How bad are microplastics?

24:06That's fine. That's helpful. You know, if some squirrel wants to use their, you know, long teeth on that thing, scrape some of that burnt oatmeal off the pan, like, please help us out, man. All right. All right. Some rabid raccoon wants to, okay. All right. So we have plastics everywhere. How long has this sort of been something we've known about? Like plastics came about in large quantities like 50, 70 years ago. Was it very soon after that that we discovered that they were everywhere? I mean, I think when plastics started to go mainstream, it was, you know, easy to see plastics rolling down the street on a windy day or something.

24:39Like I think we've been aware of macro plastics as a problem for a long time. We're not very good at disposing of them. They tend to end up in the oceans. They tend to end up in animals. So we've known that's been a problem for a while. And it probably didn't surprise anyone when we first started talking about the fact that it breaks down into tiny pieces. But the first time attention was really brought to this issue was when a marine ecologist named Richard Thompson wrote a paper about how he was collecting samples of sediment from beaches and estuaries in the subtitle zone in the United Kingdom.

25:12And he found microplastics in all of those places. And he looked at plankton samples. So these are like tiny little samples from the water column. And he looked at samples from the 1960s and then at various dates getting closer to the present. And he found microplastics back from the 1960s, but he also found that they were increasing over time and that even you could find them inside of the bodies of little invertebrates that live in the water. And so he noted that we don't know the environmental consequences of having this stuff in the water, but it's in the water. This problem is getting worse.

25:44But it still took about a decade before people started really digging in and particularly thinking about the impacts on human health. I love this example of digging through past samples collected for completely separate reasons and finding evidence or answers to a question you have later on. And this is why you should always keep all of your samples and all of your notes, because who knows how it's going to be useful later. This is incredible. I love that. This is why museums are so important, because they do they keep those samples for you and they're in a location where anybody can request them.

26:15So somebody in, you know, Peru can think of a question that requires American water samples from the 1960s or something. And if a museum has them, they can get those data. So anyway, yay for archiving materials. Yay for record keeping. Exactly. All right. So it sort of came to the fore in the early 2000s and then has the field sort of exploded in research? Yeah. The last 10 to 15 years, we've become a lot more interested in what it's doing in freshwater systems, what it's doing in oceans, what it's doing in our bodies. And let's take a break. And when we get back from the break, we'll start digging into that stuff.

26:57For business owners and entrepreneurs, there's a constant challenge, getting things done fast and done well. Why not have both? That's why Wix Harmony stands out. It's an AI website builder that helps create a website quickly without compromising your vision. A fully functional site can be built for any business just by describing the idea. Then you can choose to chat with AI or edit everything manually to get it exactly right. There's also Aria, an AI agent available to answer questions or help complete tasks. And here's what makes it even better. Aria doesn't just live in a chat box. You can click anywhere on your site and ask her to make changes instantly.

27:41It's these details that make creating with Wix Harmony feel seamless. Join millions of businesses already using Wix and try Wix Harmony for free at Wix.com slash Harmony. That's Wix.com slash Harmony. Introducing the all-new Mazda CX-5, featuring more connection. Hey, Google, where's the nearest Pilates class? Safety that has your back. More discovery on the scenic routes. more passion in the details and more control in changing weather. The all-new Mazda CX-5. More to move every side of you. See it in five films at mazdausa.com slash five sides. Google is a trademark of Google LLC. Sequences shortened and simulated.

28:26This July 4th, come celebrate at America's Block Party, hosted by America 250. America's Block Party is a can't-miss 4th of July concert happening at the Los Angeles Memorial Coliseum. Experience music performances by major artists, patriotic tributes, and the kickoff to Giving Fourth, helping to make July 4th the largest day of giving in American history. It's more than just fireworks. Join this landmark celebration and get your America's Block Party tickets now for$17.76 at America250.org. Hey, everyone. It's Cal Penn. I'm the host of Earsay, the Audible and iHeart Audiobook Club. This week on the podcast, I'm sitting down with Ray Porter, the narrator of Andy Weir's audiobook Project Hail Mary.

29:14Massive sci-fi adventure about survival and science and what happens when you wake up alone very far from Earth. I really had to make a decision because I caught myself getting that frog in my throat and starting to get teary as I'm narrating some of these sections. And it's like, OK, yo, yo, yo, is this indulgent? And I really thought about it. I was like, no, at this point, it would kind of be betraying the trust the author and the listener have in telling this story if I don't go through it. But there's places in this book that deeply emotionally affected me. And I left it on the mic. That's great.

