Mounting evidence suggests that microplastics and nanoplastics can accumulate inside our bodies, though scientists still aren’t certain how risky this is for our health.
“This adds to the evidence that microplastics can lead to localized inflammatory reactions, which can raise the risk of heart attack due to plaque rupture,” says Joyce Oen-Hsiao, MD, a cardiologist at Yale Medicine in New Haven, Connecticut, who wasn’t involved in the study.
A STEMI typically occurs when a coronary artery, which brings blood to the heart, suddenly becomes blocked. This can happen when plaque ruptures and a blood clot forms. These heart attacks are considered a medical emergency because the blocked artery cuts off blood flow to part of the heart muscle.
Serious Heart Attacks Linked to the Highest Plastic Content in Blood
For the study, the authors recruited about 60 adults in Italy who were undergoing coronary angiography, a procedure doctors use to look inside the heart’s arteries.
Participants fell into three groups:
- Adults who’d had a STEMI heart attack
- Adults with chronic coronary syndrome, which happens when the arteries supplying blood narrow due to plaque buildup
- Control subjects, whose coronary arteries appeared healthy
Researchers then used advanced laboratory techniques to identify the types and concentrations of plastic particles. Microplastics are plastic fragments smaller than 5 millimeters — about the size of a pencil eraser or smaller. Nanoplastics are much tinier, smaller than 1 micrometer, roughly 1/80th to 1/100th the width of a human hair.
Testing revealed:
- Microplastics and nanoplastics were found in about 84 percent of people with STEMI, compared with 40 percent of people with chronic coronary syndrome and 32 percent of controls.
- People with detectable plastic particles also had higher levels of inflammatory markers in coronary blood, including interleukin-6 and tumor necrosis factor-alpha.
- Polyethylene, a common plastic used for everyday packaging, was the most frequently detected plastic type.
“STEMI patients not only had plastics more often, but at higher concentrations and in a greater variety of [plastic] types, with the highest levels found in the blood sampled directly at the coronary site,” says lead author Emanuele Barbato, PhD, a professor at Sapienza University of Rome in Italy and director of the cardiology unit at Sant’Andrea University Hospital. Coronary arteries are the blood vessels that supply the heart.
Study Shows a More Direct Link Between Microplastics and Inflammation
The results add to a growing body of evidence linking microplastics to negative health outcomes, including earlier work that reported plastics can accumulate within diseased arteries, and that these are linked to heart attack, stroke, and death, says Nicholas Leeper, MD, a professor of surgery and medicine at Stanford Medicine in California, who wasn’t involved in the study.
He points to a study published in 2024 that found microplastics and nanoplastics in carotid artery plaque. People whose plaques contained these particles had a higher risk of heart attack, stroke, or death over about three years.
In a separate study later that year, researchers found microplastics in blood clots taken from coronary arteries, brain arteries, and deep veins.
“These new findings extend the picture from tissue and plaque findings to the coronary circulation itself, showing plastics can reach the blood supplying the heart,” says Dr. Leeper.
Still, the study was small and observational, Leeper says, so it cannot prove that plastic particles triggered plaque rupture or caused a heart attack. It also captured a single point in time, rather than tracking people before and after a heart event.
Could the Plastics Have Come From Heart Interventions?
One challenge in studying microplastics is that plastic is everywhere — including in catheters, tubing, syringes, sample containers, and lab equipment.
That raises an important question: Were the particles really in patients’ blood? Or could they have been introduced during the heart procedure, or while the samples were collected and tested?
The team took several steps to prevent contamination, Dr. Barbato says. Researchers tested whether the procedure materials released plastic particles, found that not every patient who had the procedure had detectable plastic particles, and observed similar plastic types in peripheral and coronary blood from the same participants.
Taken together, these checks gave researchers confidence that the microplastics measured were already present, he says.
Leeper says the authors should be commended for those precautions, but the possibility of contamination can’t be ruled out completely. “Microplastics are ubiquitous — in air, water, food, and even laboratory environments — so distinguishing plastics truly present in a patient’s blood from background or procedural contamination is extremely challenging,” he says.
That’s one reason the findings are best viewed as a starting point for further research, rather than proof that microplastics directly contribute to heart attacks, says Leeper.
Smoking and Air Pollution May Help Explain Exposure
The study also examined two environmental exposures: cigarette smoking and long-term exposure to air pollution, also called PM2.5. Smoking emerged as an independent predictor of detectable microplastics, and long-term PM2.5 exposure was also linked to a higher chance of detection.
This points to the lungs as one possible route into the bloodstream, Barbato says. “Smoking may make this easier still, by damaging the lung’s protective lining and impairing its natural clearance mechanisms, so it appears to act not only as a source of toxins, but as a vector that helps plastics enter the circulation,” he says.
Dr. Oen-Hsiao says PM2.5 exposure can come from outdoor sources such as vehicle emissions, industrial processes, power plants, and wildfire smoke, as well as indoor sources such as frying, grilling, fireplaces or wood stoves, cigarette smoke, candles, incense, and some cleaning products.
When exposure is hard to avoid, such as during a wildfire smoke event or another high-pollution situation, wearing a mask may help reduce risk, she says.
Should You Try to Limit Microplastic Exposure for Heart Health?
“Heart disease has traditionally been framed around cholesterol, blood pressure, and diabetes, and this work is part of a shift toward also recognizing the environment — the air, and potentially the plastics in it — as part of the picture,” says Barbato.
But people shouldn’t panic. The study didn’t show that microplastics cause a heart attack, he says.
For now, experts say the clearest steps are the ones already known to protect the heart:
- Don’t smoke, and avoid secondhand smoke when possible.
- Reduce indoor sources of fine-particle pollution when you can, such as fireplaces, candles, incense, or heavy frying and grilling, Oen-Hsiao says.
- Cut down on unnecessary plastic use when it’s easy to do, but don’t treat that as a proven way to prevent heart attacks, says Leeper.
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