of phthalates

01:14:15.920 | that we have agency over, that we can take control over?

01:14:19.880 | - Right, so let me correct you.

01:14:22.560 | It's not the sources of phthalates necessarily.

01:14:26.760 | Pesticides, there are phthalates in pesticides,

01:14:30.180 | but that's not the worst player in the story.

01:14:35.640 | If you look at the different classes of exposures

01:14:41.840 | that are hormonally active, right?

01:14:44.760 | Pesticides are, phthalates are, bisphenols,

01:14:49.760 | like bisphenol A. - BPA.

01:14:51.840 | - BPA, certain metals are, there's the PFAS chemicals.

01:14:56.400 | There's all these different classes, right?

01:14:58.880 | And if we want to go, excuse me,

01:15:01.240 | into what in our daily life exposes us to these things,

01:15:06.240 | that's another story that we can talk about,

01:15:11.380 | but they're going to be different

01:15:13.200 | depending on the class, right?

01:15:15.480 | - So let's throw our arms

01:15:17.360 | around all of those for the moment.

01:15:19.720 | And I'll just ask you,

01:15:21.400 | given that you're an expert in this area,

01:15:24.880 | what are the top three to five sources

01:15:28.440 | of endocrine disruptors that we have agency over?

01:15:33.440 | And let's forget about pregnancy for the moment

01:15:36.280 | since we're all out of the womb if we're listening to this.

01:15:39.760 | Some people will be pregnant as they listen to it,

01:15:42.120 | but would you say it's, you know,

01:15:45.600 | drinking out of plastic bottles?

01:15:47.440 | Is it laundry detergent?

01:15:49.080 | Is it, you know, rubber tires

01:15:52.080 | that are cascading down on us through the air

01:15:54.520 | and we're inhaling them?

01:15:55.600 | I mean, presumably all of the above,

01:15:57.180 | but which ones that we have agency over

01:16:00.060 | do you think are the most, let's just say,

01:16:02.520 | concerning where people could make better choices?

01:16:05.900 | - I would say foodborne exposures,

01:16:11.360 | exposures in the food, in the food packaging,

01:16:14.760 | in the food storage, in the food, in the cooking utensils.

01:16:19.400 | We can go through the various things,

01:16:23.680 | but we're doing that all the time.

01:16:28.680 | We're eating all the time.

01:16:31.040 | We're getting food into us.

01:16:32.760 | And these are bringing in a very, you know,

01:16:37.080 | in a way that we have some control over,

01:16:38.640 | some agency over, you know,

01:16:41.240 | we can make changes in our foods.

01:16:42.880 | Very close to that is drink, you know, food and beverage.

01:16:49.320 | So I, first of all, I've talked about this a lot.

01:16:54.320 | I've written about it in my book.

01:16:57.920 | I'm also, as you know, involved in a movie

01:17:00.120 | where in the movie,

01:17:01.560 | that might be a good time to talk about that.

01:17:03.640 | What we do in the movie,

01:17:05.400 | the movie is about six couples that are infertile, okay?

01:17:10.400 | They haven't been able to conceive in 12 months.

01:17:13.520 | That's the definition.

01:17:15.240 | And then a company that I work with,

01:17:19.320 | Million Marker out of Berkeley,

01:17:21.640 | has a trained staff that interviews them.

01:17:25.020 | Not only them, but anyone who signs into this company,

01:17:29.040 | interviews them and ask them what they use.

01:17:31.880 | What do they use for their facial care?

01:17:35.200 | What do they use for their shampoo?

01:17:36.600 | What do they use for their cleaning products

01:17:38.740 | and their laundry detergent?

01:17:39.960 | And what do they store their food in?

01:17:41.840 | And on and on and on.

01:17:42.880 | So this is long inventory that they take

01:17:45.520 | of all products that people are aware of using, okay?

01:17:49.960 | And based on that,

01:17:53.360 | we identify likely bad players in the list.

01:17:58.360 | So how we do that is another,

01:18:01.560 | you know, we can talk about that later.

01:18:03.020 | But then in the film and in this little,

01:18:08.020 | it's actually an experiment that I designed

01:18:10.080 | and called an intervention.

01:18:12.600 | And we are then intervening in their exposures

01:18:16.960 | by changing out these things that they told us.

01:18:20.440 | So we will tell them, you know,

01:18:23.000 | don't use any product with fragrance, for example.

01:18:26.960 | That's a major source of exposure to phthalates.

01:18:29.760 | - Any product.

01:18:30.600 | - Any fragrance product.

01:18:31.960 | If fragrance is added-

01:18:32.800 | - So no perfume, no lotions, soap with fragrance.

01:18:36.360 | - Right.

01:18:37.200 | - Even essential oil fragrances like lavender.

01:18:38.880 | - Essential oil is a tricky-

01:18:40.440 | - Right, it's a mix.

01:18:41.440 | - It's a mix, yeah.

01:18:42.360 | So I'm gonna, that's guarded.

01:18:44.480 | But anything, you know-

01:18:47.480 | - Spray deodorants, roll-on deodorants.

01:18:49.560 | - Laundry detergent.

01:18:50.560 | - Shampoo.

01:18:51.400 | - Yep, and any, if you can smell it,

01:18:54.200 | it's probably affecting your hormones.

01:18:56.080 | - I'm so happy about this answer.

01:18:58.260 | Not because I have any stake in any company

01:19:00.160 | related to fragrance-free stuff,

01:19:01.560 | but I have a very strong sense of smell

01:19:03.920 | and I either love or hate smells,

01:19:06.460 | and I hate synthetic smells.

01:19:09.140 | Like going through the duty-free,

01:19:10.620 | especially in a European airport

01:19:12.080 | to wear it with all the perfumes,

01:19:13.400 | and I'm just, "Oh, I'm gonna hold my breath."

01:19:15.560 | It feels like I'm breathing poison.

01:19:18.320 | - I know.

01:19:19.160 | - Well-

01:19:21.640 | - Well, you are actually.

01:19:22.560 | - Yeah, yeah, and most soaps, right.

01:19:26.040 | Super interesting.

01:19:28.200 | So that's your primary intervention

01:19:29.760 | is to tell them get rid of anything with fragrances.

01:19:31.800 | - No, that's only one thing we get rid of.

01:19:33.920 | So then we talk about how the plastics

01:19:36.920 | that they use to store their food,

01:19:38.440 | food storage containers,

01:19:40.240 | trying to get them to get rid of those

01:19:41.640 | if they're made of plastic.

01:19:43.040 | We try to get them to get rid of their non-stick pans

01:19:47.320 | because of the PFAS chemicals that are in those,

01:19:49.720 | and so on and so forth.

01:19:51.120 | So we go through all steps of their life

01:19:53.320 | and try to tell them how to make changes

01:19:56.320 | that will reduce their exposure.

01:19:58.600 | - But presumably also changes,

01:20:01.120 | like if the man is obese, for instance,

01:20:03.640 | you might have him walking a bit more.

01:20:05.440 | - No, no, no.

01:20:06.280 | - You don't touch any of that?

01:20:07.100 | - Well, you see, Andrew, if we did that,

01:20:09.440 | we would be mixing up two interventions.

01:20:12.200 | We would be mixing up an obesity intervention.

01:20:14.740 | - I see, this is a study.

01:20:15.840 | I'm sorry, I thought that this group

01:20:17.400 | is missioned with helping couples get pregnant.

01:20:20.880 | - No, no, this is a study to look at what happens

01:20:24.700 | if you make these product-related changes.

01:20:27.360 | - Great, just product-related changes.

01:20:28.920 | - Right, exactly, exactly.

01:20:30.160 | We would love to do, and probably will do,

01:20:32.280 | another study, separate one on obesity.

01:20:34.800 | And a lot of these chemicals,

01:20:36.480 | just to let you know, are obesogens.

01:20:38.580 | They increase obesity.

01:20:40.960 | There's a book out called "Obesogens."

01:20:43.380 | You can read about them.

01:20:44.360 | And so it's very, there is some overlap.

01:20:48.520 | So by reducing some of these chemicals

01:20:50.680 | that are in your food storage containers,

01:20:52.320 | you're also reducing obesogens.

01:20:54.400 | So it's not a clear yes/no.

01:20:57.400 | We gave them a box, each couple.

01:20:59.760 | I went to their house, six couples

01:21:02.160 | around the United States, with a big box.

01:21:04.280 | And in this box are these alternative products.

01:21:07.720 | And so, you know, straws, and bamboo spoons,

01:21:12.720 | and you know, $500 per box, I think it was, approximately.

01:21:17.920 | It had to do with their personal, you know, exposure.

01:21:20.720 | And then they made these changes.

01:21:24.600 | Now, unlike another study that you reported,

01:21:29.600 | they are, at the end, quite happy

01:21:32.480 | to keep doing this, by the way.

01:21:33.940 | They love this.

01:21:35.040 | They love doing this.

01:21:36.600 | It was so gratifying to see that they felt,

01:21:40.960 | in many, many ways, their life got better.

01:21:43.600 | You know, I'm not a, I'm pretty careful in what I,

01:21:46.920 | so I hesitate to say this, 'cause the data is not hard,

01:21:51.120 | but the impression is that they are happy, happier.

01:21:56.120 | They're sleeping better, they report more energy,

01:21:59.440 | and so on and so forth, having made these changes.

01:22:02.320 | We need to follow that up with hard data.

01:22:04.760 | I'm not writing that, I'm not, you know.

01:22:06.440 | But that, they, but I can say, and I can write,

01:22:09.660 | that they felt very positive, and are,

01:22:12.440 | we're gonna go back and see if they did continue.

01:22:15.240 | We need to do that.

01:22:16.680 | But at the end of the six, of the three months,

01:22:19.440 | they, and hopefully in six months, they will,

01:22:22.120 | they are still making these changes in their lives.

01:22:25.140 | - Did you collect data on whether or not

01:22:27.600 | they were able to conceive after having made these changes?

