January 22, 2021

The microplastics have already reached the human intestine | Science

The microplastics have already reached the human intestine | Science

Stool samples from people from countries as far apart as the United Kingdom, Italy, Russia or Japan contained particles of polyvinyl chloride (PVC), polypropylene, polyethylene terephthalate (PET) and up to a dozen plastics different Although this is a pilot study with a small group of people, the geographical diversity of the participants and the types of plastic identified lead the authors of the research to emphasize the urgency of determining the impact of these small materials on human health.

Since the 60s of the last century the production of plastics has grown almost 9% every year. In 2015 alone, 322 million tons were produced, according to UN data. Sooner or later, much of that plastic ends up in the environment, particularly in the seas: About eight million tons per year. The action of water, microorganisms and sunlight gradually degrades the plastic to reduce it to small particles of a few microns in length (one micron is equivalent to one thousandth of a millimeter). Some are so small that microscopic plankton confuses them with food. Until very recently, the microspheres present in various cosmetic products they did not need erosion to be a problem, but their progressive withdrawal of products is minimizing their impact.

The researchers found 20 microplastics for every 10 grams of fecal matter

The rest of the story is known, the big fish eats the boy. It was a matter of time before the plastic created by humans came back to them. The study, presented on Tuesday in a gastroenterology congress which is being held in Vienna (Austria), was attended by eight volunteers from as many countries as Finland, Poland, the Netherlands and Austria itself. For a week they had to eat and drink as usual, noting everything they ate, whether it was fresh or the type of packaging that contained the food. At the end of that time, researchers from the Medical University of Vienna and the state agency for the environment of the Alpine country, took samples of their feces.

The results show that of the 10 plastics searched, they found nine of them. The most common were propylene, basic in milk and juice containers, and PET, from which most plastic bottles are made. The length of the particles ranged between 50 and 500 microns. And, on average, the researchers found 20 microplastics for every 10 grams of fecal matter. By the newspaper that took the participants, it is known that all consumed some packaged food and at least six ate fish. But the research could not determine the origin of the particles found in the samples.

"It is the first study of this type and confirms what we have been suspecting for a long time, that plastics eventually reach the intestine," says in a note the gastroenterologist and hepatologist at the Medical University of Vienna and the study's lead author, Philipp Schwabl. "Although in animal studies the highest concentration of plastics has been located in the intestine, the smallest microplastic particles can enter the bloodstream, the lymphatic system and even reach the liver," he adds, concluding that it is urgent to investigate to find out " what this implies for human health. "

Science has not yet determined the threshold at which the intake of microplastics can be harmful to humans

A report by the United Nations Food Organization 2016 collected data on the presence of microplastics in marine life: up to 800 species of molluscs, crustaceans and fish already know what it is to eat plastic. Although the vast majority of the particles remain in the digestive system, part of the fish that is discarded when eating it, there is a risk of ingestion in the case of the whole food, such as shellfish, bivalves or smaller fish. Also, a study published by Greenpeace last week showed that, in particular in Asia, the vast majority of the sea salt for domestic use contained microplastics.

But the question that science must still answer is from what amount ingested the plastic can be a problem for human health. Here, there are two risks, on the one hand the impact of the physical presence of the plastic particles and, on the other, the possible toxicity of its chemical components. Last summer, researchers from Johns Hopkins University (USA) published a review of what is known about microplastics in the sea and their possible risks to human health. One of the studies estimated that humans can swallow up to 37 plastic particles a year from salt. It does not seem like a big amount and less if it ends up expelled from the body. But they also note that a good seafood fan could eat up to 11,000 particles in a year.


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