C&EN: "Microplastics might not be as chemically inert as expected"

Via Chemical and Engineering News, this news (article by by Ananya Palivela): 

Plastics are used for making reusable containers, clothing, and packaging partly because they are considered chemically inert. That assumption has extended to microplastics—particles smaller than 5 millimeters created through the wear and tear of plastics used daily—that turn up in ecosystems and inside human tissue. A new study suggests that microplastics are chemically active in water and can damage cells (Nature 2026, DOI: 10.1038/s41586-026-11141-y).

Wei Min and Teresa Head-Gordon’s group at Columbia University and the University of California, Berkeley, respectively, find that a plastic particle’s surface makes highly reactive hydroxyl radicals in water. All six common plastics the team studies make these radicals without sunlight or any other trigger. The more hydrophobic a plastic is, the more radicals it makes, the researchers have found. Polyethylene and polypropylene make the most, and poly(methyl methacrylate) the least.

...Matthew Campen, a biochemist at the University of New Mexico Health Sciences Center, who was not involved in the study, agrees with Min. He expects microplastics in the body to be coated in phospholipids, fatty molecules that would keep water away.

“Another aspect that needs further exploration is how aged plastics interact with water,” Campen says. The microplastics that make their way into people’s bodies have often been used, worn down, and exposed to the environment. Such aged plastics can carry a mix of water-attracting and water-repelling groups, which could affect the mechanism shown in this study.

I've been around long enough to both have some skepticism about any particular result, but it will be interesting to see if it reproduces and if it will be biologically relevant.