Some scientists say research on microplastics is flawed: What does it mean for our bodies?

In recent years, there’s been a wave of studies reporting that humans are basically full of microplastics: They’ve been found in our brains , arteries , and even in placentas. But some scientists, quoted and cited in an article published by the Guardian this week, have critiqued some of those findings, saying that microplastics research has been muddied by issues like contamination and false positives. One chemist even told the outlet that these criticisms are “​​forcing us to re-evaluate everything we think we know about microplastics in the body.” However, other scientists who study microplastics and human health say that this framing is overblown. While they concede that the field of studying microplastics in our bodies is new—and that some concerns over study methodologies are valid—readers should not conclude that the entire area of study is filled with errors. And, they add, it’s an irrefutable fact that microplastics are present in human bodies. What are the critiques of microplastic studies? When plastics break down, they form these tiny fragments we call microplastics, defined as pieces less than 5 millimeters in length. There are also nanoplastics, which are even smaller particles, usually considered smaller than 1,000 nanometers— which is about 100 times smaller than the diameter of a human hair. Research has found them in the air , the soil , and our bodies. But in comments to scientific journals and a recent Guardian article, some scientists have challenged the way that researchers have identified these microplastics, particularly in human organs. One study, which said that the levels of microplastics in human brains are rapidly rising, was critiqued for having limited controls around contamination, and for not validating potential false-positives. “Fat is known to make false-positives for polyethylene. The brain has [approximately] 60% fat,” Dr. Dušan Materić, at the Helmholtz Centre for Environmental Research in Germany, told the Guardian. Other studies, which found microplastics in arteries, were criticized for not testing blank samples taken in the operating room, basically a way to measure if there’s any background contamination to start. Researchers who wrote comments to scientific journal editors also generally highlighted that the “the analytical approach” used in some microplastic studies is “not robust enough to support [their] claims.” What do these critiques really mean? Microplastics researchers do understand that there are methodological challenges to studying microplastics in human organs. That’s because the field itself is still new. “The tools are in their infancy,” Kara Meister, a pediatric ear, nose, and throat doctor with Stanford Medicine who also studies how our environment—including the presence of microplastics—affects our immune system, told Fast Company. “None of these tools [to detect microplastics] were developed specifically to look at this problem, so we’re borrowing from other science and then trying to apply that to a brand new field,” she adds. The critiques, then, do have truth to them. Yes, microplastics can be confused with fats, Meister says. That’s because microplastics are often made from polymers (meaning something with repeated bonds or a predictable structure), which...

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