Plastic, (micro)plastic everywhere. What does it do and why should we care?

Tiny Matters

Around 400 million tons of plastic are produced annually, which is the estimated weight of all of humanity! Plastic-covered beaches and litter on the side of the road is gross and depressing, but it turns out that stuff is just the visible tip of the iceberg. Plastic breaks down into tiny, tiny pieces that have now been found in almost every ecosystem on the planet—from the bottom of the ocean to mountain ranges in Europe. They’ve also been found in us. This episode of Tiny Matters is all about microplastics and both the molecules that stick to them and the ones they release, like forever chemicals (aka PFAS).

Transcript of this Episode

Sam Jones: The 20th century saw World Wars I and II, the 1918 Influenza Pandemic, nuclear weapons, space exploration, more technological advances than I can count, and… the rise of plastics.

Although semi-synthetic plastics were invented back in the 1800s, it was really a Belgian chemist named Leo Baekeland who created the first fully synthetic plastic in 1907, which was a combination of formaldehyde and phenol.

Deboki Chakravarti: A lot of historians see this as a turning point that set off the plastic boom. Tons of different industries found it valuable, and the general public found it really appealing because it could replace the more expensive paper, glass and metal materials they were used to. And single-use plastics like water bottles and grocery bags really took off in the 1970s.

Today, around 400 million tons of plastic are produced annually, which is the estimated weight of all of humanity.

Sam: I think we can agree that plastic-covered beaches and plastic litter on the side of the road isn’t exactly aesthetically pleasing. And we’ve probably all seen the horrific images of sea turtles and birds caught in plastic six-pack rings. But that stuff is just the visible tip of the iceberg.  Because plastic breaks down into tiny, tiny pieces that have now been found in almost every ecosystem on our planet—from the bottom of the ocean to the Arctic to mountain ranges in Europe. And they’ve also been found in us.

Welcome to Tiny Matters. I’m Sam Jones.

Deboki: And I’m Deboki Chakravarti. Today’s episode is all about plastic. There’s so much we could say, but at least in this episode we’re going to mainly focus on microplastics and so-called forever chemicals, particularly a group you’ve maybe read about called PFAS. Shoutout to Nick from Wisconsin and Rachel from San Diego for being the first to request an episode about these topics and to the many people who have continued to suggest them, even just over the last couple of days leading up to recording.

Sam: Microplastics and forever chemicals are really important—and big—topics, so if you leave this episode thinking, “I need to know more about them or about something we briefly touch on that you want to know more about,” please tell us! You can email

Deboki: For this episode we reached out to chemist Imari Walker-Franklin, who is a research scientist at RTI International. We started by asking about some of the basics we should know. Like we mentioned at the top of the episode, plastic breaks down. But what would scientists categorize as a “microplastic?”

Imari: Microplastics are essentially tiny pieces of plastic. How tiny? Usually we would define it as smaller than five millimeters, which is about the size of a pencil eraser tip. And  then we'll go down to about one micrometer, which is the size of a large bacteria. So it's a huge size range for us to really understand, and all these small pieces of plastic can end up in so many different places.

Sam: One of those places is rain. In 2019, a geological survey done by the U.S. Department of the Interior in Colorado was the first to report microplastics in rain droplets. They titled the survey, “It is raining plastic,” and in it they detailed their shock in finding different colored microscopic fibers, beads, and shards of plastic.

Deboki: And just last year, scientists published a study showing that over 80 tons worth of microplastics fell from the sky over Auckland, New Zealand in 2020.

Sam to Imari: There have been some listeners who have written in and said, you know, I've read that there are microplastics in our rain. Is that true? And if so, how did they get there? Do you mind speaking to that?

Imari: Yeah—so depending on the plastic itself, its material properties and its size or density, it means that it can easily float or sink in water and also be suspended into our air. So really light and small microplastics and microfibers—things that also come from our synthetic clothing are very easy to resuspend into the air and travel globally and even regionally depending on the size.

Deboki: Microplastics can generally be split into a few major categories. Microfibers, which Imari just mentioned, are the most prevalent type of microplastics. They can shed from fabric when we do a load of wash, but some might also be coming off my clothes as I speak, maybe lofting into the air to one day come down in rain.

