We've all heard about microplastics by now. Tiny plastic particles have turned up in oceans, bottled water, seafood and even the air we breathe. Over the past few years, researchers have also found them in different parts of the human body, including the placenta, lungs and brain.

Now, a new study from Italy has added another surprising place to that list: the blood vessels that supply the heart.

While the findings are thought-provoking, researchers say there's an important point to remember. The study doesn't prove that microplastics cause heart disease. Instead, it raises new questions about how these tiny particles might be entering our bodies, especially in people who smoke.

A closer look at the heart

The research, published in the European Heart Journal, looked at 61 people who were undergoing coronary angiography, a test used to examine the heart's blood vessels.

Participants were divided into three groups: people who had recently experienced a heart attack, those living with stable coronary artery disease and people whose coronary arteries appeared normal.

When researchers analysed blood from the arteries supplying the heart, they found microplastics and nanoplastics far more often than expected.

The tiny particles were detected in 84 percent of people who had suffered a heart attack. Among those with stable coronary artery disease, the figure was 40 per cent. In participants with healthy coronary arteries, plastics were found in 32 percent.

Polyethylene, a plastic commonly used in food packaging and shopping bags, was the material detected most often.

The smoking connection

One of the study's most striking findings involved smoking. Researchers found that smokers were six times more likely to have detectable microplastics in the blood supplying their hearts than people who had never smoked.

The numbers became even more striking when air pollution entered the picture.

Every participant who both smoked and was exposed to higher levels of air pollution had detectable plastic particles in their coronary blood. Among people who neither smoked nor experienced high pollution exposure, only around one in eight had detectable plastics.

That doesn't automatically mean cigarettes contain all of these plastic particles. Instead, researchers believe smoking may make it easier for plastics already present in the environment to enter the bloodstream.

How could that happen?

Every day, we breathe in tiny particles from our surroundings.

Microplastics can come from synthetic clothing fibres, tyre wear, food packaging and countless other everyday sources. They are already floating in the air around us.

When someone smokes, cigarette smoke carries thousands of extremely fine particles deep into the lungs. Researchers believe these particles may help microplastics travel across the tiny air sacs in the lungs, known as alveoli, and into the bloodstream.

Air pollution may encourage a similar process.

Cigarette filters themselves are also made from cellulose acetate, a type of plastic, although this study did not determine whether the plastics detected came directly from cigarettes or from the surrounding environment.

The study also found that patients with detectable plastics had higher levels of inflammatory markers.

Inflammation is already known to play an important role in heart disease. It can weaken fatty deposits inside arteries, making them more likely to rupture and trigger a heart attack.

This doesn't prove the plastics caused the inflammation, but researchers believe the connection deserves further investigation.

What the study doesn't tell us

As eye-catching as the findings are, they should be interpreted carefully. The research involved only 61 participants and was observational, meaning it could identify patterns but could not prove that one thing caused another.

Smoking is already linked with many health problems, and smokers may also have greater exposure to air pollution or other lifestyle factors that influence heart health.

Researchers also point out that patients being treated for heart attacks often receive intravenous fluids and medical devices, which could potentially introduce tiny plastic particles into blood samples.

In other words, this study provides another piece of the puzzle rather than a final answer.

The research highlights a growing idea in medicine known as the exposome. This refers to the collection of environmental exposures we experience throughout our lives, from the air we breathe to the chemicals, pollutants and materials we come into contact with every day.

Rather than looking at smoking, air pollution and plastic pollution as separate issues, scientists are beginning to study how they may work together to affect our health.

It's a reminder that our wellbeing isn't shaped only by our genes or the choices we make. The environments we live in also play an important role.

None of this changes what we already know about smoking. It remains one of the biggest preventable causes of heart disease, stroke, cancer and chronic lung disease.

If future research confirms that smoking also makes it easier for microscopic plastics to enter the bloodstream, it would simply add another reason to the long list of why quitting benefits your health.

Perhaps the most memorable finding from this study is also the simplest. Every participant who both smoked and lived with higher air pollution exposure had detectable plastics in the blood supplying their heart. Among people with neither exposure, only about one in eight did.

It's too early to say what that means for long-term health. But it does show that researchers are uncovering new ways in which our modern environment and everyday habits may be more connected than we once realised.