As many as 238,000 people may be occupationally exposed to benzene in the United States. Research has shown benzene to be a carcinogen (cancer causing substance). Benzene is colorless and has a strong sweet odor. It is used primarily to make other chemicals and plastics, and benzene is commonly found in solvents and degreasers. Benzene is widely used in the United States; it ranks in the top twenty chemicals for production volume. Individuals employed in industries that make or use benzene may be exposed to the highest levels of benzene. These industries include benzene production (petrochemicals, petroleum refining and coke and coal chemical manufacturing), rubber tire manufacturing and storage or transport of benzene and petroleum products containing benzene. Other workers who may be exposed to benzene because of their occupations include: laboratory technicians, mechanics, chemical plant workers, steel workers, paper and wood pulp workers, printers, rubber workers, shoe makers, firefighters, gasoline truck drivers, pipe fitters, refinery workers, maritime workers and gas station employees.