section_path: Causes/Chemicals
section_name: Chemicals
paragraph_text: Chemicals
  
  Exposure to particular substances have been linked to specific types of cancer. These substances are called carcinogens.
  
  Tobacco smoke, for example, causes 90% of lung cancer. Tobacco use can cause cancer throughout the body including in the mouth and throat, larynx, esophagus, stomach, bladder, kidney, cervix, colon/rectum, liver and pancreas. Tobacco smoke contains over fifty known carcinogens, including nitrosamines and polycyclic aromatic hydrocarbons.
  
  Tobacco is responsible for about one in five cancer deaths worldwide and about one in three in the developed world. Lung cancer death rates in the United States have mirrored smoking patterns, with increases in smoking followed by dramatic increases in lung cancer death rates and, more recently, decreases in smoking rates since the 1950s followed by decreases in lung cancer death rates in men since 1990.
  
  In Western Europe, 10% of cancers in males and 3% of cancers in females are attributed to alcohol exposure, especially liver and digestive tract cancers. Cancer from work-related substance exposures may cause between 2 and 20% of cases, causing at least 200,000 deaths. Cancers such as lung cancer and mesothelioma can come from inhaling tobacco smoke or asbestos fibers, or leukemia from exposure to benzene.
  
  Exposure to perfluorooctanoic acid (PFOA), which is predominantly used in the production of Teflon, is known to cause two kinds of cancer.
  
  Chemotherapy drugs such as platinum-based compounds are carcinogens that increase the risk of secondary cancers
  
  Azathioprine, an immunosuppressive medication, is a carcinogen that can cause primary tumors to develop.