Science Vs - Is There Really a Plastic Spoon in Our Brains?

Episode Date: May 8, 2025

Headlines are screaming that we have tons of microplastics in our brains — the equivalent of an entire plastic spoon. OK, that sounds terrifying, but is it true? We talk to chemist Prof. Oliver Jones.  Find our transcript here: https://bit.ly/PlasticSpoonBrain  In this episode, we cover: (00:00) A plastic spoon’s worth of microplastics?! (05:21) Something dodgy here? (17:39) So how much plastic is in our bodies, really? This episode was produced by Rose Rimler, with help from Wendy Zukerman, along with Ekedi Fausther-Keeys, Meryl Horn, and Michelle Dang. We’re edited by Blythe Terrell. Mix and sound design by Bobby Lord. Fact checking by San Lemonick. Music written by Peter Leonard, Emma Munger, So Wylie, Bumi Hidaka, and Bobby Lord. Thanks to all the researchers we spoke to for this episode, including Dr. Roger Kuhlman, Prof. Martin Wagner, Dr. Elke Fischer, Dr. Marie-France Dignac, and Rachel Kozloski.  Science Vs is a Spotify Studios Original. Listen for free on Spotify or wherever you get your podcasts. Follow us and tap the bell for episode notifications. Learn more about your ad choices. Visit podcastchoices.com/adchoices

Hi, I'm Wendy Zuckerman and you're listening to Science Versus. So there are a lot of scientific papers out there that you will never read and that I will never read and only nerds really know about them. But every now and then there is a scientific paper that will break out of the ivory tower and go viral. You see it all over the news, it's all over your feed. And sometimes these papers make these very extraordinary claims that, I don't know, maybe sound a touch dodgy,

it's hard to know what to make of them. And that is where our brand new segment, Viral Papers, comes in. And here with our very first Viral Paper is Science vs. Senior Producer, Rose Rimla. Hi, Rose! Hi, Wendy. I also have the honor of debuting the jingle for this new type of episode,

which I know you had asked our very talented sound engineer to mix up a jingle. He sent it to me and I have it here for you to listen to. Yes! So I was thinking the jingle could be something like... Viral papers, viral papers, they're everywhere, but something's gone wrong. Oh, that was just a suggestion.

I didn't think it was going to be the... I didn't think it was... A good idea is a good idea, you know? You can't just throw out a great melody like that. Or vocal performance. I thought it was a Greenlight brainstorm session. Oh, well, I hope everyone's excited. They should be excited.

Because today we're going to talk about a paper that makes a very extraordinary claim. I'm just going to play you some of the headlines here. The new study has found an alarming amount of plastic in our brains. This morning, a new study is raising concern about microplastics after researchers found an entire spoon's worth inside samples taken from human brains. And get this, when they looked at the average brain, the amount of microplastics in the brain

was equivalent to the weight of a plastic spoon. Yeah, this was everywhere. New York Times, CNN. Yeah, it got a lot of American press, but internationally, it was everywhere. New York Times, CNN. Yeah, it got a lot of American press, but internationally it was everywhere. It was, you know, down in Australia where you are, India, Brazil, Mexico. We have the equivalent of a spoon of plastic in the head.

France. The equivalent of a small spoon of plastic. It got a ton of attention on socials as well. And that's because it sounds terrifying, right? You and me and everyone you meet has enough plastic in their f***ing brain to make a spoon. If that doesn't scare you into changing everything from plastic, then I don't know what will. Yeah, I mean, the idea that a plastic spoon is sitting in our brains, yeah, very potentially scary.

What's it doing in there? How is it affecting our behavior, our health? Yeah, but you know, Wendy, my reaction here was less alarm and more like, really? Like I was very skeptical. Tell me more. Well, we did this episode about microplastics last year. And in the course of working on that episode, I just came across a lot of bullsh**,

including like bullsh** in the science and papers. We're talking really sloppy math and overestimates. There's even a case where it looked like the scientists forgot to convert kilograms to milligrams and then they overestimated this thing that they were trying to estimate by six orders of magnitude. What? That's a primary school era. Yeah.