01:22:30.320 | - Yes, we did, but I actually can't talk about that.

01:22:33.240 | - Can't talk about it, until the babies are born.

01:22:35.240 | - Just kidding.

01:22:36.840 | - And we did get their sperm count

01:22:38.700 | at the beginning and the end,

01:22:40.040 | and had some very interesting data on that, which--

01:22:42.680 | - Too early to report.

01:22:44.040 | - Too early to report.

01:22:44.880 | - Let me ask you this then, and I appreciate that the,

01:22:48.600 | not wanting to share specific results until this,

01:22:52.440 | all the data are in, and it's published.

01:22:54.440 | If somebody listening were having trouble conceiving

01:23:01.960 | for 12 months or more,

01:23:03.400 | are the sorts of replacement interventions,

01:23:07.640 | product interventions that you're talking about here,

01:23:10.040 | things that you would at least feel comfortable saying

01:23:14.120 | might be a good place to start, or to explore?

01:23:16.600 | - Absolutely, absolutely.

01:23:18.040 | There's no harm.

01:23:19.080 | None of the changes are putting people at risk

01:23:22.800 | or doing anything that could be harmful to them.

01:23:24.880 | I'm sure of that.

01:23:26.000 | We're very careful.

01:23:27.200 | - And some are going to be cost-saving.

01:23:29.840 | And I think that's where drinking out of plastic bottles,

01:23:34.160 | far less, if at all.

01:23:35.480 | Just for reasons related to wanting to reduce waste,

01:23:39.640 | I use a mason jar, or I use these, or ceramic.

01:23:42.920 | Although you'll probably tell me

01:23:43.880 | that the lining on the ceramic mug

01:23:45.620 | might have endocrine disruptors.

01:23:47.320 | No, I don't.

01:23:48.160 | - I don't think so.

01:23:49.000 | - Okay, great, okay.

01:23:49.820 | Well, then I'll keep drinking.

01:23:51.320 | But it's very reassuring to me that there are things

01:23:54.920 | that we can do in terms of cost-saving elimination

01:23:57.100 | or replacement of consumables.

01:23:59.120 | - Buying in bulk.

01:23:59.960 | - That can improve endocrine status, maybe fertility also.

01:24:02.920 | - If you can buy in bulk, bring a container to the store

01:24:05.960 | and fill it up, a glass jar,

01:24:07.640 | instead of buying something in plastic,

01:24:09.840 | you're winning on both ends

01:24:11.240 | because those bulk products are cheaper.

01:24:13.280 | One of the things I did with the couples

01:24:16.160 | was go shop with them.

01:24:17.480 | And we went around and we looked at various products.

01:24:19.840 | And for example, we looked at the produce

01:24:22.080 | and there was option to buy freestanding bunches of lettuce,

01:24:27.480 | heads of lettuce, or wrapped up

01:24:29.600 | in plastic bunches of lettuce.

01:24:31.520 | And I said, "Let's compare the price."

01:24:33.360 | I actually didn't know until we did it.

01:24:35.720 | But the freestanding unwrapped lettuce was cheaper.

01:24:39.560 | And I think that's, you know, because that makes sense

01:24:42.480 | 'cause there's a work involved in wrapping it up

01:24:45.240 | in the container and so on.

01:24:46.960 | And so not only are you getting something that's more toxic,

01:24:50.880 | but it's more expensive.

01:24:53.040 | - When it comes to reducing BPA exposure

01:24:55.400 | and some of these forever chemicals that you mentioned,

01:24:58.400 | it seems like reducing fluid intake from plastic vessels

01:25:04.200 | is gonna be number one.

01:25:06.640 | - The primary source of BPA is in the lining of cans.

01:25:09.800 | So any drink or soup or anything that comes in a can

01:25:14.800 | is going to be-

01:25:17.480 | - Any can, all can. - Any can.

01:25:21.000 | Unless it's a high-end, you know, elite company

01:25:26.000 | that's made the change from BPA to an alternative lining.

01:25:29.880 | And they'll say that.

01:25:31.240 | So, and by the way, BPA has some bad relatives

01:25:36.240 | such as BPS and BPF.

01:25:39.160 | And maybe you'd be interested in this story.

01:25:41.480 | So when it came out that BPA was estrogenic,

01:25:44.960 | which is what it is, and by the way,

01:25:48.480 | it's kind of the evil twin of phthalates

01:25:51.400 | because phthalates are androgenic and BPA is estrogenic

01:25:55.400 | and phthalates make plastic soft and BPA makes plastic hard.

01:25:59.200 | You don't want either.

01:26:01.440 | Okay, so when this came out that this was a bad thing,

01:26:05.100 | the manufacturers started selling things that say BPA-free.

01:26:10.400 | I'm sure you've seen that.

01:26:12.480 | The trick is that instead of BPA, they use BPS.

01:26:16.240 | - Sneaky rats. - And BPF.

01:26:18.820 | And these are chemicals, these are lookalikes,

01:26:21.320 | they're analogs, and they're just as harmful.

01:26:23.680 | - Sneaky, sneaky, sneaky.

01:26:26.380 | I'm not a conspiracy theorist, but it's just so dirty.

01:26:29.480 | It's so dirty.

01:26:30.500 | It's like, it's, you know, right now

01:26:32.960 | is a really important time to be having this discussion

01:26:35.880 | because there's been a lot of movement on Capitol Hill

01:26:38.620 | and there's been a lot of movement on social media

01:26:40.480 | about trying to call attention to metabolic syndromes

01:26:43.560 | and highly processed foods and issues like this.

01:26:46.240 | And it's become unfortunately politicized.

01:26:48.400 | I mean, I hear this stuff and I just think to myself,

01:26:52.380 | the only good faith that we can really trust

01:26:55.840 | is our own desire to be healthier

01:27:00.080 | and to have our families and friends be healthier

01:27:03.360 | and to try and consume and not consume things

01:27:05.440 | on the basis of that.

01:27:06.720 | My belief is that we can't trust any larger agency

01:27:11.720 | to either protect or harm us.

01:27:14.120 | It's like, it's not, it's like,

01:27:15.640 | they're gonna do what they're gonna do.

01:27:16.960 | We just have to be informed.

01:27:18.440 | As opposed to trying to dismantle the systems

01:27:21.400 | that led to this,

01:27:22.240 | which just seems like infinitely complicated.

01:27:24.340 | Maybe you can do that, but I'm far less optimistic.

01:27:27.780 | And now that I'm 49 years old,

01:27:29.120 | I can say things like, now that I'm 49, I feel like.

01:27:32.520 | But what you're saying is really important.

01:27:34.440 | If I look at a can, it says BPA-free.

01:27:36.760 | Doesn't mean anything.

01:27:37.600 | It could have BPSs or other endocrine disruptors.

01:27:41.480 | - Right.

01:27:42.320 | - So drinking out of glass vessels,

01:27:45.360 | drinking out of ceramic vessels.

01:27:47.520 | - Metal.

01:27:49.200 | - Metal, but not cans, not metal cans, not aluminum cans.

01:27:52.840 | - Right, not cans, no.

01:27:54.060 | - Goodness, okay.

01:27:55.320 | - You know, you can get a metal water bottle.

01:27:58.360 | It's not lined with BPA.

01:28:00.120 | - Steel.

01:28:00.960 | - Steel, yeah.

01:28:01.780 | - Steel.

01:28:02.620 | And is it true that microwave safe means,

01:28:06.000 | it just means that the plastic won't melt in the microwave,

01:28:08.760 | but it's-

01:28:09.600 | - Never, never put plastic in a microwave.

01:28:13.760 | So here's the story.

01:28:16.040 | The BPA, phthalates, plasticizers are added to the plastic,

01:28:21.040 | but they're not chemically bound to it, okay?

01:28:26.960 | So if you put anything in a container

01:28:30.660 | that has these chemicals in it, they will,

01:28:34.800 | and then put it in a hot environment,

01:28:37.640 | they will come out of the plastic and go into the food.

01:28:41.180 | So if you, in a microwave, or you put your bottle in the car

01:28:46.440 | and the sun comes in, it warms up the bottle,

01:28:48.960 | and then the stuff goes into your water.

01:28:51.920 | You don't wanna mix these chemicals and your food,

01:28:54.940 | but if you do, the worst thing is to do it

01:28:57.320 | in a heated environment.

01:28:58.760 | - I think about all the food that was consumed in college

01:29:01.680 | in the '90s and 2000s, like the cup of noodles

01:29:05.840 | with the styrofoam, the things in packaging,

01:29:10.840 | stuff like that is pretty straightforward to eliminate

01:29:13.240 | once one understands and decides.

01:29:16.040 | Then we start getting into the more nuanced thing of like,

01:29:19.460 | okay, you can buy a really nice tasting anyway,

01:29:22.820 | grass-fed, grass-finished steak, but it's wrapped in plastic.

01:29:26.320 | Well, or you can go to the butcher,

01:29:29.680 | but most people don't have time to go to the butcher.

01:29:32.300 | Or you can get strawberries at the farmer's market,

01:29:34.960 | blueberries at the farmer's market,

01:29:36.120 | which is what I try to do,

01:29:37.840 | but sometimes I buy strawberries at the market

01:29:39.880 | and they have those plastic flip-top things,

01:29:41.600 | and of course I recycle the plastic.

01:29:43.180 | How bad is it if you rinse the strawberries off

01:29:48.180 | with good clean water that were in the plastic container?

01:29:51.920 | - We have to do that experiment, I don't know.

01:29:53.840 | - Yeah, so it sounds to me like not drinking out of cans,

01:29:58.600 | not drinking out of plastic bottles,

01:30:00.560 | it's gonna be not microwaving plastic ever.

01:30:03.640 | And in general, just avoiding plastic intake.

01:30:07.200 | - If you can afford it, buy organic.

01:30:09.880 | So you're gonna avoid the pesticides,

01:30:12.240 | and then phthalates are actually added to pesticides.

01:30:15.920 | And they're added because they increase absorption.

