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Most us recognize Polystyrene in the form of Styrofoam used for beverage cups, however, Polystyrene is also used as a building material, electrical appliances, and other household items. In 1941, researchers from the Dow Chemical Physics Lab found a way to make foam from polystyrene. The Dow company acquired exclusive rights to use a Swedish inventor's patent and found ways to make large quantities of extruded polystyrene as a closed cell foam that resists moisture. In 1942 the U.S. Coast Guard adopted the use of Styrofoam in a six person life raft.  Polystyrene is an aromatic polymer, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry. Polystyrene is one of the most widely used kinds of plastic worldwide. Polystyrene is a thermoplastic substance, which is in solid (glassy) state at room temperature, but flows if heated above its glass transition temperature (for molding) and becoming solid again when cooling off, it can be cast into molds with fine detail. Uses of Styrofoam: building material, insulated sheathing, pipe insulation, floral and craft products, model cars and airplanes, and computer housings. Uses of Solid Polystyrene: In disposable Cutlery, Plastic Models, CD and DVD Cases, and Smoke Detector Housings. According to the ICB, the US manufacturing of Polystyrene has decline from 3.01 M tons in 2007 to 2.95 M tons in 2001. Exports in 2007 were 433,000 tons while imports were 281,000 tons. 
How it's made
Polystyrene is made with ethylene from natural gas and benzene from petroleum yielding tiny pellets of polystyrene. The spheres are then placed into a chamber where they are heated to 392°F to allow the pentane gas to escape. As pentane escapes, the surrouinding air fills in the empty space. The chamber then releases some of the pressure forcing the air inside the plastic spheres to expand. The expansion increase the pellets size up to forty times making the pellets 95% air by volume. The expanded pellets are then placed in a mold and steam fused into shape.
- Polystyrene is made from fossil fuels, a limited resource.
- Polystyrene can be buried and show no signs of biodegredation.
- Polystyrene can be broken down into smaller and smaller pieces and mistaken for food by animals, which can be lethal.
- Polystyrene builds up in waterways, dumps and in Ocean gyres.
- Acute- irritation of skin, eyes, and lungs.
- Chronic- can depress central nervous system and is considered a possible carcinogen (inconclusive for humans). 
Currently, the life cycle of polystyrene foam most commonly ends by dumping in landfills. At present, the United States averages 547,945 tons of garbage per day. Styrofoam products make up 0.25% of this weight amounting to 1,369 tons of Styrofoam waste. By volume, Styrofoam waste takes up 25-30% of landfill space. <ref>http://188.8.131.52/search?q=cache:jpc96z_lRmIJ:https://oraprdnt.uqtr.uquebec.ca/pls/public/docs/GSC40/F1793448949_Styrofoam.ppt+styrofoam+powerpoint&cd=1&hl=en&ct=clnk&gl=us&client=firefox-a</ref>