Microplastics databaseKitchen tools and containersChecked 2026-10-01
Microplastics in PET bottle caps and opening packaging
It has been reported that each time a PET bottle cap is opened and closed, the neck and cap rub together and particles increase. Particles were also released from the cut edge when packaging was opened with scissors, torn by hand or opened with a knife.
Amounts found in studies
| Study | What was tested | Size range and method | Results |
|---|---|---|---|
| Winkler et al. (2019) | PET bottle and HDPE cap | SEM-EDS | After opening and closing 1, 10 and 100 times, particles on the surfaces of the neck and cap increased (especially on the cap). Crushing the bottle by hand did not increase particles in the water |
| Winkler et al. (2022) | Polyethylene seal | — (confirmed in the abstract) | Particles of several hundred nm to 1 μm. A few hundredths of an ng or so per opening and closing |
| Sobhani et al. (2020) | Opening plastic packaging | QCM (converted from the amount collected) | 0.46–250 particles per cm of cut edge with scissors, tearing by hand, a knife and twisting |
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 Sobhani 2020 collects about 0.05% of the particles generated and converts that to the total.
Data from Japan
No study measuring Japanese containers was found.
Types of plastic found
Sources
- Winkler A et al. Water Res 2019;166:115082 (PMID 31542550)
- Winkler A et al. 2022 (PMID 35901554)
- Sobhani Z et al. Sci Rep 2020;10:4841 (PMID 32193409)
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.
Public bodies such as WHO, FAO and EFSA do not currently recommend that individuals avoid any particular food because of microplastics. This page lists facts from research and public agencies' documents; it does not judge whether a food is good or bad.