“The average global amount of plastic consumed per person per week is equivalent to a bank card.”

　　"Microplastics are first discovered in human thrombosis."

　　"Microplastics invade the brain for 2 hours."

　　...

　　The news about "microplastic invasion of human bodies" has frequently become hot searches, and public anxiety seems to be increasing day by day: Are we silently swallowed by plastic?

　　Plastics was once known as one of the greatest inventions of the 20th century and was widely used in various fields of production and life. But decades later, the white pollution caused by plastics has made it a global public enemy.

　　The United Nations has made many decisions on the global plastic pollution issue, but to this day, controlling white pollution is still a common problem facing mankind.

　　Unfortunately, in the field of plastic pollution control, the old questions have not been solved and new questions have been added.

　　Microplastics are one of them. From the ice and streams in the highest Everest area on Earth, to the most remote sea ice and fresh snow in the north and south poles, to the deep-sea sediments in the Mariana Trench, from the human placenta to the brain... the microplastics scattered in every corner touch the nerves of the public.

　　However, a recent article published by Nature magazine's official website emphasized that "it is not clear which discoveries are trustworthy and what they may mean." The article believes that regarding the harm of microplastics "needs more rigorous scientific research."

　　Microplastics everywhere

　　The word microplastic was born in 2004.

　　Back then, the team of Richard Thompson, a marine ecologist at the University of Plymouth, UK, published a far-reaching article in Science. He used a page of paper to summarize amazing discoveries on the British coast and in the seabed silt over the past decade - places with lots of rice-sized plastic debris, which he called "microplastics."

　　Most of these microplastics are less than 5 mm in size, so the scientific community has conventionally called plastics less than 5 mm microplastics.

　　Ji Junhui, a researcher at the Institute of Physics and Chemical Technology of the Chinese Academy of Sciences and director of the National Engineering Research Center for Engineering and Ecological Plastics, told reporters that although there was no concept of microplastics before, scientists have reported that since the 1960s, they have reported a large number of plastic fragments in the environment.

　　The emergence of the term microplastic also marks the beginning of research on microplastics.

　　Over the past decade, the number of research on microplastics has increased explosively. In 2014, there were 20 papers containing the keyword "microplastics" in Elsevier's Scopus database. In 2024, this number is close to 6,000. "The research directions of these papers mainly include monitoring, characterization, distribution and harm of microplastics," said Ji Junhui.

　　Over the past 20 years, scientists around the world have given detailed microplastic distribution: in the deep sea, in the Arctic snow and Antarctic ice, shellfish, salt tanks, drinking water and beer, floating in the air, or falling in the mountains and cities with the rain...

　　Where does the almost ubiquitous microplastic come from? Some people believe that the abuse and unreasonable disposal of plastic products are the main sources of microplastics. According to statistics, from 1950 to 2020, the global annual plastic production increased from 2 million tons to more than 450 million tons.

　　The recycling and treatment effect is not ideal for the massive amount of plastics produced. In 2019, the global recycling rate of plastic products was only 9%, and 69% were treated according to traditional models (including landfill and incineration); another 22% of plastics were unmanaged and were randomly trapped in the environment and degraded into microplastics.

　　Scientists have also discovered other sources of microplastics. "We cannot carry all the 'pots'." Ji Junhui said that the particles falling off the car tires and synthetic microfibers falling off the clothes can form microplastics. "The car running all over the streets has become thinner in three to five years, but no marks are left on the road, and the worn materials have become microplastics floating in the air."

　　The biggest feature of microplastics is diffuse. "Because of its small size and light weight, it can be suspended in the air for a long time, the microplastic can be transmitted by the wind to places far away from the source," said Ji Junhui. "Theoretically, it exists in any corner of the earth."

　　In 2021, Albert Kurmans, an environmental scientist at Wageningen University in the Netherlands, published a paper saying that their limited survey of microplastics in air, water, salt and seafood found that children and adults may consume more than 100,000 to 100,000 microplastic particles per day. If the worst-case assessment is made, the amount of microplastic the human body may consume in a year is about the weight of a credit card.

