Can polystyrene in styrofoam cups weaken your immune system?
Styrene can migrate from polystyrene cups into hot drinks, and a 2026 mouse study found airborne polystyrene nanoplastics changed spleen immune balance. This does not prove one foam cup weakens your immune system.
What's actually in it
Foam cups are usually made from polystyrene. Small amounts of styrene, the building block chemical, can remain in the material.
Heat and fat can change how much styrene moves from a cup into a drink.
What the research says
A 2009 Toxicology Mechanisms and Methods study tested general-purpose and high-impact polystyrene cups with hot tea, hot milk, and hot cocoa milk. Styrene migration ranged from 0.48 to 8.65 micrograms per liter, and migration depended on drink fat content and temperature.
A 2026 Ecotoxicology and Environmental Safety mouse study found airborne polystyrene nanoplastic exposure led to spleen cell senescence and immune imbalance. That exposure route is not the same as drinking from a foam cup.
This does not prove one foam cup weakens your immune system. It does support using glass cups for hot drinks when you can.
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 |
| Airborne polystyrene nanoplastic exposure leads to splenic cell senescence and immune imbalance. | Ecotoxicol Environ Saf | 2026 |