You forgot to convert? It's like that Simpsons episode where they're like, oh, sorry, I forgot to carry the wand. Yeah, exactly. There's also all that stuff about how much of the chemicals and black plastic cooking utensils were leaking into our food. Yeah. That made a big splash. People were throwing out their spatulas.

But turns out that those researchers also screwed up their math. And in fact, the chemicals that are leaching out of the utensils are way lower than what first got reported. So I'm just skeptical of this whole field. Which takes us to the plastic spoon paper? Yes, and as it turns out, the science here is also kind of fraught. Actually in a way that has big implications for a lot of the headlines that we see about microplastics. So let's get into it. What is going on?

headlines that we see about microplastics. So let's get into it. What is going on? Do we all have an entire spoon's worth of plastic lodged into our brain? Coming up after the break, do you want to sing us out with the jingle, Rose? As wonderful as that melody was, I don't remember it. I would have to listen again. Wasn't an instant earworm?

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Stand Up Against Street Harassment by L'Oreal Paris with Right2Be. We're worth it. Get trained at standup-international.com. Hey there. Do you like learning wild and wonderful new things about science? Well, have I got a show for you. I'm Rachel Feldman, the host of Scientific American's podcast, Science Quickly. Every Monday, Wednesday, and Friday, Science Quickly offers bite-sized deep dives into the latest breakthroughs in science and tech.

Whether you're into sexual health or supernovas, quick news roundups or immersive narratives, we've got you covered. Check out Science Quickly on your favorite podcast app today. We promise we'll make it worth your time. Welcome back. Today on the show, Rose Rimla, senior producer, has been smelling something fishy in a scientific paper that claimed to find a lot of plastic swimming around in human brains. So where do we begin?

Well, we've been hearing about microplastics for years. We've been hearing that they're all around us, that they're in our food, in our water, and even in the air that we breathe. Right. And now we're hearing that they might be getting into our bodies. And that's alarming, you know, because we know that plastics kind of come hand in hand with endocrine-disrupting chemicals. We talked about this in our episode last year.

That's right. The chemicals can interfere with our hormones. Yeah, there's also early evidence that microplastics could irritate the immune system, like causing inflammation. So we don't want a lot of microplastic in our bodies, even beyond the fact that it's gross. Like, that could be really bad. Yes. So we have good reasons to not want a spoons worth of tiny microplastics in our brain. Yeah. I mean, believe it or not, yes. Science is on our side with that gut feeling. So let's dive into this paper. Let's find out what's going on here.

I talked to a bunch of scientists about this. One person I spoke to was a professor of chemistry named Oliver Jones. He is at RMIT University in Australia. Do you remember when you first heard about this paper that said there's enough plastic in the human brain to add up to a plastic spoon? Yes, I remember reading it. I thought it was pretty un-likely to me once. I was a bit suspicious when I saw the headline. Like our old friend Rose here.

Yes, yeah, just like me. He thought to himself. Was that actually true? So why suspicious? Well, to understand that, you have to understand exactly what these scientists did. So they got little pieces of brain tissue from dozens of people who had died for a variety of reasons.

And they were looking for evidence of plastic in these tissue samples. And the way to do that is, you know, there's no magic wand that you can wave over a tissue sample and it beeps like, boop, boop, plastic detected. There's nothing like that. So what these scientists did is they used this technique that's called pyrolysis, what is it? Pyrolysis, I can't say that. Pyrolysis gas chromatography mass spectrometry. Pyrolysis gas chromatography mass spectrometry.

