Myth: One Joint Equals One Pack (or 16, or
maybe just 4) Cigarettes
Some critics exaggerate the dangers of
marijuana smoking by fallaciously citing a study by Dr. Tashkin
which found that daily pot smokers experienced a "mild but
significant" increase in airflow resistance in the large
airways greater than that seen in persons smoking 16 cigarettes
per day[07] What they ignore is that the same
study examined other, more important aspects of lung health, in
which marijuana smokers did much better than tobacco smokers. Dr.
Tashkin himself disavows the notion that one joint equals 16
cigarettes.
A more widely accepted estimate is that
marijuana smokers consume four times as much carcinogenic tar as
cigarettes smokers per weight smoked[08] This
does not necessarily mean that one joint equals four cigarettes,
since joints usually weigh less. In fact, the average joint has
been estimated to contain 0.4 grams of pot, a bit less than
one-half the weight of a cigarette, making one joint equal to two
cigarettes (actually, joint sizes range from cigar-sized spliffs
smoked by Rastas, to very fine sinsemilla joints weighing as
little as 0.2 grams). It should be noted that there is no exact
equivalency between tobacco and marijuana smoking, because they
affect different parts of the respiratory tract differently:
whereas tobacco tends to penetrate to the smaller, peripheral
passageways of the lungs, pot tends to concentrate on the larger,
central passageways[09] One consequence of
this is that pot, unlike tobacco, does not appear to cause
emphysema.
Myth: Prohibition Reduces the Harmfulness
of Pot Smoking
Whatever the risks of pot smoking, the
current laws make matters worse in several respects: (1)
Paraphernalia laws have impeded the development and marketing of
vaporizers and other devices that could significantly reduce the
harmfulness of marijuana smoke. (2) Prohibition encourages the
sale of pot that has been contaminated or adulterated by
insecticides, Paraquat, etc., or mixed with other drugs such as
PCP, crack and heroin. (3) By raising the price of marijuana,
prohibition makes it uneconomical to consume marijuana orally, the
best way to avoid smoke exposure altogether; this is because
eating typically requires two or three times as much marijuana as
smoking.
Unlike the government, NORML is interested
in reducing the dangers of pot smoking. California NORML and MAPS
(the Multidisciplinary Association for Psychedelic Studies) have
sponsored research on alternative inhalation systems, in
particular vaporizers,
which are designed to deliver smoke-free cannabinoid vapors. The
results indicate that it is possible to virtually eliminate the
risk of smoking-related respiratory damage by using vaporizers
instead.
References on Marijuana and Smoking:
Donald Tashkin, "Is Frequent Marijuana
Smoking Hazardous To Health,?" Western Journal of Medicine
158 #6: 635-7; June 1993; Research Findings on Smoking of Abused
Substances, ed. C. Nora Chiang and Richard L. Hawks, NIDA Research
Monograph 99 (National Institute on Drug Abuse, Rockville, MD
1990); NAS Report,op. cit.; California NORML, "Health Tips
for Marijuana Smokers."
Myth: No One Has Ever Died From Using
Marijuana
The Kaiser study also found that daily pot
users have a 30% higher risk of injuries, presumably from
accidents. These figures are significant, though not as high as
comparable risks for heavy drinkers or tobacco addicts. That pot
can cause accidents is scarcely surprising, since marijuana has
been shown to degrade short-term memory, concentration, judgment,
and coordination at complex tasks including driving[10]
There have been numerous reports of pot-related accidents - some
of them fatal, belying the attractive myth that no one has ever
died from marijuana. One survey of 1023 emergency room trauma
patients in Baltimore found that fully 34.7% were under the
influence of marijuana, more even than alcohol (33.5%); half of
these (16.5% used both pot and alcohol in combination[11]
This is perhaps the most troublesome research ever reported about
marijuana; as we shall see, other accident studies have generally
found pot to be less dangerous than alcohol.
Nonetheless, it is important to be informed
on all sides of the issue. Pot smokers should be aware that
accidents are the number one hazard of moderate pot use. In
addition, of course, the psychoactive effects of cannabis can have
many other adverse effects on performance, school work, and
productivity.
Myth: Marijuana is a Major Road Safety
Hazard
Numerous research studies have found that
marijuana is on balance less of a public road hazard than alcohol.