29:48Because it served the story. People will say like, oh, my God, I cried at the end. It's like, yeah, dude, me too. Listen to Earsay, the Audible and iHeart Audiobook Club on the iHeartRadio app or wherever you get your podcasts.

30:12All right, so we have already established that microplastics are like everywhere. They're kind of unavoidable. And so let's start digging into, you know, whether or not we need to worry about that. So one thing that you maybe need to worry about a little bit is that they bioaccumulate. So you might have heard this word from Rachel Carson's book Silent Spring about DDT and how as you move up the food chain, you get more and more concentrated levels of these chemicals. And so an example for microplastics is that there was a study looking at the soil in Mexico and they found that microplastics were a bit less than one particle typically in each gram.

30:55But if you pulled an earthworm out per gram of earthworm, you would find almost 15 particles. So the earthworms were going through the soil. And as they would ingest a piece of microplastic, it was like staying in them. And then they looked at chickens that were eating the earthworms. And there were 130 particles per gram of chicken feces because, you know, chickens were eating those. And so as you go up the food chain for the same like mass, you're finding more and more of these particles. So why do the earthworms accumulate them? Is it because they get filtered out of the soil and they stay in the earthworms?

31:30Like there's something inside the earthworm that's like accumulating these things? So if you were to take a snapshot of what's inside of that earthworm over like a year of an earthworm's life, and I don't know how long earthworms live, it might not be a year, but like there might be a lot of particles that they ingested, but they pooped out. But because they're going through so much soil, if you take a snapshot, they might have about 15 particles per gram of earthworm because they're just moving through tons of soil and just sort of accumulating it as they go. But in order to accumulate it, they have to eat more than they poop.

32:03So they preferentially don't poop out microplastics, right? Otherwise, they would have the same density as the soil. Like if you just pass a tube through the soil, it's going to have exactly the same density as the soil. Unless there's some filter in there that's like accumulating the microplastics or preferentially not pooping them out, right? Yep. Yeah. That's a great point. You're right. They're accumulating them. They might poop some of them out, but in general, they tend to be accumulating them. Yeah, interesting. And so then the chickens eat those and then it gets more concentrated. And eventually when you're eating chicken, it's like half plastic.

32:35Yeah, not necessarily half plastic, but there's a fair bit of plastic in there. But one thing that's important to keep in mind is that not all plastic matters the same from a standpoint of ingesting it. So you can get plastics in your body either by inhaling it, because a lot of it goes airborne, or by ingesting it. And our bodies will defecate and urinate out a lot of the plastics that we consume. and if you breathe it in our what is it called our mucociliary elevator or something basically like we will like hawk it up and actually maybe matt wants to remove that uh sound effect i don't think so no i think you should keep that and i just wish that the audience could see the face you made i was pretty expressive there but uh but so you know you cough it up and then you can spit it out or swallow it and then it'll end up in your feces.

33:28And anyway, all very gross. But our body has ways of getting rid of a lot of this stuff. But if you've got nanoplastics that are small enough, they can pass across our alveoli, which is a point in our lungs where our lungs are sort of interfacing with our blood and they can get into our bloodstream or sometimes they can move across our gut into the rest of the body. So very small pieces can end up in other parts of the body where they're not going to get removed or they're much less likely to get removed. And I've heard it said that we eat like a credit card's worth or a bottle cap worth of plastics every year or every week or whatever.

34:01Is that true or is that people over worrying? There was a study that came up with that figure and that went like global, just like microplastics. It ended up everywhere. But there was another study that looked at the numbers a little more critically and they ended up deciding something like you would require 23 ,000 years or something like that to acquire the amount of plastic that that paper was estimating. And so I think what most of us have heard about plastic getting in our body is pretty overblown. But that said, they have found plastic in human brains. So this was they did autopsies. So somebody had already passed away and they looked through the brain to look for plastics and they found it.

34:45Plastics have been found in plaques in our arteries. So when your arteries are getting clogged, there's some little pieces of plastic in there, too. It has been found in testicles, kidneys, livers, like anywhere you can imagine maybe not wanting plastic to be. Plastic is there. And we found plastic in meconium. Daniel, do you remember? I mean, I probably said it wrong. Let's just be clear. But do you remember what meconium is? This is a word I only needed to know the definition of once or twice in my life. Oh, it sounds familiar. It sounds like mucus. Is it something gross inside the body? It's your baby's first poop.

