You have probably heard that you eat a credit card's worth of plastic every week. That number is a myth. It comes from the highest of several rough scenarios in a single 2019 industry-commissioned report, and a later independent re-examination found the calculation did not hold up. The real story does not need exaggerating. Peer-reviewed research has now confirmed actual plastic particles inside human blood, lungs, liver, placenta, breast milk, and artery plaque, and a 2024 study in the New England Journal of Medicine tied their presence in artery plaque to a measurably higher risk of heart attack, stroke, and death.
Where Microplastics Have Actually Been Confirmed in the Body
Detection studies, not exposure guesses, are the best-established part of this field. Leslie and colleagues reported the first plastic particles in human blood in 2022, finding them in 17 of 22 healthy donors, in Environment International. Ragusa and colleagues found microplastic fragments in 4 of 6 human placentas in 2021, also in Environment International. Jenner and colleagues confirmed microplastics in living human lung tissue in 2022, in Science of the Total Environment. Horvatits and colleagues found microplastics in cirrhotic human liver tissue in 2022, in EBioMedicine, and Ragusa's team detected them in human breast milk that same year, in Polymers. A 2024 study in Toxicological Sciences found microplastics in human testis and semen samples. None of this proves the particles are causing harm in those tissues. It confirms that exposure is essentially universal and that the particles reach further into the body than early researchers expected.
The Strongest Human Data: A Real Link to Heart Disease Risk
The most direct human evidence comes from Marfella and colleagues, published in the New England Journal of Medicine in 2024. Researchers analyzed carotid artery plaque removed from 304 surgery patients, with 257 completing an average follow-up of 33.7 months. Polyethylene was detected in 58.4 percent of plaque samples. Patients whose plaque contained microplastics and nanoplastics had a hazard ratio of 4.53 for the combined outcome of nonfatal heart attack, nonfatal stroke, or death from any cause, compared with patients whose plaque did not contain detectable particles. Inflammatory markers were also elevated in the group carrying plastic particles. The authors stated directly that their results do not prove causality, noting other unmeasured differences between the groups could explain part of the gap. Independent commentary published in the same journal raised a separate concern, that the study lacked adequate anti-contamination controls given how much polyethylene and PVC exists in a typical operating room.
New Evidence It Might Not Just Be a Bystander
A November 2025 study in Environment International, led by researchers at UC Riverside and the University of New Mexico, was designed to address exactly that uncertainty. Mice bred to develop atherosclerosis were fed microplastics for nine weeks on a normal diet. In male mice, arterial plaque increased 63 percent in the aortic root and 624 percent in another key artery, without the mice becoming obese or developing high cholesterol, which points to a direct plaque-building effect rather than an indirect one. Female mice, oddly, showed no significant change. The researchers described this as some of the strongest evidence so far that microplastics may directly contribute to cardiovascular disease rather than simply showing up alongside it, while acknowledging the sex-specific result still needs to be explained and confirmed in humans.
Other Effects the Research Points To
Beyond the heart, a 2025 umbrella review covering 52 systematic reviews found solid evidence linking BPA, phthalates, and PFAS, chemicals commonly carried by plastics, to hormonal and reproductive harm, but it found no meta-analyses yet evaluating the plastic particles themselves, which is an important distinction to keep straight. A 2024 study of 113 men in China, published in EBioMedicine, found an association between microplastic exposure and reduced semen quality. A 2022 study found that fecal microplastic concentrations were higher in patients with inflammatory bowel disease than in healthy controls. A 2025 systematic review of human liver cell studies found that microplastic exposure triggered oxidative stress and disrupted lipid metabolism, though this evidence comes from cells in a dish, not living patients.
What the Evidence Doesn't Prove
A 2024 rapid systematic review in Environmental Science and Technology, built to evaluate exactly this question, found only three human observational studies covering reproductive and respiratory outcomes, compared with 28 animal studies. No major health authority has set a safe exposure limit for microplastics. The FDA stated in 2024 that current evidence does not show the levels of microplastics found in food pose a health risk, and the European Food Safety Authority does not expect to issue a full risk opinion until the end of 2027. A widely shared 2025 claim that the human brain contains a spoonful of plastic has also drawn scrutiny: the underlying paper was corrected for duplicated images, and independent microplastics researchers have said its mass estimate may be significantly inflated. As for the credit card figure, the 2019 report's own combined estimate was closer to 0.7 grams per week, not 5, and a more rigorous 2021 modeling study in Environmental Science and Technology put realistic weekly ingestion at roughly 4 micrograms, about a million times lower than the viral number.
Bottom Line
Microplastics are confirmed inside essentially everyone's body, and the best current human data ties them to a real, not hypothetical, increase in cardiovascular risk. New animal research in 2025 strengthens the case that this is a direct effect rather than coincidence. But the field is young, most non-cardiovascular claims still rest on cells and animals rather than people, and the loudest statistics in circulation are the ones scientists trust the least. Treat this as a developing risk worth watching, not a settled verdict.
Sources
Leslie HA, et al. Discovery and quantification of plastic particle pollution in human blood. Environment International, 2022.
Ragusa A, et al. Plasticenta: First evidence of microplastics in human placenta. Environment International, 2021.
Jenner LC, et al. Detection of microplastics in human lung tissue using uFTIR spectroscopy. Science of the Total Environment, 2022.
Horvatits T, et al. Microplastics detected in cirrhotic liver tissue. EBioMedicine, 2022.
Marfella R, et al. Microplastics and Nanoplastics in Atheromas and Cardiovascular Events. New England Journal of Medicine, 2024.
Lin TA, et al. Microplastic exposure elicits sex-specific atherosclerosis development in mice. Environment International, 2025.
Chartres N, et al. Effects of Microplastic Exposure on Human Digestive, Reproductive, and Respiratory Health: A Rapid Systematic Review. Environmental Science and Technology, 2024.
Mohamed Nor NH, et al. Lifetime Accumulation of Microplastic in Children and Adults. Environmental Science and Technology, 2021.
Symeonides C, et al. An Umbrella Review of Meta-Analyses Evaluating Associations between Human Health and Exposure to Major Classes of Plastic-Associated Chemicals. Annals of Global Health, 2025.
