Image Credit: Peter Dazeley / Contributor / Getty Images 
Microplastics drive the formation of arterial plaques in mice, a condition that leads to heart disease, according to a new study.
The study, published in the journal Environment International, revealed significant increases in plaque buildup in the arteries of male mice exposed to microplastics, at doses similar to those found in the environment.
The researchers also found changes to cells and gene expression linked to plaque buildup.
The mice did not develop obesity or high cholesterol, which have traditionally been linked to the condition; although the cholesterol theory of heart disease—often referred to as the “lipid-heart hypothesis”—has been largely debunked since it first appeared in the 1950s.
Interestingly, female mice were no affected in the same way by the tiny pieces of plastic.
The authors of the study suggest the “female” hormone estrogen may exercise some kind of protective effect against plaque formation.
“This study emphasizes the importance of limiting human exposure to sources of microplastics and of implementing approaches to limit their production,” said Timothy O’Toole, an associate professor of medicine at the University of Louisville.
“While the presence of microplastics of various types have been identified in blood vessels and diseased hearts, and the levels of these microplastics have been associated with severity of disease and likelihood of future adverse outcomes, their direct involvement in cardiovascular disease has been uncertain,” he added.
More than nine billion tons of plastic are estimated to have been produced between 1950 and 2017, with over half of that total having been produced since 2004. The vast majority of plastic ends up in the environment in one form or another, where it breaks down, through weathering, exposure to UV light and organisms of all kinds, into smaller and smaller pieces—microplastics and then nanoplastics.
Within our homes, microplastics are mainly produced when synthetic fibres from clothes, furnishings and carpets are shed. They accumulate in large quantities in dust and float around in the air, which we then inhale.
New studies appear regularly linking microplastic exposure to virtually every chronic disease, from irritable bowel syndrome, obesity and autism, to cancer, Alzheimer’s and infertility.
If you want to know more about microplastics and the threat they pose to human health, as well as how to protect yourself and your loved ones, read our detailed primer, “The Microplastic Menace.”
