Living near oceans, while idyllic, may pose health risks due to microplastic pollution. A recent study links higher concentrations of microplastics in coastal waters to increased prevalence of Type 2 diabetes, coronary artery disease, and stroke among residents.

Ocean and cardiometabolic disease risk

What are microplastics

The findings

low pollution (0–0.005 pieces/m³): almost nothing visible — maybe one tiny plastic speck in 200 bathtubs of ocean water;

medium pollution (0.005–1 pieces/m³): up to 1 small plastic particle per 200 bathtubs of ocean water;

high pollution (1–10 pieces/m³): likely to be a small handful of small plastic bits floating in each bathtub of ocean water; and

very high pollution (10+ pieces/m³) every scoop of ocean water (about the size of a bathtub) could contain 10 or more plastic particles.

The Plastics Problem: Nano & Microplastics and Their Dangerous Impact on Heart Health

The sea breeze, magical evenings, blissful rains — living near the ocean is almost as perfect as a dream. But all that serenity may come at the cost of your health. A recent study found that people living near the ocean have an increased risk of certain diseases.A study published in the Journal of the American Heart Association has found that residents of the US coastal counties may face a significantly higher risk of cardiometabolic diseases such as Type 2 diabetes, coronary artery disease, and stroke.The researchers found that the risk of heart and metabolic diseases, such as type 2 diabetes, coronary artery disease, and stroke , is higher in people living near the ocean water, due to the higher concentrations of microplastics. They also found that the risk was low in residents of coastal counties with low levels of microplastic pollution in nearby waters.“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. Plastic pollution is not just an environmental issue – it may also be a public health issue,” Sarju Ganatra, M.D., senior author, vice chair of research at Lahey Hospital & Medical Center in Burlington, Massachusetts, and president of Sustain Health Solutions, said in a statement.Microplastics are plastic particles that are less than 5 millimeters (mm) in size, which is about the size of a pencil eraser. For better visualization, know that human hair is about 80,000 nanometers wide. There are also microplastics, which are even smaller, invisible to the naked eye, and measuring smaller than one-thousandth of a millimeter. They are known as nanoplastics. Both of these are formed from the chemical breakdown, aka decomposition, of larger plastic waste, including food packaging (like single-use water bottles), synthetic fabrics, and personal care products. These microplastics and nanoplastics were found in drinking water, seafood, and the air.According to the study, seawater intrusion, which is a natural process where seawater mixes with groundwater, is reported extensively in coastal areas and results in high concentrations of contaminants, including microplastics, in groundwater aquifers.The researchers found that the concentration of plastic particles in ocean water near coastal communities was associated with a higher incidence of Type 2 diabetes, coronary artery disease, and stroke among residents in those counties. They also investigated the concentration of the micro plastics within 200 nautical miles of the counties, and dividing the pollution levels into four categories based on mean marine microplastic levels (MML)The researchers found that people living in counties with very high levels of microplastic pollution had 18% higher adjusted prevalence of Type 2 diabetes, which is known to double the risk of heart disease. They also had a 7% higher for coronary artery disease, a plaque buildup in the heart’s arteries that may lead to a heart attack or stroke. The study also revealed a 9% increase in incidences of strokes. A stroke happens when a blood vessel in the brain gets blocked or bursts. Strokes are the fifth leading cause of death and a leading cause of disability.They also found that the Gulf of Mexico (also known as the Gulf of America) and Atlantic coasts had a higher prevalence of Type 2 diabetes, coronary artery disease, and stroke compared to those on the Pacific coast.“ While this study measured pollution in ocean water, pollution isn’t limited to the sea. Microplastics are everywhere: in drinking water, in the food we eat, especially seafood, and even in the air we breathe. So, while we examined data from microplastics collected from ocean water and the health status of people living in communities nearby, microplastic pollution affects all of us, regardless of where we live. Ironically, even in health care – a field devoted to healing – we rely heavily on single-use plastics, from IV bags and syringes to gloves, tubing, medication blister packs and surgical drapes. Much of it ends up in landfills or the ocean, where it fragments into microplastics and enters the ecosystem,” Ganatra added.“This study adds to a growing body of evidence that the garbage we discard into the environment often finds its way back to us. It’s time to shift from awareness to action. We urge policymakers to view plastic pollution as an environmental crisis as well as a potential health crisis,” he added.

Could the plastic in our oceans be quietly harming our hearts? A nationwide study reveals a concerning correlation between marine microplastic pollution and cardiometabolic diseases in US coastal communities.

