From CaliforniaNORML.org – an older but relevant study sponsored by NORML and MAPS.
California NORML Press Release – Jan 8, 2001
Medical marijuana patients may protect themselves from harmful toxins in marijuana smoke by inhaling their medicine using an electric vaporizer, according to results of a study by California NORML and MAPS (Multidisciplinary Association for Psychedelic Studies).
The study showed that it is possible to vaporize medically active THC by heating marijuana to a temperature short of the point of combustion, thereby eliminating or substantially reducing harmful smoke toxins that are normally present in marijuana smoke. Vaporizers may therefore substantially reduce what is widely regarded as the leading health hazard of marijuana, namely respiratory harm due to smoking.
Details of the study are published in D. Gieringer, “Cannabis Vaporization: A Promising Strategy for Smoke Harm Reduction,” Journal of Cannabis Therapeutics Vol. 1#3-4: 153-70 (2001). Reprints available for $5 from California NORML, 2261 Market St. #278A, San Francisco CA 94114.
NORML and MAPS sponsored the study in the hopes of helping medical marijuana patients and others reduce the health risks of smoking. The hazards of smoking were cited as a major obstacle to approval of natural cannabis by the Institute of Medicine in its 1999 report, “Marijuana and Medicine.” However, the IOM report failed to note the possibility of vaporization.
The NORML-MAPS study tested a device called the M1 Volatizer, an aromatherapy vaporizer
developed by Alternative Delivery Systems, Inc. It consisted of an electric heating element in a chamber that radiates heat downwards over a sample of marijuana sitting in a standard pipe or “bong” bowl. Output from the vaporizer was analyzed and compared to smoke produced by combusting the sample with a flame.
The vaporizer produced THC at a temperature of 185° C. (365° F.) while completely eliminating three measured toxins – benzene, a known carcinogen, plus toluene and naphthalene. Carbon monoxide and smoke tars were both qualitatively reduced by the vaporizer, but additional testing is needed to quantify the extent of the decrease.
Although the study was not designed to detect the highly carcinogenic tars known as polycyclic aromatic hydrocarbons, which are thought to be a leading culprit in smoking-related cancers, there was good reason to believe that they were suppressed, since they normally form at much higher temperatures of combustion.
When vaporized, the marijuana emitted a thin gray vapor and was left with a green to greenish-brown “toasted” appearance, whereas the combusted sample produced thick smoke and turned to ash.
Significant amounts of benzene began to appear at temperatures of 200° C. (392° F), while combustion occurred around 230° (446°F) or above. Traces of THC were in evidence as low as 140° C. (284° F).
Further details of the study will be published in a forthcoming issue of the Journal of Cannabis Therapeutics.
The vaporizer study was undertaken as a follow-up to a previous NORML-MAPS marijuana smoking device study, which concluded that vaporizers offered the best prospects for smoke harm reduction. The study found that neither waterpipes nor solid filters were effective at reducing exposure to smoke tars, due to the fact that they filtered out even more THC, thus forcing patients to inhale more to achieve the same effective dose. A recent Australian study also found that waterpipes failed to reduce tars or carbon monoxide (Linda Gowing et al., “Respiratory Harms of Smoked Cannabis,” Research Monograph No. 8. Adelaide: Drug and Alcohol Services Council of South Australia, 2000).
Other methods of marijuana smoke harm reduction include oral ingestion and potential new delivery systems, such as inhalers and patches, that are still under development. Smokers may also reduce their respiratory risks by using higher-potency marijuana, allowing them to inhale less smoke to obtain a given effective dose of THC. The medical marijuana popularly used in cannabis patients’ clubs is several times more potent than that commonly provided to researchers by the National Institute on Drug Abuse, according to a potency survey by NORML and MAPS. However, the Australian study found that higher potency marijuana does not always deliver more THC, apparently because THC output is highly sensitive to variations in the burning properties of different samples.
A wide variety of vaporizers are presently available on the market. Many medical marijuana patients say they prefer vaporizers because they deliver smoother, less irritating medication. However, there have been no published scientific studies of their effectiveness heretofore.
NORML and MAPS are currently seeking support for further research and development of vaporizers. Tax-deductible donations to the vaporizer research project can be made through the NORML Foundation c/o California NORML, 2261 Market St #278A, San Francisco CA 94114 (415) 563-5858.