How can the presence of microplastic in the human body affect our health?

Plastic particles have been found in the human brain, arteries, placentas, umbilical cords, livers, kidneys, lungs, and testicles. There's also evidence that they circulate in our blood. With each new scientific study, the ubiquity of this waste becomes more worrying: if plastic was previously considered primarily an environmental problem, accumulating on beaches or floating islands in the oceans, now it's inside us—and can also harm our health.

A study published in 2024 in the New England Journal of Medicine detected plastics in atherosclerotic plaques removed from carotid arteries. The presence of these particles was associated with a higher risk of heart attack, stroke, or death over a 34-month period, compared to patients whose plaques were free of plastic.

A study published in February in Nature Medicine confirmed the presence of microplastics in the brains, kidneys, and livers of cadavers. The particles were found in all brain tissue analyzed, with a predominance of polyethylene, material from plastic bags and food packaging.

"The situation is at a critical point, because it's gone from external pollution, seeing plastic scattered everywhere, especially in the oceans. Now it's also something that's inside all of us," summarizes nurse Lis Leão, senior researcher at the Albert Einstein Teaching and Research Center at Einstein Hospital Israelita, and editor of the book *Nature, Climate and Public Health* (2024).

The warning also comes from the World Health Organization (WHO): while acknowledging that evidence on the risks is still limited, the organization classifies microplastics as emerging contaminants and recommends further research, as well as measures to reduce exposure. In 2022, the WHO reinforced the need for continuous monitoring and warned that, even without direct evidence of health harm, the mere fact that these particles are being detected in human organs is sufficient cause for concern.

Pathologist Thais Mauad, a professor at the University of São Paulo (USP), shares this concern and says she imagines there is no human being without plastic circulating in their body. "I believe that everyone in urban areas, who comes into contact with food, who buys food in supermarkets, is eating plastic," she states.

Mauad is a co-author of a study published in September 2024 in JAMA Network Open that found microplastics in the olfactory bulb, the part of the brain responsible for detecting smells, in cadavers of people who lived for at least five years in the city of São Paulo. In each tissue fragment analyzed, one to four plastic particles measuring between 5.5 micrometers (µm) and 26.4 µm were found.

Three routes of exposure

Exposure to micro- and nanoplastics occurs through different pathways—and with a frequency that's difficult to avoid. According to Mauad, there are three main routes: through food, respiration, and, possibly, skin absorption. "We know that water is contaminated, that all foods are contaminated, especially seafood, which is embedded in plastic," explains the pathologist. "When people apply those creams containing microplastics, or exfoliants, there's also a risk of absorption."

Particles also float in the air, resulting from tire wear, industrial emissions, or the resuspension of waste in the soil, for example. "We inhale microplastics," summarizes Thais Mauad. Once in the body, these polymers can reach any organ. Another study from the University of New Mexico, this one published in the journal Toxicological Sciences , detected microplastics in all human testicular samples analyzed, averaging 328 micrograms per gram of tissue—values even higher than those found in placentas and some regions of the brain. "In every tissue where microplastics were searched, they were found," summarizes the USP professor.

Potentially toxic effect

The list of plastics already found in human tissue includes polyethylene, PVC, polystyrene, polyurethane, and PET. Besides acting as foreign bodies, capable of causing inflammation and cellular changes, they contain potentially toxic additives—such as plasticizers, pigments, and flame retardants—whose effects on the body are still being investigated.

"Although we have preliminary data, we know that microplastics can induce chronic inflammation, hormonal changes, and have toxic effects on the nervous and immune systems," says Lis Leão. "They also carry chemical compounds that can interfere with our biological processes."

Laboratory studies and animal models indicate possible adverse health effects. Research published in the journals Particle and Fibre Toxicology and Environment International showed that microplastics can affect liver metabolism and increase the risk of insulin resistance. Another study suggested impacts on the reproductive system , with initial evidence of the presence of particles in human follicular fluid.