Various accident surveys have found that over half of fatal
drivers have alcohol in their blood, as opposed to 7 - 20% with
THC, the major psychoactive component of marijuana (a condition
usually indicative of having smoked within the past 2-4 hours)[12]
However, the great majority (70% - 90%) of THC-positive drivers
also have alcohol in their blood. There is little accordingly
little evidence that marijuana use by itself is a major
public safety hazard [ 13].
Two major studies by the National Highway
Transportation Safety Administration have confirmed marijuana's
relative safety compared to alcohol. The first, the most
comprehensive U.S. drug accident study to date, surveyed blood
samples from 1882 drivers killed in car, truck and motorchycle
accidents in seven states during 1990-91[14]
Alcohol was found in 51.5% of specimens, as against 17.8% for all
other drugs combined. Marijuana, the second most common drug,
appeared in just 6.7%. Two-thirds of the marijuana-using drivers
also had alcohol. The report concluded that alcohol was by far the
"dominant" drug-related problem in accidents. It went on
to analyze the responsibility of drivers for the accidents they
were involved in. It found that drivers who used alcohol were
especially culpable in fatal accidents, and even more so when they
combined it with marijuana or other drugs. However, those who used
marijuana alone appeared to be if anything less culpable than
non-drug users (though the date were insufficient to be
statistically conclusive). The report concluded, "There was
no indication that marijuana by itself was a cause of fatal
accidents." (It must be emphasized that this is not the case
when marijuana is combined with alcohol or other drugs).
The second NHTSA study, "Marijuana and
Actual Driving Performance," concluded that the adverse
effects of cannabis on driving appear "relatively small"
and are less than those of drunken driving[15]
The study, conducted in the Netherlands, examined the performance
of drivers in actual freeway and urban driving situations at
various doses of marijuana. It found that marijuana produces a
moderate, dose-related decrement in road tracking ability, but is
"not profoundly impairing" and "in no way unusual
compared to many medicinal drugs." It found that marijuana's
effects at the higher doses preferred by smokers never exceed
those of alcohol at blood concentrations of .08%, the minimum
level for legal intoxication in stricter states such as
California. The study found that unlike alcohol, which encourages
risky diring, marijuana appears to produce greater caution,
apparently because users are more aware of their state and able to
compensate for it (similar results have been reported by other
researchers[16]).
However, a recent Australian study by
Drummer found that drivers with high blood levels of THC (> 5
ng/ml) had a significantly higher rate of accident culpability
than drivers who were drug-free, comparable to drunken drivers
[16A]. This was not true of drivers with only trace amounts of
cannabinoids in their systems. High blood levels are indicative of
recent use within the last couple of hours. This suggests that
acute, current pot use is a driving hazard, though not residual
after-effects of chronic use, which often show positive in drug
tests.
Another survey of 2,500 drivers in South
Australia failed to find evidence that marijuana is a significant
road safety hazard[16B]. The researchers
examined blood samples from drivers in non-fatal accidents for
traces of alcohol, cannabinoids (marijuana), benzodiazepines
(tranquilizers), and amphetamines. The researchers then assessed
the drivers' degree of culpability for the crashes. Overall, they
found no increase in culpability for drivers showing cannabinoids
alone compared to drug-free drivers. In contrast, there was a very
strong relation between alcohol blood levels and accident
culpability. The combination of marijuana with alcohol also showed
strongly increased accident culpability. Benzodiazepines, but not
amphetamines, also showed higher culpability. Another
analysis of 1,052 fatal drivers in Australia suggested that
marijuana is if anything associated with a decreased risk
of accidents.
Similar results have been reported in other
driving studies as well[16C]. It should be
noted that these results may not apply to non-driving related
situations, where forgetfulness or inattention can be more
important than speed (this might explain the discrepancy in the
Baltimore hospital study, which looked at accidents of all kinds).
In addition, the second NHTSA study warned that marijuana could
also be quite dangerous in emergency situations that put high
demands on driving skills.
A good summary of the literature on driving
under the influence of marijuana may be found at Dr. Franjo
Grotenhermen's IACM
- DUIM Project site. See also Cannabis
and Driving: A Review of the Literature and Commentary (U.K.
Department for Transport)
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