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What's in cigarette smoke?

Cigarette smoke contains over 4,000 chemicals and poisons. More than 70 of them have been shown to cause cancer in human studies or lab tests. Some of the poisons and chemicals in cigarette smoke are:

  • carbon monoxide (found in your car’s exhaust)
  • ammonia (found in window cleaners)
  • cadmium (found in batteries)
  • arsenic (found in rat poison)
  • benzene
  • benzo[a]pyrene
  • beryllium
  • chromium VI (hexavalent compounds)
  • ethylene oxide
  • formaldehyde
  • nickel compounds
  • N-nitrosamines such as N’-nitrosonornicotine (NNN) and 4-(N-methylnitrosoamino)-1-(3-pyridyl)-1-butanone (NNK)
  • polonium-210
  • vinyl chloride
  • 1,3-butadine
  • 2-naphthylamine
  • 4-aminobiphenyl

When you smoke, many of these chemicals mix together and form a sticky tar. The tar sticks to tiny hairs that line the insides of your lungs – hairs that are supposed to keep your lungs clean by sweeping out dirt and germs. But when they’re covered in tar, they can’t do their job properly. This is what leads to smoker’s cough to spit up the dirt that’s still in your lungs. It also leads to many other health problems.

  • Nicotine

    Nicotine is what makes smoking cigarettes so addictive. This drug makes your body crave more cigarettes and that means inhaling all those chemicals.

  • Tar

    Many of the cancer-causing chemicals in tobacco smoke mix together and form a sticky tar. This tar sticks to clothing and skin. When you breathe in tobacco smoke, the tar sticks to the tiny hairs that line the insides of the lungs. These hairs normally help clean dirt and germs from the lungs. If they are covered in tar, the hairs can't do their job properly. As a result, germs, chemicals and dirt stay in the lungs and cause lung problems.

  • Hydrogen cyanide

    Hydrogen cyanide is another very toxic chemical in tobacco smoke. Many toxic effects of cigarette smoke have been linked to hydrogen cyanide. Exposure to this chemical can irritate the eyes and skin and cause dizziness, weakness, headache, nausea and vomiting.

  • Don’t be fooled by light or mild

    Many smokers of low-tar and low-nicotine brands think they are reducing their health risks from smoking. They believe they inhale less tar compared to regular cigarettes.

    They don't. Regular smokers who switch to low-tar and low-nicotine cigarettes tend to adjust their smoking habits by inhaling deeper or longer or covering up the ventilation holes to get enough nicotine. This also means they’re inhaling more chemicals and tar.



Canadian Cancer Trials Group researcher Dr Christopher O’Callaghan The Canadian Cancer Trials Group is improving glioblastoma survival in the elderly.

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Making progress in the cancer fight

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The 5-year cancer survival rate has increased from 25% in the 1940s to 60% today.

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