Microplastics Found in Human Plaque Linked to Stroke

For years, scientists have detected tiny plastic particles in the deepest oceans and the highest mountain peaks. However, a groundbreaking study published in the New England Journal of Medicine has brought the issue much closer to home. Researchers have identified microplastics and nanoplastics directly within the fatty plaque of human arteries. More alarmingly, the presence of these plastics has been statistically linked to a significantly higher risk of heart attack, stroke, and death.

The Landmark Study Explained

In March 2024, a team led by Dr. Raffaele Marfella at the University of Campania Luigi Vanvitelli in Italy released findings that have shifted the medical community’s understanding of environmental pollution and cardiovascular health.

The study focused on 257 patients who were undergoing a carotid endarterectomy. This is a surgical procedure used to remove built-up plaque from the carotid arteries, which are the main blood vessels in the neck that supply blood to the brain. Once the plaque was surgically removed, researchers analyzed it using advanced techniques like electron microscopy and pyrolysis-gas chromatography-mass spectrometry to see what was inside.

What They Found

The results provided concrete evidence of contamination. Of the patients studied, nearly 60% had detectable levels of plastics embedded within their arterial plaque. The researchers identified two specific types of plastic polymers:

• Polyethylene: This was the most common, found in 58.4% of patients. Polyethylene is the most widely used plastic in the world, commonly found in plastic bags, films, and bottles.
• Polyvinyl Chloride (PVC): This was found in 12.1% of patients. PVC is durable and often used in water pipes, flooring, and plastic packaging.

The particles found were jagged and foreign, visibly distinct from the biological material of the plaque itself.

Quantifying the Health Risk

The mere presence of plastic in the body is concerning, but the study went further to track the health outcomes of these patients. The researchers followed the participants for an average of 34 months (nearly three years) after their surgery.

The correlation they discovered was stark. Patients who had microplastics or nanoplastics in their arterial plaque were 4.5 times more likely to experience a heart attack, stroke, or death from any cause compared to patients who had plaque free of plastics.

This hazard ratio remained high even when researchers accounted for other risk factors, such as diabetes, high blood pressure, and smoking habits. This suggests that the plastic itself may play an independent role in destabilizing cardiovascular health.

The Mechanism: Why Plastic Causes Problems

Understanding why plastic in arteries is dangerous requires looking at how the body’s immune system reacts to foreign objects. The study noted that the plaques containing microplastics showed much higher levels of inflammatory markers.

When microplastics lodge in arterial tissue, the body perceives them as invaders. This triggers an immune response. Macrophages, a type of white blood cell, attempt to engulf the plastic particles to remove them. However, because the body cannot break down these synthetic materials, the result is chronic inflammation.

Inflammation leads to instability:

• Plaque Rupture: Inflamed plaque is softer and more friable (prone to crumbling).
• Clot Formation: If the plaque ruptures, the body rushes to clot the area.
• Blockage: This clot can block blood flow to the brain, causing a stroke, or to the heart, causing a heart attack.

The researchers found elevated levels of interleukin-18 and other inflammatory cytokines in the patients with plastic-contaminated plaque, supporting the theory that the plastics are actively irritating the arterial walls.

Pathways of Exposure

A common question arising from this data is how these particles enter the bloodstream in the first place. While the study did not track the specific origin of the plastics for each patient, general scientific consensus points to three main entry points:

1. Ingestion: Drinking from plastic water bottles and eating food heated in plastic containers are primary sources. Microplastics are also found in seafood and salt.
2. Inhalation: Tires wearing down on asphalt release microplastic dust into the air, as do synthetic clothing fibers (polyester and nylon) in household dust.
3. Absorption: Nanoplastics are small enough (less than 1 micrometer) to potentially pass through skin barriers or mucosal linings.

Once these particles enter the body, they can cross the intestinal barrier or the lungs and enter the bloodstream, where they eventually lodge in vascular tissues.

Limitations and Future Research

While the New England Journal of Medicine study is a critical piece of evidence, experts urge caution in interpreting the results. The study establishes an association, but it does not definitively prove causation. It is possible that people who are exposed to more plastics also have other lifestyle factors or environmental exposures that contribute to their heart risk.

However, the strength of the correlation (the 4.5x risk factor) makes it difficult to dismiss the findings as coincidental. Future research will need to focus on confirming these results in larger populations and determining if reducing exposure to plastics can lower the levels found in the body.

Frequently Asked Questions

Can I get tested for microplastics in my arteries? Currently, there are no standard clinical tests available for the general public to detect microplastics in arteries or blood. The methods used in the study involved analyzing tissue surgically removed during an operation.

Does this mean plastic causes strokes? The study shows a strong link, or correlation. It implies that plastic presence makes plaque more dangerous, likely by causing inflammation. However, “cause” is a strong scientific term that requires further verification. It is safest to say that plastic presence is a significant risk marker.

How can I reduce my exposure to microplastics? To minimize intake, consider switching from plastic water bottles to stainless steel or glass. Avoid heating food in plastic containers, as heat accelerates the release of polymers. Additionally, vacuuming regularly with a HEPA filter can reduce the amount of plastic fibers inhaled from household dust.

Are the plastics found in the study rare? No. Polyethylene and PVC are among the most common plastics used globally. They are found in everything from grocery bags and plumbing pipes to shrink wrap and credit cards.