They're in our building materials, homes, cars, clothing, personal care products, food containers, and even our water. I'm talking about microplastics like polypropylene, nylon and polyethylene terephthalate (PET). Now, for the first time scientists have discovered these tiny particles of plastic in our poop.

The scientific study was small, using samples from only eight participants in Europe, Japan and Russia, but every stool sample was found to contain microplastics. In total, researchers found nine of the 10 microplastics they tested for. The most common microplastics were polypropylene and PET.

Any plastic piece smaller than 5 millimeters (about the diameter of a push pin) is considered a microplastic, and the particles found were between 50 and 500 micrometers. Five hundred micrometers is about half a millimeter. On average, 20 particles were found in each 10g of poop tested.

Although the study was small, it suggests that microplastics may be widespread in our food chain. We're eating a lot of plastic.

The culprits

salmon, asparagus Microplastics can end up on the food on this plate in several ways. (Photo: Jacek Chabraszewski/Shutterstock)

Although it's not really surprising, this is the first study to confirm that plastics are finding their way into our guts. They're finding their way there through various paths. Recent studies have shown that microplastics make their way into fertilizer via large-scale food composting efforts in Germany. Another study found up to 600 microplastics in one kilogram of sea salt. Microplastics even float in the dust in our air, and when that dust lands on our dinner plates, we ingest them. Plastic particles have also been found in the water we drink.

If you think about it, that plate of salmon and asparagus above may be contaminated with microplastics because the fish ingested them in the sea and the asparagus was grown in tainted fertilizer, cooked in tainted water, and salted with tainted sea salt. Finally, tainted dust landed on the food while you were saying words of gratitude before you dug in.

The unknown harm

woman holding hands on stomach/abdomen area How much harm microplastics can do to our bodies once they reach our gut is still unknown. (Photo: Viktoria Gavrilina/Shutterstock)

The lead researcher of the study was Philipp Sychwabl from the Medical University of Vienna. He says now that his team has confirmed there are microplastics inside humans, further research needs to be done to find out exactly what it means for our health. Microplastics can enter the blood stream, the lymphatic system, possibly even the liver. The extent of harm they can cause is still unknown, particularly to those who already have gastrointestinal disease.

There's already some research under way to help answer this question. Earlier this year, when microplastics were found in drinking water, the World Health Organization (WHO) said it would launch its own review of what harm the particles in drinking water could do, including the impact the particles could cause over a lifetime.

WHO usually has a "safe" limit for various things that can contaminate food, water, air and soil, but there isn't enough research yet to know if the particles are truly dangerous and if they are, at what level can they become a health hazard.

Robin Shreeves ( @rshreeves ) focuses on food from a family perspective from her home base in New Jersey.

Scientists have found plastic in our poop
In a small sample, scientists have discovered microplastics in human poop, with every sample containing some. The most common were polypropylene and PET.