Study: Marine Microplastic Levels and the Prevalence of Cardiometabolic Diseases in US Coastline Counties. Image Credit: Tint Media / Shutterstock

In a recent article published in the Journal of the American Heart Association, researchers analyzed whether higher levels of marine microplastics in ocean water near US coastlines are linked to greater county-level prevalence of stroke, coronary artery disease, or type 2 diabetes.

After adjusting for local vulnerabilities and demographic factors, coastal counties with very high levels of microplastics had significantly higher prevalences of all three conditions than those with low levels.

Background

Plastics have become deeply embedded in modern life due to their affordability and versatility; however, their widespread use has also led to severe environmental pollution. Disposed plastic waste often breaks down into tiny particles called microplastics and nanoplastics through the process of weathering and degradation.

While the environmental impacts of plastic pollution are well-documented, its direct effects on human health are still being explored. Concerns have grown over the health risks associated with chemicals in plastics, such as phthalates and bisphenol A, which are known to disrupt hormone function and cause other health issues.

More recently, micro- and nanoplastics have been shown to cause cell damage by inducing inflammation, oxidative stress, and even cell death. Early studies suggest that high levels of these tiny plastic particles may lead to changes in blood vessels and the heart, including damage to blood vessel linings, reduced heart function, and abnormal blood flow, which can contribute to heart disease and related conditions.

Additionally, microplastics have been found in artery plaques, raising the possibility that they increase the risk of cardiovascular problems. However, it remains unclear how these findings affect entire populations.

About the study

This study was designed to fill an important research gap by assessing the relationship between ocean microplastic pollution near US coastlines and local rates of major cardiometabolic diseases.

To investigate this link, the researchers utilized ocean microplastic concentration data spanning the years 2015 to 2020. They mapped microplastic levels within 200 nautical miles of the US coastline, aligning with the United Nations’ definition of exclusive economic zones where coastal nations manage ocean resources.

They identified 152 US counties bordering these coastal waters and calculated the average microplastic levels for each of these areas. Counties were then grouped into four categories: low, medium, high, or very high microplastic levels and linked to county-level estimates for stroke, coronary artery disease, and type 2 diabetes from 2019 to 2020.

To account for other factors influencing health, they included demographic details such as sex and age, physician availability, and broader social, environmental, and infrastructure vulnerabilities, using tools like the Climate Vulnerability Index (CVI).

Statistical analysis involved quasi-Poisson regression, which is suited for data with overdispersion and non-normal distributions. Population weights were applied to ensure that counties with larger populations had appropriate influence.

Key findings

Counties bordering ocean waters with very high microplastic concentrations had significantly greater average rates of stroke, coronary heart disease, and type 2 diabetes compared to counties with low microplastic levels.

Specifically, the mean prevalence of diabetes was about 13% in areas with very high microplastic levels, compared to 11.2% in areas with low levels. Likewise, stroke and coronary heart disease were also more common where microplastic pollution was greatest.

Statistical models confirmed this trend even after adjusting for key factors like sex, age, ethnic and racial composition, healthcare access, and environmental and socioeconomic vulnerabilities. In the fully adjusted models, very high microplastic levels were associated with a 5% to 6% higher prevalence of diabetes and artery disease, and about a 4% increase for stroke compared to low-level areas (with the finding for stroke being on the margin of statistical significance).

Regional patterns also emerged. The prevalence of all three diseases was highest in counties along the Gulf of Mexico, while the highest microplastic concentrations were measured off the Atlantic coast, both in contrast to the Pacific coast, which had lower disease rates and microplastic levels.

Conclusions

This ecological study provides population-level evidence that higher marine microplastic pollution may be associated with a greater burden of cardiometabolic diseases in US coastal regions.

Proposed pathways include contamination of seafood and groundwater, which supplies about 35% of U.S. drinking water, as well as possible inhalation or skin contact near polluted shores. Experimental studies and animal models back the plausibility of microplastics causing vascular damage, inflammation, and metabolic disruption.

However, limitations exist: the analysis is ecological and cross-sectional, so individual cause-and-effect relationships cannot be confirmed. There was also no direct measurement of human microplastic exposure or detailed analysis of different plastic types. Population movement, other confounding factors, and variations in local pollution controls could have influenced results.

Despite these gaps, the study highlights a concerning environmental health risk and underscores the need for further research to establish clear exposure thresholds and elucidate the underlying biological mechanisms. Policymakers should consider stronger regulations to curb plastic pollution and protect communities that rely on seafood and coastal waters.

