Microplastics and nanoplastics — microscopic bits of plastic cast off into the environment — have been found everywhere from oceans to food to human breast milk. Despite growing recognition of microplastics as an environmental hazard, the health effects of these minute particles still isn’t well understood.

Now, in what is being hailed as a landmark study, researchers have identified microplastics in human arterial plaque and linked them to adverse cardiovascular outcomes, such as heart attack and stroke.

The study was published this month in The New England Journal of Medicine.

“This is a new space and definitely a wake-up call,” Dr. Rick Ferraro, a general cardiology fellow at Johns Hopkins Medicine who wasn’t affiliated with the research told Healthline.

“This is correlation, so it doesn’t prove causation. That being said, just finding [microplastics] in plaque at all is pretty concerning. Then to have this association with subsequent cardiac outcomes is quite striking,” he said.

“The major findings of the study were two: first, the identification of nanoplastics in the atherosclerotic plaques; second, the patients with atherosclerotic plaques contaminated by nanoplastics had a greater incidence of cardiovascular events as myocardial infarction, stroke, or death than patients who did not have evidence of nanoplastics within the atheroma [plaque,]” Dr. Raffaele Marfella, a professor of medicine at Università degli Studi della Campania Luigi Vanvitelli in Italy, and first author of the study, told Healthline.

For their study, Marfella and his team looked at samples of arterial plaque of more than 250 patients undergoing a plaque removal surgery known as a carotid endarterectomy. They found the presence of polyethylene microplastics in nearly 60% of patients, while polyvinyl chloride microplastics were discovered in about 12% of patients.

Polyethylene and polyvinyl chloride, are two of the most commonly manufactured forms of plastic and are used in everything from bottles to construction materials.

Over an average of 34 months following the surgery, patients with microplastics in their arterial plaque were 4.5 times more likely to experience a severe cardiovascular health outcome, including heart attack, stroke, or death, compared to individuals whose arteries didn’t contain plastic.

However, the study does not show causation, meaning that it does not prove that the health outcomes are due to microplastics or other causes.

“This study included patients who were already at higher risk because they had carotid plaque that was significant enough to require surgery. However, it is sobering and concerning to see how strong the downstream cardiovascular risk was for patients with microplastics in their plaque,” said Dr. Aaron Aday, director of vascular medicine at Vanderbilt University Medical Center. Aday wasn’t affiliated with the research.

Over 380 million tons of plasticTrusted Source are produced every year. Plastics are incredibly durable, which is one of the reasons they are so popular. When they begin to break down, they shed tiny plastic particles into the environment.

Microplastics, particles smaller than 5 millimeters, and nanoplastics, particles smaller than 1000 nanometers, have been found almost everywhere, including some very unlikely places. A study from 2022 discovered the presence of plastics in breast milk; in 2023, researchers found significant amounts of microplastics in Cliff Cave in Missouri, even though the cave has been closed to the public for the past thirty years.

Tiny plastic particles have even been discovered in the Mariana Trench Trusted Sourceand other areas of deep ocean, sometimes tens of thousands of feet down.

They are in our food supplyTrusted Source and in our waterTrusted Source. They are even in the airTrusted Source we breathe.

The prominence of microplastics has increasingly led researchers to wonder about their potential on human health.

“Microplastics and nanoplastics can enter our circulatory system and can be detected in various organs, including the heart. In animal studies, [they] can cause harmful changes to the heart and blood vessels, but we haven’t had any large human studies until now,” said Aday.

The study published this month is provocative, but there’s much more work to do before the health effects of microplastics can be proven to affect heart health.

Experts contacted by Healthline stress that large-scale studies need to be undertaken before that can happen. Several also pointed out the need for better demographic and environmental data for the participants.

“There are huge disparities in terms of environmental exposures and the people who suffer from the negative effects of environmental exposures. This study didn’t look at zip code or who was affected where,” said Ferraro.

“We would certainly like to see this study repeated with a larger number of patients and in other parts of the world,” said Aday, who pointed out that the individuals in this study were mainly from the same location and were the same ethnicity. “We need to understand the cardiovascular risk of microplastics and nanoplastics in other regions as well as other races and ethnicities.”

A groundbreaking new study found the presence of microplastics and nanoplastics in human arterial plaque.

The presence of microplastics in plaque was associated with a 4.5 fold increase in risk of heart attack, stroke, and death.

More research is needed to prove causation between the presence of microplastics and these cardiovascular disease outcomes.