Is the main drug in all forms of tobacco. Nicotine is one of the most heavily used and most addictive drugs in the U.S. Whether smoked or chewed, nicotine is one of the most highly addictive drugs used in today's society.

Smoking harms your immune system and can affect nearly every organ of your body. The nicotine gets you hooked, but it’s the other chemicals in tobacco like carbon monoxide, tar, formaldehyde, cyanide and ammonia that cause the major damage--many of these are known carcinogens (cancer-causing poisons). Carbon monoxide keeps red blood cells from getting the full load of oxygen needed for healthy cellular growth. This encourages the carcinogens in tobacco to bind to the cells throughout your body and cause cellular damage.

Chewing or sniffing tobacco is just as dangerous as smoking and also has a high risk of addiction. And prolonged use of smokeless tobacco leads to a high risk of cancers of the mouth.

You probably already know that the greatest long-term risk of smoking is cancer and lung disease. Here are some numbers to consider: In the 40 years between 1964 and 2004, cigarette smoking caused an estimated 12 million deaths, including 4.1 million deaths from cancer, 5.5 million deaths from cardiovascular disease, 1.1 million deaths from respiratory disease and 94,000 infant deaths related to mothers smoking during pregnancy.

Even after 30 years of warnings on packages, tobacco continues to impact our health. In 2010, more than 220,000 new cases of lung cancer were reported, and more than 150,000 Americans died as a direct result of the disease.