Microplastics in electric kettles and kettles
In a Chinese study that boiled water in plastic kettles for 100 days, using water containing calcium, iron and copper cut release by more than 89% after 40 days. This is because a film (calcium carbonate and others) forming inside acts as a lid. The baby bottle research team says polypropylene kettles also released about the same amount as baby bottles.
Amounts found in studies
| Study | What was tested | Size range and method | Results |
|---|---|---|---|
| Shi et al. (2022) | Plastic kettles, 100 days | — (confirmed in the abstract) | With water containing calcium, iron and copper ions, release dropped by more than 89% after 40 days. The film inside was also confirmed in actual household kettles |
| Li D et al. (2020) | Polypropylene kettles | Confirmed in the university press release | About the same as baby bottles |
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
- Most tap water in Japan is soft (low in calcium), and it has not been examined whether the film forms in the same way.
What you can do at home (shown in research)
- The baby bottle research team proposes boiling water in a non-plastic kettle or pot.
Data from Japan
No study measuring Japanese kettles was found.
Types of plastic found
Related explainers
Sources
- Shi et al. J Hazard Mater 2022;425:127997 (PMID 34986566)
- Li D et al. Nature Food 2020 (PMID 37128027)
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.