Sam: Then you have both primary and secondary microplastics. Primary microplastics are bits of plastic designed to be that small. This would include things like microbeads, which used to be used in a lot of cosmetic stuff in the US, like toothpaste and face wash, marketed as being great for exfoliation. Growing up I definitely used a lot of face wash with microbeads in it.

Deboki: In 2015, the US banned the manufacturing, packaging, and distribution of rinse-off cosmetics containing plastic microbeads, which included toothpastes and body washes. But there are plenty of others, like body glitter for example, which you wouldn’t necessarily think of but, yeah, it’s a microplastic. And secondary microplastics come from the wear and tear of larger plastics due to exposure to things like UV light, weather and temperatures.

Sam: So there are a lot of microplastics out there and I for one am very happy people like Imari are studying how they come about and what they might do to us and our environment.

Imari: What made me want to study microplastics was actually a class that I took at Duke when I was finishing my PhD in environmental engineering. And it was an environmental organic chemistry class looking at the great garbage patch.

Sam: You’ve probably heard of the Great Pacific Garbage Patch aka the Pacific trash vortex. It’s actually two distinct collections of debris in the North Pacific Ocean, and it is mostly made up of microplastics.

Imari: So I was learning that there are chemicals in the ocean that have been there for years, that we have made and produced, and overproduced that are potentially toxic that would actually gravitate towards plastic floating in the ocean and be carried away almost like a sponge carrying away, you know, spaghetti sauce, down to different parts of our world that did not even produce that plastic in the first place or utilize those items. And so that really just blew my mind that plastic could be used as a vector of transport for other harmful chemicals. But then I learned later that plastic already has chemicals placed within it that also need to be looked at because those chemicals can be easily released into things like our water, into stomachs, into maybe even lung fluid.

Deboki: Plastics can leach chemicals like endocrine disruptors, which mimic or prevent the natural binding of hormones. But, like Imari mentioned, toxic chemicals can also hitch a ride on microplastics.

Sam: For example, dichlorodiphenyltrichloroethane or DDT. So DDT is a pesticide that the US used a ton during World War II to ward off mosquitoes carrying malaria. It was banned in the 70s but it has stuck around in our environment. People first realized DDT was really toxic because of how it was affecting wildlife, like bald eagles. Bald eagles were eating fish that had been contaminated with DDT, and it interfered with their ability to produce strong eggshells, so their eggs had shells so thin that they often broke while the unborn chick was growing or failed to hatch.

Deboki: Plastics can also transport per- and polyfluoroalkyl substances, or PFAS. Aka “forever chemicals.”

Imari: PFAS are defined as human-made chemicals that are typically fire resistant, can repel oil stains, grease, and even water. And they represent thousands of different chemicals. And the main thing that makes them a PFAS is a strong bond between the carbon and the fluorine—that CF bond is usually what makes perfluoro- or polyfluoroalkyl substances.

Deboki: Because they’re water, heat, corrosion, and oil-resistant they’re useful in jet engines and firefighting foams. But they’re also found in more common stuff like non-stick pans, the lining of fast food wrappers so that something like burger grease doesn’t soak right through, and even microwave popcorn bags to keep them from catching fire in the microwave.

Sam: And, just like BPA, PFAS are also in a lot of plastics. So it’s not so surprising that last year scientists reported that levels of PFAS found in rainwater in both urban and rural environments exceeded what the EPA considers safe for our drinking water.

So let’s talk about the implications. Just a warning, things will feel a little bleak for a sec, but closer to the end of the episode Imari does offer up some hope as well as suggestions for how to avoid microplastics and PFAS as best as possible.

Sam to Imari: Why should we care that there are microplastics in the ocean and our water, in the rain? Why does it matter?

Imari: Yeah. I think a lot of it is just because we don't really know what the implications are for the fact that they're so widespread. Especially when we think about the fact that we're now finding microplastics in not only remote parts of our world, but also within our body. We can find them in our lungs, in our colons, and now even being transported in our blood to being found in the placenta. What does that mean for the development of children? What does that mean when we're exposing ourselves to hundreds to thousands of different tiny pieces of microplastics in our own bodies, interactions with them, let alone things that we're already seeing within the environment, like for microplastics that are exposed to fish that also are exposed to a certain disease or pathogen. That pathogen actually causes wider mortality events for the fish itself when there's microplastics present.

