When microplastics and nanoplastics get stuck in fatty plaques on the lining of arteries, they can increase the risk of stroke, heart attack and death by nearly five times, a new study suggests.

This study New England Medical Journalcompared the health effects between people with arterial plaque containing these tiny plastic particles and those without plaque.

“No one expected to see such a big difference between the presence and absence of nanoplastics in plaques,” said study author Antonio Ceriello, M.D., head of the diabetes division at IRCCS MultiMedica in Milan, Italy. Told. health. “Five times the risk of heart attack is a huge difference.”

Nanoplastics are less than 1 nanometer long. Microplastics are slightly larger, ranging from 1 nanometer to 5 millimeters, about the size of a pencil eraser.

These degraded plastic particles are found everywhere, from arctic snow to lakes and rivers. Scientists have discovered them in human lungs, placenta, breast milk, and recently even arteries.

Plaque buildup is primarily composed of cholesterol and fatty substances, which itself increases the likelihood of cardiovascular problems. Still, new research shows that the addition of plastic particles may further increase that risk.

“That’s pretty alarming,” says Mary Johnson, M.D., a research fellow at Harvard’s T.H. Chan School of Public Health who specializes in environmental health.

Cerieello and his team tested plaque samples taken from 257 adults.

The participants were considered to be at high risk for heart disease and needed to have plaque built up in their carotid arteries (blood vessels on the side of the neck that carry blood and oxygen between the heart and brain) removed.

Participants had to have their plaque removed anyway, creating an easy opportunity for researchers to analyze samples from living people. Most studies that have found the presence of microplastics in human tissue have looked at samples from people who have died.

The researchers detected polyethylene, the most common type of plastic, in 150 participants, or about 60% of the participants. Approximately 12% also contained measurable amounts of polyvinyl chloride, or PVC. Researchers found more nanoplastics than microplastics stuck in dental plaque.

The researchers followed the participants for about three years and monitored their health. After adjusting for factors that increase the risk of heart disease, such as older age and type 2 diabetes, researchers found that people whose plaque contained microplastics and nanoplastics were 4.5 times more likely to have a stroke or heart attack. It was revealed by. , or died within 3 years.

As an observational study, this study only showed an association between plastic and a higher risk of cardiovascular events or death. This does not prove that the presence of plastic is the cause of this increased risk.

“Association does not necessarily mean causation,” said Dr. Pankaj Pasricha, chief of internal medicine at Mayo Clinic in Arizona. health. However, he added that the relationship between the two is “strong.”

“These people were given adequate treatment for blood pressure and thrombosis because they are at high risk for cardiovascular disease,” Cerriero said. “The only difference was the plastic. We found this huge difference.”

Johnson said researchers have some idea of ​​how microplastics and nanoplastics set off a chain of events that can cause disease.

One theory, Johnson said, is that the material itself is the trigger. A recent report found that of the 16,000 unique chemicals identified for making plastics, at least 4,200 are considered “very hazardous” to human health and the environment. It has been found.

“It’s not just the particles themselves; the additives used during plastic manufacturing can also cause harm,” she explained.

Furthermore, studies examining the effects of adding microplastics to cells and animals suggest that inflammation may be involved.

“This is a foreign object, and every time a foreign object enters the body, some inflammatory mechanism kicks in,” Pasricha said. “Sometimes it’s subtle, sometimes it’s covert. Sometimes it activates the immune system in ways we don’t fully understand.”

Pasricha added that as with other ways plastic particles can affect human health, human studies are needed to understand the underlying mechanisms.

Experts say this is especially true given its ubiquity. “Plastic is almost everywhere,” Johnson says. “We’re all exposed to it.”