01:30:18.880 | So you want your pesticides to get into the plant, right?

01:30:23.000 | And to kill the bad stuff and insects.

01:30:26.680 | And so the same property of phthalates

01:30:32.000 | that makes them good for pesticides

01:30:34.640 | also makes them good for our hand cream.

01:30:37.040 | Just mentioning, absorption, absorption.

01:30:39.180 | Anything that's absorbed in the body

01:30:41.520 | is gonna have phthalates in it.

01:30:43.520 | And it also holds scent and color.

01:30:47.120 | So it's added to those scents,

01:30:49.040 | and it's also added to your lipstick

01:30:50.760 | and to your colored, you know,

01:30:53.280 | whatever you put on your face and so on.

01:30:55.360 | Anything that holds scent and color,

01:30:57.200 | that's gonna be phthalates.

01:30:59.000 | (laughs)

01:31:00.320 | I'm sorry.

01:31:01.160 | - I'm accused online of being a sunscreen truther.

01:31:04.920 | I'm not a sunscreen truther.

01:31:06.560 | I'm gonna keep repeating this as many times as I can.

01:31:08.520 | I understand that UV damage to the skin

01:31:13.520 | can cause certain cancers.

01:31:15.220 | I get that.

01:31:16.100 | I agree with that.

01:31:18.200 | The data are pretty clear to me

01:31:21.560 | based on having researched this pretty extensively

01:31:23.600 | and talked to many, many people,

01:31:24.720 | including dermal oncologists,

01:31:25.960 | that mineral-based sunscreens like zinc oxide

01:31:28.900 | and titanium dioxide,

01:31:30.360 | but certainly zinc oxide,

01:31:31.640 | are safer than the chemical sunscreens.

01:31:34.520 | A lot of people get upset when I say that,

01:31:36.160 | and they say, "Well, in Europe,

01:31:37.080 | "there's tons of evidence

01:31:37.940 | "that the chemical-based sunscreens are gonna save it."

01:31:39.840 | Okay, fine, you use them.

01:31:41.200 | I'm not going to.

01:31:42.560 | The point being that UV damage is bad.

01:31:46.100 | There are ways to protect ourselves from the sun,

01:31:51.120 | including physical barriers like clothing, hats, et cetera.

01:31:57.520 | But pretty much all sunscreen that I'm aware of

01:32:00.760 | is designed to be absorbed.

01:32:02.380 | So what do we do if we want to get some UV protection

01:32:05.160 | from whatever kind of sunscreen we deem safe for ourselves,

01:32:08.680 | but we want to avoid these exposures to these other things?

01:32:11.360 | What do we do?

01:32:12.520 | Do we have to hunt really carefully

01:32:13.920 | for the right sunscreen?

01:32:15.120 | - Yeah, I think that's a good idea.

01:32:19.360 | Are you familiar with Environmental Working Group?

01:32:22.520 | - Is another one out of the Bay Area?

01:32:24.260 | - No. - Oh, okay.

01:32:25.100 | - I don't know actually where they are.

01:32:26.440 | They're pretty big.

01:32:27.280 | - It sounds familiar, but I'm not,

01:32:28.920 | I can't say I'm familiar with them.

01:32:29.760 | - So they have consumer guides,

01:32:31.840 | and in those consumer, so Environmental Working Group,

01:32:35.160 | I'm not part of them, but I like their work.

01:32:38.680 | And in these consumer guides, you can put in the product,

01:32:41.640 | and they have categories.

01:32:42.660 | You can put sunscreen,

01:32:44.140 | if we had time, we could do it right now,

01:32:45.880 | and then you can put the name of your sunscreen,

01:32:47.720 | and it'll give you a number.

01:32:49.040 | And then if the number is less than 10,

01:32:51.440 | it'll tell you why.

01:32:52.480 | - Are they independent of any funding?

01:32:56.360 | - Yeah.

01:32:57.380 | - That question will probably come up for you too.

01:32:59.880 | People will say, "Where did she get her funding?"

01:33:04.520 | You know, people get very suspicious about this.

01:33:06.480 | - I can tell you that.

01:33:07.600 | - Yeah, that'd be great.

01:33:08.480 | - Yeah, so I am a tenure professor at Mount Sinai,

01:33:13.480 | get some salary there because I'm only part-time,

01:33:16.880 | and I have a funder, one funder,

01:33:19.840 | who funded my sperm decline,

01:33:25.140 | second sperm decline analysis,

01:33:26.720 | and the publicity of my book.

01:33:27.880 | So it's a foundation.

01:33:30.640 | - So it's philanthropy.

01:33:31.800 | - Yeah, it's philanthropy, yeah.

01:33:33.120 | And it's actually not a lot of money.

01:33:34.800 | - And so there's no reason to think

01:33:36.160 | that anything that you're telling us

01:33:37.760 | is linked to like the food industry

01:33:40.800 | or an alternative product or anything.

01:33:42.560 | - I'm very, very careful not to endorse any product

01:33:45.640 | because I don't want that complication.

01:33:48.200 | - Yeah, thanks for clarifying that.

01:33:49.720 | I wasn't suspicious, but I think nowadays,

01:33:53.560 | people have just been taught to, you know,

01:33:55.680 | appropriately so, they've been taught to say,

01:33:57.240 | well, wait, where does this funding come from?

01:33:58.680 | Because a lot of the studies about the,

01:34:01.000 | that led to the food pyramid, for instance,

01:34:03.560 | people were under the impression

01:34:04.920 | that somehow that was biased by companies

01:34:08.060 | that were funding the work.

01:34:09.320 | And I don't know, I haven't done the forensics on that.

01:34:11.400 | I don't have the time or the energy.

01:34:13.480 | All I know is that when it comes to what people eat,

01:34:18.480 | when it comes to what people put on their body,

01:34:22.060 | it becomes a very personal thing

01:34:24.280 | and it's woven in with a lot of psychological

01:34:28.060 | and emotional issues.

01:34:29.400 | - Yeah. - Yeah, okay.

01:34:31.000 | What are a few things that you do

01:34:36.440 | and or avoid in light of what you know

01:34:42.040 | about these endocrine disruptors?

01:34:44.120 | And by the way, it goes without saying

01:34:46.000 | that you're in spectacular cognitive

01:34:48.980 | and physical shape for any age,

01:34:51.080 | but it's really remarkable.

01:34:52.700 | I feel comfortable sharing this

01:34:54.400 | because someone else published it online recently.

01:34:56.480 | You are soon to enjoy your what birthday?

01:34:59.760 | - 89th. - 89th birthday, amazing.

01:35:02.400 | And with all the talk about longevity,

01:35:04.740 | cognitive and physical longevity,

01:35:06.020 | everyone's thinking, including me, like, what does she do?

01:35:08.680 | Well, she avoids all these endocrine disruptors

01:35:11.800 | and she has a wonderfully rich life

01:35:13.440 | of curiosity and other things.

01:35:15.920 | But yeah, what are some other things that you do

01:35:18.680 | and avoid in light of what you know

01:35:21.360 | for which there may or may not be a controlled study,

01:35:24.280 | but I think we're all just curious.

01:35:25.900 | We'll frame this as what you do.

01:35:28.400 | - So water, our water, I worry about the water.

01:35:32.740 | I studied water for a long time in my past life.

01:35:36.160 | So we actually distill our water.

01:35:39.240 | So we have a tabletop distiller.

01:35:42.180 | My husband, Steven, cleans it out.

01:35:44.280 | There's a lot of gunk in it, by the way,

01:35:45.860 | even though it's San Francisco that has clean water,

01:35:48.220 | at the end of the day, after you've distilled the water,

01:35:50.760 | there's a lot of gunk.

01:35:51.600 | - So you distill the water, so this is not reverse osmosis.

01:35:54.040 | - No, distilling. - Okay.

01:35:55.800 | - Yeah, so it's steam distilled

01:35:57.840 | and then it condenses in a glass container.

01:36:00.520 | And then we put that in glass containers in the fridge.

01:36:03.400 | And so, and it tastes really good, by the way,

01:36:06.360 | really, really.

01:36:07.320 | Somebody was just over and he said,

01:36:09.360 | "This tastes like melted snow."

01:36:12.240 | I thought it was lovely.

01:36:13.080 | - And you use that for drinking, for coffee, for tea,

01:36:15.340 | for cooking too, if you make rice, you're using distilled.

01:36:17.600 | - Actually, no, no.

01:36:18.660 | But for ice cubes and, you know,

01:36:20.900 | whenever I can think about it.

01:36:22.480 | We can't use too much 'cause it'd be too busy.

01:36:25.520 | He always does it.

01:36:26.920 | But he does it once a day.

01:36:28.560 | It's just the two of us.

01:36:29.680 | So water is important.

01:36:31.520 | We try to leave our shoes at the door.

01:36:36.080 | - Tell me about that one.

01:36:37.120 | - Well, dust that you bring in contains a lot of the,

01:36:41.200 | particularly the PFAS chemicals.

01:36:43.340 | And so that's actually, I'm not 100% good on that,

01:36:48.340 | but we try to do that.

01:36:51.060 | And I'm careful with the products I put on my face.

01:36:55.460 | I check them out the way I suggested,

01:36:57.980 | you know, environmental working group.

01:37:00.500 | And I go to the farmer's market.

01:37:02.860 | I always buy organic, always buy organic.

01:37:06.540 | But I know that's a cost issue for some people

01:37:08.940 | and an availability issue for some people.

01:37:12.340 | But in San Francisco, you can do that.

01:37:14.580 | Some areas where I don't do more of what I should,

01:37:21.260 | I think I'm starting to be aware of the chemicals

01:37:25.180 | in clothing.

01:37:26.580 | We haven't talked about that,

01:37:27.740 | but there's a, turns out there's a lot of,

01:37:30.380 | particularly in, it's a problem for workout wear

01:37:33.580 | because you're absorbing so much,

01:37:35.020 | you're sweaty, you're hot,

01:37:36.100 | and you're bringing these chemicals into your body.

