What You Need to Know About Microplastics Found in the Human Body

From remote Arctic locations to our everyday drinking water, microplastics - tiny fragments of degraded plastic - have been detected virtually all over the planet.

What's more, recent research suggests these tiny plastic particles are also present within us, housed in our kidneys, liver and other parts of our body.

Microplastics can vary in size: from 5 millimeters in diameter, approximately the thickness of pencil lead, right down to 1 nanometer. Some microplastics are so small they are known as nanoplastics and research has confirmed their presence in the human body. There's growing concern nanoplastics could be more harmful due to their size.

While the potential health effects of these plastics lodged in our bodies are not fully understood, scientists are becoming progressively alarmed about the possible impact.

The following areas containing plastic have warranted particular attention from experts.

Throughout 2022, multiple studies revealed microplastics within nearly 80% of the 22 healthy subjects from whom blood samples were taken. Within a few months, the existence of microplastics in human lungs had also been established.

Scientists hypothesize that the abundance of plastic particles in the air is often the entry point for micro- and nanoplastics within the body.

Environmental health researcher, Dr. Mary Johnson, explained to Health magazine that nanoplastics are more likely to penetrate deeper within the body. Larger particles typically settle in the lungs, although any particles under 2.5 micrometers can infiltrate the bloodstream via the lungs.

Once within the bloodstream, these plastic particles can spread throughout the body, accumulating within tissues.

A study from March, published in the New England Journal of Medicine, found microplastics and nanoplastics within arterial plaque. Worryingly, those individuals with plastic-filled arterial plaque were at a higher risk for future heart attacks or strokes.

This research involved 257 individuals requiring carotid artery plaque removal - the arteries that transport blood and oxygen between the brain and heart. All were already at a heightened risk for cardiovascular disease, stroke and death.

Over three years, 60% of those with micro- and nanoplastics in their plaque were 4.5 times more likely to have suffered a heart attack or stroke or died, even accounting for risk factors like age and diabetes.

While Dr. Johnson acknowledged that association doesn't confirm causation, she notes that the study represents a milestone moment providing a possible link between plastics detected earlier within the body and the future health outcomes of individuals - a theory that had only been explored in lab studies thus far.

Another study from January 2021 found evidence of microplastics within four out of six analyzed placentas. Three years later, every one of the 62 examined placentas contained micro- and nanoplastics.

Jacques Robert, chair of the University of Rochester Medical Center’s Department of Microbiology and Immunology, expressed concern to Health magazine, that due to placental exposure, these contaminants may induce lasting developmental effects on various organs and biological systems of a fetus.

While the exact effects of placental microplastics on fetal development remain unknown, they may contribute to issues within a baby's immune system. They can potentially increase allergy risks, encourage inflammatory and autoimmune conditions, and increase susceptibility to infections.

Scientists have discovered that ingested nanoplastic particles can cross the blood-brain barrier and have found microplastics in the brains of mice fed polystyrene nanoparticles.

Robert says that the presence of plastic in the central nervous system introduces questions about potential effects on brain function, such as memory and behavior. Furthermore, there are concerns about microplastics' potential role in diseases like Alzheimer's.

Although the aim should be to reduce our plastic use, complete avoidance of microplastics is impossible, says Garcia. This is a result of their omnipresence within our environment.

Even if we stopped producing plastic today, he added, the 8.3 billion metric tons produced since the 1950s would still be breaking into tiny pieces that infiltrate our environment and bodies.

The reassuring news is that researchers are pushing forward to determine how microplastics affect health.

“We are investigating this so we are all aware of what it’s doing,” Garcia said. “Down the line, if there are any policies that need to be put in place, we want to come from a data-driven source so we can say, ‘this is what we are seeing, what can we do to ensure we have a better future?’”

Moving forward, Johnson said researchers need to work together to standardize how everyone is measuring microplastics and nanoplastics in human tissues.

“There is not one gold standard that’s realistic to be able to replicate yet,” she said, noting that replication of studies such as the plaque one will be key for establishing whether there is a clear link—rather than an association—between plastic and health outcomes.

Future research will also need to examine the mechanism behind how microplastics might damage human health.

Robert said one hypothesis is that cells are unable to metabolize plastic, which may disrupt their ability to carry out duties and cause inflammation that leads to everything from Alzheimer’s disease to a heart attack.

Marcus Garcia, PharmD, a fellow at the University of New Mexico Health Sciences Center Department of Pharmaceutical Sciences, told Health he wants to see research assessing how specific types of plastic—or the chemicals that make them—affect health outcomes. 

“The dose is the poison,” he said. “At what level is it okay for us to have this accumulation? We need to know: At what levels do these create health conditions?”