Can polypropylene food containers release nanoplastics into hot and cold water?

What's actually in it

Polypropylene (PP) is one of the most common plastics used for food storage containers, takeout boxes, and microwaveable dishes. It's labeled with recycling number 5 and is often considered one of the safer plastics. But even PP breaks down over time, shedding particles too small to see.

What the research says

A 2025 study in J Agric Food Chem tested nanoplastic release from polypropylene food containers into both hot and cold water. The results showed that PP containers released nanoplastics under both conditions. Hot water pulled out far more particles than cold water did.

The tiny particles released were in the nanometer range, small enough to pass through cell barriers in your body. Repeated heating and cooling cycles made the containers shed even more particles over time.

To cut your exposure, avoid microwaving food in plastic containers. Transfer hot liquids and soups to glass or stainless steel containers instead. If you use PP containers, save them for cold or room-temperature foods.