01:37:38.380 | And that may be one of the interventions that we do,

01:37:41.100 | get a bunch of athletes to use safe clothing

01:37:46.060 | and traditional clothing

01:37:48.260 | and see what their body burden is.

01:37:50.460 | That's how you know.

01:37:51.460 | - So erring toward cotton as opposed to synthetic materials.

01:37:56.460 | - Right, and the dyes are important.

01:37:58.580 | So you don't want, you want maybe plant-based dyes.

01:38:01.940 | It's not my area of expertise.

01:38:03.380 | I have a colleague who I work with on this

01:38:05.340 | and I'll go with her advice.

01:38:07.300 | But I'm just saying that's another area

01:38:10.460 | that I think people will soon be paying attention to.

01:38:13.660 | There's also the area that is much more difficult,

01:38:17.700 | which is what's in building materials and furniture.

01:38:21.140 | But a lot of these PFAS and the flame retardants

01:38:24.180 | are in our furniture and in our building materials

01:38:27.100 | and trying to think about how to build.

01:38:30.260 | I was asked about safety in a new village

01:38:32.780 | that's being built in California, by the way.

01:38:34.740 | And it's really challenging to think about

01:38:37.780 | if you were gonna do this right

01:38:40.100 | and you were gonna build a town that was toxic-free,

01:38:44.380 | how would you do that?

01:38:45.540 | I'm thinking about that.

01:38:48.740 | - I'm thinking about the opener of "The Simpsons"

01:38:50.700 | and doing the exact opposite,

01:38:52.420 | where like in the opener of "The Simpsons"

01:38:54.020 | there's like a three-eyed fish

01:38:55.220 | and there's the chemical plant.

01:38:56.740 | And I'm just thinking,

01:38:57.580 | you just look at the opener of "The Simpsons,"

01:38:58.740 | you do the inverse of everything that's there,

01:39:01.100 | the inverse of everything that's there,

01:39:04.020 | including alcohol intake,

01:39:07.780 | which is robust on "The Simpsons."

01:39:10.740 | - Yeah, right.

01:39:11.580 | - But interesting.

01:39:12.900 | So, and when it comes to food sourcing,

01:39:17.260 | like non-fruit, non-vegetable food sourcing,

01:39:20.260 | is there anything we can do?

01:39:21.700 | I mean, it's so hard for people to get eggs from farms.

01:39:24.740 | I mean, you can if you go to a farmer's market,

01:39:26.340 | but this stuff can get pretty tricky, pretty expensive.

01:39:29.540 | And most people listening are not gonna be

01:39:32.660 | living in Sonoma where they might have a neighbor

01:39:35.300 | that has chickens or something.

01:39:36.780 | - Yeah.

01:39:38.540 | - It's a hard problem.

01:39:40.500 | - It is a hard problem.

01:39:41.740 | And I think maybe people asking for it more would help.

01:39:46.740 | I don't know.

01:39:48.300 | I mean, in San Francisco, I'm lucky

01:39:50.220 | 'cause I can just get, you know, just on the phone,

01:39:54.340 | fresh, direct order, and I know it's okay.

01:39:57.540 | But I know that's not the case everywhere.

01:40:00.620 | So I think being aware, honestly, is a really big step.

01:40:06.300 | If you're aware that this is something you want to change,

01:40:10.100 | you will find ways to change it.

01:40:12.540 | - It's interesting because a few years back,

01:40:14.300 | there was a lot of discussion about dyes in children's toys,

01:40:18.780 | in particular toys from overseas, right?

01:40:22.340 | Remember, kids are not,

01:40:23.260 | young babies are always gnawing on stuff and teething.

01:40:25.660 | And there was a lot of attention,

01:40:27.020 | like, "Hey, what's in these sippy cups?"

01:40:28.700 | And my understanding is, toys and sippy cups,

01:40:31.380 | and my understanding is that BPAs

01:40:32.820 | were banned from sippy cups.

01:40:34.500 | - Phthalates.

01:40:35.340 | - Phthalates, excuse me.

01:40:36.300 | - Based on my work.

01:40:37.140 | - Based on your work.

01:40:37.960 | Thank you so much.

01:40:38.800 | Thank you for the clarification, truly,

01:40:40.500 | and for the work that led to that.

01:40:43.020 | We have this innate, thankfully,

01:40:47.740 | innate reflex to protect our young,

01:40:50.580 | as does most every species, thank goodness.

01:40:55.100 | And we know that baby skin

01:40:57.900 | is more absorbent than older skin, we know.

01:41:00.180 | And so there are literally laws in place

01:41:02.580 | and restrictions in place to make sure

01:41:04.540 | that this stuff is minimized in young kids.

01:41:06.860 | But then we sort of, after age 12,

01:41:09.380 | we're kind of like, "Okay, well, it's a free-for-all.

01:41:11.020 | "It depends on your budget, where you go."

01:41:12.220 | And so we can't rely on governing bodies to do this.

01:41:15.840 | But I think it's a useful conversation,

01:41:18.660 | especially given your relationship to Scandinavia,

01:41:22.060 | which is a fun one to elaborate on,

01:41:24.380 | to illustrate some of the discrepancy

01:41:27.540 | between the US and Europe.

01:41:32.260 | What sorts of chemicals are banned in Europe,

01:41:37.260 | in food, in lotions, et cetera,

01:41:40.740 | that you're aware of that are prominent here in the US?

01:41:44.900 | Maybe that's a good filter

01:41:46.020 | to play some of this choice-making through.

01:41:48.100 | Europe has had a policy called REACH.

01:41:52.900 | And under REACH, you have to show

01:41:56.500 | that a chemical is safe

01:41:57.700 | before it's put into the marketplace.

01:42:00.700 | Not, I mean, so the way our system is here

01:42:04.380 | is put in the marketplace,

01:42:06.220 | and then if somebody gets worried about it,

01:42:08.860 | they might do a study, they might find harm.

01:42:12.700 | Remember how long it took me to find that phthalate connection?

01:42:15.660 | It was 10 years, two studies, 10 years,

01:42:18.160 | $10 million, by the way.

01:42:19.820 | So if you're gonna wait for that,

01:42:22.400 | I don't know, given the number of chemicals out there,

01:42:26.700 | 80,000 or more, forget it.

01:42:29.620 | So I think the REACH policy of testing

01:42:33.340 | before something's put in the market

01:42:35.180 | is making a big difference in Europe.

01:42:38.020 | I think that's one reason why they're much better off.

01:42:41.820 | - Are those animal tests or animal and human tests

01:42:44.820 | that they're doing over there?

01:42:45.780 | - Whatever defines safety.

01:42:47.260 | It depends on the chemical.

01:42:48.540 | It depends on what the product is.

01:42:50.920 | I can't answer that in general.

01:42:52.840 | - So that might be a good avenue

01:42:54.160 | for changing legislature here, right?

01:42:56.620 | To install something similar to REACH.

01:42:59.500 | - Absolutely, but it's not gonna happen, I don't think.

01:43:02.740 | - No? - No.

01:43:03.580 | Because there's too many forces against that.

01:43:06.500 | It's very, very hard for manufacturers to make changes.

01:43:09.860 | I'll give you one example.

01:43:11.320 | So you know that, you might not know, but should know,

01:43:16.260 | that phthalates are very prevalent in the hospital setting.

01:43:19.400 | If you think of a tube to dialysis, to chemotherapy, to IV,

01:43:25.580 | it's all plas, that's all phthalates, right?

01:43:28.700 | And that's going into your body.

01:43:30.820 | And there was a recently, a bill passed in California

01:43:35.300 | that DEHP could not be in IV bags.

01:43:37.900 | It's fantastic, a success.

01:43:40.380 | - In the actual bag? - Yes.

01:43:42.300 | - The bags could not contain these endocrine disruptors?

01:43:45.020 | - Yes, DEHP specifically. - DEHP, okay.

01:43:47.500 | - Diethylhexyl phthalate, the most antiandrogenic phthalate.

01:43:50.780 | So that was a great step forward,

01:43:53.340 | but that's like one chemical, right?

01:43:57.100 | In one product, and that was a battle.

01:44:00.380 | So you see how hard it is to do this, extremely hard.

01:44:05.380 | There's a company, B. Braun, which makes hospital products,

01:44:10.260 | and they are very forward-thinking,

01:44:13.100 | and they set up a factory in Florida

01:44:16.800 | to make alternative IV bags

01:44:19.540 | out of another product, polyolefin.

01:44:22.900 | And the problem is that we're not sure

01:44:26.780 | about the safety of polyolefin.

01:44:28.900 | So it gets really difficult.

01:44:30.980 | You can say remove DEHP,

01:44:33.460 | but now we scientists have to say,

01:44:36.420 | what does it mean for a chemical to be safe?

01:44:39.540 | And we don't know that.

01:44:40.840 | I don't mean to disillusion you and your listeners,

01:44:44.580 | but that's a huge challenge that we're up against.

01:44:48.220 | We know it's safer, we know it's safer,

01:44:50.980 | and we know what the bad actors are,

01:44:52.660 | and we know the things we don't want to be exposed to,

01:44:55.020 | but we have to be careful when we think

01:44:57.380 | about what do we want to put in instead.

01:44:59.820 | - Yeah, I'm thinking about this.

01:45:04.020 | A former president of Stanford,

01:45:07.360 | who has also happened to be a family friend years ago,

01:45:10.360 | he's since passed, Don Kennedy,

01:45:13.180 | when he retired as president of Stanford went in,

01:45:17.260 | my understanding is that he went and directed the FDA.

01:45:20.180 | And I was just thinking to myself,

01:45:21.260 | like, when did this happen?

01:45:24.260 | Because I know he was super into health.

01:45:27.020 | He was like an avid runner.

01:45:28.400 | He was very fit, well into his seventies.

01:45:30.740 | Yeah, hip replacement, kept running,

01:45:32.100 | or maybe it was knee replacement, I don't know.

