Shocking discovery: Plastic in the arteries of stroke patients increases risk

Scientists have discovered a "shocking" amount of plastic in the arteries of stroke patients. 

Tiny microscopic pieces of plastic have been found almost everywhere researchers look, including the human body.

Microplastics and their even smaller relatives, nanoplastics, are likely flowing through your blood and accumulating in your organs, such as your lungs and liver.

Now a new study links the mysterious correlation of microplastics with the risk of heart attack and stroke.

"There is some amount of microplastics in normal, healthy arteries," Dr. Ross Clark, a medical researcher at the University of New Mexico who led the study, told Business Insider before presenting his findings at the American Heart Association meeting in Baltimore on Tuesday.

"But the amount that is there when they get sick – and get sick with symptoms – is really, really different," Clark said.

Clark and his team measured microplastics and nanoplastics in dangerous fatty plaques that can form in arteries, block blood flow, and cause strokes or heart attacks.

Compared to the walls of healthy arteries without plaques, plaque formation was 16 times more plastic – only in people who had no symptoms. In people who had a stroke, mini-stroke, or vision loss, the plaque had 51 times more plasticity.

"Wow, and that's bad," said Jaime Ross, a neurobiologist at the University of Rhode Island who was not involved in the study but has studied microplastics in mice, after reviewing the results.

"It's very shocking to see 51 times higher," she said, adding that in her study, a signal that is only three times stronger is "very reliable and impressive."

What exactly the plastic does there, if it does anything at all, remains a mystery. However, the new study offers some possible clues.

This study has not yet been peer-reviewed, but Clark said he plans to submit it for publication in a peer-reviewed scientific journal later this year after repeating some of the results.

With plastic, genetic activity looked different

Clark is a vascular surgeon, not a microplastics specialist. However, the idea for this study came to him during a conversation with his colleague Matthew Campen, who recently discovered that the human brain contains a spoonful of plastic.

"We realized together that there wasn't really much data on nanoplastics and microplastics in the vascular system, in blood vessels," Clark said.

Previous studies have shown that people with microplastics in arterial plaques are more likely to suffer a heart attack, stroke, or death.

To find out the cause, Clark examined samples of carotid arteries from 48 people – a pair of highways in your neck that direct blood to the brain.

The difference in the amount of plastic surprised him, but his team discovered another disturbing trend. Cells in plaque with a lot of plastic showed different gene activity than those with low plastic content.

In a highly plastic environment, one group of immune cells turned off a gene that is associated with stopping inflammation. Clark's team also found genetic differences in a group of stem cells that are believed to help prevent heart attacks and strokes by reducing inflammation and stabilizing plaque.

"Could it be that microplastics somehow change the expression of their genes?" Clark said.

He added that "more research is needed to fully establish this, but at least it gives us a clue where to look."

Ross, who specializes in the genetic mechanisms behind diseases, agreed that more research is needed, but added that she thinks "this plastic is doing something to these plaques."

"We just don't know"

Tracking microplastics in the human body is a new scientific endeavor in the last few years. It's not perfect.

Clark's team heated plaque samples to temperatures above 1,000 degrees Fahrenheit to evaporate the plastic polymers and break them down into smaller organic molecules that can be identified and measured by their mass and other properties.

Unfortunately, lipids in plaque can break down into chemicals that look very similar to polyethylene, the most common plastic found in everything from plastic bags to car parts.

"Because we are aware of this problem, we have taken many steps to remove these lipids and confirm their removal so that we are sure that we are measuring polyethylene," Clark said.

However, he added, "this is a major limitation, and it should be recognized that these types of methodologies are constantly being improved."

Clark is trying to get funding to further study the interaction between microplastics and immune cells in blood vessel walls. He hopes to expand this study beyond the carotid artery, as well as conduct several animal experiments to test causal relationships.

"We just don't know," Clark said. "Almost everything we know about microplastics in the human body, no matter where you look, can be summed up as: it's there, and we need to continue studying what it does, if it does anything at all."