Microplastics found in the human body? Not only invading the blood, liver, etc., what other harms does it have?

Microplastic pollution has finally reached humans.

At the recent European Congress of Gastroenterology, researchers reported that they had detected up to nine types of microplastics in human feces for the first time. Their diameters range from 50 to 500 micrometers. This study shows that plastics can ultimately reach the human gastrointestinal tract. This may not be good news for us.

What's even more worrying is that microplastics are now everywhere. These plastics, which are 5 millimeters or the size of a grain of rice, come from degraded plastic fragments, synthetic fibers, and plastic pellets. Some studies have found large amounts of microplastics in marine organisms such as tuna and lobsters, and they have also been found in 83% of tap - water samples worldwide.

Therefore, it is very likely that humans ingest microplastics through the food chain or other means. According to the diaries provided by eight subjects from different countries who participated in this study, they all ate food in plastic packaging and drank bottled water, and six of them had also eaten seafood. There were 20 particles in every 10 grams of fecal samples. The most common particles were polypropylene (PP) and polyethylene terephthalate (PET), which are the main components of plastic bottles and bottle caps.

Experts say that the specific sources of these microplastics cannot be determined yet, and further research is needed to determine whether they can remain in the human body. However, it is worth being vigilant that the smallest microplastics can enter the blood, lymphatic system, and even the liver, and microplastics in the intestines may also affect the immune response of the digestive system.

Microplastics can cause physical damage to organs. The toxic chemicals filtered out from them, such as the endocrine disruptor BPA and pesticides, can also damage the immune function and harm the growth and reproduction of organisms. Microplastics and toxic substances may also accumulate in the food chain, bringing potential impacts on the entire ecosystem, such as the health of the soil for planting. In addition, microplastics in the air and water can also directly affect humans.

More and more scientists are trying to figure out how this widespread and complex microplastic pollution affects animals and the ecosystem. From the decrease in fishery production to the change in the soil microbial environment, some tantalizing evidence is emerging. As researchers accumulate more data, they are beginning to realize that these findings are just the tip of the iceberg of the problem.

Threatening organs and blood

Before 2008, many researchers believed that animals could excrete any microplastics they ingested, such as what he called "non - natural fibers." However, ecotoxicologist Mark Browne was not entirely convinced. He conducted an experiment: he first put blue mussels into a water tank and then added microplastics coated with a luminescent material, which were smaller than human blood cells. After the blue mussels ingested these microplastics, he put them into clean water.

The presence of microplastics in the bodies of fish, earthworms, and other animals is disturbing enough. But if these particles remain in the body, especially if they move from the internal organs to the circulatory system and other organs, they can cause real harm. Scientists have observed signs of physical damage, such as inflammation caused by particles hitting and rubbing against the organ walls.

The polymers added during the plastic production process can transfer from microplastic particles to the environment. These environmental pollutants (and the pesticides adsorbed on the plastic surface) can be trapped by microplastics. Researchers have found that they can all damage organs such as the liver. Ecotoxicologists like Marco Vighi are testing which types of pollutants different polymers can adsorb and studying whether these pollutants will be ingested by freshwater and terrestrial animals. The total amount of microplastics in lakes and soil is comparable to that floating on the ocean surface - they may exceed 15 trillion tons.

The most important question is whether these physical and chemical effects will ultimately affect the growth, reproduction, or disease susceptibility of organisms. A study published in March this year showed that fish exposed to microplastics had reduced reproduction, and so did their offspring even when they were not directly exposed to microplastics. This shows that microplastics can affect the offspring of species.

Researchers point out that some animals are not negatively affected by microplastics, such as freshwater crustaceans of the amphipod type. Maybe they can deal with indigestible natural substances like stones. For some organisms, a certain type of microplastic may be toxic, while others are not.

Most studies on the effects of microplastics are conducted in the laboratory, and the experimental time is very short. Researchers usually only study one type of plastic, and the particles of these plastics are larger than those ingested by organisms and have a higher concentration than those found in the natural environment. However, ecotoxicologist Martin Wagner says that we have no idea about the long - term ecological consequences of low - concentration microplastics.