I'm just slowly getting into the field of microplastics for human health. But some of the work that I previously did was actually focused on environmental health. And so I did exposures of microplastics to simulated freshwater environments and looked at the release of chemicals over time to determine like, what is the rate of release and also what kinds of chemicals are being released, because it's not always the original chemical that will come out and stay and be present in the water, but it can also be transformed by UV light, by the water that it's present in and just anything else that's also present in the water with it. And so the question is, if that chemical transforms, is it more harmful or less harmful?

Sam to Imari: I know that microplastics and PFAS are so closely linked, but in some of the research that I did leading up to our conversation today, I felt like there was a lot more written about the potential harm of PFAS in humans. Is that true? Is that a little bit better understood?

Imari: Yeah. I think that it's a lot easier to focus on a chemical by chemical basis than to look at hundreds of chemicals in so many different kinds of particles. And that's what makes the field of microplastics so difficult. But to study a class of compounds like PFAS it's just been a little bit more of an easier swing towards understanding what are the mechanisms of harm.

Sam to Imari: And what are some of the things that scientists have maybe found related to PFAS?

Imari: I think the biggest thing is what you said before, that PFAS are forever chemicals. They take a really long time to degrade, and that also means that they can also accumulate in our bodies or in just about any matrix that's present. But exposure to PFAS also increases the risk of cancer, it harms the development of fetuses and can also reduce the effectiveness of vaccines. So that's really scary to think about in times of pandemic.

Deboki: So when it comes to PFAS, we’re still trying to figure out the chemistry behind why these compounds seem to be so bad for us. Like Imari mentioned, they’re linked to cancer, issues with fetal development and reduced vaccine effectiveness. They’ve also been linked to higher cholesterol and to immune and endocrine disruption. They seem to stick around by binding to proteins in our blood, which is probably why we’re finding them in tons of different tissues, especially tissues with lots of blood vessels, like our liver and kidneys.

Sam: It’s not like there’s been no effort to phase out PFAS, but it’s been super limited. In 2006, the EPA and 8 major manufacturers agreed to by 2015 eliminate certain PFAS from their products. But remember, there are thousands of other potential PFAS compounds still out there being used.

Deboki: So in terms of microplastics and PFAS getting into your body, you’re mostly looking at ingestion—through food and water and even cosmetic products like mascaras and foundations. There is some evidence that small amounts of PFAS can get in through the skin but it really sounds like more of an ingestion thing.

Also, we wanted to clear something up related to this. Things labeled “organic” do not mean they don’t have PFAS. USDA organic certification does not require that the soil where food is grown be tested for PFAS. We also asked Imari about clothing labeled as having no PFAS and she said… be wary of those kinds of claims for a couple of reasons.

Imari: That reminds me kind of, well, my first line of thought would be with BPA where water bottles now say BPA free. But we now know that the plastic that actually was using BPA was likely substituting that with a different form of bisphenol, whether that's BPS or BPF, which ended up being more toxic sometimes. So saying PFAS free, I don't, I wonder what they define as PFAS free. Maybe it means that they don't have PFOA or PFOS or GenX chemicals, and they might be substituting with a different perfluorinated chemical, or it's kind of like a greenwashing gimmick… because they didn’t put them in there anyway and they just want to be able to proclaim they don’t use them.

Deboki: OK, so, we’ve reached a very important part of this episode: what do we do?

Imari: If I can avoid it, I try not to use single-use plastic water bottles. But I would like to acknowledge that there are some parts of the world that actually still need to use water bottles because their drinking water is unsafe. So whenever I make that advice for, you know, should everybody avoid single use plastic water bottles, I think it is kind of dependent on where you are. And so doing your own research, whether that's with looking up your city or your municipality on the environmental working group website or whatever is, you know, the equivalent for, for your location is really gonna arm you with that knowledge to say, yes, this is a smart switch.

But as far as things that I do or I recommend for avoiding microplastics in particular, I always say dust your house often, and vacuum because a small fraction of that dust is microplastic particles, whether that's from your carpets or your clothing and furniture. And then replace your single-use plastics when you can with reusable glass and stainless steel wear. And I think urging governments to make change, I think that's the only way that we can kind of push this forward. Especially with California setting a new standard for microplastics and drinking water soon, maybe we'll see that replicated in other places.

