Is polypropylene recycling code 5 plastic safe for hot foods?
No. A 2025 study showed polypropylene releases billions of nanoplastic particles into hot water.
What's actually in it
Polypropylene (recycling code 5) is the default plastic for takeout containers, microwave meal trays, and many baby bottles. Old tests that ran cold water through the plastic found little migration, which built its reputation. New measurements at the nanoscale show a very different picture.
Softening temperatures are above typical food contact, but particle release starts well below the softening point.
What the research says
A 2025 study in J Agric Food Chem filled polypropylene containers with hot and cold water. Hot water released many times more nanoplastic particles than cold. Brand-new containers shed the most; scratched ones shed more too.
Use glass, ceramic, or stainless steel for hot food. Keep polypropylene for cold storage or brief room-temp use.
The research at a glance
| Study | Journal | Year |
|---|---|---|
| Release of Nanoplastics from Polypropylene Food Containers. | J Agric Food Chem | 2025 |
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