Which I feel like I could imagine there's like a Lin-Manuel Miranda rap to be written about. Gas chromatography mass spectrometry. So I've got my brain tissue. Yeah. And how do I put it through the pyrolysis? Gas chromatography. Yeah. Well, the very first step is pyrolysis,

which is what it sounds like. Which is essentially burning the sample so that you get a smoke coming off, right? So then you've got a gas sample? Yeah, so they literally get these bits of brain and then burn them. And the game is to try to search for evidence of plastics in the gas that comes off. Oh, that's cool. So you take the smoke that you've created, you run it through a machine, that's the gas chromatographer. It separates and sorts all the different components of the gas,

all the separate molecules. And then the mass spectrometer weighs those molecules. And that helps scientists identify them. Mmm, okay. Yeah, it spits out something that looks like a chart, where all the molecules that are present in the sample are broken down by weight. So the scientist gets this printout that looks like... It's a lot of lines of different lengths. And then, so then what do you do with that? How do you go from that to like, oh, this

is what the material is? So well, each bunch of lines, so to speak, is sort of like a fingerprint. Aha. So they're looking for the fingerprints of plastics within those brain samples that they just burnt up. Yeah, basically. They're looking for the molecular weights of different types of plastic. And in this study, they reported that they did find this in these brain samples. In particular, they said that they found evidence of a lot of polyethylene.

And that's the kind of plastic used for plastic packaging and plastic bottles and stuff like that. Yeah, that does sound scary. Yeah. Yeah. And to lay people like us, that sounds pretty irrefutable at first. It's like, dang, okay, they found plastic bits in these brains. But there's a problem here. Remember that the first step of this process was the pyrolysis, the burning part? Oh, that was the funnest part.

So of course you remember. The thing is that when you burn your sample up, you've changed its identity from what it was originally. So what was initially polyethylene, for example, would now be a handful of different molecules. And the problem is there are other materials that can break down into those same molecules when they're burned. So it's kind of like if you had a bunch of baked goods, muffins, loaves, soufflés, I

don't know, anyway, and then you burnt them all up and put them through your pyrolysis spectrometer, whatever, and then on the line it all just looked like flour or something. Yeah, it's like if you were to see a line for flour and you're like, aha, I know this was a souffle. You're like, well, no, it could have come from something else. It could have come from the pie or something. Yeah, I guess I'm going with it, so I'm approving that analogy. Excellent.

And bringing this back to plastics. Yes, yes. So here's what the polyethylene could get mistaken for. That's kind of a big problem. Fat. And here's Oliver. The fingerprint of fat is very similar to the fingerprint of polyethylene. They look so similar that it's quite easy to mistake one for the other.

Oh, this is a big deal because the brain is full of fat. Exactly. The brain is very fatty. Uh-huh. That feels like a huge problem. So I asked Oliver, could this supposed plastic spoon in our brains just be normal human fat? Yes. I think the majority of it. Wow.

What's more likely that I actually have a plastic spoon's worth of plastic in my brain or there's a measurement issue from a technique that I know has issues with measuring plastics? I mean, dang. That's a big problem, right? Yeah. Yeah. So that headline could have just been human fat in the brain. Human brain has human fat in it. Yeah, it doesn't really have the same ring to it. No.

And it's not just Oliver that's raising alarm here. There's a group in Australia that was so concerned about the problems of this technique that they really put it to the test. They spiked blood samples with microplastics, so like they had a known quantity of microplastics. They put it in the blood and then they ran this analysis to see, could it accurately read how much was in there? And they found that it couldn't. And actually they concluded that this technique is, quote, unsuitable for looking for these

particular plastics in our bodies. So what did the authors of that plastic spoon paper say about this general problem, that you can't tell the difference between healthy fats and plastics? Well, yeah, so I reached out to them and they did acknowledge to me, this is a quote, that the paper is a single study and the science is nowhere near settled. But they also say that they tried to solve this problem by trying to remove all the fat in their samples before they put the samples through the spectrometer at all. So basically before they burned it up, they soaked it in a solution to break down all

the organic matter and then they centrifuged it to get rid of that stuff. Oh, that seems smart. So they thought they got rid of all the fat, so anything they're saying is truly plastic. Yes, but other scientists I spoke to were skeptical that they did work or that it worked well enough to get all the fat out, like not even a little residue left behind. to get all the fat out, like not even a little residue left behind. And just in general, more and more scientists are looking at this technique and they're saying, hold up. You know, one scientist I spoke to, he was very blunt. He said that papers that look for microplastics in human tissues

using this technique are, quote, garbage. Ooh. And the thing is, a lot of the studies that you see that say things like microplastics are in our testicles or this or that part of the body, they use this technique. Mmm. Okay. And in our microplastics episode, we talked about blood.

