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Marijuana Water pipe and Vapouriser study
From the Newsletter of the Multidisciplinary Association for Psychedelic Studies
MAPS - Volume 6 Number 3 Summer 1996
Dale Gieringer, Ph.D. Contrary to popular impression, waterpipes don't
necessarily protect smokers from harmful tars in marijuana smoke, according
to a new study sponsored by MAPS and California NORML (National Organization
for the Reform of Marijuana Laws). The reason is that waterpipes filter out
more psychoactive THC than they do other tars, thereby requiring users to
smoke more to reach their desired effect. The study does not rule out the
possibility that waterpipes could have other benefits, such as filtering out
gases, but it suggests that other methods, such as the use of high potency
marijuana, vaporizers, or oral ingestion are needed to avoid harmful toxins
in marijuana smoke.
Seven Devices Tested
The study, which was supported by the Drug Policy Foundation and private
donors, was conducted at a research lab with expertise in the analysis of
various chemical properties of tobacco and marijuana. Researchers tested the
smoke from seven different sources: a regular rolled joint, a joint with a
cigarette filter, three different waterpipes, and two vaporizers, designed
to heat
marijuana to a temperature where psychoactive vapors form without producing
smoke. The waterpipes included a standard bong (Picture #1), a small
portable device with a folding pipestem (Picture #6), and a battery-operated
model with a motorized paddle to thoroughly mix the smoke in the water
(Picture #3). The first vaporizer (Picture #5), commercially produced in
Canada, consisted of a battery-powered metal hot plate inside a jar to trap
the marijuana vapor. The second (Picture #4) was a homemade, hybrid
apparatus, in which vapors were produced by a hot air gun and then drawn
through a beaker of water, thereby combining vaporization with water
filtration. The smoke was produced from standard NIDA-supplied marijuana
drawn through a smoking machine adjusted to mimic the puff length of
marijuana smokers.
Focus: Cannabinoid/Tar Ratio
The study focused on two key components of the smoke: (1) total solid
particulates, or tars, which are noxious waste by-products of burning leaf
like those from tobacco; and (2) cannabinoids, the chemicals distinctive to
marijuana, including its major psychoactive ingredient,
delta-9-tetrahydrocannabinol (THC), and its two commonest chemical
relatives, cannabinol (CBN) and cannabidiol (CBD), which are only weakly
psychoactive but may have medical benefits.
Like tobacco, marijuana tars are rich in carcinogenic compounds known as
polycyclic aromatic hydrocarbons, which are a prime culprit in
smoking-related cancers. However, cannabinoids themselves are not
carcinogenic. An obvious way to protect smokers' health is therefore to
minimize the content of smoke tars relative to cannabinoids.
One way to do this is to increase the THC potency of the marijuana. Assuming
smokers adjust their smoke intake to the cannabinoid dosage, the higher the
concentration of cannabinoids, the lower the amount of tars they are likely
to consume.
Another strategy is to try to reduce the tars in the smoke with some kind of
filtering device. Obviously, this is beneficial only to the extent that THC
isn't also reduced, thereby inducing users to smoke more to compensate. A
major aim of the study was to determine the efficacy of various smoking
devices at reducing the concentration of tars relative to cannabinoids. The
performance of each device was accordingly rated in terms of the
cannabinoid-to-tar ratio in its smokestream.
Joints and Waterpipes
Surprisingly, the unfiltered joint outperformed all devices except the
vaporizers, with a ratio of about 1 part cannabinoids to 13 parts tar. This
disturbingly poor ratio may be explained by the low potency of the
NIDA-supplied marijuana used in the study, which was around 2.3%.
Disappointingly, waterpipes performed uniformly worse than the unfiltered
joint. The least bad waterpipe, the bong, produced 30% more tar per
cannabinoids than the unfiltered joint. Ironically, the pipe with the
electric mixer scored by far the worst of any device. This suggests that
water filtration is actually counterproductive, apparently because water
tends to absorb THC more readily
than noxious tars. Like the waterpipes, the cigarette filter also performed
worse than the unfiltered joint, by about 30%. Researchers speculate this is
because cannabinoids are exceptionally sticky and adhere to other solids.
Hence, any filtration system that picks up particulates is likely also to
screen out cannabinoids.
Vaporizers
The vaporizer results appeared more promising, but confusing. The two
vaporizers were the only devices to outscore unfiltered joints in terms of
raw cannabinoid/tar ratio. The electric hotplate vaporizer did best, with a
performance ratio about 25% higher than the unfiltered joint. The hot air
gun was just marginally superior, but might have done better had it not been
for its water filtration component.
However, the situation was complicated by the fact that the cannabinoids
produced by the electric hotplate vaporizer were unusually high in CBN,
leaving 30% less THC as a percentage of the total cannabinoids than with the
other smoking devices. Since CBN is not psychoactive like THC, recreational
users might be expected to consume more smoke to make up for the deficit.
(The situation may be different for medical users, who could experience
other, medicinal benefits from
CBN). For this reason, it seemed advisable to recompute the performance
efficiencies of the vaporizers in terms of THC, rather than all
cannabinoids. When this was done, the electric hotplate vaporizer turned out
to have a lower THC/tar ratio than the unfiltered joint, while the hot air
gun was still marginally higher.
