Microplastics in baby bottles and formula preparation
A 2020 Irish study (Nature Food) reported that preparing formula in polypropylene baby bottles released up to 16.2 million particles per liter, increasing with sterilization and higher temperatures. The research team proposes steps such as rinsing after sterilization and preparing formula in a non-plastic container.
Amounts found in studies
| Study | What was tested | Size range and method | Results |
|---|---|---|---|
| Li D et al. (2020, Nature Food) | Polypropylene baby bottles (10 types, accounting for 68.8% of the market) | — (confirmed in the abstract and the university press release) | Up to 16.2 million per liter. 600,000 at 25°C, 16.2 million at 70°C, 55 million at 95°C. Infants: 14,600 to 4.55 million per day (estimate for 48 regions) |
| Zhang et al. (2023) | Preparing powdered formula | — (confirmed in the abstract) | The amount an infant takes in from the baby bottle is 6.8 times that from the powdered formula itself |
| Song et al. (2021) | PC and PP water bottles, PPSU baby bottles | — (confirmed in the abstract) | 53–393 per mL after opening and closing 100 times. Fewer in high-quality plastic bottles and glass 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
- The lower limit of the particle size counted in Li 2020 and the identification method could not be confirmed from the full text.
- The research team has announced that polypropylene kettles and lunch boxes released about the same amount as baby bottles.
What you can do at home (shown in research)
- Proposals by the research team (Li 2020): after sterilization, rinse at least 3 times with sterilized room-temperature water. Boil water in a non-plastic kettle or pot. Prepare formula in a non-plastic container with water at 70°C or higher, let it cool, then transfer it to the baby bottle. Do not reheat in plastic containers or shake vigorously.
- For how to prepare formula, please also check the MHLW/WHO guidelines “Safe preparation, storage and handling of powdered infant formula” (prepare with water at 70°C or higher).
Data from Japan
No study measuring Japanese baby bottles was found. The Consumer Affairs Agency’s materials state that leaching of bisphenol A from Japanese polycarbonate baby bottles is around the limit of quantification (0.0005 ppm).
Types of plastic found
Related explainers
Sources
- Li D et al. Nature Food 2020;1:746-754 (PMID 37128027)
- Trinity College Dublin press release (reposted by ScienceDaily), October 2020
- Zhang J et al. 2023 (PMID 36758924)
- Song K et al. 2021 (PMID 34148170)
- Consumer Affairs Agency, “Q&A on bisphenol A”
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.