Scientists Challenge Claims of Microplastics-Riddled Bodies

Microplastics may not be quite as deeply embedded in our bodies as some headline-grabbing studies have suggested. A growing group of scientists say many recent claims of plastic particles in human brains, testes, arteries, and other organs are likely inflated—or flat-out wrong—because of contamination and shaky lab methods. The Guardian reports 20 recent studies have been criticized for methodological issues, with at least seven formally challenged in journals. One critic calls the situation a "bombshell" for the field, though Vox reports the debate has been playing out among academics for months.

A widely publicized study suggesting microplastics in human brains were surging over time was later questioned for weak contamination controls and a failure to rule out fat-producing signals that mimic common plastics like polyethylene, the Guardian reports, though Vox speaks to a co-author who says the brain's fatty molecules were, in fact, considered. At the core of the dispute is how hard it is to reliably detect tiny plastic particles in human tissue. A common method, Py-GC-MS, essentially vaporizes samples and analyzes the fumes—but some molecules from human fat can look like those from plastics, creating false positives. One review flagged 18 studies that didn't adequately address this risk.

Other papers tying plastics in artery plaques to heart attacks, or reporting microplastics in testes and blood, have been criticized for missing basic quality controls like testing blank samples or running enough checks for background contamination. Critics stress they are not alleging misconduct, but say the rush to publish in an immature field has led to "extraordinary claims" without "ordinary evidence." Scientists interviewed by the Guardian agree that plastic particles likely end up in the body, but say current tools are weak at measuring the smallest, most concerning fragments. They warn flawed evidence on the level of plastic could distort health policy and fuel scaremongering, even as plastic production and pollution continue to soar globally.