Plastic is everywhere, and there’s basically no way to avoid it. When broken down into microplastics, which are pieces less than 5 millimeters in length, and nanoplastics—even smaller fragments less than 0.001 millimeter—plastic infiltrates our food, from seafood to produce; swirls around in our wind; and is found in our tap water. We consume tens of thousands of microplastic particles every year—but how many of those microplastic particles are staying stuck in our lungs and livers, and what health impacts are they having on our bodies?
Scientists don’t yet know, but they’re working on finding out. Microplastics have already been discovered in human stool, so we know they pass through our bodies. Similarly, plastic components such as bisphenol A, aka BPA, have been discovered in urine—but also in samples of human tissue including lungs, meaning they linger in our bodies, not just pass through them. Knowing that, the question for researchers at Arizona State University was whether microplastics linger in our organs as well, so they developed a way to detect them.
Charles Rolsky and Varun Kelkar, graduate students under Rolf Halden, director of the Center for Environmental Health Engineering at the Biodesign Institute at ASU, who are presenting their findings at a virtual meeting of the American Chemical Society on Monday, spiked samples of human livers, kidneys, lungs, and spleens with microplastic beads. Those organs were chosen, they explain, because of how they filter out unwanted materials from our bodies, making them the most likely organs to be contaminated with microplastics, and because plastics have been found in these organs in animals. Then they recovered those beads by using a strong acid and a filtration system that left behind everything but the plastic.
This proves that microplastics can be recovered from human samples in a reliable way, and the researchers say they’re among the first to develop a way to examine micro- and nanoplastics in human organs. Now, the researchers are using this method to try to detect microplastics in tissue samples from human lungs, kidneys, spleens, and livers, in collaboration with Plastic Oceans International and the Banner Sun Health Research Institute Brain and Body Donation Program. Those samples, 47 in total, come with detailed information about the donors’ diet, lifestyle, and occupational exposure—for example, if someone worked in a textile plant with polyester or nylon—that could help the researchers understand how microplastics get into our bodies.
But to make sense of those findings, they also need a way to quantify the microplastic amount. That’s why the researchers also created a tool that can convert the number of plastic particles found in human tissue to one standard measurement of contaminant mass and volume. Different researchers can report the presence of microplastic in a variety of ways, such as by counting the number of microplastic particles per square inch. “But the size range of contaminating plastics varies greatly, so the count of particles may tell you little about the sizes and shapes detected,” Halden says by email. With this tool, researchers across organizations can better compare their findings because they use the same metric, and they’ll have access to an interactive database on microplastic pollution.
Why the need to figure out if microplastics are stuck in our lungs, and how many particles could be accumulating in our organs? “Given the massive amount of plastic we use as humans daily, plastic contamination within our bodies is not a huge surprise, although the toxicological implications are still uncertain,” Halden says. “This contamination is not going away; on the contrary, it is growing continuously. It thus behooves us to find out where these polluting polymers travel and how they impact our health and well-being. Plastic pollution is not ‘just’ an environmental issue. It is personal.”