Sam: Beginning in the fall of this year—2023—around 30 of California’s largest water providers will be ordered to start quarterly microplastics testing for two years, which is huge, and hopefully other parts of the country and world follow suit. By the way, in the episode description, we’ve provided a link to where you can check your region’s drinking water in case you’re interested. Alright, back to recommendations. Tips for staying away from PFAS:

Imari: Avoiding grease repellent coatings, like microwave popcorn bags or fast food wrappers, avoiding stain resistant treatments on clothing or furniture or carpets. Those are almost always some form of PFAS. And also avoiding or reducing your use of a non-stick cookware. And especially stop using it if you see, you know, scrapes and signs of deterioration on the surface, if you see a lot of scrapes and, and stuff like that, that means that you're eating PFAS… very, very much so. And then if you wanna treat your own water, your tap water, definitely look at granulated activated carbon and reverse osmosis filters and look into the kinds of fish that you eat too, because some of them have higher levels of PFAS than others.

I think one sign of good news is that the European Chemical Agency is actually working to create a plan to restrict over 10,000 PFAS chemicals by 2040. I think that's huge news for how we're gonna simplify our products and even plastics to not contain harmful chemicals. The other big thing for plastics is that the United Nations is working to get a resolution for plastic pollution to have this treaty essentially by 2024, that we can all kind of have agreement on to address plastic pollution.

Deboki: And if you want to really dive into plastics and solutions for moving away from them, Imari is writing a book all about that right now.

Sam to Imari: Imari, tell me about the book that you are writing that is coming out in August, correct? August, 2023.

Imari: Yes. So the book called Plastics is part of the MIT Essential Knowledge series, and it's also co-written by Professor Jenna Jambeck at the University of Georgia. And really the book is trying to help us understand the entire lifecycle of plastics, why we're using it so much to the history of what happens to the plastic once it's used, how it ends up in our environment, how that could be potentially harmful to not only us, but other organisms, and then some of the alternatives to plastic or figuring out how to address some of these, these solutions, um, for plastic pollution. So it's a very short read, very easy for anybody who wants to understand anything about plastic pollution and some solutions.

Sam to Imari: Yeah. Solutions are always good. I think there's a lot of doom and gloom and knowing that there are things that you can do to mitigate your harm, to maybe mitigate harm to the environment. These are all really positive things. We need that.

Sam: Umm Tiny Show and Tell?

Deboki: Yeah. It's that time.

Sam: I can go first this time.

Deboki: Yeah, sounds good.

Sam: So I will start by saying that I think you should, and by you I mean listeners, and myself, and you, Deboki, should probably take this research with less than a grain of salt. I'll explain in a second, but let's just get into it.

So researchers at the University of Queensland have shown that mushrooms, specifically Lion's Mane mushrooms, which I know are often talked about in the health sphere and I worry because there's not a lot of research to actually provide evidence that they are as helpful for brain health as these claims often are on the packaging. But I did think that it was kind of interesting that researchers from the University of Queensland have discovered the active compound in these edible mushrooms that seems to, in the lab, in a dish, boost nerve cell growth and enhance what would be considered a potential enhancement of memory based on this sort of growth.

I thought it was interesting, to be honest, what brought me to even look at this story was that I've been watching The Last of Us, and so I feel like fungus and mushrooms have really been on my mind lately. So I thought it was cool that this group had the goal of identifying some of the active compounds in this mushroom that has been touted as having all these health benefits.

They're actually trying to figure out, is that true? But also what are the compounds that might be involved? So I just think it's interesting in terms of a field of study, I don't have a whole lot to say about it. But essentially, the laboratory tests that they did looking at cultured brain cells, found that the active compounds they identified actually seem to promote the projection of neurons to other neurons, so that extension and connection between neurons, which is very cool. It's super interesting.

