Tiny plastic particles drifting in ocean waters may be quietly fueling a health crisis. A sweeping new study has linked high concentrations of microplastics in coastal U.S. waters to elevated rates of Type 2 diabetes, coronary artery disease, and stroke among residents living nearby.

The findings are stark. In counties facing the most plastic-contaminated oceans, diabetes rates were 18% higher, coronary artery disease 7% higher, and strokes 9% more frequent compared to those in low-pollution coastal areas, according to research published in the Journal of the American Heart Association.

“This is one of the first large-scale studies to suggest that living near waters heavily polluted with microplastics may be linked to chronic health conditions,” Dr. Sarju Ganatra, senior author and medical director of sustainability at Lahey Hospital & Medical Center, told the American Heart Association Newsroom.

Microplastics are linked to higher rates of diabetes, heart disease, and stroke.

Plastic Pollution Moves from the Sea to Our Bodies

Microplastics and their even smaller counterparts, nanoplastics, result from the breakdown of discarded plastic items such as bottles, bags, synthetic fabrics, and packaging. They are now present almost everywhere — in drinking water, seafood, and the air itself.

What’s less known is the toll they may take inside the human body.

A study led by researchers in Italy revealed microplastics in the arteries of 58% of patients undergoing surgery for carotid artery plaque removal. Those with detectable plastic particles were nearly five times more likely to experience a heart attack, stroke, or death in the next three years, NBC News reports.

“We know cardiovascular disease, particularly myocardial infarction, is usually triggered by an inflammatory response,” said Dr. Martha Gulati of Cedars-Sinai, noting that plastic-laden patients had higher levels of inflammation markers. But whether those markers are caused by plastics or something else is still under investigation.

Plastic particles are present in seafood, drinking water, and even the air.

County-Level Data Reveals Troubling Trends

The U.S. coastal study analyzed microplastic levels in ocean water within 200 nautical miles of 152 coastal counties between 2015 and 2020. Researchers then compared local rates of diabetes, stroke, and heart disease using data from the CDC and adjusted for other health and demographic variables.

In areas with very high microplastic pollution — defined as 10 or more plastic particles per cubic meter of water — residents had consistently higher rates of all three conditions. As News-Medical.net reports, these links held even after controlling for age, sex, race, physician availability, and environmental and social vulnerabilities.

Notably, counties along the Gulf of Mexico and the Atlantic coast saw the highest disease prevalence, while Pacific coast counties had lower pollution and lower disease rates overall.

Residents near polluted oceans have up to 18% higher diabetes rates.

How Do Plastics Harm the Body?

Though the studies cannot definitively prove causation, mounting research supports biologically plausible mechanisms. Plastic particles may trigger systemic inflammation, oxidative stress, and cellular damage. These responses are already known to contribute to the development of diabetes and cardiovascular conditions.

Microplastics have also been found in artery plaques, raising concerns that they could be physically contributing to the blockage of blood flow. Scientific American covered one of the first human studies showing plastic in arterial plaque, where those affected had significantly higher health risks over time.

Dr. Raffaele Marfella, who led that study, told NBC News that researchers suspect the particles degrade artery health in much the same way as other chronic irritants.

The Gulf and Atlantic coasts show the highest health risks from microplastics.

Not Just a Coastal Problem

Although this recent research focused on coastal waters, the threat isn't limited to oceanside communities.

“Microplastics are everywhere,” Dr. Ganatra told the NBC affiliate NBC26. “They’re in our food, our air, and our drinking water. So while this study measured ocean pollution, the implications extend far beyond.”

He also noted that even healthcare settings — meant to heal — rely heavily on single-use plastics that eventually break down and enter the ecosystem.

Experts warn that what we discard into the ocean may come back to kill us.

Urgent Need for Deeper Research and Action

Experts stress that more research is needed to trace how microplastics enter the human body, what levels are dangerous, and how exposure influences biological systems over time.

Until then, the evidence continues to accumulate.

“The garbage we discard into the environment often finds its way back to us,” Dr. Ganatra told the American Heart Association. “It’s time to shift from awareness to action.”

Whether by limiting plastic use, strengthening pollution regulations, or funding follow-up studies, one thing is clear: what floats in the ocean may already be flowing through our veins.