Tobacco.

Tobacco products, including cigarettes, cigars, chewing tobacco, snuff, and loose pipe tobacco, contain the dried, processed leaves of the tobacco plant Nicotiana rustica or Nicotiana tabacum. All forms of tobacco contain nicotine, an extremely addictive drug that can act as both a central nervous system stimulant and depressant. In addition to nicotine, tobacco contains thousands of other chemicals and additives to enhance the effects and flavor of the tobacco. Many of these chemicals are known to cause cancer and various other ailments. Tobacco use remains the leading preventable cause of death in the United States today, causing more than 430,000 deaths per year.