35:21Oh, of course. Yes, of course. Meconium, I remember that now. It's weird looking. Yeah, yeah, yes. It's weird looking and it has plastic in it. And so that means it's probably microplastics or nanoplastics, probably nanoplastics, are passing from mom to the fetus. And the fetus is already, you know, defecating them out pretty soon. So we start our life with these microplastics with us. And we talked recently about water filtration systems and these amazing processes that clean up our water. Are microplastics too small to be filtered out? No. So about 95 % of the microplastics that go into the wastewater treatment plant are removed through the various processes.

36:03There's a lot of microfibers that go to wastewater treatment plants because a bunch of the wastewater that goes to those treatment plants is from when we wash our laundry. Or from like our shampoos and body washes and stuff. And our clothes, every time we wash them, are shedding loads of microplastics. And so lots of stuff gets to the wastewater treatment plants. About 95 % of it gets removed. Sometimes the sludge that gets collected at some of these plants will get used for other purposes, like as a fertilizer. And in that case, the microplastics could get back into the environment. But if they're just put in a landfill, they're probably going to be fine.

36:39But a lot of them do still get through these wastewater treatment plants. And there were some data from 2014 to 2016 that estimated that something like 8 to 13 billion pieces of microbeads were being released from treatment plants into freshwater systems every day. And we're trying to use fewer microbeads, but there's still a bunch of these getting into our freshwater systems. But they also get into freshwater systems or our oceans through other routes. For example, a huge source of plastic is our tires. And so when we drive, we're wearing some of the plastic off of those tires, and that ends up either in the air or sometimes it ends up on the side of the road.

37:18And then the next time it rains, it takes those little pieces of plastic into our rivers and our lakes. And then in some cases, it brings it to our oceans. And so, yeah, those are some major sources of plastic into our aquatic systems. And so it's everywhere, and we found it in our bodies, including our brains and all the other important bits. Why is this an issue or is it an issue? Or why might it be an issue for our health? Yeah, so we're not super clear on it. First, I want to say that we've done some experiments on fish, and the fish seem to get kind of messed up. So fish end up, you know, they eat the little invertebrates that eat the microplastics, and then they accumulate it in their own body.

37:58And we found that microplastics can mess with things like how the fish move. It can damage their intestines. I think in some cases we found that it reduces their growth. And it seems to reduce their growth because it essentially like takes up space in their gut and they like feel like they've eaten, but they haven't eaten anything that's nutritious. And so, you know, they lose weight and that can impact their reproduction and stuff like that. So we know that there are some examples where it's been a problem in fish, but fish are swimming in this environment with loads of microplastics. So that might not tell us what we need to know about people.

38:30So here are some of the top issues that we worry about for microplastics. One of the main issues that we worry about is that these microplastics tend to attract and stick to other stuff in the environment. So, for example, they stick to heavy metals, PCBs, which are polychlorinated by phenols and some other kinds of toxic material. And they get what's called sorbed by the plastic. Not absorbed, not adsorbed, just sorbed. I think it's sorbed. Is that what the kids are saying these days? Wow. That's what the science kids are saying these days. Very generous to call us kids. So they pick up these toxic compounds, and then when they get into your body, they could release those toxic compounds.

39:20And so while a piece of plastic on its own might not cause a problem, if it's bringing, for example, mercury into your body and then depositing the mercury, the mercury could be the problem. Does that make sense? Yeah, absolutely. It does. Yeah. Other things that tend to stick to these fibers include bacteria. And there's some concern that the way bacteria aggregate, they form like biofilms where maybe they could be sharing like antibiotic resistant genes or something. This sounded a little bit more speculative from what I could tell, but bacteria stick to them and so do viruses. And so these pieces of plastic could be ways that bacteria and virus make it into your body.

39:57So basically they're dirty. They're not just weird and artificial and everywhere. They're dirty. They are. But this also contributes to why they're so hard to study, right? Because whether or not plastic is bad for you is going to depend on what the plastic saw before it went to you. So like the same kind of plastic in an environment with no mercury might do nothing. But the same kind of plastic in an environment where it can pick up mercury and then get to you could cause a lot of trouble. Yeah, exactly. And these things must be easier to study in the lab. And then that doesn't really answer questions about what happens in reality where most of us live.