01:45:33.500 | The guy was obsessed with health.

01:45:34.900 | And so I don't think that there's a lack of interest

01:45:39.540 | in health at the level of it was like the FDA.

01:45:42.680 | And, but there's clearly a problem.

01:45:46.940 | And I'm just trying to think of solutions.

01:45:50.580 | And it seems to all boil down

01:45:52.500 | to what we can take control of in our home.

01:45:56.340 | Like when we go to a restaurant,

01:45:57.460 | it's challenging to know what they're doing in the kitchen.

01:46:00.380 | And at some point it becomes neurotic to, you know.

01:46:04.060 | Although I know people that won't go to restaurants

01:46:05.740 | where they use seed oils.

01:46:06.700 | There's this whole new thing cropping up

01:46:08.060 | about avoiding seed oils,

01:46:10.380 | but maybe they're more significant issues, who knows?

01:46:13.960 | The seed oil crowd is pretty intense.

01:46:17.620 | And I like olive oil anyway, so I err to that.

01:46:19.920 | But I think if people are interested

01:46:23.140 | in limiting their exposure to these endocrine disruptors,

01:46:25.500 | one of the key questions that's gonna come up again

01:46:27.420 | and again, especially in light of PCOS and sperm counts

01:46:30.100 | is we can't control what happened to us during pregnancy.

01:46:34.060 | But once we have some sense of agency

01:46:37.500 | over what we put into our body

01:46:38.820 | and how we put it into our body,

01:46:40.700 | do you think that there's a,

01:46:43.820 | that there's plasticity and resilience to this system?

01:46:49.460 | So, you know, God forbid if somebody was exposed

01:46:51.760 | to a lot of these things early on, can they, you know,

01:46:54.140 | by making changes, can they rescue themselves

01:46:57.720 | to any degree?

01:46:58.560 | No? - No.

01:46:59.380 | - So it's really just dependent on what your parents did.

01:47:01.760 | - Yes, that's not to say that your own exposure

01:47:05.440 | cannot change things further and make things worse.

01:47:07.780 | But here's a fact.

01:47:10.480 | If a male's mother smokes when he's in the womb,

01:47:15.480 | then he has a, this is a Danish study, by the way,

01:47:19.980 | 50% reduction in sperm count.

01:47:22.180 | - If his mother smoked while he was in the womb,

01:47:23.820 | how much smoking are we talking?

01:47:25.420 | - I don't know, I don't remember.

01:47:27.220 | But the reason I bring this up is because

01:47:30.140 | there's nothing he can do to change that, okay?

01:47:34.180 | If he smokes as an adult,

01:47:36.500 | he has, I think, a similar reduction in the sperm count.

01:47:39.620 | He can stop and his sperm will be restored.

01:47:43.420 | He can get his sperm health back.

01:47:45.240 | But whatever happened in the womb stays in the womb,

01:47:47.480 | if you will, so to speak.

01:47:48.940 | It's developmental.

01:47:50.140 | It's not going to, you know, it's gonna be there for life.

01:47:54.180 | And that's true of the brain as well.

01:47:55.880 | So I think anybody who's thinking of conceiving a pregnancy

01:48:00.880 | or pregnant has a responsibility to really learn

01:48:07.220 | how to reduce their exposure.

01:48:09.500 | Because these things are, by the way,

01:48:10.900 | passed on for several generations.

01:48:12.860 | It's your child and your child's child,

01:48:15.340 | because the germ cells for your grandchild

01:48:19.040 | are going to be carried in within your child.

01:48:22.080 | - So germ cells are not germs as in infectious germs.

01:48:26.300 | It's the cells that will produce the egg and sperm,

01:48:28.980 | that germinate, hence the word germ.

01:48:31.940 | - So it's a huge responsibility.

01:48:34.420 | And I think people should take it very seriously,

01:48:36.980 | that they have, you know,

01:48:40.580 | they're going to be affecting the health

01:48:42.920 | of subsequent generations.

01:48:44.060 | Some labs say it's seven generations.

01:48:45.940 | I don't know if that's true,

01:48:46.940 | but certainly three generations are affected.

01:48:50.420 | And so I should mention my book.

01:48:53.700 | Can I mention that? - Yeah, please.

01:48:54.620 | I'll mention it.

01:48:55.460 | Yeah, I believe I mentioned it in my introduction.

01:48:57.780 | - Yeah. - Yeah, please.

01:48:58.600 | - So in "Countdown," two words, by the way,

01:49:02.460 | 'cause if you say "Countdown" one word, you won't find it.

01:49:05.020 | But "Countdown," we have two chapters

01:49:08.740 | on things you can do.

01:49:10.060 | Very practical things you can do.

01:49:11.740 | And also websites you can go to and links you can go to.

01:49:14.600 | Now this came out a while ago, so '21.

01:49:18.820 | So there are many more things now,

01:49:20.820 | but I think it's a good start.

01:49:22.920 | - How lonely are you in this expedition

01:49:26.900 | of identifying endocrine disruptors in food,

01:49:31.260 | in pesticides, in the sorts of things you're talking about?

01:49:35.340 | Like, is there a whole field of this, of excellent people?

01:49:38.620 | Are you a small team of people that are against the grain?

01:49:43.620 | I mean, I confess I don't know many people

01:49:46.700 | doing the sorts of work that you're doing,

01:49:48.020 | but you're the most public-facing and prominent.

01:49:51.180 | And I guess my question is like,

01:49:54.940 | is the NIH funding a lot of this sort of thing?

01:49:57.860 | - Absolutely.

01:49:59.380 | We're an army and it's international.

01:50:02.400 | And there is now a global plastics treaty

01:50:06.980 | under negotiation, by the way.

01:50:08.900 | - Tell us about the plastics treaty.

01:50:10.860 | - People are trying to create,

01:50:15.180 | get passed by various countries

01:50:17.900 | an international plastics treaty.

01:50:20.620 | I can't, I don't want to talk a lot about it.

01:50:22.540 | I'm not involved in that process,

01:50:23.820 | but in the process you could see, if you looked into there,

01:50:28.820 | hundreds of scientists and concerned citizens

01:50:33.420 | and activists and people in legislation

01:50:38.260 | who are working to specifically

01:50:41.300 | on the chemicals in plastic.

01:50:42.660 | Now, plastic is really a bad actor,

01:50:45.320 | but it is not the only bad actor.

01:50:48.700 | So I want to just mention that plastic is really important,

01:50:52.340 | but pesticides are not plastic and so on.

01:50:55.940 | So there are many other classes

01:50:57.420 | that you have to worry about,

01:50:58.380 | but certainly controlling our exposure to plastic is huge.

01:51:03.140 | And you asked about scientists in this area.

01:51:07.260 | Yes, there's a huge amount of science going on for this,

01:51:11.500 | in this, there's, and it's funded by NIH

01:51:14.540 | and it's funded by the EU and primarily,

01:51:19.540 | I think those are the two funders of Scandinavia

01:51:22.260 | has funding within, in Scandinavian countries.

01:51:26.900 | So there's a lot of work

01:51:28.340 | and a lot of very good people working really hard,

01:51:31.180 | but it's a huge problem.

01:51:32.460 | And it's been here since,

01:51:35.060 | well, plastic started to rise in popularity in 1950.

01:51:40.100 | So we have like 75 years to battle against

01:51:43.660 | and it's not going down anytime soon.

01:51:45.900 | - Lifespan is increasing pretty significantly,

01:51:50.020 | presumably in large part

01:51:51.980 | because of the reduction in smoking.

01:51:53.980 | - And control of infectious disease.

01:51:56.540 | - And control of infectious diseases.

01:51:59.220 | But lifespan is definitely increasing,

01:52:02.020 | whereas the use of plastics has clearly increased.

01:52:07.100 | And so I guess one could argue that we're living longer,

01:52:11.940 | but we are less robust than we were,

01:52:15.300 | less reproductively competent.

01:52:18.620 | Is that-

01:52:19.460 | - The people that are reflected in that long lifespan

01:52:22.940 | were not necessarily exposed early in life,

01:52:26.260 | which is when it's most critical.

01:52:28.660 | So, you know, I was born in 1936,

01:52:31.300 | there was no plastic then.

01:52:33.140 | There was no, you know,

01:52:35.100 | and there were other things of course,

01:52:37.100 | but not as they are today.

01:52:39.820 | So I don't think that you can make the inference

01:52:44.700 | that because we're living longer,

01:52:46.500 | plastic growth, you know,

01:52:48.340 | the growth of the plastics industry

01:52:49.740 | is somehow driving that longevity.

01:52:51.540 | Absolutely not.

01:52:52.780 | Absolutely not.

01:52:53.620 | I think what it's driving is decrease in fertility.

01:52:56.820 | And what's happening is that the shift in populations

01:53:00.500 | is pretty dramatic.

01:53:01.340 | We're getting, you know, the pyramid used to be like this.

01:53:04.420 | I'm making a triangle with my arms

01:53:07.420 | showing very few people on top

01:53:09.180 | and a lot of people on the bottom.

01:53:10.620 | But what's happening is that that's getting inverted.

01:53:13.860 | So we're getting more and more people on top

01:53:15.660 | and fewer and fewer people on the bottom.

01:53:17.780 | - Birth rates are way down.

01:53:18.940 | - Birth rates are way down.

01:53:20.380 | And so this is an enormous problem for societies

01:53:25.060 | because the people in that small support group

01:53:28.020 | at the bottom can't drive the society

01:53:31.620 | to support the large growth on top.

01:53:36.420 | You see what I'm saying?

01:53:37.260 | - Is this true in other countries as well?

01:53:38.260 | - Yes, absolutely.

01:53:39.340 | Absolutely.

01:53:40.180 | It's all over the world.

01:53:41.340 | And the decline in fertility in my mind is probably,

01:53:46.340 | well, one of the biggest challenges we're facing now

01:53:50.580 | because it's everywhere.

01:53:53.620 | It's very acute.

