Tobacco contains over 4,000 chemicals including 43 cancer-causing compounds. Nicotine is the addictive substance in tobacco. Cigarette smoke also contains other toxins like formaldehyde, ammonia, arsenic and pesticides which are linked to various cancers and birth defects. The three most heavily advertised cigarette brands, Marlboro, Newport, and Camel, are most popular among youth smokers. Tobacco use kills over 440,000 Americans each year, more than died in WWII and Vietnam combined, with the average smoker starting at age 15 and becoming a daily smoker by 18.