Having microplastics in it. Are you now questioning that paper? Yeah. That paper, that was, we looked at a paper that found microplastics in the arterial plaque that got scraped out of people's arteries. And that, I'm sorry to say, did use this now controversial technique that we just shit all over. Uh-huh. Okay.

Interesting. When I asked the authors of that paper about this problem, they pointed to the fact that they had looked at their samples under a powerful microscope, and they had seen what looks like little jagged pieces in the cells, which they think must be bits of microplastic. So they argued that that meant their findings were legit. Mm-hmm.

And interestingly, the plastic spoon brain paper did the same thing. They also looked at their samples under a microscope and they also saw some irregular shaped pieces and think that they're plastic. But the truth is that we don't actually know what those bits are. And even if they are plastic, it doesn't mean they got in there from the person eating or inhaling microplastics while they're alive. What do you mean? It could be this other very simple but very like infernal problem that researchers in

this space have to deal with. And that is the problem of contamination because these samples, they're analyzed in a lab and labs are full of plastic. Oh. You've got plastic tubes, plastic equipment, plastic fibers that can shut off lab coats. And at any point, any of those things could have snuck into the sample. So even if you find actual plastic in your sample, you don't know if it was in people's brains while they were

walking around in the world. It could have just gotten into the sample from the lab. Right. I could even have come from the medical examiner's office as the brains are being harvested, you know? I doubt that's a plastic-free zone. So the authors tried hard. They talk about it.

They like, they thought about it and they tried as best they could to keep plastic away from their samples when they had the opportunity to, but it's pretty hard to do. There's actually a plastics research group that has set up a lab that's supposed to be as plastics-free as possible. And even they can't get contamination down to zero. Wow! So if some plastic particle or fiber got into the sample, then that means it could have really blown up these results.

Right. And because you mentioned they're starting with these tiny tissue samples, they weren't analyzing the entire brain for plastics, right? They've got a tiny tissue sample. Yeah. And then to get this idea of how much could possibly be in the whole brain, you've got to multiply it out. If you've got two tiny pieces of plastic contamination and then you multiply that out by a hundred,

a thousand, whatever, now all of a sudden you have a plastic spoon in your brain. It could be. It could be. Yeah. So then, do we have any idea how much plastic is in our body and our brain and our testicles? I'm going to tell you about that after the break. Welcome back today on the show, Viral Papers. Viral Papers. We don't need to play the jingle again. Welcome back. Today on the show, viral papers.

Viral papers. We don't need to play the jingle again. We have just said that the headline that you might have heard that we have a plastic spoon worth of plastics in our brain might be garbage, strong words from some scientists. But there is still this question of how much plastics are in our body. Right. That's right. And even the people critiquing the study and other studies like it, they say that there

probably is some plastic in our bodies. But right, we want to know how much. So there are other techniques that are used to look for microplastics in the body. They're not perfect, but some of the scientists I talked to think that they're more reliable. They haven't gone up in smoke just yet. No, and literally they don't use that technique. They basically shine a laser. This is very oversimplified, but it's a technique that uses light to identify molecules instead

of what we talked about before. And they look for individual particles. And the most reliable papers that have used those kinds of techniques, they do report microplastics in different parts of the body. They have found microplastics in human lungs. They've also found microplastics in unhealthy livers from livers from people who have cirrhosis. But here's the thing.

These studies that use these other methods, they report small amounts of plastic. So for example, this one study that found microplastics in lung tissue, they reported an average concentration of less than one microplastic particle per gram of lung tissue. And most of these particles were smaller than a grain of sand. I know microplastics are small, but it still doesn't sound great? It doesn't sound great.

And it would probably be better if there weren't any, but it's not like the mass of cutlery, you know? Right. Right. And Oliver isn't freaked out by it. If we could collect all the microplastics and nanoplastics from our body and wad it up into one thing, what would it be? You can write that headline. What do you think? Personally, I reckon it'd be pretty...

