Microplastics in paper cups and coffee
The inside of a paper cup is thinly coated with polyethylene or similar so that water does not soak in. Particles have been reported to be released when hot drinks are poured in, and the amount increased above 80 °C and with shaking. Coffee drip bags released many rayon (regenerated cellulose) fibers.
Amounts found in studies
| Study | What was tested | Size range and method | Results |
|---|---|---|---|
| Ranjan et al. (2021) | 100 mL of 85–90 °C water in a paper cup for 15 minutes | Fluorescence microscopy and electron microscopy (material not identified) | About 25,000 microparticles |
| Son et al. (2024, Korea) | Paper cups | — (confirmed in the abstract) | Polyethylene coating released up to 26 times as many as polylactic acid coating (up to 19 million per cup). Increased above 80 °C and with shaking. Thick, reusable cups released far fewer |
| Wang et al. (2023) | Coffee drip bags | — (confirmed in the abstract) | Over 10,000 particles per cup at 95 °C for 5 minutes. Over 80% was rayon |
Results can differ by orders of magnitude depending on the smallest particle size counted and whether particles are counted or weighed. Numbers from different studies cannot be compared directly (→ Why numbers differ).
Good to know
- Ranjan 2021 did not identify the material of each particle.
What you can do at home (shown in research)
- Thick, reusable cups released far less than single-use paper cups (Son et al. 2024).
Data from Japan
We found no study that measured paper cups in Japan.
Types of plastic found
Related explainers
Sources
- Ranjan VP, et al. J Hazard Mater 2021;404:124118 (PMID 33091697)
- Son, et al. J Hazard Mater 2024;464:133014 (PMID 37984146)
- Wang, et al. Food Chem 2023;415:135717 (PMID 36848832)
Last checked 2026-10-01. “Confirmed in the abstract” means we report only what the paper's abstract says. This page is a translation of our Japanese page; if they differ, the Japanese page is the reference.