"While there is no scientific evidence linking marijuana smoking to lung cancer, vaporizers do provide an effective non-smoking delivery system that eliminates the unnecessary products of combustion," said NORML Board Member Rick Doblin, president of MAPS.

Marijuana vapors induced by the device ­ marketed in Germany as the Volcano ­ were found to consist overwhelmingly of THC, and contained only minute amounts (less than 5 percent) of a suspected carcinogen, according to a gas chromatography mass spectrometer (GCMS) analysis of the vapor performed by Chemic Labs. By contrast, combusted smoke contained over 100 other chemicals, including several polynuclear aromatic hydrocarbons (PAHs), carcinogenic toxins that are common in tobacco smoke.

The respiratory hazards of marijuana smoke are due to toxic byproducts of combustion, not the active ingredients of the plant, known as cannabinoids. Vaporizers heat marijuana at a temperature sufficient to vaporize cannabinoids (about 200° C), but short of the point of combustion, which is approximately 250° C.

Although previous studies have found vaporizers to reduce harmful toxins in marijuana smoke, this is the first to analyze the gas phase of the vapor for a wide range of toxins. An earlier study conducted by California NORML and MAPS on the efficiency of waterpipes as filtration systems found that the devices do little to shield smokers from harmful tars in marijuana smoke because they filter out similar amounts of THC and unwanted particulates.

"[This] study suggests that medical marijuana patients can avoid the respiratory hazards of smoking by using a vaporizer," said California NORML Coordinator Dale Gieringer. According to a 1999 National Academy of Sciences Institute of Medicine (IOM) report on the efficacy of marijuana as a medicine, "Except for the harms associated with smoking, the adverse effects of marijuana use are within the range tolerated for other medications."

Currently, no federally approved studies allow the use of vaporizers on human subjects, though a grant request for a research protocol to study the subjective effects and cannabinoid blood levels of vaporization compared to smoking has been submitted by University of California at San Francisco (UCSF) AIDS researcher Dr. Donald Abrams to the California Center for Medical Cannabis Research (CMCR).

For more information, please contact either Dale Gieringer of California NORML at (415) 563-5858 or NORML Foundation Executive Director Allen St. Pierre at (202) 483-8751. A summary report of this study is also available online at: http://www.maps.org/mmj/vaporizer.html. A summary of California NORML's previous waterpipe and vaporizer research is available online at: http://www.canorml.org.