Microplastics are in bottled water, tap water, fish and seafood, and even table salt. There are more microplastics littering the planet than stars in the sky; it’s impossible to avoid them. Most recently, researchers have discovered microplastics in human poop, and you probably have some in yours, too.
In what is being called a first-of-its-kind study, researchers discovered microscopic bits of plastic in stool samples taken from people around the world. According to the study’s lead author, Dr. Philipp Schwabl, a physician scientist at the Medical University of Vienna’s Division of Gastroenterology and Hepatology, the study “confirms what we have long suspected, that plastics ultimately reach the human gut.”
It’s unclear what kinds of health effects might be caused by ingesting microplastics, but there is concern among scientists that they can affect gastrointestinal health and even affect other organs.
“Now that we have first evidence for microplastics inside humans, we need further research to understand what this means for human health.”
In the study, Schwabl and his colleagues analyzed stool samples from 8 healthy volunteers, each hailing from 1 of 8 countries: Finland, Italy, Japan, the Netherlands, Poland, Russia, the United Kingdom, or Austria.
Read: Plastic Bottles Could Lead to a Real Environmental Crisis, Scientists Warn
The team used a new type of analytical procedure to look for microplastics in the volunteers’ stool. The most common types of microplastics the researchers found were polypropylene and polyethylene terephthalate, both used in plastic bottles and a host of other common products. On average, 20 microplastic particles per 10 grams of stool were observed.
The volunteers were not assigned any particular diet, but food diaries revealed that 6 of the participants ate fish in the week before providing a stool sample. All 8 of the individuals ate plastic-wrapped food or drank from plastic bottles in the week before the samples were collected.
More than 95% of the microplastics the researchers detected came from plastic used to wrap or store food. 
The findings suggest that “more than 50% of the world population might have microplastics in their stools.” 
The study was small, but considering the range of countries the participants came from, it’s safe to say that there’s “a high likelihood that also many other people involuntarily ingest microplastics,” according to Schwabl. 
A larger study to confirm the findings is in the works. Schwabl said that he and his team hope to be able to identify factors that could help explain why a person would have microplastics in their stool, such as diet, lifestyle, and geographic location.
The scientists are also planning further research into the effects of microplastics on human health. Studies in animals indicate that microplastics can enter the bloodstream and lymphatic system, and may reach the liver. Moreover, researchers suspect that microplastics can damage the intestines and alter the way the body absorbs nutrients.
Read: Microplastics in the Ocean are Killing Baby Fish, Study Finds
Schwabl said: 
“Of particular concern is what this means to us, and especially patients with gastrointestinal diseases.”
He added: 
“I believe that trying to reduce plastic usage and plastic-packed food might be beneficial for nature and for us. Certainly, plastic is a very useful material and has a lot of clever applications. But maybe we should try to rethink about the necessity of abundant plastic use, and search for and support ecological and sustainable alternatives.”
Schwabl presented the results of the study on October 22 at UEG Week in Vienna, a European gastroenterology meeting. The findings have not been published in a peer-reviewed journal.
 Live Science