Microplastics in tea bags
A 2019 study, which drew a lot of attention, reported that steeping a nylon or PET tea bag in boiling water releases 11.6 billion particles into one cup. Germany’s Federal Institute for Risk Assessment (BfR) assessed that the actual number is 2–3 orders of magnitude lower, because short plastic chains (oligomers) that appear when the extract is dried were counted as particles.
Amounts found in studies
| Study | What was tested | Size range and method | Results |
|---|---|---|---|
| Hernandez et al. (2019) | Nylon and PET tea bags | Steeped in 95 °C water, the extract dried and counted | About 11.6 billion particles per cup (plus about 3.1 billion nano-sized) |
| BfR / Busse et al. (2020) | The same types of bags | Micro-Raman | 5,800–20,400 particles over 0.001 mm per bag. Most of the particles were oligomers. Assessed as posing no health risk |
| Banaei et al. (2024) | Nylon 6, polypropylene and cellulose bags | NTA (does not distinguish particle material) | Per mL: polypropylene 1.2 billion particles, cellulose 135 million, nylon 6 8.18 million. Uptake into cultured intestinal cells confirmed |
| Yue et al. (2024) | Commercial tea bags | Raman and Py-GC/MS | 80–1,288 particles per bag. Woven nylon 6 had fewer than nonwoven |
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
- The method in Banaei 2024 (NTA) does not distinguish particle material, so many particles were counted even from cellulose (paper) bags.
- A typical case where how you count makes a difference between “billions” and “thousands” (→ How measurement changes the numbers).
What you can do at home (shown in research)
- Rinsing three times in room-temperature water before use reduced the particles released by 76–94% for micron-sized ones and by 80–87% for smaller ones (Yue et al. 2024).
- You can also brew with loose tea leaves, a teapot and a strainer instead of tea bags (we found no study comparing loose leaves and bags).
Data from Japan
We found no study that measured tea bags in Japan.
Types of plastic found
Related explainers
Sources
- Hernandez LM, et al. Environ Sci Technol 2019;53:12300 (PMID 31552738)
- Busse K, et al. Environ Sci Technol 2020;54:14134 (comment) (PMID 33052042)
- BfR, “BfR assesses study on tea bags and microplastic particles”
- Banaei G, et al. Chemosphere 2024;368:143736 (PMID 39542373)
- Yue, et al. Food Chem 2024;445:138740 (PMID 38359569)
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.