A European Heart Journal study found more microplastics in the blood of heart attack patients, renewing scrutiny of polyester and recycled polyester, synthetic fabrics that shed microfibers throughout their use.
Microplastics have already been detected in human blood, lungs, placentas, and breast milk. New research now places them in the arteries of the heart, in higher concentrations among patients who have had heart attacks.
People who had suffered a serious heart attack carried higher levels of micro and nanoplastics in the blood supplying their hearts than other cardiac patients did, according to a new study published in the European Heart Journal, a finding that has renewed scrutiny of the synthetic fabrics that dominate the clothing industry.
The study, a collaboration among researchers at Sapienza University of Rome, the University of Verona, and the University of Campania Luigi Vanvitelli, examined blood from 61 patients undergoing coronary procedures. Plastic particles were detected in 84 percent of heart attack patients, compared with 40 percent of patients with chronic ischemic heart disease and 32 percent of patients with normal coronary arteries, the European Society of Cardiology reported. The most common plastic identified was polyethylene, a polymer used in packaging and consumer goods. Smokers were six times more likely to have plastics in their blood.
“Micro and nanoplastics are tiny plastic particles that are found virtually everywhere in the environment, including the air we breathe, the water we drink, and many foods we consume,” Dr. Pasquale Paolisso of Sant’Andrea Hospital, Sapienza University of Rome, the study’s first author, said in a statement. “In recent years, scientists have begun to detect these particles in human tissues and organs, raising concerns about their potential health effects.”
The researchers stopped short of a causal claim. “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,” said Professor Emanuele Barbato, who led the research and directs the cardiology unit at Sant’Andrea University Hospital. The authors noted the small sample size. An accompanying editorial in the journal linked the work to a 2024 finding that patients with plastics in their carotid artery plaque faced a higher risk of heart attack, stroke, and death.
Why the findings point to fashion
The result carries weight for the clothing industry because synthetic textiles are among the largest sources of microplastic pollution. Washing synthetic fabrics accounts for roughly 35 percent of the primary microplastics entering the world’s oceans, the single largest source, according to a 2017 assessment by the International Union for Conservation of Nature.
Polyester is the material at the center of that problem. It made up 59 percent of global fiber production in the most recent accounting by Textile Exchange, a nonprofit that tracks the industry’s raw materials, and it is overwhelmingly fossil-based. Recycled polyester, which brands frequently cite as a sustainable alternative, accounted for about 12 percent of the polyester market in 2024, and roughly 98 percent of it is made from plastic bottles rather than from discarded clothing. Fiber recovered from old textiles remains under one percent of the market. Textile Exchange put total polyester production at about 78 million tons in 2024, up from roughly 71 million the year before.
Recycled polyester does not resolve the shedding problem, because it is chemically the same polymer as virgin polyester. Both are polyethylene terephthalate, and both release microscopic fibers throughout their use. A single wash of synthetic clothing can release more than 700,000 microfibers, according to research by Imogen Napper and Richard Thompson at the University of Plymouth. A separate study found that wearing the garments releases fibers into the air at a comparable rate.
“The key story here is that the emission of fibres while wearing clothes is likely of a similar order of magnitude as that from washing them,” said Richard Thompson, head of the university’s International Marine Litter Research Unit and a senior author on the wearing study. “That constitutes a substantial and previously unquantified direct release to the environment. The results also show textile design can strongly influence both release to the air and release due to laundering; that is a crucial message highlighting the importance of sustainable design for the fashion industry.”
The lead author on that study located the problem in the material itself. “This is a type of pollution that should be mainly fought at its source, the fabric itself,” said Dr. Francesca De Falco of Italy’s Institute for Polymers, Composites and Biomaterials, in a statement.
Regulators target ‘recycled’ claims
Marketing built on recycled content is already drawing enforcement. In June, the United Kingdom’s Advertising Standards Authority banned advertisements from Adidas, Uniqlo, and Calvin Klein over their use of the term “recycled,” ruling that shoppers would reasonably understand it to mean a product was made entirely from recycled material when it was not. Uniqlo argued that its recycled polyester carried a recognized certification and that consumers understood the term to signal a meaningful proportion of such material. The regulator rejected the argument. The rulings followed earlier bans on Nike, Lacoste, and Superdry on similar grounds.
Recycled content changes the source of the plastic, not its tendency to shed, and materials researchers say no synthetic performance fabric yet withstands weather and washing without releasing fibers. Guidance for reducing exposure remains modest, centered on buying fewer synthetic garments, washing them less often and at lower temperatures, and using laundry filters.
The study’s authors said their findings belong in a wider conversation about environmental exposure and public health. “The results highlight the need to consider microplastic pollution as part of the broader environmental determinants of health,” Barbato said. “Policies that reduce air pollution, tobacco exposure and environmental plastic contamination could have benefits that extend beyond environmental protection and potentially improve cardiovascular health.”
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