the most often used illegal drug in this country.
As the number of people who use marijuana has
increased, the number who view the drug as harmful
has decreased. Among those surveyed in 2001, current
marijuana use has increased by about 62 percent
since 1991. The proportion of those who believe
regular use of marijuana is harmful has dropped by
about 27 percent since 1991.
Researchers are examining the possibility that
long-term marijuana use may create changes in the
brain that make a person more at risk of becoming
addicted to other drugs, such as alcohol or cocaine
Marijuana is derived from the cannabis plant and
grows in many countries, including the United
States. People have been known to put it in rolling
papers to make marijuana cigarettes, smoke it in
bongs or pipes, or mix it in baked goods or tea and
eat or drink it. The cannabis plant also yields
hashish, a stronger form of marijuana, and hash oil,
the strongest form that has very high levels of THC,
the psychoactive ingredient in cannabis.
Marijuana is a green, brown, or gray mixture of
dried, shredded leaves, stems, seeds, and flowers of
the hemp plant (Cannabis sativa). Before the 1960s,
many Americans had never heard of marijuana.
Cannabis is a term that refers to marijuana and
other drugs made from the same plant. Strong forms
of cannabis include sinse-milla (sin-seh-me-yah),
hashish ("hash” for short), and hash oil.
All forms of cannabis are mind-altering
(psychoactive) drugs; they all contain THC
(delta-9-tetrahydrocannabinol), the main active
chemical in marijuana. They also contain more than
400 other chemicals.
The effect of Marijuana on the user depends on the
strength or potency of the THC it contains. THC
potency has increased since the 1970s but has been
about the same since the mid-1980s. The strength of
the drug is measured by the average amount of THC in
test samples confiscated by law enforcement
Most ordinary marijuana has an average of 3
percent THC, Sinsemilla (made from just the buds and
flowering tops of female plants) has an average of
7.5 percent THC, with a range as high as 24 percent,
Hashish (the sticky resin from the female plant
flowers) has an average of 3.6 percent, with a range
as high as 28 percent, Hash oil, a tar-like liquid
distilled from hashish, has an average of 16
percent, with a range as high as 43 percent.
HOW IT IS USED
Most users roll loose marijuana into a cigarette
(called a joint or a nail) or smoke it in a pipe.
One well-known type of water pipe is the bong. Some
users mix marijuana into foods or use it to brew a
tea. Another method is to slice open a cigar and
replace the tobacco with marijuana, making what's
called a blunt. When the blunt is smoked with a 40
oz. bottle of malt liquor, it is called a
Lately, marijuana cigarettes or blunts often include
crack cocaine, a combination known by various street
names, such as "primos" or
"woolies." Joints and blunts often are
dipped in PCP and are called "happy
sticks," "wicky sticks," "love
boat," or "tical."
Aunt Mary, skunk, boom, gangster, kif, or
ganja,Texas tea, Maui wowie, and Chronic. A recent
book of American slang lists more than 200 terms for
various kids of marijuana.
Marijuana contains chemicals that act on the
marijuana receptor in the brain. Scientists have
recently identified the natural chemical,
anandamide, designed to fit the marijuana receptor.
While scientists do not know all of the drug's
effects, several studies have established that
marijuana interferes with memory and learning. A new
study confirms that heavy (daily) marijuana use
impairs critical skills related to attention, memory
and learning. In this study, "Heavy users could
not pay attention to the material well enough to
register the information in the first place so that
it could be recalled and repeated later," say
the researchers in the Journal of the American
Medical Association (2/21/96).
These deficits persisted up to 24 hours after users
stopped feeling high. Marijuana also impairs
judgment and reaction time. A special study showed
that one-third of drivers stopped for reckless
driving were high on marijuana. Another study
revealed that of drivers involved in accidents who
were treated at a trauma center, 15 percent had been
smoking marijuana. Daily use of from 1 to 3
marijuana cigarettes appears to produce the same
lung damage and cancer risk as smoking 5 times as
many cigarettes. Finally, researchers have found for
the first time that marijuana can cause withdrawal
symptoms in laboratory animals, and that marijuana
acts on the brain and nervous system as do other
Marijuana affects many skills required for safe
driving: alertness, the ability to concentrate,
coordination, and reaction time. These effects can
last up to 24 hours after smoking marijuana.
