In March 2024, the New England Journal of Medicine published a study that moved the microplastics question from environmental concern to clinical medicine. Researchers found polyethylene and polyvinyl chloride microplastics in arterial plaque removed from surgery patients, and found that patients with microplastics in their plaques had a 4.53 times higher risk of heart attack, stroke, or death over a 34-month follow-up period. It was the first study to establish an association between microplastic tissue accumulation and hard cardiovascular outcomes.
What the study found
The study, conducted by a team based at the University of Campania in Italy, enrolled 257 patients undergoing surgery to remove carotid artery plaques. After excising the plaques, researchers used electron microscopy and spectroscopy to analyse them for microplastic and nanoplastic particles. They found detectable microplastics in 58.4% of samples. In those patients, the primary materials identified were polyethylene (found in 52.4% of plaques) and polyvinyl chloride (found in 12.1%).
The 34-month follow-up measured a composite outcome of heart attack, stroke, and death from any cause. After controlling for standard cardiovascular risk factors including age, sex, smoking history, diabetes, hypertension, body mass index, cholesterol levels, and statin use, patients with microplastics in their arterial plaque remained at significantly elevated risk. The adjusted hazard ratio of 4.53 is a substantial effect size. For comparison, smoking roughly doubles cardiovascular event risk. This single study does not establish causation, but the magnitude of the association and the quality of the journal give it significant weight.
How microplastics reach the heart
Microplastics enter the body primarily through ingestion and inhalation. Once in the digestive system, smaller particles, particularly those below one micrometre in size (nanoplastics), can cross the gut wall and enter the bloodstream and lymphatic system. From there, they circulate throughout the body, accumulating in tissues. The blood-brain barrier and the placental barrier, which protect highly sensitive biological compartments, have both been found to be permeable to nanoplastics under certain conditions.
A 2022 study published in Environment International by Dutch researchers found microplastics in the blood of 77% of healthy adult volunteers. The particles identified included polyethylene terephthalate (PET), polystyrene, and polyethylene. This was not a study of people with known plastic exposures or existing health conditions: it was a random sample of healthy adults. The finding established that systemic plastic contamination is routine, not exceptional. The 2024 NEJM study then showed that once in the bloodstream, these particles can embed in arterial plaque.
“Microplastics were found in the blood of 77% of healthy adult volunteers in a 2022 study. The 2024 NEJM study then showed these particles can embed in arterial plaque and are associated with a 4.5-fold increase in cardiovascular events.”
How much plastic are we actually ingesting?
A 2019 study commissioned by the WWF and conducted by researchers at the University of Newcastle, Australia, estimated that the average person ingests approximately 5 grams of plastic per week through food, water, and air. This is frequently cited as “the equivalent of a credit card.” The estimate is a rough approximation with wide uncertainty bounds, but it has been broadly replicated in methodology by subsequent studies. A 2022 WWF report calculated an average ingestion of approximately 100,000 microplastic particles per year through food and drink alone.
Bottled water is a significant source. A 2018 analysis by researchers at the State University of New York found an average of 325 microplastic particles per litre in bottled water, more than twice the level found in tap water. Seafood is another major pathway: shellfish in particular, consumed whole, deliver concentrated microplastic loads. Heating food in plastic containers accelerates particle shedding. The sources are multiple and overlapping, which is precisely why cumulative exposure is so difficult to avoid entirely, and why partial reductions remain meaningful.
What you can do to reduce exposure
Filter your drinking water
Reverse osmosis filtration removes microplastics from tap water effectively. Solid block activated carbon filters also reduce particle counts significantly. Bottled water, despite its marketing, contains more microplastics than well-filtered tap water on average.
Switch to glass, stainless steel, or ceramic for food storage
Plastic food containers and non-stick cookware shed particles into food, especially when heated or scratched. Replace with glass or ceramic containers for storage and cast iron, carbon steel, or stainless steel for cooking.
Choose natural fibre clothing where possible
Synthetic textiles (polyester, nylon, acrylic) shed plastic microfibres when worn and washed. These fibres become airborne and are inhaled, or enter water systems and eventually food supplies. Prioritise cotton, wool, and linen for items worn against the skin.
Never heat food in plastic containers
Even plastics labelled microwave-safe shed particles when heated. Transfer food to a glass or ceramic container before microwaving. This single change eliminates one of the most concentrated routes of plastic ingestion.