　　Some studies are out of reality

　　How long will the microplastics entering the human body stay and what harms will it bring? This is a topic that scientists are committed to solving but have no definite answers yet.

　　Martin Wagner, a biologist at the Norwegian University of Science and Technology, believes that until about 10 years ago, researchers began to shift their research focus from studying microplastic particles in the environment and animals to assessing their condition and impact on human health.

　　Since the first report on microplastics in human intestines in 2018, the existence of microplastics has been detected in the lungs, liver, spleen and kidney tissues. Subsequently, studies have found that microplastics have arrived at the placenta.

　　Toxicologist Matthew Kampen tracks the distribution of microplastics by dissolving tissues of human corpses. In January this year, his team published a study in Nature Medicine showed that the level of microplastics in brain samples in 2024 was about 50% higher than that in 2016. And the content of microplastics in brain samples is as much as 30 times higher than in liver and kidney samples.

　　"Study shows that microplastics have been found to exist in various organs of the human body, including the heart, brain, lungs, breast milk, etc.," said Ji Junhui.

　　The findings based on animal experiments have led researchers to suspect that microplastics may be related to human cancer, heart disease, kidney disease, Alzheimer's disease or fertility problems.

　　However, as of now, scientists seem to have found no exact evidence that microplastics are harmful to the human body. A 2022 World Health Organization report pointed out: "There is currently no sufficient evidence to prove that microplastics pose a direct threat to human health."

　　The sound is drowned in overwhelming papers on the harm of microplastics. "It is worth noting that a considerable number of the conclusions in these papers cannot stand scrutiny and have no practical significance." Li Daoji, dean of the Institute of Plastics Cycle and Innovation at East China Normal University, said bluntly.

　　Li Daoji is one of the earliest scholars in my country to engage in microplastic research.

　　"Plastic is a general term, and microplastics in the environment are also a general term for microplastics. They have a wide variety of types, different sizes, shapes, and compositions. If it has an impact, the impact on each organ or cell type will definitely be different." Li Daoji said, "How many types of microplastics are there, what are the sources? Which ones are harmful and which ones are not? If they are harmful, what mechanisms of their action are? These basic scientific issues have not been clarified yet."

　　Under this premise, many of the current studies rely on smaller sample sizes (usually 20 to 50 samples) and lack the appropriate control group. At the same time, modern laboratories themselves are hot spots for nanoplastics and microplastic pollution, and it is difficult for current technologies to detect plastics to rule out the possibility of being tarnished.

　　Another problem is that some of the data generated so far are biologically meaningless. The above article on the "Nature" website gives an example. Studies have found that microplastic particles of 5.5-26.4 microns and synthetic fibers of 19-24.5 microns appear in brain tissue. But previous studies have shown that particles over 1 micron may be too large to pass through the air-blood barrier in the lungs, and any particles larger than 10 microns may also not pass through the intestine-blood barrier.

　　"There is no compelling mechanism to explain how larger particles bypass biological barriers, so it is difficult to accept the conclusion that particles larger than 10 microns have entered human tissue," the article noted.

　　In addition, in order to pursue hot topics and publish papers, some researchers designed some experiments that were unreasonable and came to sensational conclusions. An expert who did not want to be named gave an example to reporters. A scientific researcher published an article and concluded that microplastics are toxic to the liver of mice. "But the dosage he gave was particularly large, equivalent to giving people hundreds of grams of microplastics every day. What is the significance of this conclusion drawn from data that was out of reality?"

　　Therefore, in the view of some scholars, microplastic research is mixed with chaos, fallacies and rumors.

　　For example, Swedish scholars have published an article in Science, saying that it proves for the first time that sea bass larvae selective feeding of microplastics by larvae, and that the growth and development of sea bass larvae will be affected by microplastics. This article has attracted widespread attention and controversy, and was withdrawn for academic fraud just a few days later.

