The research also found that smokers and people exposed to higher levels of air pollution had significantly higher concentrations of these tiny plastic particles in their blood, adding to growing evidence that environmental pollution may contribute to cardiovascular disease.

The study was conducted by researchers from Sapienza University of Rome, the University of Verona, and the Research Centre on Environmental Pollution and Cardiovascular Diseases at the University of Campania "Luigi Vanvitelli" in Naples, Italy.

"Micro and nanoplastics are tiny plastic particles found virtually everywhere in the environment, including the air we breathe, the water we drink and many of the foods we consume," said Dr. Pasquale Paolisso, first author of the study from Sant'Andrea Hospital, Sapienza University of Rome.

"In recent years, scientists have detected these particles in human tissues and organs, raising concerns about their potential health effects. However, very little was known about whether they are present in the coronary circulation—the blood flowing through the arteries that supply the heart—or whether environmental exposures such as smoking and air pollution influence their presence," he added.

Study findings

The study involved 61 patients treated at Sant'Andrea University Hospital and Azienda Ospedaliera Universitaria Integrata of Verona. Participants were diagnosed with either an acute heart attack, chronic ischemic heart disease, or had normal coronary arteries.

Researchers collected blood samples both from the coronary arteries and from other parts of the body. They also recorded participants' smoking history and exposure to air pollution on the day of testing as well as over the previous two years.

Microplastics and nanoplastics in coronary blood samples were analysed at the Research Centre for Environmental Pollution and Cardiovascular Diseases at the University of Campania.

The researchers detected microplastics and nanoplastics in:

84% of patients who had suffered a heart attack.

40% of patients with chronic ischemic heart disease.

32% of patients with normal coronary arteries.

Heart attack patients also showed a greater diversity of plastic particles in their blood. Polyethylene, commonly used in packaging and consumer products, was the most frequently detected plastic.

Smoking and pollution increase exposure

The study found that patients with long-term exposure to higher levels of fine particulate air pollution (PM2.5) were more likely to have microplastics in their blood.

Smokers were six times more likely to have detectable microplastics than non-smokers.

Notably, every patient who both smoked and lived with higher air pollution exposure tested positive for microplastics, compared with only 12.5% of patients who neither smoked nor experienced elevated pollution exposure.

Association, not proof of causation

Lead researcher Professor Emanuele Barbato, Director of the Cardiology Unit at Sant'Andrea University Hospital and Sapienza University of Rome, cautioned that the findings do not establish a direct cause-and-effect relationship.

"These findings do not prove that microplastics cause heart attacks, but they reveal a strong association between environmental exposures, microplastics in the blood and cardiovascular disease," he said.

"Our study also showed that smoking history was strongly linked to microplastics in the bloodstream. Smoking may make it easier for micro and nanoplastics to enter the bloodstream through the lungs, while air pollution may act in a similar way."

He added that reducing tobacco use, air pollution and environmental plastic contamination could deliver benefits beyond environmental protection by potentially improving cardiovascular health.

Experts call plastics an emerging cardiovascular risk

In an accompanying editorial, Professor Andreas Daiber of the University Medical Centre of Johannes Gutenberg University Mainz, Germany, said growing evidence suggests microplastics and nanoplastics may represent a previously underestimated cardiovascular risk factor.

He noted that these particles have already been detected in blood, lung tissue, the placenta and breast milk, indicating widespread human exposure.

While acknowledging that the current study's sample size was relatively small, Daiber said the findings add to emerging clinical evidence linking plastic particles with inflammation, vascular injury and acute cardiovascular events.

He concluded that protecting cardiovascular health in the future will require addressing not only traditional risk factors such as smoking and high cholesterol, but also environmental pollutants—including plastic contamination—as part of a broader public health strategy.