Scary! Microplastic particles found in human blood for the first time. Where do they come from?

Recently, the news that microplastics were found in human blood for the first time has sparked heated discussions among netizens. Where do microplastics come from? Where will they go?

Text/Li Li Editor/Liu Zhao

New Media Editor/Li Yunfeng

Interview experts:

Deng Yixiang (Researcher, Chinese Academy of Environmental Sciences)

Lei Kun (Researcher, Chinese Academy of Environmental Sciences)

An Lihui (Researcher at Chinese Academy of Environmental Sciences)

Plastic not only pollutes the environment, but also ultimately pollutes human beings themselves.

Recently, the news that microplastics were found in human blood for the first time sparked heated discussions among netizens, ranking third on Zhihu's hot list and reaching 240 million views on Weibo.

This latest research comes from the Free University of Amsterdam and the Netherlands Delta Institute, which are top research institutions in the field of environment.

Scientists collected blood samples from 22 volunteers and found microplastic particles in 77% of them, with an average concentration of 1.6 micrograms per milliliter.

Although "microplastics" is still a new term to the public, it has long been listed by the United Nations Expert Group (GESAMP) as a "gentle killer" of marine life, with the same degree of harm as large marine debris. Today, microplastics are everywhere, from contaminated fish and other marine life to tap water, table salt, and now to the human body. The traces of microplastics are not only in China, but more and more countries are beginning to pay attention to this new threat.

But the discovery of plastics in human blood is worrying. Today, humans may consume water and food containing microplastics every day. So where do microplastics come from? Where do they go? What are the hazards?

▲Plastic particles (Photo source: Science Popularization China)

Plastics are facing a “grey rhino” risk

In 1909, synthetic plastics first appeared. Baekeland, known as the "Father of Plastics", could never have imagined that this invention, once hailed as the greatest invention of the 20th century, would become a troublesome "naughty child" 100 years later.

Baekeland's invention of phenolic plastic was the world's first fully synthetic plastic, made by chemically reacting phenol and formaldehyde. Since then, phenolic plastic has become a telephone, radio, gun, coffee pot, jewelry, and even the first atomic bomb.

The success of phenolic plastics changed people's minds. In the 1920s and 1930s, various types of plastics emerged in laboratories around the world. People produced polystyrene for packaging, nylon that became popular because of stockings, polyethylene for plastic bags, and so on.

During World War II, when supplies of natural raw materials were tight, plastic production took off again to fill the gap. However, the excitement didn't last long: the image of plastics gradually changed.

In the 1940s, plastics began to be used in large quantities in developed countries. At that time, some people with insight warned that while plastics brought convenience to human life, they could also become a disaster. In the near future, they could even become "super garbage" that would permanently pollute our planet and bring endless troubles and disasters to our environment.

▲There is a lot of plastic garbage floating in the ocean: bottles, bags, cups, buckets, straws, etc. (Photo source: Xinhuanet)

In the 1970s, small plastic fragments were first discovered in the high seas. As research on these fragments continued to accumulate, they attracted the attention of more and more scientific researchers. In 2004, British researchers published a research paper on plastic fragments in marine water and sediments in the American magazine Science, proposing the concept of microplastics for the first time. Since then, many researchers have devoted themselves to the study of microplastics and published many important results, making microplastic pollution a global concern. In 2008, the first international microplastics seminar organized by the National Oceanic and Atmospheric Administration of the United States defined microplastics as fragments with a diameter of less than 5 mm. Scientists figuratively compare it to "PM2.5" in the ocean because it is so small that it is difficult to detect it with the naked eye.

Recently, although the voices against plastics have been growing, it seems that people have never really shaken the convenience brought by plastics. Some people believe that from the current situation, plastics are facing huge "gray rhino" risks (gray rhino incidents refer to dangers that we have seen for a long time but turned a blind eye to). And we can be sure that it is extremely unwise to ignore its existence.

Synthetic fabrics are one of the "producers" of microplastics

Plastics have caused serious environmental problems. A large amount of discarded plastics on land pollutes mountains and rivers, causing "white pollution", and the ocean is also a major disaster area for plastic pollution.

