Marijuana
Marijuana is the most commonly used illicit drug in the United States.
A dry, shredded green/brown mix of flowers, stems, seeds, and leaves
of the hemp plant Cannabis sativa, it usually is smoked as a cigarette
(joint, nail), or in a pipe (bong). It also is smoked in blunts, which
are cigars that have been emptied of tobacco and refilled with marijuana,
often in combination with another drug. Use also might include mixing
marijuana in food or brewing it as a tea. As a more concentrated,
resinous form it is called hashish and, as a sticky black liquid,
hash oil. Marijuana smoke has a pungent and distinctive, usually sweet-and-sour
odor. There are countless street terms for marijuana including pot,
herb, weed, grass, widow, ganja, and hash, as well as terms derived
from trademarked varieties of cannabis, such as Bubble Gum®, Northern
Lights®, Juicy Fruit®, Afghani #1®, and a number of Skunk
varieties.
The main active chemical in marijuana is THC (delta-9-tetrahydrocannabinol).
The membranes of certain nerve cells in the brain contain protein
receptors that bind to THC. Once securely in place, THC kicks off
a series of cellular reactions that ultimately lead to the high that
users experience when they smoke marijuana.
Extent
of Use
There
were an estimated 2.6 million new marijuana users in 2001. This number
is similar to the numbers of new users each year since 1995, but above
the number in 1990 (1.6 million). In 2002, over 14 million Americans
age 12 and older used marijuana at least once in the month prior to
being surveyed, and 12.2 percent of past year marijuana users used
marijuana on 300 or more days in the past 12 months. This translates
into 3.1 million people using marijuana on a daily or almost daily
basis over a 12-month period(1).
The percentage of youth age 12 to 17 who had ever used marijuana declined
slightly from 2001 to 2002 (21.9 to 20.6 percent). Among adults age
18 to 25, the rate increased slightly from 53.0 percent to 53.8 percent
in 2002. The percentage of young adults age 18 to 25 who had ever
used marijuana was 5.1 percent in 1965, but increased steadily to
54.4 percent in 1982. Although the rate for young adults declined
somewhat from 1982 to 1993, it did not drop below 43 percent and actually
increased to 53.8 percent by 2002(1).
Forty-two percent of youth age 12 or 13 and 24.1 percent age 16 or
17 perceived smoking marijuana once a month as a great risk. Slightly
more than half of youth age 12 to 17 indicated that it would be fairly
or very easy to obtain marijuana, but only 26.0 percent of 12- or
13-year-olds indicated the same thing. However, 79.0 percent of those
age 16 or 17 indicated that it would be fairly or very easy to obtain
marijuana(1).
Prevalence of lifetime, past year, and past month marijuana use declined
among students in 8th, 10th, and 12th grades in 2003. However, the
declines in 12-month prevalence reached statistical significance only
in 8th-graders; past year use has declined by nearly one-third since
1996(2). All three grades showed an increase in perceived risk for
regular marijuana use. This finding represents a welcome turnaround
in this perception, which has been in decline in all grades over the
past 1 or 2 years(3).
