Tobacco is a plant native to South and Central America that is now cultivated worldwide. It contains nicotine, a powerful stimulant that is highly addictive. Tobacco leaves can be burned and inhaled through cigarettes, cigars, pipes, or absorbed through spit tobacco, chew, or snuff. Nicotine is delivered through the membranes in the nose, mouth, and lungs into the bloodstream and brain. Second-hand smoke exposes non-smokers to over 4,000 chemicals, including 50 that cause cancer. It has twice as much nicotine and tar as inhaled smoke and five times the carbon monoxide.