40:31Amen. Yes, it gets super complicated. So then another thing that makes it all complicated is that added to the plastic are chemicals that help you, for example, make plastic that are soft and are like easier to move. So for example, if you think of your water bottles, you can squeeze those, it bends a little bit. But then there's other chemicals that make plastic stiffer and harder. So for example, if you have a Nalgene bottle, when you squeeze that, it doesn't have much give. And so these chemicals that we add to the plastic can also cause problems in addition to the plastic. So, for example, there is a class of chemicals called phthalates.

41:11What? It's P-H-T-H. What? P-H-T-H? That's not allowed. No, not in the English language it shouldn't be. But so I'm just going to phthalates. I'm just going to call. I'm going to pretend the P is silent. The P-H is silent. And these tend to be used to soften plastics, and they're pretty common in our bodies. So there was a survey done, and eight to ten out of the babies surveyed had phthalates in their body, and nearly all of the adults that were surveyed had them too. And this chemical is associated with reduced sperm count and motility. No. I know. I don't like that. That's not good. No, but the results here are mixed.

41:51So, like, if you were making a million sperm and now you make 950 ,000 sperm, should you care? And the answer is maybe. Those are 50 ,000 of my boys we're talking about here. You weren't going to make use of all those boys anyway, Daniel. So there was a study that was looking at, like, people who had various amounts of exposure to this stuff and how long it took for them and their partner to get pregnant or for, you know, for the woman to get pregnant. Yeah. And it looked like there wasn't necessarily an association between exposure to a certain kind of phthalate and how long it took to get your partner pregnant.

42:30And so the point is maybe sperm counts are lower, but that doesn't necessarily result in infertility issues all the time. All right. But sperm counts, I think, are dropping anyway, right? And we've been talking about how there's fertility issues already. So anything that pushes sperm counts lower is definitely not going to be good for fertility, right? I think you're arguing that this is a small effect, but still a small effect on average can have some measurable impact on the number of babies born, right? Yes. And there are some communities who would argue that a big part of the decline in fertility could be because of things like plastic-related chemicals in our water or whatever are being ingested with the food that we eat.

43:10And so, yeah, it could play a role and it could play a role in aggregate. Maybe it's just playing a small role in that overall trend. And there's some work done in lab animals like mice that do find definitely quantifiable impacts from exposure to phthalates on the mice. And so the question is, if a mouse has infertility, does that mean that a human is going to have infertility? We don't necessarily know. And often animals in the lab are exposed to much higher concentrations of the chemicals than we are exposed to on a day-to-day basis, for example. And so it's hard to know how to tie those things together.

43:45But there is some risk that these chemicals are having some impacts on fertility related issues. But we don't really know how much we should be worried about this happening for humans yet. All right. So Kelly's given us two reasons to worry so far. They can trap stuff. They can be toxic chemicals. When we come back from the break, we're going to hear about more reasons to worry, including Daniel's number one reason to worry about microplastics. Oh.

44:20For business owners and entrepreneurs, there's a constant challenge, getting things done fast and done well. Why not have both? That's why Wix Harmony stands out. It's an AI website builder that helps create a website quickly without compromising your vision. A fully functional site can be built for any business just by describing the idea. Then you can choose to chat with AI or edit everything manually to get it exactly right. There's also Aria, an AI agent available to answer questions or help complete tasks. And here's what makes it even better. Aria doesn't just live in a chat box. You can click anywhere on your site and ask her to make changes instantly.

45:04It's these details that make creating with Wix Harmony feel seamless. Join millions of businesses already using Wix and try Wix Harmony for free at Wix.com slash Harmony. That's Wix.com slash Harmony.

45:38The all-new Mazda CX-5. More to move every side of you. See it in five films at mazdausa.com slash five sides. Google is a trademark of Google LLC. Sequences shortened and simulated. This July 4th, come celebrate at America's Block Party, hosted by America 250. America's Block Party is a can't-miss Fourth of July concert, happening at the Los Angeles Memorial Coliseum. Experience music performances by major artists, patriotic tributes, and the kickoff to Giving Fourth, helping to make July 4th the largest day of giving in American history. It's more than just fireworks. Join this landmark celebration and get your America's Black Party tickets now for$17.76 at America250.org slash LA.