Deng Yixiang, a researcher at the Chinese Academy of Environmental Sciences, told reporters that microplastics are a form of plastic, and the distinction is only made in physical size. Microplastics are partly derived from the physical fragmentation of large pieces of plastic. At present, "microplastics" generally refer to plastic substances that can be seen with the help of a microscope, with particle sizes ranging from a few millimeters to a few sub-millimeters. At present, most domestic and foreign studies define 5 mm as the upper limit of the size of microplastics, but the lower limit of microplastics is not unified. It is generally believed that only micron-level and above can be called microplastics.

Lei Kun, a researcher at the Chinese Academy of Environmental Sciences, said that in addition to the physical fragmentation of plastics, some microplastics also come directly from people's production and life. For example, plastic particles are produced during the friction between car tires and the road, and plastic microbeads are produced in personal care products such as cosmetics. Laundry wastewater is also one of the important sources of microplastics.

Plastic waste is also a major source of plastic microparticles. Data shows that the average person in the world consumes about 60 kilograms of plastic each year, and residents in North America and Western Europe even consume more than 100 kilograms. It takes about 20 years for a plastic bag to decompose, and even 450 years for a plastic bottle. Plastic waste discarded in the environment worldwide may enter the sea with water flow. The plastic microparticles produced by its decomposition are chemically stable and difficult to degrade, and may exist in the sea for more than hundreds of years.

At the same time, if plastic waste is further classified, even synthetic fabrics may be the "producers" of microplastics. Currently, about 60% of clothing is mainly composed of chemical fibers. A chemical fiber jacket may release a large amount of plastic fibers during washing, and once discarded, the decomposition of plastic fibers will produce even more plastic fibers. Studies have shown that washing machines cannot completely filter out microfibers. Studies have shown that every time a piece of synthetic fabric is washed, 1,900 plastic fibers fall off and enter the environment with wastewater.

In fact, this seemingly lofty global scientific issue slips through our fingertips almost every day. Since plastic microparticles can be used to replace natural exfoliating materials in cosmetics, they are commonly used in the manufacture of hand sanitizers, soaps, sunscreens, facial cleansers, shower gels, exfoliating scrubs and other skin exfoliating products to play a cleaning role. These substances containing microplastics will flow into the environment with wastewater and migrate to rivers and oceans.

Microplastics will eventually return to nature

Since there is no device to remove microplastics in sewage treatment plants, some microplastics may penetrate the sewage treatment system and enter rivers, lakes and seas. In the United States alone, about 8 trillion plastic particles enter the water every day, covering an area equivalent to 300 tennis courts.

Today, microplastics enter the ocean from land, and eventually spread to every corner quietly. They have even been found in sediments on the seabed, remote islands, and Arctic sea ice. Microplastics in the environment are absorbed by aquatic organisms such as plankton, fish, and shellfish in the water, and then passed to humans through the food chain. In addition to animal foods, microplastics in the soil may also be absorbed by plants and enter roots, stems, and fruits. After humans eat these roots, stems, and fruits, microplastics will also enter the human body. In addition, microplastics may also exist in drinking water and table salt and be directly ingested by humans.

▲The evolution of plastic after entering the ocean

An Lihui, a researcher at the Chinese Academy of Environmental Sciences, introduced that most microplastics will be deposited in environmental media such as soil, rivers and lake bottoms. A small amount of microplastics will enter the ocean through rivers or fishing, shipping and other activities. Some of the microplastics that enter the ocean will be deposited on the seabed, while the rest will float in different water layers of the ocean and spread around the world with ocean currents, causing potential adverse effects on the growth and reproduction of marine organisms.

The problem of microplastic pollution has attracted worldwide attention. At present, the harm of microplastics to animals has become clearer. Studies have shown that microplastics have been found in the bodies of as many as 114 aquatic species in the ocean. The results of their encounters with plastics are often fatal. From small plankton to large whales, they have inevitably eaten various plastics. Microplastics can enter the blood, lymphatic system, and even the liver of animals, causing damage to the intestinal and reproductive systems. In addition, the scientific community generally agrees that microplastics will release toxic additives, accumulate persistent toxic pollutants, and can also serve as carriers for the spread of toxic or pathogenic microorganisms, which may pose a hazard to human health.

Details of microplastic attacks on humans not yet understood

In fact, over the past decade, microplastics have gradually become one of the main concerns of environmental researchers. However, up to now, there is no feasible solution to microplastic pollution at home and abroad. There is still some controversy internationally about the mechanism and severity of microplastics' damage to human health.

