Italian researchers examined plaque removed from the carotid arteries of 257 patients undergoing surgery, tested it for plastic, and followed the patients for an average of 34 months.
Polyethylene was found in the plaque of 58.4% of patients (mean 21.7 micrograms per milligram of plaque) and PVC in 12.1%. Patients whose plaque contained plastic were 4.53 times more likely to die, have a heart attack or have a stroke during follow-up than those with no detectable plastic. Allowing for chance, the true figure could be anywhere from 2 to 10 times. Their plaque also showed more inflammatory markers.
This is the first study to link plastic in human tissue to a hard health outcome, and it was published in the world's most prestigious medical journal.
It is observational, from one country, and the authors themselves note that other differences between the groups could explain part of the effect. It shows an association, not proof that plastic caused the events.