46:21Hey everyone, it's Cal Penn. I'm the host of Earsay, the Audible and iHeart Audiobook Club. This week on the podcast, I'm sitting down with Ray Porter, the narrator of Andy Weir's audiobook Project Hail Mary, massive sci-fi adventure about survival and science and what happens when you wake up alone very far from Earth. I really had to make a decision because I caught myself getting that frog in my throat and starting to get teary as I'm narrating some of these sections. And it's like, okay, yo, yo, yo, is this indulgent? And I really thought about it. I was like, no, at this point, it would kind of be betraying the trust, the author and the listener have in telling this story if I don't go through it.

47:04But there's places in this book that deeply emotionally affected me, and I left it on the mic. That's great. Because it served the story. People will say like, oh my God, I cried at the end. It's like, yeah, dude, me too. Listen to Earsay, the Audible and iHeart Audiobook Club on the iHeartRadio app or wherever you get your podcasts.

47:36Okay, we're back and we're talking about all those little bits of plastic that are everywhere in the earth and in you. Right now, swimming through your body are hundreds, thousands. How many bits of microplastic are in each of our listeners, Kelly? Oh, that would be very hard to quantify. I don't know exactly how many pieces are in each of us. We want numbers. I want an individual list of numbers for each listener. Okay, well, give me a lot more money. And also, there's going to need to be a lot of slaughter, because to get those numbers usually requires an autopsy. So let's just say we probably all have at least a microplastic piece in us.

48:09And that's probably quite an underestimate. All right. But it sounds like if you really want to know, and you're willing to volunteer for an autopsy, Kelly will give you a solid answer. Nope. That's a no. Okay. That's a no. Do not ship your body to Kelly to get an answer to this question, turns out. Nope. All right. Nope. Oh, so wait, you said you were going to tell us your number one fear from microplastics. So go ahead. Let's hear that. Yeah. Well, my number one reason to worry about microplastics is we don't understand the body. It's a big, complicated system, and there's lots of things that we do to it all the time that we don't understand how it works.

48:41Like, I think Tylenol, still not fully understood. Why does Tylenol work? Or why do all these psychoactive medications work? And so there's just a lack of a mechanistic understanding of how the body works. So it seems to me like you just throw a bunch of plastic in there. You can't predict what's going to happen. And so many weird and terrible things are happening to people all the time. It's hard to know how much of this is due to eating plastic or not eating plastic. And so to me, the number one concern is something we can't predict because the system is too complicated. And I think that is absolutely spot on.

49:15Yeah, I totally agree with you. And one point that I want to go back to really quick, we were talking about phthalates and their possible impacts on the human body. I want to be clear that we do know that at very high doses, at high exposure, these things definitely are bad. So the question isn't phthalates, good or bad. The question is phthalates at very low concentrations, are they bad enough that we want to give up all of the benefits we get by having phthalates? And there's another chemical that we have the same discussion, and that chemical is bisphenol A. And just like with phthalates, we don't totally understand whether we need to be worried about it and how much we need to be worried about it.

49:55But we know that bisphenol A acts like estrogen in the body. So in some cases, it mimics estrogen, making your body think there's more estrogen. And in other cases, it will like bind to receptor where estrogen should be. And now estrogen can't get to it. And so your body should be getting a message from estrogen. And that message isn't going through. And so this is a great example. People are like, BPA, what could it do? it's probably fine. Oh, it turns out maybe it's not fine. Yeah. And there was a study that found that about 93 % of people have BPA in their urine. So just about all of us are exposed to it.

50:28And for all of these chemicals, you might be most worried if a fetus or a baby is being exposed when like tons of development stuff is happening. And so there were rules saying like, hey, look, we need a lot less bisphenol A in things like baby bottles because we're worried about what tinkering with estrogen could do. There's some evidence that it's associated with increased blood pressure, type 2 diabetes, cardiovascular disease long down the road. It also can impact the brain and the prostate gland of feces and stuff. Lots of reasons to worry. You said prostate gland of feces, but I think you mean fetuses.

51:03I did. Feces? You just got poop on the brain. I get it. No, I do. I do. Sorry. The brain and prostate gland of fetuses. Not feces. Anyway, lots of reasons to worry. So we tried to cut down on the use of bisphenol A. But the problem is that this chemical is really helpful for making plastics stiffer and harder. And so we've replaced bisphenol A with something that has a very similar shape because we want that same shape so that we still get our nice hard plastics. So we've replaced it with, for example, bisphenol S. And we think that actually maybe this other thing does a lot of the same stuff to our body that bisphenol A does.

