Are microplastics killing us all?

For better or worse (probably for worse) plastics have become an indispensable part of our daily lives. This is not just a consumer-level problem—it’s industrial and societal, and yes, individual consumer choices matter but to what extent?

Avoiding plastics—if we wanted to—is not as simple as using them less in the kitchen. Once plastics are disposed of, they are broken down into micro- and nano-sized particles (MNPs) that are ubiquitous in the environment. We ingest them in our food, our water, even the air we breathe. Not that much is known about possible health impacts, but that gap in our knowledge is slowing filling in.

If we look closely, we can find MNPs in virtually every human tissue, but the significance of this isn’t clear. Just because it’s there and sounds “scary” doesn’t mean it’s causing harm. But the science is starting to point in that direction (and industry, predictably, is pushing back).

One of the most interesting recent studies was published last year in the New England Journal of Medicine. The scientists did some clever work. Carotid artery disease is the cause of about 10-20% of strokes. Plaques build up in these large arteries supplying the brain. Many things contribute to this: high blood pressure, high cholesterol, smoking, diabetes, genetics. Regardless of the cause, these plaques can break off, shoot up to the brain and cause a stroke. Sometimes surgery is needed to clear these blockages.

One of the ways we prevent this is by a surgery called a carotid artery endarterectomy (CEA). In this study, the scientists collected the carotid plaques that were removed during CEA surgeries and did two different kinds of tests to look for microplastics—a chemical test, and direct visualization under an electron microscope. They then followed the patients for about three years to see how what happened to them. They found that patients with MNPs (especially nano-plastics) in their carotid artery plaques were more likely to have had heart attacks, strokes, or to have died during the follow up period.

Now, there are all sorts of limitations to this sort of study. It cannot tell us that MNPs caused carotid disease, only that there was an association between them. But it does add to the growing evidence that MNPs aren’t just a benign feature of our modern environment.

Other studies have shown MNPs in brain tissue and in blood clots from heart attack patients. None of this is a “slam dunk”—we don’t really know if MNPs are a major risk, a minor one, or no risk at all (although this point seems less and less likely).

Aside from using this knowledge as a stepping stone to learning more about the potential risks of MNPs, what can we do? One thing we can’t do is avoid MNPs. They are literally in the water we drink and the air we breathe. This is not a problem that can be solved at the individual level. This will take a concerted, long-term international effort to reduce plastics use in industry and at the consumer level. I’m pessimistic.

But there are some things we absolutely can do. MNPs are suspected to contribute to strokes and heart attacks, but only suspected. We already know that high blood pressure, cholesterol, diabetes, and smoking are major, modifiable risk factors. We know that medications to address these problems work, and that healthy eating and exercise play an important role as well.

It may turn out that MNPs aren’t much of a risk factor for stroke and heart attack—we need to do more research to try to nail this down better. But the risk factors we do know about are relatively easy to track and to treat. While the scientists try to figure out the plastics question, we can get busy reducing our risks by seeing our doctors, quitting smoking, and controlling our blood pressure and cholesterol. Controlling plastics in our environment may feel like an insurmountable problem, but preventing strokes and heart attacks isn’t. We’re actually quite good at it.

Stay well.

-pal

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References (partial list):

1. Marfella R, et al. Microplastics and Nanoplastics in Atheromas and Cardiovascular Events. N Engl J Med. 2024 Mar 7;390(10):900-910. doi: 10.1056/NEJMoa2309822.

2. Nihart, A.J., Garcia, M.A., El Hayek, E. et al. Bioaccumulation of microplastics in decedent human brains. Nat Med 31, 1114–1119 (2025). https://doi.org/10.1038/s41591-024-03453-1

3. Xu JL, Wright S, Rauert C, Thomas KV. Are microplastics bad for your health? More rigorous science is needed. Nature. 2025 Mar;639(8054):300-302. doi: 10.1038/d41586-025-00702-2.

4. Luís Gabriel A. Barboza, Sara Couto Lourenço, Alexandre Aleluia, Giovanni Paolo Senes, Xosé L. Otero, Lúcia Guilhermino, Are microplastics a new cardiac threat? A pilot study with wild fish from the North East Atlantic Ocean, Environmental Research, Volume 261, 2024, 119694, ISSN 0013-9351, https://doi.org/10.1016/j.envres.2024.119694.

5. Lee DH. Microplastics and Cardiovascular Diseases: Importance of Coexisting Environmental Pollutants. Circulation. 2024 Sep 17;150(12):908-910. doi: 10.1161/CIRCULATIONAHA.124.069801. Epub 2024 Sep 16. PMID: 39283932.

6. Yun Zhang, Qianhui Gao, Qiang Gao, Mingcheng Xu, Ning Fang, Lin Mu, Xuejie Han, Hui Yu, Song Zhang, Yue Li, Yongtai Gong, Microplastics and nanoplastics increase major adverse cardiac events in patients with myocardial infarction, Journal of Hazardous Materials, Volume 489, 2025, 137624, ISSN 0304-3894, https://doi.org/10.1016/j.jhazmat.2025.137624.