Microplastics in artery plaque: what the NEJM study found, and what it didn't

In brief

• Polyethylene was detected in more than half of the carotid plaques removed during surgery [8].
• Patients with micro- and nanoplastics in their plaque had a higher risk of heart attack, stroke or death, with a hazard ratio of 4.53 [8].
• The authors write that this does not prove causation and that lab contamination cannot be firmly ruled out [8]; whether the measurement method is suitable for PE and PVC in biological samples has also been questioned [9].

Paper: Marfella, R. et al. (2024). Microplastics and Nanoplastics in Atheromas and Cardiovascular Events. New England Journal of Medicine, 390(10), 900–910. [8]

This study looks at whether finding microplastics in artery plaque is linked to cardiovascular events in the years that follow. Below I set out what was done and what was found, then the limitations the authors themselves list and the method question that came later.

What was done

• Design: A prospective, multicentre, observational study [8].
• Patients: People having surgery to remove plaque from a narrowed carotid (neck) artery that was not causing symptoms (carotid endarterectomy). 312 were screened, 304 enrolled and 257 completed follow-up [8].
• Measurement: The removed plaque was analysed for micro- and nanoplastics. The main quantitative method, applied to every sample, was pyrolysis–gas chromatography–mass spectrometry (Py-GC/MS). Plaque from 10 randomly selected patients was also examined by electron microscopy, and 26 samples by stable isotope analysis [8].
• Follow-up: Patients were followed for a mean of 33.7 months (± 6.9). The outcome was a composite of heart attack, stroke or death from any cause [8].

What was found

• Polyethylene was detected in the plaque of 58.4% of patients, and PVC in 12.1% [8].
• Patients with detectable micro- and nanoplastics in their plaque were more likely to have the composite outcome than those without: hazard ratio 4.53 (95% confidence interval 2.00 to 10.27) [8].
• Smoking rates were similar in the two groups (16.0% and 15.9%) [8].

Limitations the authors list

In their discussion, the authors are explicit about the following [8]:

• The results do not prove causation.
• Laboratory contamination cannot be firmly ruled out.
• Unmeasured confounders, such as lifetime exposures and health behaviours, may have influenced the result.
• There were no socioeconomic data on the patients.
• The findings apply only to patients without symptoms undergoing carotid surgery and cannot be directly generalised to the wider population.
• Exposure through food and drinking water, exposure to fine particulate matter (PM2.5 and PM10), and the sources of the plastic were not assessed.

The method question that came later

A separate study published in 2025 tested how well Py-GC/MS works for measuring microplastics in human blood. Its authors concluded that the technique is not currently a suitable method for polyethylene or PVC in biological samples. Fats break down under heat into products like those of polyethylene, and PVC’s breakdown products are non-specific [9].

That study was on blood, not carotid plaque, so it does not directly test the NEJM result. What the two have in common is the method and the polymers: the NEJM study also used Py-GC/MS and detected polyethylene and PVC [8][9].

For more on the measurement steps: How are microplastics measured?

References

1. [8]Marfella, R. et al. (2024). Microplastics and Nanoplastics in Atheromas and Cardiovascular Events. New England Journal of Medicine, 390(10), 900–910. https://doi.org/10.1056/NEJMoa2309822 (Open-access full text: https://pmc.ncbi.nlm.nih.gov/articles/PMC11009876/)
2. [9]Rauert, C. et al. (2025). Assessing the Efficacy of Pyrolysis-Gas Chromatography-Mass Spectrometry for Nanoplastic and Microplastic Analysis in Human Blood. Environmental Science & Technology, 59(4), 1984–1994. https://doi.org/10.1021/acs.est.4c12599 (Open-access full text: https://pmc.ncbi.nlm.nih.gov/articles/PMC11800385/)

How to cite this post

Mikroplastikveri. (2026, November 2). Microplastics in artery plaque: what the NEJM study found, and what it didn't. https://mikroplastikveri.com/en/posts/microplastics-in-carotid-plaque/

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