Recently, there have been a rush of studies revealing how tiny pieces of plastic are making it into the environment, including in the fish and even the salt we eat. Sadly, the human gut doesn't contain bacteria capable of breaking down these plastics, and it seems our stomach acid isn't up to the job either. So where does it go? For the first time, a study of human feces has confirmed the inevitable: we're starting to shit out microplastics.

You can learn a lot about a society by looking at its manure, although personally, we can think of other scientific jobs we'd prefer. Just last week, scientists at Oxford University tracked the shift from a diet dominated by fish to one heavy in beef in Lübeck, Germany, using parasites found in 700-year-old latrines.

If archaeologists of the distant future decide to undertake a similar examination of this decade's crap, it won't be parasites thanks to undercooked food they will notice. Instead, they will find tiny bits of plastic. Our science being more advanced than that of Medieval Europe, however, there is no need to wait that long: researchers from the Medical University of Vienna have already done this.

The researchers had eight people scattered around the planet keep an exact diary of everything they ate for a week. They then had their stools collected and examined for the presence of 10 different types of plastic.

Nine of these plastics were found, at an average rate of 20 particles per 10 grams (0.35 ounces) of stool. The plastics ranged in size between 50 and 500 micrometers (0.002-0.02 inches) and were found in the waste of all the participants, even though two of them didn't eat fish during the trial.

The most common plastic particles found were polypropylene – used in plastic molding and diapers – and polyethylene terephthalate (PET), which is most common in soft drink bottles.

Lead researcher Dr Philipp Schwabl presented the findings at the gastroenterology conference UEG Week. "This is the first study of its kind and confirms what we have long suspected, that plastics ultimately reach the human gut," Shwabl said in a statement. "Of particular concern is what this means to us, and especially patients with gastrointestinal diseases.” 

Negative as the effects of microplastics may be in the intestine, it's obviously preferable to them building up in our stomachs, as is common in turtles and whales. Moreover, Schwabl raises an even more frightening prospect.

“The smallest microplastic particles are capable of entering the blood stream, lymphatic system and may even reach the liver,” he said. “Now that we have first evidence for microplastics inside humans, we need further research to understand what this means for human health."

Nothing good, we're guessing.