Only about five percent of a foam package (ie. Styrofoam) is polystyrene. The rest is air.
Styrofoam has many benefits, including insulating quality that helps keep food warm. It is also of light weight, has high durability and strength, making it an excellent packaging material.
EPS is manufactured in accordance with ASTM C578.
Nevertheless, polystyrene (and hence Styrofoam) is made from petroleum. And in its production process, a carcinogenic chemical known as benzene is used. Due to the presence of benzene in Styrofoam, it is inevitable that food in direct contact with the Styrofoam food packaging would be affected. This has been one of the main reasons why over 20 cities in the United States have banned the use of Styrofoam.
Styrofoam is hardly biodegradable. In the absence of a suitable solvent, Styrofoam can last almost forever.
EPS does NOT contribute to the growth of mold or mildew.
EPS is considered to be no more toxic than Douglas Fir wood under the worst case fire scenario.