Research finds humans across the globe have microplastics in their stool

  • Researchers from the Medical University of Vienna and the Environment Agency Austria monitored eight people in eight different countries and found that every single stool sample collected tested positive for the presence of microplastics.
  • Food processing and plastic food packaging are major sources of microplastics in human diets. Microplastics can also enter the human food chain via marine animals that people consume — significant amounts of microplastics have been found in lobster, shrimp, and tuna, for instance.
  • The researchers found 9 different types of plastic in the human stools they tested — shipped to Vienna in plastic-free containers to be screened at the Environment Agency Austria — with an average of 20 microplastic particles ranging in size from 50 to 500 micrometres found in every 10 grams of stool.

A study conducted with participants from across the globe found that every single stool sample collected tested positive for the presence of microplastics.

Researchers from the Medical University of Vienna and the Environment Agency Austria monitored eight people in eight different countries — Austria, Finland, Italy, Japan, the Netherlands, Poland, Russia, and the UK — and presented their findings at the United European Gastroenterology (UEG) Week held in Vienna late last month.

Microplastics are small plastic fragments that are less than 5 millimeters (about 0.2 inches) in length. Sources of microplastic pollution in Earth’s environment include cosmetics, clothing, and a variety of other products; they can also be created when larger pieces of plastic, like water and soda bottles or plastic bags, are released into the environment and subsequently break down into smaller pieces through natural weathering processes.

A 2015 study found that about 8 million metric tons of plastic waste makes its way from land into Earth’s oceans every year. Scientists are studying the effect this plastic pollution has on marine animals and ecosystems — for instance, research released earlier this year found that microplastic particles can block nutrient absorption and damage the digestive tracts of filter-feeding marine life, while the toxins and persistent organic pollutants found in plastic can change biological processes such as growth and reproduction and even lead to decreased fertility as it accumulates in the bodies of marine wildlife over time.

Food processing and plastic food packaging are major sources of microplastics in human diets. Microplastics can also enter the human food chain via marine animals that people consume — significant amounts of microplastics have been found in lobster, shrimp, and tuna, for instance.

Dr. Philipp Schwabl, who led the research presented at UEG Week, said he started to wonder how microplastics might be impacting humans after reading about the staggering increase of plastic pollution and high microplastic burden in sea animals. “Many people assume that microplastics are likely to be present also in humans,” he told Mongabay. “However, I couldn’t find any study proving this hypothesis. Thus, I was eager to initiate such an investigation.”

While he cautions that it’s necessary to be mindful of the small sample size of the study — just eight participants — Schwabl said he found the results eye-opening nonetheless. “Personally, I did not expect that each sample would be tested positive.”

In total, Schwabl and team found 9 different types of plastic in the human stools they tested — shipped to Vienna in plastic-free containers to be screened at the Environment Agency Austria — with an average of 20 microplastic particles ranging in size from 50 to 500 micrometres found in every 10 grams of stool. Polypropylene (PP) and polyethylene-terephthalate (PET) were the most common types of plastic found, present in all eight samples.

Each study participant kept a food diary for a week before submitting their stool sample and, according to the researchers, the diaries showed that all eight participants were probably exposed to microplastics when they ate foods wrapped in plastic or drank from plastic bottles. None of the participants refrained from eating meat during the study period. Six reported eating seafood.

In a statement, Schwabl said of the research and its findings: “This is the first study of its kind and confirms what we have long suspected, that plastics ultimately reach the human gut. Of particular concern is what this means to us, and especially patients with gastrointestinal diseases.”

So far, however, there haven’t been any studies examining the health implications of people being exposed to microplastics through their diet. “Indeed, it is a very important question and we are planning further investigations to elucidate the effects of microplastics on human health,” Schwabl told Mongabay. “However, animal studies exist which show that microplastic particles are capable of entering the bloodstream, lymphatic system and may even reach the liver. Furthermore, in animal studies it has been shown that microplastics may cause intestinal damage, remodelling of the intestinal villi, distortion of iron absorption and hepatic stress.”

Schwabl said that more studies are needed to determine exactly how ingesting microplastics might affect people: “Now that we have first evidence for microplastics inside humans, we need further research to understand what this means for human health. … [T]he more samples we get the better our understanding will be for human microplastics ingestion and once the sample size is bigger we might find additional correlations between microplastics contamination and place of residence or diets and lifestyle.”

Microplastic poses a growing concern in oceans and other aquatic habitat. Now it has been found in human stools, though the implications for human health are not yet well understood. Photo by 5Gyres, courtesy of Oregon State University, licensed under CC BY-SA 2.0.

CITATIONS

• Germanov, E. S., Marshall, A. D., Bejder, L., Fossi, M. C., & Loneragan, N. R. (2018). Microplastics: No small problem for filter-feeding megafauna. Trends in Ecology & Evolution. doi:10.1016/j.tree.2018.01.005

• Jambeck, J. R., Geyer, R., Wilcox, C., Siegler, T. R., Perryman, M., Andrady, A., … & Law, K. L. (2015). Plastic waste inputs from land into the ocean. Science, 347(6223), 768-771. doi:10.1126/science.1260352

• Schwabl et al. (2018). Assessment of microplastic concentrations in human stool. Presentation, UEG Week.

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