Nobody, it seemed, had thought to look before.

When two Austrian scientists discovered last year that it’s likely most people have plastic inside their bodies, it wasn’t because they had invented some new, complicated scientific method. It was because they were the first to check.

Their approach was simple. They asked eight people, mostly in Europe, but also in Japan and Russia, to keep a weeklong food diary. Then, they examined stool samples from their subjects, looking for plastic.

They found it in every single one: On average, 20 tiny pieces in each 10 grams of stool; given that humans poop on average 400 to 500 grams a day, that means their subjects were likely passing some 800 to 1,000 pieces of so-called microplastic daily.

The scientists, Philipp Schwabl, a researcher at the Medical University of Vienna, and Bettina Liebmann of Austria’s environment agency, are the first to admit their findings are at best preliminary. Their results don’t say where that plastic came from, what exactly it contains, and how — or whether — it is affecting our health.