[1]

New research suggests that the microplastic-polluted water along America’s coasts may be linked to higher rates of certain chronic health conditions among those who live there, including type 2 diabetes, stroke, and coronary artery disease

[2] [3]

The study adds to a growing body of evidence connecting microplastics — tiny particles smaller than 5 millimeters (mm) that develop from the breakdown of plastic waste — to a variety of health risks.

What the Study Found

[1] Using measurements from the National Centers for Environmental Information between 2015 and 2020, researchers analyzed microplastic water pollution within 200 nautical miles of 152 coastal counties along the Atlantic Ocean, Pacific Ocean, and the Gulf of Mexico. Each area’s microplastic pollution levels were categorized as low, medium, high, or very high.

The researchers then compared those measurements to the county-level disease rates, as determined by 2022 population data from the Centers for Disease Control and Prevention (CDC).

Compared with those living near areas with “low” levels of coastal microplastic pollution, those who were close to areas with “very high” levels had:

A 18 percent higher prevalence of type 2 diabetes

A 9 percent higher risk of stroke

A 7 percent higher risk of coronary artery disease

“Even after adjusting for demographic and social-environmental vulnerabilities, counties exposed to very high levels of microplastics in nearby ocean waters had significantly higher disease burdens. This suggests that microplastics may represent a novel environmental cardiometabolic risk factor — a critical addition to the broader public health conversation,” says the senior study author Sarju Ganatra, MD, the medical director of sustainability and the vice chair of research in the department of medicine at Lahey Hospital & Medical Center in Burlington, Massachusetts, and president of Sustain Health Solutions.

How Do Microplastics Travel From the Water Into Your Body?

[4]

Microplastic debris from plastic waste can be found virtually everywhere, including in bodies of water.

[5] [6]

They enter the human body when you swallow them , touch them, or breathe them in.

The researchers involved in the new study theorize that people in coastal communities are apt to inhale microplastic particles from ocean water aerosolization, in which microscopic particles become suspended in the air.

“Studies have shown that microplastics can become airborne through mechanisms like sea spray, wind, or even urban dust, making inhalation a real concern — particularly near the coast where environmental concentrations are higher,” says Dr. Ganatra.

“Additionally, coastal residents may face greater exposure due to contaminated groundwater from seawater intrusion, higher seafood consumption, and proximity to recreational areas with high plastic debris,” he says.

While data suggests that living along the coast equates to higher marine microplastic exposure, Philip Kuriakose, MD, a hematologist who has studied microplastics in human blood, notes that the potential risks aren’t limited to specific geographic areas.

“[People] inhabiting inland areas have their own exposure risk to other non-marine sources of microplastics,” says Dr. Kuriakose, who is also a medical oncologist at the Henry Ford Cancer Institute in Detroit.

Future Microplastic Research Recommendations

Although the study adds to the available evidence linking microplastics to a variety of health issues, the results don’t add up to proving direct harm.

For example, Ganatra notes that the study didn’t measure specific microplastic exposure routes (for example by analyzing blood samples from coastal residents), which may limit how the findings translate to concrete health risks.

According to the microplastics researcher Sai Rahul Ponnana, a research data analyst at the Case Western Reserve University School of Medicine Cardiovascular Research Institute in Cleveland, the study used county-level data rather than a large-scale health record database, so the results may not offer a full picture of how microplastics impact health on an individual level.

Ganatra also says more research is required to better understand how microplastic exposure fits in — and adds up — with exposure to other environmental pollutants and traditional health risk factors.

What Can You Do to Lower Microplastics Exposure?

While you may not be able to completely avoid microplastics, especially if you live in a coastal area, there are some ways you may be able to limit your overall exposure — such as by reducing how often you purchase and use plastic items.

Kuriakose suggests taking microplastics as a potential risk factor for chronic disease seriously.

“For those living in coastal areas, it can only help to be aware of this risk and to be proactive — both in minimizing your own contribution to plastic waste and in remaining unflinching advocates for the population as a whole by choosing healthy lifestyle habits that decrease adding to the present problem,” he says.

Rates of Type 2 diabetes, coronary artery disease and stroke were higher among residents in 152 U.S. coastal counties near microplastic-polluted oceans, finds a new study in the Journal of the American Heart Association

Research Highlights:

A study of microplastics in U.S. coastal waters found that residents of counties adjacent to the most heavily microplastic-polluted waters had significantly higher rates of Type 2 diabetes, coronary artery disease (plaque-clogged blood vessels feeding the heart) and stroke compared to similar counties located near waters with low levels of microplastic pollution.

Microplastics are tiny plastic particles from plastic waste, such as packaging, synthetic fabrics and personal care products, that break down and collect in drinking water, seafood and the air.

More research is needed to understand how people in coastal communities are exposed to microplastics and to determine how much exposure is harmful to their health.