Marijuana use can make it difficult to judge
distances and react to signals and sounds on the
There are data showing that marijuana can play a
role in crashes. When users combine marijuana with
alcohol, as they often do, the hazards of driving
can be more severe than with either drug alone.
A study of patients in a shock-trauma unit who
had been in traffic accidents revealed that 15
percent of those who had been driving a car or
motorcycle had been smoking marijuana, and another
17 percent had both THC and alcohol in their blood.
MARIJUANA USE AND MENTAL
High doses of marijuana can induce psychosis
(disturbed perceptions and thoughts), and marijuana
use can worsen psychotic symptoms in people who have
schizophrenia. There is also evidence of increased
rates of depression, anxiety, and suicidal thinking
in chronic marijuana users. However, it is not yet
clear whether marijuana is being used in an attempt
to self-medicate an already present but otherwise
untreated mental health problem, or whether
marijuana use leads to mental disorders (or both).
MARIJUANA AND PREGNANCY
Doctors advise pregnant women not to use any
drugs because they might harm the growing fetus. One
animal study has linked marijuana use to loss of the
fetus very early in pregnancy.
Some scientific studies have found that babies born
to women who used marijuana during their pregnancy
display altered responses to visual stimulation,
increased tremors, and a high pitched cry, which may
indicate problems with nervous system development.
During pre- and early school years,
marijuana-exposed children have been reported to
have more behavioral problems and difficulties with
sustained attention and memory than no exposed
Researchers are not certain whether any effects of
marijuana during pregnancy persist as the child
grows up; however, because some parts of the brain
continue to develop into adolescence, it is also
possible that certain kinds of problems will become
more evident as the child matures.
When a nursing mother uses marijuana, some of the
THC is passed to the baby in her breast milk. This
is a matter for concern, since the THC in the mother’s
milk is much more concentrated than that in the
mother’s blood. One study has shown that the use
of marijuana by a mother during the first month of
breastfeeding can impair the infant’s motor
development (control of muscle movement).
While all of the long-term effects of marijuana
use are not yet known, there are studies showing
serious health concerns. For example, a group of
scientists in California examined the health status
of 450 daily smokers of marijuana but not tobacco.
They found that the marijuana smokers had more sick
days and more doctor visits for respiratory problems
and other types of illness than did a similar group
who did not smoke either substance .
Findings so far show that the regular use of
marijuana or THC may play a role in cancer and
problems in the respiratory, and immune systems.
MARIJUANA USE AND CANCER
It is hard to find out whether marijuana alone
causes cancer because many people who smoke
marijuana also smoke cigarettes and use other drugs.
Marijuana smoke contains some of the same
cancer-causing compounds as tobacco, sometimes in
higher concentrations. Studies show that someone who
smokes five joints per day may be taking in as many
cancer-causing chemicals as someone who smokes a
full pack of cigarettes every day. Marijuana smoking
could contribute to early development of head and
neck cancer in some people.
MARIJUANA USAGE AND THE
Our immune system protects the body from many agents
that cause disease. It is not certain whether
marijuana damages the immune system of people. But
both animal and human studies have shown that
marijuana impairs the ability of T-cells in the
lungs’ immune defense system to fight off some
MARIJUANA USE AND LUNG AND
People who smoke marijuana regularly may develop
many of the same breathing problems that tobacco
smokers have, such as daily cough and phlegm
production, more frequent chest colds, a heightened
risk of lung infections, and a greater tendency
toward obstructed airways. Cancer of the respiratory
tract and lungs may also be promoted by marijuana
smoke, since it contains irritants and carcinogens.
Marijuana smokers usually inhale more deeply and
hold their breath longer, which increases the lungs’
exposure to carcinogenic smoke. Smoking marijuana
may increase the risk of cancer more than smoking
Some frequent, long-term marijuana users show
signs of a lack of motivation (amotivational
syndrome). Their problems include not caring about
what happens in their lives, no desire to work
regularly, fatigue, and a lack of concern about how
they look. As a result of these symptoms, some users
tend to perform poorly in school or at work.
Scientists are still studying these problems.
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