Release of microplastics from disposable cups in daily use

Global concern over microplastics (MPs) is increasing because of the potential threat these substances pose to ecosystem and human health. Disposable cups, frequently used as containers of beverages, are typically made of plastic or plastic-coated paper. The release of MPs from disposable cups during use may provide a direct exposure pathway for humans. In this study, the MP release capacities of 90 batches of commercial disposable cups, including polyethylene (PE)-coated paper cups, polypropylene (PP) cups, and polystyrene (PS) cups, were investigated under daily use conditions, and the properties of released MP particles are characterized with Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The MPs release into containing beverages is detected for each of the tested cups in this study. The released MPs particles are in irregular shapes and dominantly smaller than 20 μm. The quantities of released MPs are in the range of 675-5984, 781-4951, and 838-5215 particles/L for PE-coated paper cups, PP cups and PS cups, respectively, when containing pure water at 95 °C for 20 min. No significant difference in the quantity of MP released is observed among the three types of the cups in the experimental conditions. High temperature is found to promote the release of MPs from disposable cups. The MP release is notable when the cups are used for a second time, although at a slightly lower level than the first use. Acidic carbonated beverages obviously enhance MP release from PE-coated cups over that of ultrapure water.