Professor Schwobl, a gastroenterologist at the Medical University of Vienna and the first author of the study "Up to 9 different types of microplastics found in the human body", said: The microplastics found in this experiment are unlikely to pose a serious threat (directly excreted from the body) because of their large size.

The Food and Agriculture Organization of the United Nations also believes that microplastics may not be harmful to humans based on a survey on microplastics in 2017. This is because, for rodents and dogs, microplastics with a diameter of more than 150 microns will not be absorbed, but excreted through feces, so 90% of microplastics and nanoplastic particles ingested by the human body should not be absorbed by the human body.

However, some studies hold the opposite view. They believe that microplastics may be harmful to humans. The reason and evidence are: the components of the plastic itself and the components adsorbed by the plastic may have a negative impact on the human body and the ecology and produce side effects. Because the microplastics ingested by humans may not be completely excreted through feces, they will inevitably remain in the body and accumulate to a greater or lesser extent. Previous studies have also shown that plastic particles with a diameter of less than 20 microns can enter the blood circulation system and accumulate in the internal organs. As to whether they will cause harm, further research is needed.

Some experts said that there is some controversy about the direct toxicity of microplastics. Microplastic materials used in cosmetics, toothpaste, and facial cleansers need to be strictly certified by relevant departments, and their toxicity to the human body will be strictly controlled. It is generally believed that even if microplastics with larger particle sizes enter the human body, they are difficult to be absorbed by tissues, but microplastic particles with extremely small particle sizes may enter the blood and other organs through the human digestive system.

▲Microplastics in the environment are absorbed by aquatic organisms such as plankton, fish, and shellfish in the water, and then passed to humans step by step through the food chain (Photo source: Xinhuanet)

In the future, microplastics should be made more "friendly"

Plastics are important basic materials invented by humans, which have brought great convenience to people's production and life. Since the 1950s, the global plastic annual growth rate has maintained an average of 8.5%. By 2016, the global plastic production reached 335 million tons. Today, my country is a major producer and user of plastics in the world. The production of many plastic products, such as polyvinyl chloride (PVC) and amino molding compounds, has ranked first in the world, and the potential for further growth is still huge.

Some experts say that microplastics are almost everywhere in the world today, and it is almost impossible to completely avoid them, but there is no need for humans to be afraid of them. The harm of microplastics to human health is an issue that is constantly being studied and explored. At present, some scientists point out that its harm includes harmful additives and pigments used in the production of plastics, pollutants carried on the surface of microplastics, and physical blockages that microplastics may cause. Although the toxicological mechanism of microplastics is still under continuous research, as an uninvited "guest", microplastics are definitely not welcome.

It is understood that the international community has already taken action to address the problem of plastic and microplastic pollution. For example, many countries and well-known cosmetics companies in the world have announced a ban on adding plastic microbeads to personal care products such as cosmetics. Recently, McDonald's and Starbucks announced that they would stop supplying plastic straws, which is actually a way to show the world their attitude of gradually resisting disposable plastic products.

An Lihui told reporters that everything has two sides. Between the convenience brought by plastic and the harm it causes to the environment, people should take a more positive attitude and neither demonize plastic nor turn a blind eye to plastic pollution. On the one hand, we should try to reduce the use of disposable plastic products such as plastic bags, which is also a requirement for advocating the establishment of a conservation-oriented society; on the other hand, we should strengthen the recycling of plastic waste on the basis of garbage classification, increase the recycling of plastic waste, and realize the resource utilization of plastic waste; at the same time, scientists are also stepping up the development of new plastic materials that are more environmentally friendly. In short, while people enjoy the convenience brought by plastic, they should also minimize the harm of plastic to the environment, which requires the joint efforts of the whole society.

Controlling plastic and microplastic pollution is a systematic project. Some experts said that it is necessary to gradually improve the legislation and relevant standards for plastic and microplastic pollution control, and improve the plastic waste management policy, including strengthening the management of plastic packaging, limiting the direct landfill of plastic waste, improving the plastic recycling system, and controlling the transboundary transfer of plastic waste. In addition, it is also necessary to strengthen the management of plastic microbeads, develop plastic and microplastic removal technologies, expand public participation, and jointly resist the harm of plastic and microplastics to the environment.

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(The graphic content is reproduced from Xinhuanet, Scientific American, China Ocean News, etc.)

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