The phrase "tobacco products" refers to numerous different tobacco-based items, including cigarettes, cigars, smokeless tobacco (such as snuff), bidis, Kreteks, and loose-leaf tobacco. Nicotine is the primary addictive toxin found in tobacco; it is a colorless liquid that turns brown when burned and is found in all kinds of tobacco products. It is known to be highly addictive in smaller doses (1-2mg) and can kill the average person in larger quantities. Tobacco products are used among all demographic populations, but approximately 80% of adult smokers (of whom there were 46.5 million in the United States in 2004) started smoking before the age of 18; every day, nearly 4000 youths under the age of 18 try their first cigarette. Among other effects, nicotine stimulates dopamine production in the brain and can cause the user to feel slightly euphoric. However, tobacco use accounts for about one third of all cancer deaths in the United States and is the single most preventable cause of premature deaths. In Indiana it is illegal for anyone under the age of 18 to purchase or accept tobacco for personal use. It is also illegal to knowingly sell tobacco to a person under the age of 18. Violators of these laws are guilty of a Class C misdemeanor.