The accumulation of micro-nanoplastics (MNPs) in the body may lead to adverse cardiovascular effects and may represent a novel risk factor for cardiovascular disease, according to a state-of-the-art review published in the European Heart Journal.

Few studies have previously focused on microplastics and nanoplastics – particles smaller than 5 µm and 1 µm, respectively, stemming from the degradation of plastics – that have been found in air, water, food, dust and even cosmetics.

Francesco Prattichizzo, PhD, et al., break down the current research on these MNPs, which can enter the body through inhalation, ingestion and skin contact. During in vitro experiments and in animal models, MNPs triggered oxidative stress, inflammation and cellular senescence in endothelial and immune cells among others.

In animal studies, MNPs accumulated in the blood and heart, and contributed to cardiac fibrosis, capillary hyperemia or congestion, thinner or ruptured myocardia, myocardial fiber breakage, myocardial inflammatory injury or apoptosis, and elevation of cardiac enzymes.

Additional studies documented the presence of MNPs in ex vivo samples of the human cardiovascular system, including in thrombi, saphenous veins, arteries, carotid artery plaque and assorted heart tissues. Furthermore, results of one study of 257 patients undergoing carotid endarterectomy showed that accumulation of MNPs in carotid plaques was associated with higher risk for myocardial infarction, stroke and all-cause mortality within three-year follow-up.

These findings raise unanswered questions, especially because there is no standardized MNP pollution detection or exposure-testing method. Little work has been done to evaluate the effect on the body based on MNP size or type – or at realistic doses based on exposure levels. The true connection between MNPs and cardiovascular health is only now being recognized, and the reviewers urge a greater focus on both the prevention and treatment of MNP accumulation.

"It is easy to anticipate that the coordinated use of multiple technologies in large-scale studies and consistent economic investments through dedicated funding schemes will provide detailed and much needed information on the topic," they write. "In the meanwhile, relevant stakeholders should not ignore the already available evidence and should try to maximize the ongoing efforts aimed at reducing plastic production."