But there's also a lot of things that scientists can get cells to do in a Petri dish that they would not be able to get cells in, not just your brain, but even maybe a mouse's brain to do. So again, like I said, take this with a grain of salt, maybe less than a grain of salt. But I did think it was really interesting, just this approach of trying to understand, okay, you have this mushroom, this is something that is being sold, has been sold for a long time, has been used for a long time in more traditional medicines, but what is it about this mushroom that might hold some sort of therapeutic potential or memory benefit or any of these things? And so I think it's just fun that scientists are trying to really understand what compounds might be present that could potentially have a benefit. And also, if you haven't seen The Last of Us, it's really good.

Deboki: I do need to watch it. I haven't watched it yet.

Sam: It's so good. It's so intense. It's so good.

Deboki: Yeah. No, that's so fascinating. I feel like even if it doesn't do something in my brain, it's so cool that you can do that in a dish, you can watch that happen is wild. Yeah, I really love that and now I kind of want to eat some. Well, I feel like I talk about mushrooms and then we bring up The Last of Us and I'm like, do I want mushrooms? But actually mushrooms are pretty tasty.

Sam: I know. Maybe don't eat mushrooms. Yeah, don't eat mushrooms while you watch The Last of Us, I think it might permanently ruin mushrooms for you. I just thought this was a cool study. I think there's something really cool about trying to understand to better understand how some, I guess, approaches to health that are considered more quote “holistic” or traditional medicine approaches. I think it's so complicated because I think that a lot of those approaches are often exploited and really just as a money grab. But I do think that there are a lot of things that have been around for, sometimes, thousands of years and it's cool that now we have the technology to be able to understand maybe what about those things has provided such longevity? Why are there cultures that still use certain traditional medicine practices or traditional medicines? Maybe there's something to it, it's just being able to say... Maybe there's a hundred compounds and two of them are actually beneficial and I think it's really cool to be able to break that down and better understand it.

Deboki: Totally. I agree. I want to talk about, for my Tiny Show and Tell, about octopus arms. As we know, there are eight of them, and I, with only my two arms, have a hard time coordinating these two arms. So imagine being an octopus and you gotta coordinate all eight of them. That seems to me to be really hard. But some researchers decided that they wanted to study more about these octopus arms and how they work. So they were looking at these young octopuses, and according to them, and I just love that they use this as a frame of reference for size, these young octopuses are about the size of a big Tic Tac, which I don't know what a small Tic Tac is, but I love the idea of a big Tic Tac. So they wanted to learn more about how these arms work together and coordinate with each other.

And they found that when they were using their super powerful microscope, when they looked at the nerve cords that are closest to the suckers on a given arm, they found that that cord didn't just go down the length of one arm. They would actually connect to an arm that was two arms away, so not right next door, it was like you go two arms and then it connects to that arm. And so there's just all of these connections crossing over other connections. And if you actually look at the drawing of it, the diagram, it's like this interlocking pattern of connections that goes through all of the arms and it's really cool.

This is different from other nerves that go through octopus arms. There's a larger peripheral nerve that actually connects back to the brain through the central ring structure. It makes sense when you see it where you're like, okay, this makes sense as a way to coordinate this arm that maybe senses something in the environment on one side of the octopus and needs something on the other side of the octopus to do something else.

It's a way for them to communicate efficiently. And I also loved this, I was reading about this in Scientific American, and at the end of it they have this quote from a researcher who said, quote, "We are in that intriguing, mild state of confusion that is simultaneously perplexing and exhilarating when unexpected discoveries are revealed." And I just love that on its own because I feel like there's so much stuff in science like that where you see it and you're like, that's so cool, but also I don't understand. And I love that. I love that about this.

Sam: Yeah, that's some of the fun of it. That was cool. Shall we wrap it up?

Deboki: Let's do it.

Thanks for tuning in to this week’s episode of Tiny Matters, a production of the American Chemical Society. Our exec producer is my co-host, Sam Jones.

Sam: This week’s script was written by me and was edited by Deboki and by Michael David. It was fact-checked by Michelle Boucher. The Tiny Matters theme and episode sound design are by Michael Simonelli and the Charts & Leisure team. Our artwork was created by Derek Bressler.

Deboki: Thanks so much to Imari Walker-Franklin for joining us. You can find her at @dr_imariwalker on YouTube and social media and you can find her book pre order link in this episode’s description.

If you have thoughts, questions, ideas about future Tiny Matters episodes, send us an email at You can find me on Twitter at okidoki_boki.

Sam: And you can find me at samjscience. See you next time.