Does styrene from plastic food containers leach into food?

What's actually in it

Polystyrene (PS) plastic is made from styrene monomers. Some unreacted styrene remains in the finished plastic and can migrate into food and drinks. Styrene is classified as a possible human carcinogen by the International Agency for Research on Cancer.

Polystyrene is used widely for disposable coffee cups, takeout containers, foam egg cartons, and meat trays. The faster migration happens at higher temperatures, with fatty foods (butter, oil, cheese), and with acidic foods (tomatoes, citrus, vinegar-based dishes).

What the research says

A 2026 review in Food Chem compiled migration data from polystyrene food contact materials across a range of food types and conditions. Styrene migration was consistently detected across food simulants, with fatty and hot foods showing the highest levels.

The review identified several conditions that accelerate migration: microwave heating in polystyrene containers dramatically increases transfer, as does contact with oily foods at room temperature over extended storage time. Some migration occurs even at refrigerator temperatures with prolonged contact.

The European Union has set limits on styrene migration from food packaging. Enforcement and testing vary by product and country, and many polystyrene containers currently on the market haven't been individually tested for compliance.

The simplest approach: don't microwave food in styrofoam or polystyrene containers, don't store oily or acidic leftovers in polystyrene, and switch to glass or stainless containers for any reheated food. For takeout that comes in polystyrene, transfer to a plate or glass container before eating.