Styrofoam is a plastic made from petroleum, and it is also called a styrene monomer. Styrofoam is the brand name for polystyrene foam.
Because there is so much air locked inside of polystyrene material, Styrofoam is an excellent insulator. This makes it ideal for hot and cold drink cups and picnic coolers.
However, Styrofoam's petroleum base causes problems both during its manufacture and after its disposal. During manufacturing, hydrocarbons and known carcinogens are released, putting human lives at risk. After disposal, polystyrene fills up landfills and breaks off in pieces that can cause animals to choke or to develop potentially fatal intestinal blockages.