In the study, 11 of 13 lung tissue samples were found to contain microplastic contamination.

In March, scientists found microplastics in live human blood for the first time. Now, another research team has identified the first microplastics in live human lungs among patients awaiting surgeries. But what even are microplastics, and how are they finding their way into the human body?

First, in a world filled with plastic, let’s define our term. A microplastic is a piece of plastic debris that’s about the size of a sesame seed or smaller. Some of these microplastics are the result of larger plastic pieces breaking down—remember: plastic doesn’t biodegrade, but it regularly degrades over time after being smashed or crushed into pieces that still retain all the qualities of plastic. Tiny plastic fibers may even break or shed off of synthetic materials like polyester or microfiber cloths.

Other microplastics are simply runoff from consumer manufacturing—like some beauty products, or industrial processes—that may use something called “microbeads” as an abrasive agent. These microbeads look vaguely reminiscent of poppy seeds or tiny fish eggs. Former President Barack Obama passed a law phasing out microbeads beginning in 2017. At the time, the Huffington Post reported that there were eight trillion new plastic microbeads entering the nation’s waterways every day.

Now, microplastics are everywhere: they’re found at the bottom of the ocean, near the summit of Mount Everest, and all points in between, filling our waterways (as well as the human digestive system) to the tune of 50,000 particles per person per year. Scientists have even proved that microplastics ingested through food or water could cause cell death in prepared laboratory human cell lines.

But it’s only this year that firm research has shown that the microplastics make their way into other parts of living human bodies. Why does it matter more when the particles are in our blood, for example, or our lungs? Part of explaining that involves a kind of trippy (but true) fact about the human digestive system. Technically speaking, the human body is a donut, and the alimentary canal—leading from our mouths all the way down to our anuses —is the hole in the center. Microplastics found in the digestive system or near it can be traced back to direct intake: we ate it, so it’s in there.

That’s different from the bloodstream or the lungs, which are parts of the body that don’t directly intake traditional sources of plastics. Somehow, what we ingest through water or food is migrating into the blood. And for the lungs, that means that microplastics have likely become airborne, with fibers entering the lungs in much the way same way that asbestos or fiberglass particles do. (If you don’t believe you can easily breathe in cloth fibers, we have a Triangle Shirtwaist Factory fire to show you.)

The research on microplastics in the lungs has been accepted for publication in the July issue of Science of the Total Environment, a peer-reviewed journal. In the study, 11 of 13 lung tissue samples were found to have microplastic contamination, with the most common plastic types being polypropylene, polyethylene terephthalate, and resin. Because this study is the first of its kind, the researchers explain, it will open the door to further laboratory experiments that can mimic real-life inhalation conditions in order to better understand how microplastics are traveling into our bodies.

This is also a striking blow on behalf of the much-flimsier fibrous form of microplastic, as opposed to the enduring image of microbeads that accumulate in the ocean. It means the threat posed by these microfibers is almost invisible in the air we breathe. But hopefully, understanding them better will help scientists improve filtration and other ways to clear the air of microplastics.

Caroline Delbert is a writer, avid reader, and contributing editor at Pop Mech. She's also an enthusiast of just about everything. Her favorite topics include nuclear energy, cosmology, math of everyday things, and the philosophy of it all. 

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