Harmful chemicals in tobacco

 Tobacco smoke contains chemicals that are harmful to both smokers and nonsmokers. Breathing even a little tobacco smoke can be harmful (1–3).
Of the more than 7,000 chemicals in tobacco smoke, at least 250 are known to be harmful, including hydrogen cyanide, carbon monoxide, and ammonia (1, 4).
Among the 250 known harmful chemicals in tobacco smoke, at least 69 can cause cancer. These cancer-causing chemicals include the following (1, 4):

• Arsenic
• Benzene
• Beryllium (a toxic metal)
• 1,3–Butadiene (a hazardous gas)
• Cadmium (a toxic metal)
• Chromium (a metallic element)
• Ethylene oxide
• Nickel (a metallic element)
• Polonium-210 (a radioactive chemical element)
• Vinyl chloride

Other toxic chemicals in tobacco smoke are suspected to cause cancer, including the following (3) 

• Formaldehyde 
• Benzo[a]pyrene
• Toluene
• http://www.cancer.gov/cancertopics/factsheet/Tobacco/cessation