　　Take action as soon as possible when there is a risk

　　For an emerging field of research, it is not surprising that these problems arise. But scholars believe that without stricter standards, transparency, and collaboration among researchers, policy makers and industry stakeholders, the cycle of misinformation and inefficient regulation could undermine efforts to protect human health and the environment.

　　"Microplastic research is still in its infancy, equivalent to the 'Warring States Period'. There are many areas that need to be explored in depth, including the formation mechanism, dissemination mechanism, monitoring means, hazard degree, and governance methods of microplastics." Ji Junhui believes.

　　Li Daoji analyzed that one of the reasons why there are too many differences in global microplastic research is the lack of standard and unified analysis methods, and concluding data is difficult to compare.

　　For example, there have been reports in China that different research teams have different monitoring results on the concentration of microplastics contained in seawater in the same area.

　　"The problem may be the clothing fibers in microplastics and the pollution during the analysis process. The size of clothing fibers is significantly smaller than that of other types of microplastics, but the proportion in seawater is very high." Li Daoji said that whether the sampling and statistics caliber are included in clothing fibers will lead to differences in the concentration of microplastics, "a consistent standardized method must be established among different countries and regions."

　　Scholars hope that in-depth and effective scientific research can more thoroughly understand microplastics and their potential risks, and use solid data and scientific conclusions to provide a scientific basis for the control measures that may be taken next. But their consensus is to take action as soon as possible when risks exist and to encourage public participation in decision-making.

　　"Although there are some knowledge gaps in current research on microplastic risks, policy actions do not have to wait, and measures can be taken immediately based on preventive principles." Chad Thompson, the first scientist who used the term "microplastics", pointed out that for example, banning unnecessary plastic products, better designs and supply chain adjustments can help reduce emissions.

　　The EU passed the Microplastics Ban Order in 2023, prohibiting the intentional addition of microplastics to cosmetics and detergents, and plans to reduce the release of microplastics by 30% by 2030. In the United States, California legislation in 2022 requires cosmetics to be marked with microplastic components; the National Oceanic and Atmospheric Administration funded a number of marine microplastic cleaning technologies.

　　In my country, microplastics, persistent organic pollutants, endocrine disruptors and antibiotics are called the "four major families" of new pollutants. In 2021, my country included microplastics in the monitoring scope in the "14th Five-Year Plan for Plastic Pollution Control Action Plan"; the 2023 "List of Key Control New Pollutants" clearly stipulates the control of some microplastics.

　　Some places have also begun to try to increase the pace of microplastic treatment. Hainan released the province's "List of Key Control of New Pollutants" in April last year, which included 15 categories of substances, the first 14 categories were consistent with the national list, and the new microplastics was added as the 15th category.

　　"Although there is currently no evidence to prove the harm of microplastics, at least we can conclude that it is not beneficial." Ji Junhui said that, therefore, the direction of reducing the production of microplastics from the source is certain.

　　In January 2020, my country clearly required that by the end of 2022, the sale of daily chemical products containing plastic microbeads would be prohibited. Therefore, matte toothpaste, matte facial cleanser, exfoliating scrub, etc. were once popular and are now hard to find. Because the plastic microbeads used in some "frosted" products are a major source of microplastics.

　　In the long run, Ji Junhui said that reducing the production of microplastics from the source still depends on technological innovation. "We need to innovate and upgrade the raw materials for the products that produce microplastics and do a good job in plastic pollution." He gave an example. Once the needle is inserted, the microplastic will fall off. Now the newly developed materials solve this problem. In addition, in terms of microplastic treatment, the Tsinghua University team has developed magnetic nanomaterials that efficiently adsorb microplastics, and East China University of Science and Technology has developed microplastic interception technology for sewage plant upgrades, etc.

　　"Reducing microplastics is not a slogan." Ji Junhui said that the treatment methods of microplastics are different in different items, and various industries need to form a consensus on reducing microplastic pollution, find solutions, and provide results and experience for industry governance.

　　【Produced by Shentong Studio】

　　Interview and writing: Our reporter Cao Xiuying

　　Planning: Liu Shu Li Kun

[Editor in charge: Ran Xiaoning]