To make up for the deficiencies of laboratory studies, Wagner and others have carried out outdoor research. They are trying to match animals with the polymers and pollutants they are most likely to encounter and integrate other complex factors in the real environment into the research, because microplastics "are not the only stressors." When species are affected by stresses such as chemical pollutants, overfishing, and climate change, microplastics may be the last straw that breaks the camel's back.

What about microplastics in real - life scenarios?

On the green lawn of a botanical garden in Frankfurt, researchers are trying to create a chaotic real - life scenario. They placed rows of identical small water pools on the lawn and exposed them to the natural environment. Wagner put different microplastics into each pool. Some of these particles were original polymers, and some were polymers mixed with pollutants. He wanted to know the survival status of freshwater insects and zooplankton in the pools.

Wagner has not observed any obvious effects yet, but he is studying whether there are subtle signs of damage to certain organisms, and this kind of sign will produce a "ripple effect" in the ecological food web.

This effect can occur even if some organisms seem to be unaffected. Browne's blue mussels were not harmed in the short term, but he is worried that the microplastics accumulated in the blue mussels will be transferred to their predators. "These particles may not be so friendly to other organisms," he said.

Like Wagner, Browne has also extended his research to the real environment. He and his team collected fish and other organisms from Sydney Harbour and then studied whether they were related to the route of microplastics entering Sydney Harbour. They also tried to find some signs of ecological damage, such as changes in population size. This research method means that organisms can show normal behavior while being exposed to typical environmental conditions, facing stressors such as tides, storms, changes in ocean temperature, and industrial pollutants. Wagner said that if microplastics can have an impact beyond other stressors, we really need to be worried.

Plant ecologist Matthias Rillig has shown how microplastics can affect organisms by changing the environment. In a recently published co - authored paper, he wrote that soil containing polyester microplastics is fluffier and has higher humidity, which seems to affect the activities of certain microorganisms - they are very important in the nutrient cycle of the soil. This research is still in its early stages, but it is worthy of attention because farmers around the world are using treated sewage sludge rich in microfibers as fertilizer. Rillig and others also want to figure out how microfibers in the soil affect crop growth.

Inhalation, blood accumulation, microplastics are everywhere

The threat of microplastics to humans may be more direct. A study published in April this year showed that researchers found microplastics and microfibers in packaged sea salt, beer, bottled water, and tap water. Therefore, it is almost certain that humans have been ingesting microplastics. During the process of filling beverages, microplastics can seep into the beverages; microfibers in the atmosphere can also fall into tap - water storage tanks. Researchers were shocked by this: "This shows that we are once again exposed to the problem of poor waste management."

Since it is unethical to deliberately let humans ingest microplastics, researchers like Browne have turned their attention to medical research - using microplastics to deliver precise doses of drugs to specific areas of the human body. Through these studies, they can better observe the transfer of microplastics in the human body. If the particles are small enough, they may leave the organs and accumulate in the blood. A study on hamsters injected with microplastics showed that these particles can cause blood clots.

Humans can also inhale microfibers that fall from the air. It is known that air particles can lodge deep in the lungs, leading to various diseases including cancer. There is evidence that workers dealing with nylon and polyester fibers are exposed to harmful fibers to a much higher degree than the general population, and their lungs will be irritated and their lung capacity will be reduced (although not cancer).

Some scientists believe that focusing on microplastics in the human body may cause researchers to miss more important problems: at least for the chemicals added to plastics (such as the endocrine disruptor BPA), the plastic food and beverage packaging that humans come into frequent contact with is a major source of these substances. In other words, microplastics from packaging are also worthy of vigilance.

Some researchers also point out that, like many pollutants, the harm of microplastics is likely to depend on a threshold. Only when they exceed a certain value can they really affect organisms.

However, experts say that the fact that harmful microplastic pollutants are everywhere is enough to launch environmental protection actions.