The tiny pieces of plastic that flake off of water bottles; rinse out of polyester blouses; and chip off of cutting boards, coffee pods, and myriad other objects don’t just build up in the environment. Scientific evidence is suggesting that microplastics also accumulate in our bodies—and they might not be harmless. A 2024 study found that microplastics had made their way into arterial plaques, which are fatty deposits inside people’s blood vessels. What’s more, people whose plaques contained plastic particles were more likely to suffer heart attacks or strokes or to die from other causes in the following years than people without plastic detected in these plaques. 

Now, in a new study published in the European Heart Journal designed to shed light on the relationship between plastic pollution and the heart, researchers sampled the blood flowing around 61 people’s hearts. They found that 84% of the people who had a heart attack had plastics in their blood, compared to only 40% of people with less severe heart disease and 32% of control patients with normal arteries. The results provide further evidence that heart-disease risk may be linked to plastic exposure.

Does plastic in the environment damage the heart?

The mainstays of protecting the heart remain lowering levels of “bad” LDL cholesterol, controlling blood pressure, and quitting smoking.

“But it has become increasingly clear that where and how people live—the pollutants they are exposed to—leaves a real mark on the heart, and we wanted to understand that better rather than treat it as background noise,” wrote two co-authors of the new study, Dr. Emanuele Barbato of the Sant’Andrea University Hospital in Rome and Dr. Pasquale Paolisso of Sapienza University of Rome, in an email. 

The study collaborators, who are both cardiologists, were part of the team behind the 2024 study of more than 300 patients that found a link between microplastics in people’s arterial plaques and an increased risk of serious cardiovascular events. They then wondered whether levels of micro- and nanoplastics were higher in the blood of people with heart disease. 

So, for this new work, they and their colleagues sampled blood from 61 patients—some of whom were receiving emergency treatment for a heart attack with arterial blockage, some of whom had chronic coronary syndromes, and some of whom had normal coronary arteries. 

Not only were the heart-attack patients far more likely to have plastics in the blood running through their coronary arteries than the other groups, but they also had higher concentrations and a wider variety of plastics. In these patients, the highest levels of plastics were in blood drawn from the blocked artery itself, at the site of the blockage. Their arteries also had elevated levels of inflammatory markers, confirming previous research linking plastic exposure with inflammation.

The potential importance of other environmental exposures

The researchers also looked at air pollution where patients lived and recorded whether they were smokers. Living with higher pollution levels and a smoking habit made patients much more likely to have plastics in their blood, and the researchers speculate that smoking might be part of how plastics arrive there.

“When we looked at patients who both smoked and lived with higher levels of air pollution, every single one of them had detectable microplastics—100%—whereas among those who neither smoked nor were heavily exposed, only about one in eight did,” Barbato and Paolisso wrote by email. “We were somewhat surprised that of all the variables we examined, smoking emerged as an independent predictor of carrying plastics—pointing to cigarette smoke as not just a source of chemical toxins but a carrier that helps plastic particles into the body.”

“It’s very important work,” says Dr. Rocco Montone, an interventional cardiologist at Fondazione Policlinico Gemelli in Rome who was not involved in the study. “We have improved the management of coronary artery disease, reducing traditional cardiovascular risk factors such as dyslipidemia, diabetes, hypertension. But heart attacks still occur, because there is something else. There is something beyond the traditional risk factors.”

As research continues to explore how plastics may be one of those risk factors, an important next step will be establishing an accessible way to test for these substances. “At the moment, we cannot measure our exposure to plastics,” he says, beyond tests used in labs for research purposes. 

Might it ever be possible to remove the plastic from our bodies? That seems unlikely, says Montone, as studies suggest that plastics are nestled within our own cells.

Instead, “we have to measure our exposure and try to reduce the exposure by limiting the use of plastics,” he says. At the moment, plastic production is projected to continue to grow over the next 20 years. “We have to reverse this process,” he says. “We are increasing our knowledge in this field, and we have to ask politicians to help us in our daily habits to reduce the exposure to this known risk factor.”