51:43So when you see a bottle that says doesn't contain BPA, that doesn't mean that it doesn't contain a very similar bisphenol thing. So yeah, it's hard to replace these things while still keeping the plastics we love doing the things that we love them to do. I love those indications on food that make you feel like, oh, it's healthy. Like when you look at Jolly Ranchers and they say fat-free. And you're like, yeah, that's because it's 100 % sugar. That's right. That's right. Doesn't make it a health food. I like things that are like cholesterol-free. I'm like, well, yeah, because it couldn't have cholesterol in it because we know where cholesterol comes from.

52:20And it's like, no rat feces in this. It's like, well, it shouldn't have rat feces. And what does that imply about the other material? Anyway, it's a... But I do appreciate the nuance here that you could say, let's just get rid of all of it. But you're right that plastics have improved our lives and there's positivity there. And it sounds like we're being shills for big microplastics, as ironic as that name is. But it's true that you wouldn't want to just get rid of plastics, even if there is a cost to human health, because it also saves lives, right? Having these medical supplies, et cetera, et cetera, does save lives.

52:55And so really the question, as always, is a nuanced one. It's like, does it do more harm than good? Yeah. And so let's dig in for a second into all the reasons why it's hard to really understand why this stuff is bad for people. So, one, we talked about how you can cough, sneeze, poop, or pee a lot of this stuff out. So just because you're exposed to something like bisphenol A doesn't mean that your body isn't going to excrete it before it causes any damage or break it down before it causes any damage. But maybe it is causing damage. And so we need to research this a lot more to figure out how we get exposed to it, how our bodies respond to it, how much of it is bad.

53:33But there does seem to be a move, for example, in Europe to decrease the amount of allowable things like bisphenols because we are deciding as the data comes in, oh, this is a little scary. We don't want to risk it. The other problem is that plastics come in loads of shapes and sizes, and some of them are more likely to get into our bloodstream, for example, than others. and when they break down, they break down into thousands of different chemicals, many of which we haven't looked at for health impacts yet. So it could be that like 90 % of plastics are okay, but there's 10 % that break down into super toxic stuff and that's what's causing the problem.

54:10Or maybe all the chemicals that it breaks down into are bad. I don't want to sound like you've got me worried now that I sound like I'm a shill for big microplastic. This stuff is complicated and you need to decide on your own how worried you are about it. We also don't have very good methods for counting and quantifying plastics in the human body. I mentioned that you can look at this stuff during an autopsy, but then once you've got these nanoplastics that you've collected from an autopsy, how do you know what kind of plastics they were in particular and what about it was bad? So, you know, maybe one plastic in the brain has phthalates attached to it and one has bisphenol A And how do you quantify the like total impact of all of that on our bodies?

54:53It's very complicated when there's lots of stuff interacting. And one thing that also makes it complicated is that for things like bisphenol A, this old phrase, the dose makes the poison doesn't really stand. So for things like mercury, probably the more mercury you ingest, the worse it is. We don't want to have a lot of that. But with a lot of hormones, they have this weird way of interacting with our body where low doses and high doses can have the biggest impact, but intermediate doses sometimes have low impact. So it's almost like the letter U if you're looking at it on a graph. And so it's not necessarily the case that more and more and more and more is worse, but having a little bit could be really bad or having a lot could be really bad.

55:37And so it just makes it even harder to figure out these associations and try to get a handle on how bad and what doses are OK for people. OK, so then give me a overview of like potential things to worry about in terms of effect on human health. I'm not going to have more kids, so I don't really need to worry about my boys swimming anymore. But beyond fertility, what concerns are there for human health? OK, so again, we don't really understand the mechanism totally for some of this stuff. But one concern is that there might be earlier puberty. So, for example, from the 1970s to today, I think puberty has moved up by something like a year on average.

56:16And so the question is, do having all of these chemicals that mimic estrogen in the environment, is that, for example, moving up puberty time for women? And women who enter puberty earlier, I believe they have a higher risk of things like breast cancer later on. So there could be bigger implications than, oh man, I've got my period a year earlier. It could have more health impacts down the line. There's also some proposed link between obesity and microplastics. So obesity has increased in the United States, you know, roughly along the line as our increasing use of plastics. But a lot of things have changed about the United States over that amount of time, too.

