Can polystyrene in styrofoam cups cause cancer?
Styrene can leach from polystyrene food containers at very low levels, and NTP lists styrene as reasonably anticipated to be a human carcinogen based mainly on higher occupational exposure evidence. One foam cup is not proven to cause cancer.
What's actually in it
Foam cups are usually made from polystyrene. Polystyrene is made from styrene.
Hot drinks can increase chemical movement from some food-contact materials, including polystyrene cups.
What the research says
A 2009 Toxicology Mechanisms and Methods study found styrene migrated from polystyrene cups into hot tea, hot milk, and hot cocoa milk. Migration depended on drink fat content and temperature.
The National Institute of Environmental Health Sciences says styrene can leach from polystyrene containers used for food products, but levels in food are very low. NIEHS also notes that the National Toxicology Program lists styrene as reasonably anticipated to be a human carcinogen, based on evidence that includes workers exposed to higher levels.
This does not prove one foam cup causes cancer. It does support using glass cups for hot drinks and daily use.
The research at a glance
| Study | Journal | Year |
|---|---|---|
| Determination of migration monomer styrene from GPPS (general purpose polystyrene) and HIPS (high impact polystyrene) cups to hot drinks. | Toxicol Mech Methods | 2009 |
| Styrene | National Institute of Environmental Health Sciences | 2026 |