Do polypropylene takeout boxes shed plastic particles into hot food?
Yes. 2025 studies found polypropylene food containers can release microplastics and nanoplastics, especially after hot-water contact.
What's actually in it
Polypropylene, or PP, is the plastic used in many takeout boxes and meal-prep containers. Heat can help tiny plastic pieces move from the container into food or water.
Nanoplastics are smaller than 1 micrometer. Microplastics are larger, up to 5 millimeters.
What the research says
A 2025 study in Journal of Agricultural and Food Chemistry tested PP food containers. The containers released PP nanoplastics and microplastics into room-temperature water and 90 C water. More particles were found after the 90 C test.
A second 2025 study in Food Chemistry found that plastic containers released about 10,000 microplastics and 10 million nanoplastics after hot-water treatment. The released particles also increased the toxic response of some drinking-water disinfection byproducts in human cell tests.
The honest takeaway is not a precise number for every cup of soup. It is simpler: hot food and PP takeout tubs are not a great daily pair.
Move hot leftovers into glass or stainless steel. Do not microwave food in PP takeout containers, and let hot takeout cool before transferring it when you can.