56:57You know, it's probably easier to get fast food and less healthy food. So it's really hard over time to tease these things apart. But plastics could be playing a role because we have seen that some kinds of plastics and the chemicals that they carry into our bodies change the way our bodies metabolize food and the way our bodies make fat cells and stuff like that. And we found that lab animals and domestic pets are more likely to be obese as well. And those are animals that are exposed to plastics a lot because of us. And so, you know, maybe we're seeing an indirect effect in our lab animals and our pets.

57:32Though we have to be very cautious in concluding anything from correlation studies, right? Because these things could just be random. I don't know if you've seen the correlation between ice cream and murder. It's very tight. It doesn't mean ice cream causes murder. It means you tend to have ice cream more in the summer and people tend to commit murders more in the summer. Maybe because they're not getting enough ice cream, actually. So maybe ice cream suppresses murder. Who knows? That's right. I think we probably all need more ice cream. Now we're big shills for ice cream. Great. I'm okay with that.

58:01That I'm okay with. Microplastic-free big ice cream. All right. There you go. So we're worried about puberty. We're worried about obesity. What else should we be worried about? There's some concern about cardiovascular issues. So, for example, there was a 2024 paper in the New England Journal of Medicine where people went through surgeries to remove plaques in their arteries. So this is like removing the buildup of stuff that was clogging up the stuff in the arteries leading to the heart. and after they removed that stuff, they put it under a microscope and they looked to see if there were microplastics in there.

58:33And about half of the people that they looked at had microplastics in there. A couple different kinds of microplastics. They tried to quantify the different kinds. But then they followed those people for 34 months after the plaque was removed and the people who had microplastics in there were more likely to have encountered a myocardial infarction, a stroke, or death. Essentially, their heart was likely to have some additional problems in the like year and a half or more after plaque removal if those plaques had plastic. Infarction is a word. It's not just a typo for infraction. An infarction is an obstruction of the blood supply to an organ or region of tissue, typically a thrombosis or embolus causing local death of the tissue.

59:16So yes. It's also a word that for some reason is just hilarious. It's a word like weasel or booger. Infarction. It just sounds funny to me. I don't know. I know it's not funny when it kills you, but it's a funny word. Yes, yeah, yeah. A booger is funny when it happens to you, and infarction is not. Maybe a booger is not funny depending on the context. But anyway, it makes me laugh. So you mentioned that a problem with observational studies is that you don't know what is causing the correlation. So, for example, it could be that the people who had microplastics in their plaques are people who were more likely to, I don't know, get McDonald's that are in those like plastic wrappers.

59:56And, you know, something about their diet resulted in them having more microplastics. And then they didn't change that aspect of their life after the surgery. And that's what led to the problems they had down the road. So it's really hard to tease apart cause and effect and what is causing this problem when you're looking at an observational study. All right. So there's lots of reasons to worry, but we don't have a great mechanistic understanding or really an idea for what problems could be caused. So what can we do? What are your prescriptions for improving our lives? Yeah. So I'd say that the emerging picture is that there are reasons to potentially worry.

1:00:36There's always reasons to worry, Kelly. There's always reasons to worry. I know. And so you can decide how concerned the information we've talked about, how concerning that is to you. But there are some things you can do in your day-to-day life to protect the environment. Let's start with those. So one, there are like filters that you can get that go on your laundry machine to collect some of those microfibers so that they don't go into the wastewater treatment plant and then they don't go into the ocean. You can, you know, try to buy clothes that are meant to last a little bit longer so that you're not buying as many clothes.

1:01:08And that would result in less, you know, microplastics. You could take public transportation so that you're not wearing out your own tires. There's lots of little things that you could do. You could invent flying cars so we don't need tires anymore. Well, I think some people are working on devices to collect plastic as they get released from tires. And that seems like it could be pretty tough. You'd maybe never get all of it. But, you know, you could try to work on technologies that make this stuff easier to remove from the environment. But if you're worried about your own personal risk, some things that you can do include eating from glass or metal containers instead of plastic.

1:01:44If you have Tupperware containers, don't wash them in your dishwasher because that gets really hot. It starts breaking down the plastics. Those microplastics could come off in your food. Things like vacuuming regularly are important because you're dropping plastic fibers all the time from your clothes. And they end up on the floor and then they can get kicked up into the air as you're walking around. Maybe not drinking bottled water because those tend to have plastics. But there's also plastic in tap water. But if you get a reverse osmosis filter, you can take some of it out. But those are expensive.