The reason for the excess CBN from the hotplate vaporizer remains
unexplained. Because CBN is produced from THC by chemical oxidation, it has
been suggested that the device somehow exposed the sample to too much
oxygen. However, there is no evidence that this was the case. As for the
second, hybrid vaporizer, it seems likely that its performance could have
been improved by deleting its water component. The results clearly indicate
that more developmental work needs to
be done on vaporizers. Theoretically, an ideal vaporizer could minimize
production of tars by holding the temperature just above 155 C, the point at
which THC vaporizes, which is well below the temperature where carcinogenic
hydrocarbons are thought to be produced. In practice, both vaporizers
produced over ten times more tars than cannabinoids, indicating that there
is plenty of room for improvement.
In the late 1970s, a vaporizer known as the Tilt appeared on the market.
According to the manufacturer, laboratory tests showed that it released 80%
more THC and 79% less tar than a regular pipe, a performance ratio almost
ten times better than any observed in this study. It is to be hoped that
these impressive results can be replicated in the future. Unfortunately, the
Tilt was withdrawn from the market in the early 1980s due to the passage of
anti-paraphernalia laws.
As for waterpipes, the prospects for improvement appear more dubious. It has
been suggested that the performance of waterpipes could be improved by using
liquids other than water or by changing the temperature of the liquid.
However, it seems doubtful whether such tactics would circumvent the basic
problem of separating the tars from the sticky cannabinoids.
Are Waterpipes Counterproductive?
The study results are obviously discomforting to waterpipe enthusiasts, many
of whom prefer the cooler, milder smoke they produce, and have naturally
assumed it is also more healthful. Unfortunately, however, the study
indicates that waterpipes may actually be counterproductive in increasing
consumption of carcinogenic tars.
Nonetheless, it is still premature to judge that waterpipes are actually
unhealthful, since they may filter out other, non-solid smoke toxins
occurring in the gas phase of the smoke, which was not analyzed in the
study. Noxious gases known to occur in marijuana smoke include hydrogen
cyanide, which incapacitates the lung's defensive cilia; volatile phenols,
which contribute to the
harshness of the taste; aldehydes, which promote cancer; and carbon
monoxide, a known risk factor in heart disease. Previous studies indicate
that water filtration may be quite effective in absorbing some of these
[Nicholas Cozzi, Effects of Water Filtration on Marijuana Smoke: A
Literature Review, MAPS Newsletter, Vol. IV #2, 1993]. If so, waterpipes
might still turn out to have net health benefits.
MAPS and California NORML are planning to undertake a second phase of the
waterpipe study for the purpose of analyzing the gaseous phase of marijuana
smoke.
In the meantime, the easiest way for most smokers to avoid harmful smoke
toxins may be simply to smoke stronger marijuana. This strategy is apt to be
more effective than any smoke filtration device. By simply replacing the
low, 2.3% potency NIDA marijuana used in this study with high-quality
12%-sinsemilla, smokers could presumably reduce their tar intake by a factor
of five while still
achieving the same effect. Further improvements could be had by using pure
THC or hash oil, which has been tested at potencies of 60%.
The notion that high-potency marijuana is less harmful directly contradicts
official government propaganda, which maintains that marijuana has become
more dangerous since the '60s due to increased potency. This claim appears
to rest less on scientific evidence than on the desire to frighten the
public. A careful analysis of government data by Dr. John Morgan has shown
that the supposed increase in potency has been greatly exaggerated [American
Marijuana Potency: Data Versus Conventional Wisdom, NORML Reports (1994)].
In any case, however, there is no good reason to presume that higher potency
marijuana is more harmful, given the potential respiratory benefits of
reduced smoke consumption. The hazards of excessive potency are purported to
be an increased risk of acute overdose and greater susceptibility to
dependency. However, both problems can be avoided if users adjust their
dosage to potency. For most users, such hazards may
well be outweighed by the benefits of reduced smoke consumption.
Research in Australia
The Australian government is currently conducting another study that may
cast further light on the effects of potency variations. The study is
designed to determine baseline THC, tar, and carbon monoxide levels from
marijuana and marijuana-tobacco mixtures smoked through joints and
waterpipes. The samples being tested come from police seizures in six
different Australian states.
Researchers say that they have observed "incredible" variations in tar and
THC potency among different samples. Their report is expected shortly.
THC Transfer Rate
The MAPS-NORML study provides new information on the efficiency of different
devices in delivering THC from marijuana to the user. Previous studies have
shown that 60% - 80% of the THC burned in joints or waterpipes is lost in
slipstream smoke, adhesion to the pipestem and bowl, pyrolysis, etc. [Mario
Perez-Reyes, Marijuana Smoking: Factors that Influence the Bioavailability of
Tetrahydrocannabinol, in C. Nora Chiang and Richard Hawks, ed., Research
Findings on Smoking of Abused Substances, NIDA Research Monograph 99, 1990].
The percentage of total THC delivered to the user is called the THC transfer
rate. The unfiltered joint scored surprisingly well in smoking efficiency,
coming in second place with a transfer rate close to 20%. The portable
waterpipe did slightly better, and the bong slightly worse. The other
devices did notably worse. The vaporizers and electric waterpipe did
especially poorly, with transfer rates less than one-third that of the top
three devices. Thus, heavy smokers could literally be blowing most of their
stash away with bad pipes.
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