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You just might have heard that plastics are bad for you— that you shouldn't microwave foods in tupperware, for example, because there's nasty stuff in the plastic that leaches out when you do. Now, that's not really true anymore for plastics labeled “microwave-safe”, but it turns out you probably eat plastic all the time anyway.

At least that's the conclusion of a preliminary study presented in October 2018. The findings have yet to undergo peer review, but if they're right, it would mean that plastics are already a part of your everyday meals. And that would make doctors very nervous, because we don't yet know the health effects of eating that much plastic.

The problem with eating plastics is that they often contain chemicals that look a lot like hormones. When people ingest these hormone mimics, their bodies can get confused, and that can lead to health issues like reproductive problems, diabetes, liver damage, and disruptions to fetal development. So researchers from Austria were alarmed when they examined human poop samples from around the world and found actual bits of plastic in all of them.

The fecal samples came from eight of their friends—six in Europe, one in Siberia, and one in Japan. Which... I would love to hear the conversations that ended with, “Can you please overnight your poop to me?” For one week, the participants kept records of their food and beverage consumption and plastics they came in contact with.

Then, they each shipped their fecal samples to the researchers in glass jars. All of the poops contained tiny plastic fibers called microplastics. Microplastics are any bits of plastic five millimeters in diameter or smaller.

They're classified as either primary, meaning they were that small to begin with, or secondary, meaning they came from larger hunks of plastic. A lot of the primary microplastics are nurdles, which is the cutest name I've ever heard for a pollutant. Nurdles are the raw pellets of plastic that are melted to make pretty much all our plastic materials.

And they're sometimes used as-is to make facial scrubs and other exfoliating skin products, although the practice is now banned in the US, Canada, New Zealand, Taiwan, and some European countries. Nurdles escape into water systems like nobody's business, and they can also be the secondary sources of microplastics because they lack the UV protection of finished plastics, so they degrade easily. Secondary microplastics are the ones that flake off from cracks in the surface of larger plastic pieces which form as the plastic degrades.

Usually, when you hear about microplastics, it's because they're water pollutants. Aquatic microplastics were first noticed in the early 1970s, and since then, they've been found in nearly every water system, even the oceans surrounding Antarctica. And they're especially good at delivering toxins, because they can pick up other contaminants from the water.

Their high surface-to-volume ratio plus their tendency to be slightly hydrophobic, or water-repelling, mean they readily absorb other highly toxic pollutants. And then, when the particles are eaten, they deliver a concentrated dose straight into the body of the creature that consumed them. It's not yet clear how damaging the microplastics found in aquatic habitats actually are, but laboratory studies have suggested consuming them can cause serious health problems for lots of important species.

So biologists have understandably become concerned that they've found microplastics in the bodies and droppings of all sorts of aquatic animals, from shellfish to seals. And, if that's not bad enough, a lot of these compounds—and maybe even the tiny bits of plastic themselves— tend to stick around and concentrate in an animal's tissues. So when a bigger animal eats a bunch of a smaller animal that has a bunch of these bits of plastic inside of it, the bigger animal will get a larger dose, and so on and so on up the food chain, until they're eaten by people.

Which brings us back to that study. The big question on everyone's minds is where the plastic bits came from. Since they were found in the participants' poop, they must have somehow consumed them.

The whole plastic-in-marine-animals thing might suggest a love of seafood is to blame, but only six of the participants reported eating fish or shellfish. And in fact, the vast majority of microplastics are thought to form on land, because that's where plastics are exposed to the most intense sunlight and heat. They can also be found in the air.

Plastic fibers in carpeting and our clothing contribute to microplastic dust, which like your garden variety dust can become airborne and then settle on things, such as your plates or food. Studies have suggested you're exposed to a lot more microplastic via dust than your favorite mussel linguine. And if dust was the source of the plastic particles seen in the study, it could be a tiny silver lining, as air-based microplastics may not absorb other contaminants like aquatic ones do.

But even the best case scenario here isn't good news. The presence of plastic in human poop suggests that even when we think plastics have broken down and disappeared, they're still around—just in microscopic form. Not only are they in our waters, they're apparently in or on the food we eat, too.

And the plastics in our world aren't going away any time soon. Which, in many ways, is a good thing. Plastics have allowed us to do great things in terms of medicine and technology.

But if most or all of us are eating microplastics all the time, a lot more research is needed to understand where they come from, what chemicals they contain, and ultimately, how they affect our health. Thanks for watching this episode of SciShow! And thanks especially to our patrons on Patreon.

Around here, patrons are what make everything possible, as without their continued support, we wouldn't be able to make educational science videos like this one. If you want to join our patron community or simply learn more about how you can help support our team, you can head on over to Patreon.com/SciShow. ♪.