"A total of 304 patients were enrolled in the study, and 257 completed a mean (±SD) follow-up of 33.7±6.9 months. Polyethylene was detected in carotid artery plaque of 150 patients (58.4%), with a mean level of 21.7±24.5 μg per milligram of plaque; 31 patients (12.1%) also had measurable amounts of polyvinyl chloride, with a mean level of 5.2±2.4 μg per milligram of plaque."
- 21.7±24.5 μg per milligram is 0% to 4.62% by weight
- 5.2±2.4 μg per milligram is 0% to 0.76% by weight
This means that some patients' plaque contained up to 5% plastic.