01:53:55.180 | And there's only limited things we can do to counter it.

01:54:00.180 | There's a wonderful website, it's by the World Bank,

01:54:06.220 | put out by the World Bank.

01:54:07.460 | It's called Fertility Data.

01:54:09.540 | And if you go in there,

01:54:11.060 | you can see what is the fertility rate every year,

01:54:14.500 | but you can plug in a country or a year

01:54:19.180 | and see what the fertility rate in each country

01:54:21.980 | in the world each year.

01:54:22.900 | And you can see that.

01:54:23.740 | And what you see is that a decline,

01:54:27.820 | about the same rate as sperm decline, by the way,

01:54:30.180 | about 50% in 50 years.

01:54:33.460 | And the critical point for fertility is two.

01:54:38.460 | So what's that mean?

01:54:41.060 | That's called replacement.

01:54:42.340 | And that's two people replace themselves

01:54:45.020 | with a total fertility rate of two.

01:54:46.700 | Actually, 2.1, because you have a little bit of loss,

01:54:49.180 | but 2.1, you're good to go, society.

01:54:52.420 | When you fall below that, you're shrinking.

01:54:54.980 | And there are many countries in the world

01:54:57.780 | that are below that, including the United States.

01:55:01.060 | And for example, the worst I've seen

01:55:04.140 | is actually South Korea, which is at 0.78.

01:55:09.140 | Japan is at one.

01:55:12.020 | So large parts of the world

01:55:14.260 | are just not replacing themselves.

01:55:17.480 | And why that is, is maybe another discussion,

01:55:20.580 | or we can talk about it.

01:55:21.620 | I don't know if you wanna go into that,

01:55:22.820 | but it's not just sperm count, for sure.

01:55:26.180 | - Yeah, along those lines,

01:55:27.460 | let's talk about egg count and quality.

01:55:30.620 | You mentioned the PCOS results earlier.

01:55:33.540 | Before we were on, Mike,

01:55:35.700 | you mentioned an interesting study that you did

01:55:38.220 | about the use of electric blankets

01:55:41.300 | and assessing whether or not the use of electric blankets

01:55:43.700 | had impacted egg number or quality in women.

01:55:47.100 | And the answer was?

01:55:48.360 | - Actually, what we looked at in women,

01:55:51.100 | I'm sorry to correct you,

01:55:52.220 | but it was the outcome of their pregnancy,

01:55:54.940 | their fertility, and if they got pregnant,

01:55:57.420 | how did that turn out?

01:55:58.780 | - Excuse me, so thank you for that clarification.

01:56:01.220 | - But I'm sure there'd be a lot of other studies

01:56:04.220 | that have looked at that.

01:56:05.300 | I just have been away from that field for a long time.

01:56:07.780 | But so far, I don't see convincing evidence

01:56:10.980 | that the use of cell phones

01:56:13.260 | or other exposures to electromagnetic radiation

01:56:18.260 | are affecting our pregnancies and our fertility.

01:56:21.060 | That's not to say it's not happening,

01:56:23.180 | but I have not looked at it.

01:56:25.520 | And I don't like to make statements

01:56:27.980 | about things I haven't looked at.

01:56:29.900 | - My understanding of the cell phone data

01:56:31.980 | for sperm count and motility, aka quality,

01:56:36.900 | is I discussed a meta-analysis covering this

01:56:41.100 | on the podcast previously,

01:56:42.480 | is that there are some heat effects of cell phone use

01:56:45.740 | and keeping the phone in the pocket

01:56:47.180 | that may, I want to be careful here,

01:56:49.820 | impact sperm count and motility quality,

01:56:54.660 | but direct effects of EMFs on sperm,

01:56:58.940 | there's no evidence that it is disrupting sperm,

01:57:02.460 | at least to my knowledge.

01:57:03.300 | - I honestly have to say,

01:57:04.620 | just going to say I don't know,

01:57:06.500 | but I do know that heat is related

01:57:10.220 | to fertility and sperm count.

01:57:12.100 | And you can look at the birth rates

01:57:16.700 | as a function of the month of conception,

01:57:19.260 | and you can see that, for example,

01:57:20.860 | in warm months, in warm climates, there's less.

01:57:25.100 | So heat does play a role,

01:57:27.260 | but how much that's tied to cell phone use,

01:57:29.940 | I think that's something that's now under investigation

01:57:33.460 | by a lot of groups, and we'll see what they find.

01:57:36.460 | - Yeah, the data on sitting more than a few hours a day,

01:57:39.180 | on having legs that are very large

01:57:42.060 | as a consequence of obesity,

01:57:43.540 | or even just legs that are large, heating the scrotum,

01:57:47.260 | those data are fairly, I would say, solid

01:57:51.340 | in terms of the relationship to reducing sperm count.

01:57:54.260 | Heat is not good for sperm,

01:57:55.860 | which is why the scrotum has the features that it does

01:57:59.620 | to move the testicles further or closer to the body.

01:58:04.260 | Getting back to egg count and quality,

01:58:06.800 | there's some evidence

01:58:07.700 | that girls are entering puberty earlier,

01:58:12.380 | but that women are also undergoing

01:58:14.940 | perimenopause menopause earlier.

01:58:16.740 | - Earlier, that's right.

01:58:18.180 | - Do we know what that is the consequence of?

01:58:20.900 | - There are several new papers actually

01:58:22.940 | on the menopausal age showing relation

01:58:26.460 | to a number of chemicals,

01:58:27.540 | but I can't quote them to you right now.

01:58:30.220 | I don't remember which class it was that they looked at,

01:58:33.940 | but I think that's right.

01:58:35.980 | I think there is growing evidence

01:58:38.300 | that earlier, fewer...

01:58:41.740 | It's also called premature ovarian failure,

01:58:45.140 | so that women are just not producing the eggs

01:58:49.280 | as long as they used to.

01:58:50.820 | I just want to say something about the fertility.

01:58:57.500 | Can we go back to fertility?

01:58:58.740 | - Please.

01:58:59.860 | - So when this comes up,

01:59:02.740 | and I'm sure you've seen the literature,

01:59:04.420 | there's a lot of literature on this,

01:59:06.280 | that say fertility is going down,

01:59:09.960 | fewer children are being born.

01:59:11.460 | A, people say, well, that's a good thing

01:59:13.980 | 'cause it's less of a load on the planet,

01:59:15.700 | which is another discussion.

01:59:17.580 | And then they say, well, this is due to choice,

01:59:21.380 | that people are choosing to have fewer children

01:59:24.320 | and they're choosing to delay childbearing

01:59:28.460 | till they're no longer as fertile.

01:59:30.660 | They're using more contraception.

01:59:32.860 | Women are more educated.

01:59:34.300 | They're entering the workforce.

01:59:36.100 | All of these social factors are given

01:59:39.660 | as the reason for decline in fertility.

01:59:43.140 | And I just need to point out,

01:59:47.340 | whenever I hear this,

01:59:48.860 | that it's not just human fertility that's declining.

01:59:53.540 | The number of species that are becoming extinct

01:59:58.180 | is increasing rapidly,

02:00:00.240 | and there have been, for at least 40 years,

02:00:05.240 | evidence that those pesticides that affect us

02:00:08.060 | are affecting animals as well.

02:00:09.780 | And so the decline in fertility in non-human species

02:00:14.780 | cannot be attributed to delayed childbearing

02:00:19.260 | or use of contraception.

02:00:21.300 | - Or rent crisis, right?

02:00:23.640 | And it's interesting because we usually hear first

02:00:28.100 | about species that are about to go extinct,

02:00:29.940 | that are badly endangered.

02:00:31.620 | I don't know what the proper language is,

02:00:32.800 | but it's about to go distinct.

02:00:34.440 | Like the Florida panther.

02:00:37.820 | Or we hear that there are these species

02:00:39.980 | that there's a very small subset of them left.

02:00:42.900 | The black-footed ferrets in Montana,

02:00:45.020 | I think one ferret, his name is Scarface,

02:00:48.540 | sired something like 300 litters

02:00:50.380 | that then led to the,

02:00:51.740 | eventually they started out breeding,

02:00:53.580 | 'cause if you do too much inbreeding,

02:00:54.740 | obviously it's not good.

02:00:56.180 | But then they were able to at least partially recover,

02:00:58.760 | maybe fully recover those populations.

02:01:01.180 | And people forget the domino effect of these ecosystems

02:01:05.300 | when one species is compromised.

02:01:06.900 | Like when the black-footed ferrets,

02:01:08.940 | I know it might sound kind of silly,

02:01:10.140 | but were compromised in terms of their populations,

02:01:14.100 | the prairie dog population went up,

02:01:16.260 | the grasses were getting eaten far more.

02:01:18.420 | And then there's all these downstream consequences

02:01:20.780 | on bugs and I'm not an expert in this,

02:01:23.820 | but one doesn't have to be an expert to understand,

02:01:26.480 | you move one pin here and the whole web moves.

02:01:30.200 | And so, or you move one node and the whole web reconfigures.

02:01:35.200 | And that's what nature has been doing

02:01:38.660 | for millions of years, right?

02:01:41.120 | But at some point it is conceivable, no pun intended,

02:01:45.800 | that we are going to be the species

02:01:48.560 | on the endangered species list, right?

02:01:50.400 | I mean, that's not like an outrageous sci-fi movie.

02:01:53.720 | - No, that's right.

02:01:54.560 | - Like at some point humans might be added

02:01:56.400 | to the endangered species list.

02:01:57.240 | - With the exception that we have, we're very clever.

02:02:00.600 | And so we found a lot of ways

02:02:02.540 | to do medically assisted conception.

02:02:07.160 | - Right, ICSI, the literally gentle grabbing of one sperm

02:02:11.800 | and forcing it to fertilize the egg

02:02:16.800 | is something we've covered on this podcast

02:02:19.460 | in our fertility episode with Natalie Crawford

02:02:22.000 | and a solo episode that I did.

