Plastic is everywhere these days—even in our poop. When people toss plastic products, the material doesn’t break down naturally in the environment. Instead, it splits into smaller and smaller pieces. This microplastic can stick around for hundreds of years and end up in unlikely places, including what we eat.

Philipp Schwabl, a researcher at the Medical University of Vienna in Austria, recently tested the stool of people around the world. All the samples contained some microplastic. “We don’t yet know the consequences for human health,” he says, “nor all the sources of the microplastic we ingest.”