Styrofoam is the trade name of an expanded polystyrene product made by the Dow Chemical Co. Expanded polystyrene products are used as insulators for home and household products, including disposable cups. These products are designed for a single use. While some people use expanded polystyrene cups multiple times, there are some issues that must be considered.

Bacteria

Expanded polystyrene is a porous, lightweight foam material. This porosity helps the product maintain the heat or chill of its contents. The problem arises in that the porosity also provides a harbor for bacteria. Once food or drink particles get caught in these pores, they lodge there. Bacteria and other microorganisms feast on these particles. In addition, the bacteria from one person’s mouth could also find a home in expanded polystyrene’s air pockets. Reuse of expanded polystyrene gives these organisms a chance to grow between uses.

Heat

Heat, such as that provided by warm beverages or by heating in a microwave, leaches some chemicals from expanded polystyrene and into the contents of the cup. These chemicals include styrene, benzene and smaller amounts of other toxic materials. Heat breaks down the expanded polystyrene, which releases these chemicals. Hot tea or coffee poured into the cup causes some leaching, and microwaving a cup intended for reuse poses a greater risk.

Food Interactions

Acidic drinks, and those containing alcohol, can also cause chemicals to leach from expanded polystyrene. Tea with lemon, fruit juice, wine or beer are examples of drinks that fall into these two categories. In addition, vitamin A tends to produce toluene, a harmful chemical, as it decomposes. Microwave temperatures are high enough to break down vitamin A. Acidic drinks and foods that contain vitamin A -- carrots are an example -- should not be consumed from expanded polystyrene cups whether they are used once or reused.

Health Problems

Most of the health problems associated with expanded polystyrene are effects that plague workers in manufacturing plants that produce this product. Long-term exposure produces headaches, depression, fatigue and general weakness in some people. Acute health issues, however, show up in some people with continued use of expanded polystyrene products. These illnesses include gastrointestinal disorders and irritation of eyes, skin and upper respiratory track.