1:02:16And if you remove the microplastics, you're also removing minerals and salts and stuff. And you might want to add some of that stuff back in. A lot of this stuff is complicated, so you need to decide what are your most likely exposure risks and how concerned are you? Because, again, there are tradeoffs. Maybe a lot of this stuff at doses, you know, like I live in the middle of nowhere. I don't probably breathe in a lot of tire stuff. My water comes from the ground, and while groundwater does sometimes have some plastics, my groundwater where I am probably doesn't have a lot of it. So we should all move in with you, it sounds like.

1:02:50I mean, no. No, actually. because then it wouldn't be quite as pristine. But anyway, I'm not too worried about my exposure to plastics because I use a lot of ceramic and stainless steel stuff. So I'm not too worried. But you should think about the various ways you encounter plastic in your life and then decide if you are concerned or not and if you want to make any changes. It's up to you. And as is my habit, the night before we record, I usually ask Katrina what she thinks about an episode just to hear if she has some ideas. So I asked her what she thought we could do to reduce our microplastics.

1:03:26And here's what she had to say. Well, eating fiber forms a matrix that will protect you from all toxins. Think of it like a Brita filter where it's sucking up the toxins and preventing them from being absorbed into your body. So if you're eating fiber, then you've got this gel that sticks with you down to your colon. And if there's also microplastics in your food and water, it gets sucked up into that so that it doesn't get absorbed by your intestinal cells. So Katrina's big on fiber, so maybe no surprise that she prescribes fiber for everybody. Yeah, I was going to ask if the answer to every question in the Whiteson household is beans.

1:04:04Beans, chia seeds, beans, fiber. It's good for you. She's just rooting for the microbes inside everybody to help with the microplastics. Well, we could probably all use more fiber anyway. And there are some studies in mice, for example, that find that microplastics disrupt the gut microbiome. So fiber can help you in the battle against plastics in a lot of different ways. And so, you know, I want to be clear throughout this episode, you know, I've tried to make sure I was including caveats about whether or not this is likely to be important. Like, I don't want people to be freaking out. There are some reasons to be concerned, but at the moment, there's just so many different places we can encounter plastics and so many different kinds of plastics and so many different contingencies that matter, like where the plastic was before it got to you, that we just don't have a very good handle on this problem yet.

1:04:51And this is all the more reason to invest in basic science so we can try to understand this better. But like so many risks in life, you got to kind of decide for yourself, how concerned am I going to be given what we know about this? So don't worry too much. Don't worry too little. Worry just the right amount. That's right. Just the right amount. Good luck with that. And the reason we talked about microplastics today is because a listener sent us an email saying, I would love to know more about microplastics. So I sent this episode to them and let's see what they had to say. Plastic is a wonderful material in all its different applications and all the different fields where it's an essential material.

1:05:34although I do believe that we need to be more picky how we use plastic and we need to cut some products from our lives, especially the disposable single-use ones that are quite unnecessary, I believe. I'm deeply concerned for the effects microplastics have on smaller creatures, especially ocean creatures, as you mentioned in the episode, and the effects that they may have on their larger food chains and ecosystems. It might sound bleak, but I'm less so concerned for the effects on human health as we are, of course, the responsible ones. But thank you, Daniel and Kelly, for the episode. It was informative.

1:06:24I learned some new things. And thank you for picking my suggestion. Thank you very much for that feedback. We did end up focusing a lot on human aspects of impacts of microplastics, but there's definitely evidence that microplastics in aquatic ecosystems are bad and impact a variety of different organisms in negative ways. So I think at a minimum, it would be important for all of us to think about how we can cut back on plastics in our lives, and we should think about what we're doing to organisms beside ourselves. So yes, thank you for making that important point. All right. Well, thanks everyone for sending in your questions and for being curious about the nature of the world.

1:07:04Though we don't have a clear prescription about how you should live your life, at least now you're better informed about what we do and don't know about microplastics.

1:07:18Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We would love to hear from you. We really would. We want to know what questions you have about this extraordinary universe. We want to know your thoughts on recent shows, suggestions for future shows. If you contact us, we will get back to you. We really mean it. We answer every message. Email us at questions at danielandkelly.org. Or you can find us on social media. We have accounts on X, Instagram, Blue Sky, and on all of those platforms, you can find us at D &K Universe. Don't be shy. Write to us.

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