There’s probably microplastic in your poop

Tiny pieces of plastic have been found in beer, fish, sea salt, honey, and other food. It’s not surprising, then, that a new pilot study also found microplastic in human poop.

The study, which was the first of its kind, was very small–the researchers, from the Medical University of Vienna and the Environment Agency Austria, only studied stool samples from eight participants. But each participant came from a different country, ranging from Japan and Russia to the U.K. And every sample tested positive for microplastic, fragments of plastic smaller than 5 millimeters across.

On average, there were 20 microplastic particles in every 10 grams of poop. Some samples had as many as nine different types of plastic inside. The most common forms were polypropylene–commonly used in bottle caps and in packaging for food like yogurt–and PET, commonly used in water bottles. All of the participants in the study drank from plastic bottles during the study and ate food that had been wrapped in plastic; six of them ate fish from the ocean.

Microplastic is widespread in food. One study found plastic fibers in the majority of tap water. A report commissioned by the nonprofit journalism organization Orb Media found it in 90% of bottled water. One sample, a bottle of Nestle Pure Life, had 10,000 plastic pieces per liter (Nestle criticized the methodology). In the ocean, tiny pieces of plastic flow through the food chain in tuna, lobster, shrimp, and other animals. As pieces of plastic accidentally land in city compost bins, they may end up being spread on farm fields.

It’s not yet known what this means for human health.The next step is research on those potential health impacts of having plastic inside our guys, says lead researcher Philipp Schwabl, who is presenting the findings at the United European Gastroenterology Week event in Vienna. But a study in lab mice found that microplastics accumulated in the intestines, kidneys, and liver. Microplastics can also potentially pass into the bloodstream. The plastic could possibly transmit toxic chemicals or pathogens, and as it accumulates, might affect the immune response and cause intestinal damage.