"These studies are very recent, so we have little information. Therefore, the dissemination and dissemination of this knowledge is still insufficient for people, and society in general, to understand it," says Leão, coordinator of the eNatureza research line at Einstein, which works to generate knowledge about the relationship between human health and the environment, in addition to producing educational materials and free courses.

She emphasizes that science needs to advance in the standardization of methods for analyzing human tissues and in the development of sensitive biomarkers capable of measuring the impacts of exposure over time.

Risk naturalized by modern life

The lack of information helps explain why, despite the accumulated scientific evidence on the presence of microplastics in the human body and their potential health risks, society's response remains timid. Part of this inertia is also due to the way plastic has become naturalized in modern life: it represents convenience, accessibility, and speed. "If plastic is part of our lives and is everywhere, then society still fails to perceive it as a real threat," Leão points out.

Added to this is the invisibility of contamination. Microplastics (less than 5 millimeters) and nanoplastics (less than 1 micrometer), by definition, cannot be seen with the naked eye—which makes it difficult to perceive the threat with the urgency it deserves.

This is reflected in the lack of more forceful political and regulatory mobilization. While some countries are moving forward with restrictive policies, Brazil, for example, has yet to sign global commitments such as the Global Plastics Treaty, which has been under negotiation at the United Nations (UN) since 2022.

During the UN Ocean Conference, held in France in June 2025, representatives from several countries warned that plastic pollution poses a growing threat to human health and marine life. "Brazil refused to sign the treaty calling for a reduction in production. The country made a mistake by not signing this," opines the USP pathologist.

The Einstein expert points out another structural obstacle: economic interests. "We know there's a lot of pressure, and this ends up hindering, as in all other areas, this connection between science, public policy, and social perception," says Lis Leão. "We need more awareness-raising and knowledge-dissemination efforts to ensure a more effective response from society regarding how to control and position ourselves regarding the use of plastic in our lives."

Disposable culture

Given the ubiquity of these particles in the human body, scientists are beginning to investigate possible removal methods. A study published in the journal Brain Medicine , led by researchers at the Technical University of Dresden in Germany, suggested that therapeutic apheresis—a blood filtration technique used in some autoimmune diseases—may be a promising approach.

The procedure was applied to patients with myalgic encephalomyelitis, and the waste discharged by the equipment was analyzed using spectroscopy. The analyses revealed compounds with characteristics similar to polyamide and polyurethane, two widely used plastics.

Another way to mitigate the impacts is to reduce the use of single-use plastics and replace them with biodegradable or reusable materials. "We have to end the throwaway culture. Much of the plastic in nature comes from things you use for a minute and then throw away, like opening a water bottle," says Mauad.

Beyond individual choices, the Einstein researcher advocates for a broader transformation based primarily on environmental education. "It needs to begin in childhood and continue throughout life. Environmental education can awaken a more critical awareness, better connect people's individual choices, and collectively leverage this to push for more structural changes," says Leão.

In this scenario, it is also necessary to include the industry in the agenda of extended producer responsibility — a principle that transfers responsibility for the life cycle of their products, from start to finish, to manufacturers — already applied in sectors such as electronics.

"We need to overhaul the production and consumption model. We need to hold industries accountable, because today, disposal is the responsibility of each consumer. And those who produce, package, and distribute plastic seem to have no responsibility for the entire universe of plastic that is being disposed of, most of the time, inappropriately," criticizes Leão.

Brazil has made progress in this regard. The most notable example is the National Solid Waste Policy, regulated by Decree No. 11,413/2023, which created two types of certificates issued to companies: the CCRLR (Reverse Logistics Credit Certificate), which certifies environmental compensation for recycling, and the CERE (Packaging Structuring and Recycling Certificate), which focuses on financing and structuring collection systems.

Both instruments seek to increase traceability and transparency in waste management, in addition to encouraging companies to invest directly in recycling solutions and environmental impact reduction—thus alleviating the responsibility of individuals and governments to reduce plastic waste. "Complex problems require a little more intersectoral cooperation, greater awareness of all the chains involved in plastic production and consumption," summarizes Leão. "But much still needs to be adapted and restructured in our society regarding plastic use."

Source: Einstein Agency

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