Embargoed until 4 a.m. CT/5 a.m. ET Wednesday, June 18, 2025

DALLAS, June 18, 2025 — Living in a U.S. coastal county bordered by ocean waters with very high concentrations of microplastics may increase the risk of heart and metabolic diseases, such as Type 2 diabetes, coronary artery disease and stroke. This risk was higher compared to residents of coastal counties with low levels of microplastic pollution in nearby waters, according to new research published today in the Journal of the American Heart Association, an open-access, peer-reviewed 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. Plastic pollution is not just an environmental issue – it may also be a public health issue,” said Sarju Ganatra, M.D., senior author of the study, medical director of sustainability, vice chair of research in the department of medicine at Lahey Hospital & Medical Center in Burlington, Massachusetts, and president of Sustain Health Solutions.

Microplastics are tiny plastic particles less than 5 millimeters in size, the width of a new pencil eraser or smaller. Nanoplastics are even smaller, invisible to the naked eye, and measuring smaller than one-thousandth of a millimeter. Both sizes of plastic particles come from the chemical breakdown (decomposition) of larger plastic waste, including food packaging (like single-use water bottles), synthetic fabrics and personal care products. Micro and nanoplastics have been found in drinking water, seafood and the air. Seawater intrusion, which is a natural process where seawater mixes with groundwater resources, is reported extensively in coastal areas and results in a high concentration of various contaminants including microplastics in groundwater aquifers in coastal areas, according to the study.

In this study, researchers examined whether the concentration of plastic particles in ocean water near coastal communities was associated with higher incidence of Type 2 diabetes, coronary artery disease and stroke among residents in those counties. Researchers examined concentrations of marine microplastic pollution (likely a combination of both micro- and nano-plastics) within 200 nautical miles of the counties, dividing the pollution levels into four categories based on mean marine microplastic levels (MML):

low pollution (0–0.005 pieces/m³): described as almost nothing visible — maybe one tiny plastic speck in 200 bathtubs of ocean water;

medium pollution (0.005–1 pieces/m³): up to 1 small plastic particle per 200 bathtubs of ocean water;

high pollution (1–10 pieces/m³): likely to be a small handful of small plastic bits floating in each bathtub of ocean water; and

very high pollution (10+ pieces/m³) every scoop of ocean water (about the size of a bathtub) could contain 10 or more plastic particles.

The analysis found that, compared to residents of U.S. coastal counties with low levels of microplastic pollution in nearby waters, those living in counties with very high levels of microplastic pollution had:

18% higher adjusted prevalence of Type 2 diabetes, which is known to double the risk of heart disease;

7% higher for coronary artery disease, a buildup of plaque in the heart’s arteries that may lead to a heart attack or stroke; and

9% more strokes. A stroke happens when a blood vessel in the brain gets blocked or bursts. Strokes are the No. 5 cause of death and a leading cause of disability.

In addition, the analysis found that U.S. counties along the Gulf of Mexico (also known as the Gulf of America) and Atlantic coasts had a higher prevalence of Type 2 diabetes, coronary artery disease and stroke compared to those on the Pacific coast.

The association between high microplastic pollution levels and more people with cardiometabolic diseases was consistent even after adjusting for age, gender, access to doctors, socioeconomic status (education, unemployment, household income, neighborhood status, etc.) and environmental considerations (air pollution, noise pollution, closeness to parks, walking space, etc.).

“While this study measured pollution in ocean water, pollution isn’t limited to the sea. Microplastics are everywhere: in drinking water, in the food we eat, especially seafood, and even in the air we breathe. So, while we examined data from microplastics collected from ocean water and the health status of people living in communities nearby, microplastic pollution affects all of us, regardless of where we live,” Ganatra said.

He said scientists are only beginning to understand the full impact of microplastics on health. “Ironically, even in health care – a field devoted to healing – we rely heavily on single-use plastics, from IV bags and syringes to gloves, tubing, medication blister packs and surgical drapes. Much of it ends up in landfills or the ocean, where it fragments into microplastics and enters the ecosystem,” Ganatra said.

“This study adds to a growing body of evidence that the garbage we discard into the environment often finds its way back to us. It’s time to shift from awareness to action,” he said. “We urge policymakers to view plastic pollution as an environmental crisis as well as a potential health crisis.”

