- Between 65 and 75 million Americans have smoked marijuana according to a 1994 study, and one third of voting adults acknowledge having smoked it at some point. - Marijuana is made from the dried leaves, flowers, stems and seeds of the Cannabis Sativa plant. It contains THC which causes the high and is classified as psychologically addictive. - Marijuana can negatively impact memory, judgment and perception and increase the likelihood of making mistakes that could be embarrassing or hurtful.