Microscopic plastic levels far higher in those who suffer strokes, study finds
1 of 4 | Fears that microplastic and even smaller nanoplastic particles are emerging as a threat to cardiovascular health were reinforced Tuesday with the release of new research finding a correlation between high levels of the particles in the carotid artery and strokes. Photo by Sébastien Vincon/Pexels
Patients who suffered strokes, mini-strokes or temporary blindness had levels of “nanoplastic” particles in their necks far higher than in healthy people, an abstract of a small-scale study released Tuesday shows.
The abstract, released by the American Heart Association at the start of a scientific conference this week in Baltimore, is adding to a growing list of “troubling” evidence linking vascular disease to nanoplastics, the medical group says.
Nanoplastic fragments are even smaller than “microplastics” and can be absorbed into the body, penetrating biological barriers as they accumulate. While microplastics are loosely defined as particles smaller than 5 millimeters in diameter, nanoplastics are far smaller — typically thought of as less than 1 micrometer, or 1,000 nanometers.
These tiny fragments of plastic come from products like water bottles, food packaging and synthetic fabrics, and have been found concentrated in major organs, including the lungs, heart, liver and even the placenta, prompting scientists to warn that evidence is mounting they pose a risk to cardiovascular health.
In March 2024, an Italian study determined that patients with carotid artery plaque in which “microplastics and nanoplastics,” or MNPs, were detected had a higher risk of a myocardial infarction, stroke or death from any cause at 34 months of follow-up than those in whom the fragments were not detected.
Meanwhile, University of New Mexico Health Sciences researchers in February revealed they had detected microplastics in human brains at much higher concentrations than in other organs. Even more alarmingly, the plastic accumulation appears to be growing over time, increasing 50% over just eight years.
In the current study of fewer than 50 participants, University of New Mexico researchers examined carotid artery samples taken from three groups of patients: those who had artery-clogging plaque in the neck and experienced stroke, mini-stroke or temporary loss of vision; those who had plaque but did not suffer such symptoms; and those who had healthy carotids with no plaque.
They found that the group that suffered strokes had MNP concentration levels 51 times higher than those who had no plaque build-ups, while those who had plaque but didn’t suffer strokes had levels 16 times higher than those with no plaque.
The study has yet to be peer-reviewed or published in a medical journal, but the results nonetheless provide a “very interesting and troubling” look into the possible relationship between MNPs and vascular disease, said Dr. Karen Furie, volunteer vice chair of the hear association’s Stroke Brain Health Science Subcommittee.
Furie also is a professor of neurology at the Warren Alpert Medical School of Brown University in Rhode Island.
“To date, we have not considered exposure to plastic micronanoparticles a modifiable risk factor for stroke,” Furie said in an AHA-issued statement, adding that although research efforts are still a very early stage, the findings point to nanoparticles as “a novel potential target for stroke prevention.”
The study’s lead author told UPI that while it remains unknown if nanoplastics can actually cause stroke or other illness and that the small study has limitations, the results showing such a sharp, sizable swing in plastics levels between those who suffered strokes and those who didn’t raises eyebrows.
Dr. Ross Clark, a vascular surgeon and researcher at the University of New Mexico School of Medicine in Albuquerque, said his findings largely mirror the results of last year’s Italian study, but “with some additional layers of nuance.”
“It’s pretty compelling to see a 16-fold greater presence of nanoplastics in asymptomatic carotid plaques compared to a normal, healthy artery, and a 51-fold increase in those who are having symptoms,” he said. “So what is it about those symptoms and the plastics? Do they have anything to do with them directly?
“The answer is it’s too early to tell. But it’s interesting that those two groups are really different.”
Clark said he suspects the interaction between microplastics and the cardiovascular system is complex and will not be easily definable by obvious measures such as looking at inflammation.
“We actually didn’t find any correlation between the amount of plastics in the plaque and biomarkers of inflammation,” he said. “So it’s not just as easy as saying, ‘Having microplastics in these plaques causes inflammation.’ It’s not that simple. There’s definitely something more nuanced going on here, which is going to take quite some time to unravel.”
Dr. Isaac George, surgical director of the Heart Valve Center at New York Presbyterian/Columbia University Medical Center, noted last year it’s important to remember that no direct, causal relationship has yet been found between microplastics and heart disease.
“This doesn’t show that having particles in your body forms atheromas [artery plaque], but it is a very strong association, and I think it’s just more evidence that plastic has invaded our whole lifestyle,” he said in a video posted after the Italian study was released.
“I think the moral of the story is we really need to be careful and be aware of the exposure we have to plastics and try to reduce it as much as possible.”
Dr. Gregory Katz, a clinical cardiologist at NYU Langone Health and an assistant professor at NYU Grossman School of Medicine, agreed the study results are “concerning, just like basically all of the research on micro and nanoplastics and human health outcomes has been.”
But, he added, it remains difficult to answer the biggest questions about the potential dangers of nanoplastics exposure.
“It’s impossible with a study like this to know whether it’s plastics driving bad health outcomes or whether people who are sicker tend to accumulate more plastic and that their underlying condition drives those outcomes,” he told UPI.
“Second, this doesn’t tell us anything about exposure — where is the plastic coming from? Is it related to our volitional choices or is related to ambient exposure as a consequence of being alive in the year 2025?
“This type of limitation on exposure is a really big deal when you think about how we should or should not change our behaviors.”
The next steps in quantifying the effects of nanoplastics on the heart depend on how quickly new methods can be developed to study them — the field so new that there are currently very few protocols.
For example, it’s challenging to measure the particles, especially those made of polyethylene, which produces a confusingly similar signature to certain kinds of body fat in gas chromatography-mass spectrometry.
“Even to this day, we’re still refining those techniques,” Clark said.
Katz said the next step in establishing the science “isn’t so much proving causation that micro and nanoplastics cause human disease — although we certainly haven’t proven it. It’s helping to understand the exposures that drive accumulation of these substance in our bodies because that’s where we can take action.”