Chair of the writing committee for the 2024 American Heart Association Scientific Statement: Environmental Exposures and Pediatric Cardiology, Justin Zachariah, M.D., M.P.H., FAHA, said “The authors conducted a very careful county-level analysis suggesting more data individual-level studies are needed to understand how plastic affects us and interventions to reduce those effects, or limits on micro- and nanoplastics in the environment. In the absence of such data or policies, transparency and labels about plastic content could empower consumers to make choices that are right for them. We must remember these plastics can indefinitely persist in our bodies, possibly subjecting persons at every age to accumulating risks throughout their lifespan.” Zachariah, who was not affiliated with this study, is an associate professor of pediatric cardiology at Baylor College of Medicine and medical director of the cardiovascular clinical research core at Texas Children’s Hospital, both in Houston.

The study has several limitations. First, the association with microplastics compared county-level data rather than individuals. This type of study cannot prove a cause-and-effect relationship between nearby ocean microplastic levels (measured in water only, not in fish or plant life) and the development of cardiometabolic diseases.

“We also didn’t measure plastic levels in residents of these counties, and we don’t yet know the exact ways these particles may harm the body. So, while the findings are compelling, they should be a call for more in-depth research, not for making definitive conclusions,” Ganatra said.

Ganatra and colleagues say their findings point to several key areas for future research:

How do microplastics get into the human body?

At what levels do microplastics become harmful?

Where do these particles accumulate in the body?

How do microplastics affect long-term health?

The research team is currently designing follow-up studies to measure individual microplastic exposure through water, food and air, and to evaluate how exposure influences biological markers of inflammation and cardiovascular stress.

Study details, background and design:

Using information from the National Centers for Environmental Information, marine microplastic concentrations were obtained and measured between 2015 and 2020 for the ocean waters within 200 nautical miles (the marine Exclusive Economic Zone) of 152 U.S. coastal counties along the Pacific Ocean, Atlantic Ocean and the Gulf of Mexico (also known as the Gulf of America).

The average age of the county residents was 43 years, and about half were female. About 75% were white adults, 13% Black adults, 1% American Indian and Alaska Native adults, 4% Asian American adults, 0.1% Native Hawaiian and other Pacific Islander adults, and the remaining 7% of adults did not self-identify their race or ethnicity.

County prevalence rates of Type 2 diabetes, coronary artery disease and stroke were obtained from the 2022 Centers for Disease Control and Prevention’s Population-Level Analysis, which is based on the 2019-2020 Behavioral Risk Factor Surveillance System and the 2015-2019 American Community Survey.

Researchers compared the prevalence of diseases between counties with low vs. very high concentrations of microplastics, both with and without adjusting for several county-level risk factors, such as age, sex, race, ethnicity, access to physicians, and indicators of socioeconomic and environmental issues faced by people living in coastal communities.

Co-authors, disclosures and funding sources are listed in the manuscript.

Studies published in the American Heart Association’s scientific journals are peer-reviewed. The statements and conclusions in each manuscript are solely those of the study authors and do not necessarily reflect the Association’s policy or position. The Association makes no representation or guarantee as to their accuracy or reliability. The Association receives more than 85% of its revenue from sources other than corporations. These sources include contributions from individuals, foundations and estates, as well as investment earnings and revenue from the sale of our educational materials. Corporations (including pharmaceutical, device manufacturers and other companies) also make donations to the Association. The Association has strict policies to prevent any donations from influencing its science content. Overall financial information is available here.

Additional Resources:

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About the American Heart Association

The American Heart Association is a relentless force for a world of longer, healthier lives. Dedicated to ensuring equitable health in all communities, the organization has been a leading source of health information for more than one hundred years. Supported by more than 35 million volunteers globally, we fund groundbreaking research, advocate for the public’s health, and provide critical resources to save and improve lives affected by cardiovascular disease and stroke. By driving breakthroughs and implementing proven solutions in science, policy, and care, we work tirelessly to advance health and transform lives every day. Connect with us on heart.org, Facebook, X or by calling 1-800-AHA-USA1.

For Media Inquiries and AHA/ASA Expert Perspective: 214-706-1173

Karen Astle: Karen.astle@heart.org

For Public Inquiries: 1-800-AHA-USA1 (242-8721)

heart.org and stroke.org

Theresa Gaffney is the lead Morning Rounds writer and reports on health care, new research, and public policy, with a particular interest in mental health, gender-affirming care, and LGBTQ+ patient communities. You can reach Theresa on Signal at theresagaff.97.

For women, Audre Lorde wrote, poetry is not a luxury. Rather, it is “a vital necessity of our existence.” Here’s a poem I read this week: “Overwhelm” by Joy Harjo, in the New Yorker. Tomorrow is Juneteenth, and the newsletter is off. I hope you read a poem instead. The newsletter is back on Friday, and I’ll be back next week.

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