1,3-Butadiene ranks 36^th in the most produced chemicals in the United States. Three billion pounds per year are produced in the United States and 12 billion globally. 1,3-butadiene is produced through the processing of petroleum and is mainly used in the production of synthetic rubber, but is also found in smaller amounts in plastics and fuel. Exposure to 1,3-butadiene mainly occurs in the workplace, including the following industries: synthetic elastomer (rubber and latex) production, petroleum refining, secondary lead smelting, water treatment, agricultural fungicides, production of raw material for nylon, and the use of fossil fuels. Exposure can also occur from automobile exhaust; polluted air and water near chemical, plastic or rubber facilities; cigarette smoke; and ingestion of foods that are contaminated from plastic or rubber containers.