02:02:24.500 | There are questions that people have,

02:02:26.180 | reasonable questions about whether or not

02:02:27.720 | the offspring of those types of scenarios

02:02:30.980 | are the same as the genetic probability experiment,

02:02:35.980 | as you mentioned before, of having 200 million sperm

02:02:39.940 | and then letting nature select the one

02:02:42.100 | that is most robust in that environment.

02:02:45.220 | - Yeah, and the number of technologies is increasing.

02:02:50.140 | We're a very clever species.

02:02:52.400 | And for example,

02:02:54.580 | I don't know if you've heard of gametogenesis.

02:02:57.740 | So it is now possible to create an embryo

02:03:02.260 | from a skin cell.

02:03:06.380 | A skin cell can produce a sperm cell and an egg cell.

02:03:11.380 | - You give it the right transcription factors

02:03:13.900 | and you can-

02:03:15.340 | - So this is kind of interesting, exciting and scary.

02:03:18.420 | - This is like the, what is it?

02:03:20.660 | I think the vultures, the females,

02:03:23.100 | there's some way in which two female vultures

02:03:26.440 | or maybe a single female vulture

02:03:28.440 | can create offspring in the absence of a male.

02:03:32.280 | There's also a three-party IVF.

02:03:33.960 | I don't know if you're aware of this.

02:03:35.880 | This was developed where there's a mitochondrial disease.

02:03:39.720 | You can take the two eggs, one from the intended mother,

02:03:43.980 | you take the nucleus, so you get the DNA,

02:03:46.160 | you put it into an egg of somebody

02:03:48.760 | that where the DNA has been removed,

02:03:51.200 | but where the spindles, which are rich with mitochondria

02:03:54.120 | are from a typically a much younger host,

02:03:57.560 | and then you use a sperm.

02:03:58.680 | So it's actually three parents.

02:04:00.000 | It's the spindle of one mom,

02:04:01.200 | the DNA of another mom and a sperm.

02:04:03.440 | They do this in the UK for mitochondrial disease.

02:04:05.760 | It's still illegal in the United States,

02:04:07.480 | as far as I understand.

02:04:08.960 | And it's done in other countries.

02:04:11.320 | And in theory-

02:04:12.600 | - Legal issues must be.

02:04:14.400 | - Yeah, but in theory, this would allow women of any age,

02:04:18.380 | provided they still have eggs,

02:04:21.860 | to have their DNA propagated forward

02:04:25.400 | because the DNA can be put into a younger egg

02:04:28.560 | that has the spindle quality

02:04:31.800 | that allows for the production of more cells.

02:04:35.200 | I mean, this can and has been done in humans.

02:04:38.160 | - Yeah. - Yeah.

02:04:39.120 | - So we're, I mean, you and I won't think

02:04:43.160 | of all the things that will be developed

02:04:45.360 | in the next 10, 20 years to meet the challenge

02:04:49.940 | of declining fertility by ordinary conception.

02:04:54.220 | I mean, I think that's how we're gonna solve

02:04:56.460 | this problem for us.

02:04:57.340 | We're going to just be smarter and smarter

02:04:59.100 | about how to do a medically-assisted conception.

02:05:02.720 | And then the question is going to be,

02:05:09.700 | and it'll take time to know this,

02:05:11.280 | is whether there are effects in the offspring,

02:05:15.620 | adverse effects in the offspring.

02:05:17.280 | It's a little tricky because, for example,

02:05:21.740 | if you use the sperm of an infertile couple

02:05:24.340 | and you see, let's say the son is subfertile,

02:05:27.700 | that's born that way,

02:05:29.340 | but you do it in a test tube or whatever.

02:05:31.980 | And then you can say, well, maybe that's

02:05:36.100 | because the father was infertile

02:05:37.380 | and he's got inheritance from the father from that.

02:05:40.380 | You know what I'm saying?

02:05:41.440 | So you can't know whether the,

02:05:44.480 | if you see an adverse effect in an offspring,

02:05:47.040 | you have to be very careful that it's not something

02:05:49.840 | that they've gotten because of problems

02:05:52.040 | that led the couple to seek assisted reproduction.

02:05:55.920 | You see, you following me?

02:05:57.000 | - Yep. - Yeah.

02:05:57.840 | - Super challenging, fascinating problem.

02:06:02.260 | So in anticipation of this sit down together,

02:06:07.160 | I put a question out on X, formerly known as Twitter.

02:06:12.100 | I let people know that I was hosting an expert

02:06:16.300 | in endocrine disruptors, in phthalates and pesticides,

02:06:21.300 | reproductive implications, et cetera.

02:06:24.260 | And I asked for questions and they came up

02:06:28.180 | with a huge number of excellent questions,

02:06:30.780 | many of which you've already answered.

02:06:32.260 | Things like, is tap water safe?

02:06:35.460 | What can we do to our tap water?

02:06:36.620 | You mentioned you distill water.

02:06:38.580 | My understanding is that reverse osmosis

02:06:40.460 | provided there's remineralization, excuse me,

02:06:44.320 | difficult word to say, can also be effective, et cetera.

02:06:47.620 | There were a lot of questions about cosmetics

02:06:50.820 | and laundry detergents.

02:06:52.280 | I don't know if we discussed laundry detergents.

02:06:55.880 | What do you use in terms of laundry detergent?

02:06:58.900 | Or that is presumably one can find-

02:07:02.000 | - I don't even remember. (laughs)

02:07:03.500 | - Okay.

02:07:04.660 | - Don't go by my products.

02:07:05.900 | - Okay.

02:07:07.080 | - For one thing, I'm not gonna be pregnant anytime soon.

02:07:09.940 | - I believe there are some solutions related to the,

02:07:17.060 | like instead of bleach, people can use hydrogen peroxide.

02:07:21.020 | - I can't speak about specific products, actually.

02:07:24.300 | You know, I can tell you who can.

02:07:25.860 | Maybe you might like to talk to her.

02:07:27.340 | So you remember I mentioned Million Marker,

02:07:29.780 | the company that did the inventory?

02:07:31.320 | Not the company, well, they are a company, but.

02:07:33.620 | So they, look at Million Marker.

02:07:36.340 | I think you'd be interested.

02:07:37.900 | - Okay.

02:07:38.740 | - Yeah, and the person who runs that,

02:07:41.020 | Jenna Wah, is a Chinese-American who,

02:07:46.020 | and a friend of mine, and we're gonna be

02:07:48.100 | writing a grant together.

02:07:50.060 | And she participated in the film.

02:07:52.440 | So our participants sent their,

02:07:54.580 | so if you go to Million Marker, you log on,

02:07:58.460 | and if you agree to pay whatever it is, $199, I think,

02:08:02.820 | you send your urine in, they give you a kit,

02:08:05.100 | you send your urine in, and they test it

02:08:06.740 | for all these things in your urine.

02:08:07.820 | So you know what's in your body.

02:08:09.180 | You might want to think about it.

02:08:10.020 | It might be interesting.

02:08:11.280 | And then if you pay another 100, I think,

02:08:13.800 | you get this counseling and so on, blah, blah.

02:08:16.940 | So you can see the different levels.

02:08:18.820 | But she knows all about products.

02:08:21.160 | I don't know about products, 'cause it's a moving target.

02:08:23.980 | And also, I don't like to talk about product names,

02:08:27.340 | because it sounds like I'm endorsing them, so.

02:08:29.900 | - Right, and we won't expect you to give product names,

02:08:32.900 | and I'll follow your recommendation that you just gave.

02:08:36.340 | Somebody asked about food dyes,

02:08:38.500 | just generally, the dyes in foods.

02:08:40.260 | I saw an incredible study recently

02:08:42.460 | that Science Magazine covered.

02:08:44.020 | So Science Magazine, very reputable, of course.

02:08:46.700 | Yellow number five, I forget what the precise name is,

02:08:50.100 | but the thing that makes Cheetos really bright.

02:08:52.320 | They put it on the bellies of adult mice,

02:08:55.140 | and it literally makes them translucent.

02:08:58.780 | - Oh, yeah, I saw that.

02:08:59.620 | - You can see the organs.

02:09:00.460 | - I saw that.

02:09:01.300 | - It's wild. - It's scary.

02:09:02.580 | - It's so scary.

02:09:03.460 | I sent it to Rogan, and he, I won't,

02:09:06.260 | he was like, "Whoa," his version of "Whoa."

02:09:09.420 | I was like, I also said, "Whoa."

02:09:11.420 | - He probably said, "Holy shit," right?

02:09:13.820 | - No, he said. - Or worse.

02:09:15.300 | - No, no, I'm not gonna say what it said,

02:09:17.100 | but it wasn't, he didn't curse.

02:09:18.460 | There were a number of questions about household items.

02:09:21.080 | Again, we're not looking for specific products,

02:09:23.880 | but for instance, soaps, body wash,

02:09:27.940 | cleaning sprays, floor cleaners,

02:09:29.900 | laundry-related cleaners,

02:09:31.360 | do any or all of these contain endocrine disruptors,

02:09:36.180 | unless one is careful to find the ones that don't, okay.

02:09:40.280 | Receipts, how serious is it?

02:09:42.480 | Should we be concerned about the BPAs

02:09:44.180 | and other endocrine disruptors on receipts?

02:09:46.780 | - Yes, and my suggestion is

02:09:49.460 | just ask for an electronic receipt,

02:09:51.260 | and then you don't have to deal with it, yeah.

02:09:54.820 | But they're definitely absorbed into your body.

02:09:57.980 | - Any impact of endocrine disruptors

02:10:01.820 | of the sort we've talked about today on the thyroid system?

02:10:04.620 | - Yes.

02:10:06.060 | - Presumably in the bad direction.

02:10:08.200 | - Yeah, I mean, this is an interesting point.

02:10:09.900 | Let me just say another word about it.

