Is polystyrene foam safe for hot drinks like coffee or soup?
Avoid. Hot liquids accelerate styrene migration from foam cups and containers. Styrene is a possible human carcinogen that gets into your drink.
What's actually in it
Polystyrene (Styrofoam) is made from styrene monomers. When hot liquid contacts foam, residual styrene monomer and other compounds migrate into your drink. The higher the temperature, the more migration occurs. Coffee served in a foam cup is hotter than the same liquid in a glass or stainless steel cup, and sits in contact with the foam through the entire drinking experience.
Styrene is classified by the EPA as a possible human carcinogen. It's also a nervous system irritant. The migration is small per cup, but daily coffee from foam cups adds up to consistent ongoing exposure.
What the research says
A 2026 study in Food Chem Toxicol found that polystyrene nanoplastics activate fat-producing genes inside cells, with metabolic implications beyond just chemical toxicity. A separate 2026 study confirmed that polystyrene breakdown products cause oxidative stress in gut cells at concentrations consistent with beverage container exposure.
The International Agency for Research on Cancer (IARC) classified styrene as a Group 2A possible human carcinogen in 2002. More recent 2026 data adds to the mechanistic evidence for harm at low-dose chronic exposure.
The research at a glance
| Study | Journal | Year |
|---|---|---|
| Polystyrene nanoplastics promote adipogenesis | Food Chem Toxicol | 2026 |
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