Marijuana is a combination of shredded leaves, stems and flower buds of the Cannabis sativa plant. Marijuana can be smoked, eaten, vaporized, brewed and even taken topically, but most people smoke it.
The intoxicating chemical in marijuana is tetrahydracannabinol, or THC. According to research from the Potency Monitoring Project, the average THC content of marijuana has soared from less than 1 percent in 1972, to 3 to 4 percent in the 1990s, to nearly 13 percent in 2010. Today, some retail marijuana has 30 percent THC or more. The increased potency makes it difficult to determine the short- and long-term effects of marijuana
How Cannabis is consumed
In a 2010 National Survey on Drug Use and Health (NSDUH), 17.4 million people in the United States said they had used marijuana in the past month. Since then, many states have made it legal to use marijuana recreationally or medically. As of
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