in 2018 microplastics was voted Word of the Year by Fundeu and defined as plastic pieces smaller than five millimeters that are already produced in this size or broken from larger plastic.
The choice was not accidental. An investigation that year by the Austrian Federal Environment Agency and the Medical University of Vienna found that microplastics had been found in human feces, confirming that these particles moved from the food chain into the human digestive system.
This pilot study aimed to explore a growing problem about which little is known and to assess potential health impacts. The results were significant.
Feces containing microplastics
The researchers recruited eight participants, five women and three men, aged 33 to 65, from several European countries, Japan and Russia. For a week, they kept a diary of their usual diet and noted how the foods were packaged. Afterward, the participants donated a sample of their feces.
Nine different plastic types were found ranging from 50 to 500 microns. Ten grams of stool contained an average of 20 particles. Among them were polypropylene and polyethylene terephthalate, plastics commonly used in packaging, containers and textiles.
We have the first evidence of microplastics in humans, and more research is needed to understand what this means for health, said lead researcher Dr Philipp Schwabl.
microplastics
A fact in line with the European Commission’s 2018 balance sheet on plastics in the circular economy. The report notes that world plastic production rose twentyfold since 1960, reaching 322 tons in 2015, and is expected to double in the next two decades.
In the European Union alone, about 25.8 million tons of waste is generated annually from this material, with less than 30% recycled. A sizable portion leaves the EU to be managed in other countries with looser environmental rules.
Earlier work published in Royal Society journals in 2017 confirmed that the seabed had become a site of plastic accumulation, with millions of fish swallowing this substance. It followed that humans could be exposed through food or even drinking water.
The growing body of scientific research on microplastics in the environment and the human body prompted the World Health Organization to call for a comprehensive study of actual exposure and urged the international community to curb plastic pollution to protect ecosystems and reduce human exposure.
Plastic affects not just oceans but many environments. Humans may be exposed through air as fine particles are inhaled, through the digestive tract via food and water, and through mucous membranes.
microplastic cycle in the sea
plastic in blood
Plastic surrounds daily life everywhere. Containers, clothing, bags, toothpaste, aprons, office supplies, disposable tableware and car components all break down into microplastics over time.
Spanish immunologist Juan J. García Vallejo and colleagues at Amsterdam UMC began examining indoor exposure after confirming microplastics in feces. The search extended to blood where four polymer types—polyethylene terephthalate, polyethylene, styrene polymers and polymethyl methacrylate—were detected in the blood of 22 volunteers, averaging 1.6 micrograms per milliliter of plasma.
While the figure raises questions, it confirms that plastic is present not only in feces but also in blood. The novelty of this finding invites scrutiny of how microplastics move from air to blood and what health effects they may have.
Also in the lungs
Another team from the University of Hull and Castle Hill Hospital in England published findings shortly after the Netherlands work, reporting microplastics detected in lung tissue from living patients at Castle Hill Health Centre.
Thirteen samples were analyzed under a microscope, revealing twelve polymer types in eleven samples. The study also noted a higher presence among men.
The general trend shows a rise in global plastic use and a corresponding invasion of microplastics in natural ecosystems, with exposure extending to humans and animals in feces, lungs, blood, liver, kidneys and even the placenta.
Researchers are now focused on potential health consequences. The scientific community continues to investigate.
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INTERVIEW. Juan J. García Vallejo
immunologist and researcher at Amsterdam UMC
“There are microplastics in the air we breathe”
The Immunoplast study at Amsterdam UMC confirmed microplastics in human blood, and researchers are pursuing the implications.
Four common plastics have been identified: polyethylene terephthalate, polyethylene, styrene polymers and polymethyl methacrylate. Plastic surrounds everyday life because most items contain these materials. Over time they break down into microplastics and can linger in air, food, and plants.
The study notes a blood concentration of 1.6 micrograms per milliliter, a number that raises concerns about potential toxicity. Determining risk requires understanding both exposure and toxicity. While some fear the worst, the long-term health impact remains under study. If a polymer proves toxic, researchers expect industry shifts toward safer alternatives. The goal is to reduce exposure without sacrificing modern convenience.
Questions remain about whether plastic can affect the immune system. If any effects are found, they may extend beyond immunity, touching endocrine and neurological systems due to chemicals like BPA and other related compounds used in plastics. The research community continues to explore these connections. Acknowledging widespread exposure, some occupational cases show higher levels among workers in polyester and related industries.
Do these findings suggest a decline in plastic use? The hopeful answer is that safer polymers could replace the ones with harmful effects. Progress in science may guide industry changes, while acknowledging the need to balance utility with health and environmental goals.
Environmental and health experts emphasize prevention and better chemical management to minimize risks from microplastics and related substances.