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the Tilt was withdrawn from the market in the early 1980s due to the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.
California NORML
2215-R Market St. #278
San Francisco, CA 94114
CANORML@igc.apc.org
from the Spring 1996 MAPS Bulletin
---------------------------------------------------------------------------
MAPS Inc.
1801 Tippah Avenue
Charlotte, NC 28205
USA
Rick Doblin, President
tel: 704-358-9830
fax: 704-358-1650
email: sylvia@maps.org (Sylvia Thyssen, Network Coordinator)
---------------------------------------------------------------------------
--- PPoint 2.00
---------------