Since its invention, plastic has been filled with every corner of human life. It is broken down into tiny "plastic particles" when it is treated as garbage. The presence of these particles can be detected both in the deep sea and in the mountains. The latest research tells us that these particles are still present in our feces.
At this moment, a large amount of plastic waste is being dumped into the ocean on the earth, with an annual total of about 8 million tons. Once these plastics fall into the water, they will eventually be broken down into pieces, unless they are washed ashore. The smallest of these fragments is less than 5 mm wide, which we call "microplastics." There are many homes for microplastics: some float in the size of Alaska-sized plastic debris circulation, and rotate in the Pacific Ocean; others sink into the water, distributed in different depths depending on density, and spread throughout the world; Some are ingested by marine organisms such as fish and shellfish, and indirectly by other animals such as birds and humans.
From an ecological point of view, this is a mess. Especially the last link - the penetration of micro-plastics in food webs has even raised concerns among gastroenterologists. If microplastics invade the food we eat, they can also invade our stomachs and intestines. Chemicals that cannot be degraded or difficult to degrade in nature are gradually enriched in organisms through the extension of the food chain and the increase in trophic levels. Like Russian dolls, the concentration is getting bigger and bigger. Although this nature of the food chain clearly indicates that human viscera contains microplastics, no one has previously explored this problem in a systematic way.
On October 22, 2018, at the European Gastroenterology Conference in Vienna, researchers announced that they had detected microplastics in every stool sample of a small number of subjects worldwide. “In everyday life, plastics are everywhere, and people have many ways to get in touch with plastics,” says Philipp Schwable, a gastroenterologist at the Vienna Medical University. He led the research by e-mail on the Internet. However, he did not expect the surprising result that each stool sample was positive.
This experiment tested eight projects from eight countries. The countries from which the participants came were: Austria, Italy, Finland, Japan, the Netherlands, Poland, Russia and the United Kingdom. Each volunteer recorded a dietary diary one week before donating the feces. They placed the feces in glass bottles, packed them in biohazard bags, and sent them to the Austrian Environment Agency for analysis using cardboard boxes labeled “B-type biomass”. This set a precedent in similar research. “Maybe it’s because this job has to deal with the least enjoyable things,” Schwable said. Another reason is that this work requires the cooperation of doctors and analytical chemists. The latter uses a method called "Fourier Transform Infrared Microspectral" to detect microplastic components in the feces.
The plastic components in each of the subjects' stool samples were positive. The plastics involved are: polyethylene (the main component of plastic bags), polypropylene (the main component of plastic caps), polyvinyl chloride (that is, PVC, the main component of plastic pipes). In fact, nine of the ten plastics tested by researchers were detected in humans. The researchers found that every quarter of a pound (about 113 grams) of feces contains 20 plastic particles.
The results of the study have spawned many problems, the most important of which is: How does microplastics enter the stool? Is it harmful to the human body?
Because there are fewer participants in the study and there are many ways to ingest microplastics, it is difficult for researchers to answer the first question. “Where we look for microplastics, we can find it,” said Stephanie Wright of King's College London. Wright has nothing to do with this research, he studied the potential impact of microplastics on human health. The diet diary showed that of all subjects (not vegetarians), six had eaten fish a week before collecting samples. All subjects had eaten food in plastic packaging and used plastic bottles to drink water. Whether the micro-plastics in their feces are from seafood, plastic packaging or anything else (all foods contain micro-plastics, even beer or salt) are not clear. “Now we know that there is microplastics in the feces, and we know how to detect it. Our goal is to conduct larger studies, including recruiting more subjects,” Schwable said.
Wright said that in the future, technical means will be used to observe smaller-sized plastic particles. Microscopy used by Schwable and colleagues is common in microplastic analysis, but this does not detect particles less than 20 microns wide. This granule is comparable in size to human skin cells. Wright said another method called Raman spectroscopy can resolve microplastics as small as 1 micron wide.
In the same way, it is difficult to say how much micro-plastics are harmful to the human body, because we have never done research on human micro-plastic toxicity. Animal studies have shown that microplastics can penetrate into the blood, lymphatic system and liver of living things, all of which are present in the internal organs and have potentially harmful effects on animal organs, gut and hormone regulation.
This study clearly shows that microplastics have penetrated the world's oceans and have invaded many organisms, including our humans.