Probably if you could take it all and wad it up, it'd probably be a very small little particle that you probably might not even be able to see with your naked eye. Oh, wow. Yeah, I think it's pretty small personally. Mmm, it's a very tiny spoon. Which kind of makes sense, right? Because I don't know if you remember this, Wendy,

but in our episode on microplastics, we talked about there was a stat that it got around that we eat a credit card's worth of plastic a week or something. Yes. In reality, the better paper that tried to estimate how much we eat, they found that it would take 23,000 years to eat a credit card's worth of plastic.

Yeah. If it takes 23,000 years to eat a credit card's worth of plastic, then how would a spoon show up in a single human lifetime, right? Because that's roughly the same amount. Right, yeah. And some of these more reliable studies have found microplastics in our poop, which suggests that we are eating some plastic,

but we're also getting rid of at least some of it. So I know on the bright side, like we're not totally helpless here. Like our body can get rid of stuff. Yeah. If we're finding it in the poop, that's actually a potentially good sign. Yeah. Because we know intuitively we are ingesting it if it's sloughing off food products. Right. But if we're pooing out a bunch of it, that's great. The body's like, I don't want this. Yeah.

So where are you at? How much do you think we need to worry about microplastics in our body and our brain? I mean, I think not that much really. Even one of the authors of this brain paper told me that he thinks that the media hype has gotten a little out of control, and it's like freaking everyone out when they probably shouldn't be that freaked out. Mmm. I mean, I think that it's still worth limiting your exposure to plastics, especially around your food. And that's because of the endocrine disrupting chemicals

that can come off the plastics. But as far as worrying about this idea, I think that's out there that we're becoming plastic people. That we're half human, half plastic. I think that's just hype. I don't think the evidence is there. So I don't know, I guess my takeaway for the audience is like, then the next time you see a headline that's like, there's a He-Man action figure in your

prostate, you know, don't believe that, take it with a grain of salt, I would say. So more studies will come, there's going to be more information, but like, I'm just saying there's nothing to panic about. And the plastic spoon thing in your brain thing, that is panic level information. And when I asked Oliver for his takeaway, he agreed. I think there's a lot of unnecessary worry that people have about because they read these things online, they assume they're true. And then they're like, oh my goodness, I'm going to die.

I've got plastic in my brain. And it's like, the stress is probably worse than any plastic. Worrying about the plastic spoon in your brain is the bigger problem. Yeah. And that concludes our first segment of Viral Papers. Thanks, Rose. Thanks, Wendy. Should we cue the jingle again?

Viral papers, viral papers, they're everywhere, but something's gone wrong. Alright, Rose, how many citations are in this week's episode? This week there are 55 citations. And if people want to read more about this paper and this technique, where should they go? They should check the show notes because there's going to be a link to the transcript of the episode there and all of our citations are in the transcript. And also, if you have a viral paper suggestion for us, let us know. You can find us on Instagram, we're science underscore vs. I'm on TikTok at Wendy Zuckerman.

Thanks Wendy. Thanks Rose. This episode was produced by Rose Rimler with help from me, Wendy Zuckerman, along with the Keddie Foster Keys, Meryl Horn and Michelle Dang. We're edited by Blythe Terrell. Mix and sound design by Bobby Lord.

Fact checking by Sam Lemonick. Music written by Peter Leonard, Emma Munger, So Wiley, Bumi Hidaka, and Bobby Lord. Thanks to all of the researchers that we spoke to for this episode, including Dr. Roger Coleman, Professor Martin Wagner, Dr. Elka Fischer, Dr. Murray-France Diniak, and Rachel Kozloski. Science Verses is a Spotify Studios original.

Listen to us for free on Spotify or wherever you get your podcasts. We are everywhere. If you like what you're hearing, give us a five-star review on whatever podcast app you're using. And if you are listening on Spotify, then please follow us and also tap the bell icon

so you get notifications when new episodes come out. I'm Wendy Zuckerman. Back to you next time.