People with artery plaques containing microplastics were about four times as likely to have a heart attack or stroke as those with plastic-free plaques, suggesting microplastics may contribute to heart disease, say experts.
Microplastics form when sunlight, water and other agents erode plastics into fragments less than 5mm long. At this size, the particles can make their way into our bodies and blood through food, water and even the air we breathe. Yet little is known about their potential health effects.
Francesco Prattichizzo at IRCCS MultiMedica, a hospital in Italy, and his colleagues looked for evidence of microplastics in artery plaques from 257 adults, all of whom underwent surgery between August 2019 and August 2020 to have the plaques removed from arteries carrying blood to the brain.
Chemical analysis detected plastics in plaques from 150 of the participants. Using a microscope, the researchers could see jagged particles in the plaques as well – visible evidence of the microplastics, reports New Scientist.
The team then monitored the participants until July 2023 and found that during this period, those whose plaques had contained microplastics had an elevated risk of heart disease and death. On average, they were more than four times as likely to die or have a heart attack or stroke as participants with plastic-free plaques, suggesting microplastics contribute to cardiovascular disease.
However, these findings only establish a link between microplastics and heart disease, rather than proving microplastics are the cause, said Prattichizzo.
He and his colleagues couldn’t discount the possibility that other confounding factors might underlie the association, such as diet or air pollution. They did, however, find high levels of inflammatory molecules in plastic-containing plaques.
This might suggest microplastics in the bloodstream exacerbate inflammation, which increases risks of heart attacks and stroke, he added.
“Plastics contain a lot of different chemicals that we know can adversely impact health, so I’m not surprised we are starting to see increasing evidence of health effects,” said Tracey Woodruff at the University of California-San Francisco.
“Plastic production is steadily increasing and is projected to continue increasing, so we must know how (and) if any of these molecules affect our health,” Prattichizzo said.
Study details
Microplastics and Nanoplastics in Atheromas and Cardiovascular Events
Raffaele Marfella, Francesco Prattichizzo, Maurizio Municinò, et al.
Published in the New England Journal of Medicine on 7 March 2024
Abstract
Background
Microplastics and nanoplastics (MNPs) are emerging as a potential risk factor for cardiovascular disease in preclinical studies. Direct evidence that this risk extends to humans is lacking.
Methods
We conducted a prospective, multicentre, observational study involving patients who were undergoing carotid endarterectomy for asymptomatic carotid artery disease. The excised carotid plaque specimens were analysed for the presence of MNPs with the use of pyrolysis–gas chromatography–mass spectrometry, stable isotope analysis, and electron microscopy. Inflammatory biomarkers were assessed with enzyme-linked immunosorbent assay and immune-histochemical assay. The primary end point was a composite of myocardial infarction, stroke, or death from any cause among patients who had evidence of MNPs in plaque as compared with patients with plaque that showed no evidence of MNPs.
Results
A total of 304 patients were enrolled in the study, and 257 completed a mean (±SD) follow-up of 33.7±6.9 months. Polyethylene was detected in carotid artery plaque of 150 patients (58.4%), with a mean level of 21.7±24.5 μg per milligram of plaque; 31 patients (12.1%) also had measurable amounts of polyvinyl chloride, with a mean level of 5.2±2.4 μg per milligram of plaque. Electron microscopy revealed visible, jagged-edged foreign particles among plaque macrophages and scattered in the external debris. Radiographic examination showed that some of these particles included chlorine. Patients in whom MNPs were detected within the atheroma were at higher risk for a primary end-point event than those in whom these substances were not detected (hazard ratio, 4.53; 95% confidence interval, 2.00 to 10.27; P<0.001).
Conclusions
In this study, patients with carotid artery plaque in which MNPs were detected had a higher risk of a composite of myocardial infarction, stroke, or death from any cause at 34 months of follow-up than those in whom MNPs were not detected.
NEJM article – Microplastics and Nanoplastics in Atheromas and Cardiovascular Events (Open access)
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