02:10:11.700 | So there was an ongoing study

02:10:16.700 | in the Faroe Islands off of Denmark,

02:10:20.940 | and they studied PFAS chemicals,

02:10:24.420 | and showed that people who fished there,

02:10:28.380 | there were fisher people, and they ate the fish,

02:10:30.980 | and they were getting high levels of PFAS in their body,

02:10:34.500 | and had, and this is published,

02:10:37.740 | effects on their immune response.

02:10:40.620 | So my concern, and I don't know if anyone's looked at this,

02:10:44.520 | is given everyone's vaccination,

02:10:47.860 | is our response to vaccination now altered

02:10:53.100 | by these chemicals, I don't know.

02:10:54.500 | But I think it's a really interesting question.

02:10:56.660 | But there is a whole field of the effect

02:10:58.740 | of these chemicals on the thyroid system,

02:11:01.020 | and there's a lot of evidence that it's adverse.

02:11:04.340 | - Can these endocrine disruptors be detoxed from the body?

02:11:08.260 | Is there anything that we can do?

02:11:09.460 | What's the quickest ways?

02:11:10.940 | Things like sweating.

02:11:12.220 | Are there ways to improve liver clearance

02:11:15.200 | of these endocrine disruptors?

02:11:17.660 | - The answer to that depends on the class of chemicals.

02:11:19.700 | So the chemicals that are water-soluble,

02:11:22.660 | in particular the phthalates and the bisphenols,

02:11:26.300 | leave the body in a matter of hours.

02:11:29.340 | You don't have to do anything.

02:11:30.300 | You just have to stop taking them in, right?

02:11:34.780 | The forever chemicals, the PFAS chemicals,

02:11:38.740 | pesticides are, and though,

02:11:42.940 | so it has to do with how they're handled by the body.

02:11:45.540 | Are they put into the, if they're water-soluble,

02:11:48.880 | you pee them out.

02:11:49.820 | If they're fat-soluble,

02:11:51.860 | they're gonna be around for a long time.

02:11:53.460 | So it just depends on the chemical structure

02:11:55.460 | of the compound.

02:11:58.160 | - There was a question about nonstick pans.

02:12:00.700 | You covered that earlier.

02:12:01.580 | If someone had to pick between nonstick coated pans

02:12:03.740 | versus seasoned iron pans.

02:12:06.260 | - No question, iron.

02:12:07.940 | There's no risk associated with seasoned iron pans.

02:12:11.380 | - A number of other questions,

02:12:13.500 | such as why does Europe have such more stringent laws,

02:12:17.580 | et cetera, lots of questions about atrazine,

02:12:21.040 | questions about ointments and fragrances you've covered.

02:12:24.740 | And I must say that as I scroll through these hundreds

02:12:29.740 | of questions, if not more,

02:12:31.320 | you've done an amazing job at clarifying for us

02:12:37.740 | what's known, what is not known,

02:12:41.920 | and essentially where it's a probably should avoid,

02:12:45.760 | definitely avoid, and look, we just don't know.

02:12:49.660 | - I have to distinguish between we just don't know

02:12:53.640 | and I just don't know.

02:12:55.120 | I mean, there are many things that I don't know.

02:12:57.320 | (laughing)

02:12:58.640 | It's a huge field.

02:12:59.560 | So maybe with some, ask the question of CHAT-GPT.

02:13:04.560 | - Yeah, we'll be certain to ask CHAT-GPT

02:13:09.440 | and we will be certain to ask other experts in these areas.

02:13:14.680 | But I just want to make very clear,

02:13:18.420 | I and everyone listening and watching

02:13:22.000 | truly appreciate the work that you've been doing

02:13:24.360 | in this area for a number of years.

02:13:26.580 | We're so grateful that you took that airline flight

02:13:28.960 | with this chemist that you mentioned,

02:13:32.520 | that you stored the urine of those pregnant women,

02:13:37.320 | that you analyzed it and that you've gone down this path

02:13:41.360 | of exploring things that are really disruptive

02:13:44.320 | to our health and potentially to the existence

02:13:47.120 | of our species as, you know, as we talked about earlier,

02:13:51.920 | there is the possibility that we go extinct,

02:13:54.960 | not because of a meteor,

02:13:56.000 | but because we fail to replace ourselves

02:13:58.400 | and that we fail to replace ourselves

02:14:00.120 | because we destroy our biological ability

02:14:02.960 | to replace ourselves.

02:14:04.320 | I think it's hard for people to internalize

02:14:07.400 | that very real possibility

02:14:09.120 | because we feel ourselves sitting in traffic

02:14:11.200 | with thousands of other people and go,

02:14:12.720 | there's too many people, right?

02:14:14.160 | This kind of thing.

02:14:15.000 | But I want to thank you for the work that you've been doing

02:14:19.560 | and continue to do for your willingness to write books

02:14:22.680 | and to educate the public on podcasts like this and others,

02:14:25.800 | because these are topics

02:14:27.580 | that are pretty emotionally loaded for people.

02:14:31.160 | I don't think anything gets people quite as inflamed

02:14:34.100 | as the idea that what they've been ingesting and exposed to,

02:14:37.940 | especially in terms of consumables

02:14:40.360 | that they've spent their hard-earned money on,

02:14:42.500 | have been harming them and their offspring

02:14:46.080 | and generations to follow,

02:14:48.240 | that there's something that really lands deep in that way.

02:14:51.520 | But you've also offered us a lot of possibility

02:14:54.440 | and a sense of agency over these things.

02:14:57.000 | And I love that you weave your math and statistics

02:15:01.480 | and probability theory background into all of this

02:15:05.120 | because what comes through is intense curiosity,

02:15:08.580 | intense rigor, and a real desire to do good.

02:15:11.720 | So thank you so much for joining us.

02:15:13.760 | And please come back again as you make more discoveries.

02:15:17.000 | Thank you. - It's been really fun.

02:15:18.280 | - Thank you for joining me for today's discussion

02:15:20.480 | with Dr. Shauna Swan.

02:15:22.200 | To learn more about her work

02:15:23.480 | and to find a link to her excellent books on these topics,

02:15:26.400 | please see the links in the show note captions.

02:15:28.920 | Also, I should mention that if you're interested

02:15:31.000 | in learning more about microplastics

02:15:33.080 | and endocrine disruptors,

02:15:34.400 | I did a solo episode of the Huberman Lab podcast

02:15:36.780 | on that topic,

02:15:37.620 | and that is also linked in the show note captions.

02:15:40.520 | If you're learning from and or enjoying this podcast,

02:15:42.920 | please subscribe to our YouTube channel.

02:15:45.000 | That's a terrific zero cost way to support us.

02:15:47.380 | In addition, please follow the podcast

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02:15:54.580 | you can leave us up to a five-star review.

02:15:57.260 | Please also check out the sponsors mentioned

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02:16:01.060 | That's the best way to support this podcast.

02:16:03.400 | Also, if you have any questions for me

02:16:04.880 | or comments about the podcast

02:16:06.520 | or guests or topics that you'd like me to consider

02:16:08.440 | for the Huberman Lab podcast,

02:16:09.940 | please put those in the comment section on YouTube.

02:16:12.360 | I do read all the comments.

02:16:14.180 | For those of you that haven't heard,

02:16:15.320 | I have a new book coming out.

02:16:16.520 | It's my very first book.

02:16:18.120 | It's entitled "Protocols,

02:16:19.520 | an Operating Manual for the Human Body."

02:16:21.680 | This is a book that I've been working on

02:16:22.860 | for more than five years,

02:16:24.000 | and that's based on more than 30 years

02:16:26.340 | of research and experience.

02:16:27.880 | And it covers protocols for everything from sleep,

02:16:30.940 | to exercise, to stress control,

02:16:33.440 | protocols related to focus and motivation.

02:16:35.880 | And of course, I provide the scientific substantiation

02:16:39.240 | for the protocols that are included.

02:16:41.340 | The book is now available by presale at protocolsbook.com.

02:16:45.240 | There you can find links to various vendors.

02:16:47.580 | You can pick the one that you like best.

02:16:49.380 | Again, the book is called "Protocols,

02:16:51.140 | an Operating Manual for the Human Body."

02:16:53.980 | If you're not already following me on social media,

02:16:55.940 | I am Huberman Lab on all social media platforms.

02:16:58.780 | So that's Instagram, X, formerly known as Twitter,

02:17:01.460 | Threads, Facebook, and LinkedIn.

02:17:03.380 | And on all those social media platforms,

02:17:05.260 | I discuss science and science-related tools,

02:17:07.660 | some of which overlap with the content

02:17:09.120 | of the Huberman Lab podcast,

02:17:10.320 | but much of which is distinct from the content covered

02:17:12.800 | on the Huberman Lab podcast.

02:17:14.080 | Again, that's Huberman Lab on all social media platforms.

02:17:17.800 | And if you haven't already subscribed

02:17:19.160 | to our Neural Network Newsletter,

02:17:21.200 | our Neural Network Newsletter

02:17:22.480 | is a zero cost monthly newsletter

02:17:24.120 | that includes podcast summaries,

02:17:25.920 | as well as protocols in the form of brief

02:17:27.840 | one to three page PDFs.

02:17:29.800 | These protocols cover things like deliberate cold exposure,

02:17:32.840 | deliberate heat exposure, how to optimize your dopamine,

02:17:35.200 | how to improve your sleep,

02:17:36.820 | all available at zero cost.

02:17:38.540 | To access these newsletters,

02:17:39.900 | simply go to HubermanLab.com,

02:17:42.020 | go to the top right corner menu,

02:17:43.420 | scroll down to newsletter, and enter your email.

02:17:45.820 | And I should mention that we do not share

02:17:47.380 | your email with anybody.

02:17:48.980 | Thank you once again for joining me

02:17:50.540 | for today's discussion with Dr. Shauna Swan.

02:17:53.300 | And last, but certainly not least,

02:17:55.660 | thank you for your interest in science.

02:17:57.760 | [upbeat music]

02:18:00.340 | [MUSIC PLAYING]

Dr. Shanna Swan: How to Safeguard Your Hormone Health & Fertility

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