A new study has found microplastics – particles of plastic smaller than five millimeters – to be present in human stools, the Environment Agency Austria said Tuesday.



Eight participants, from Finland, Italy, Japan, the Netherlands, the U.K., Austria, Russia and Poland took part in the pilot study, which was conducted by researchers at the Medical University of Vienna and the Environment Agency Austria.



Those taking part – none of whom were vegetarian – kept a food diary in the week preceding their stool sampling. All diaries showed that they were exposed to plastics by either eating food that had been wrapped in plastic or drinking from plastic bottles. Six of the participants ate sea fish.



Their stools were analysed at the Environment Agency Austria for 10 types of plastic. As many as nine different plastics, ranging between 50 and 500 micrometers in size, were detected. Polypropylene and polyethylene terephthalate were found to be the most common.



"This is the first study of its kind and confirms what we have long suspected, that plastics ultimately reach the human gut," Phillip Schwabl, the study's lead researcher, said in a statement Tuesday. "Of particular concern is what this means to us, and especially patients with gastrointestinal diseases."



Schwabl added that while the highest plastic concentrations in animal studies had been found in the gut, the smallest microplastic particles were capable of entering the blood stream, lymphatic system and potentially even the liver.



"Now that we have first evidence for microplastics inside humans, we need further research to understand what this means for human health," he said.



Tuesday's announcement follows a study earlier in October that painted a "shocking" picture of the effects of plastic pollution on marine life.



Carried out by scientists from the University of London's Royal Holloway, The Natural History Museum and the University of the West of Scotland, the research showed that 28 percent of fish in the Thames Estuary had ingested microplastics. In Scotland's Firth of Clyde Estuary, 39 percent of fish were affected.



The study further found that, altogether, roughly one third of 876 fish and shrimp examined from both estuaries had ingested microplastics.