Scientists at San Francisco based the University of California have demonstrated that vaporising cannabis leaves can release the drug's active ingredient just as effectively as burning them, while avoiding the harmful toxins inhaled through smoking it.
The results of the pilot study are significant because marijuana is used medicinally as a pain reliever for multiple-sclerosis sufferers, for treating glaucoma, for stimulating appetite in AIDS patients, and as an anti-nausea agent for people on chemotherapy.
Led by Donald Abrams of the university, the researchers investigated the benefits of the 'Volcano', a commercially available vaporiser that heats marijuana leaves to a temperature between 180 and 200°C so that active ingredients like tetrahydrocannabinol (THC) are released from oils on the surface of the leaf. Actual combustion does not take place during the process.
Several previous studies have shown that such devices do not produce harmful toxins released through smoking cannabis that include carbon monoxide, benzene and a host of compounds known as polycyclic aromatic hydrocarbons, many of which are known carcinogens.
But the current study is the first to compare the effects of smoking and vaporising cannabis on human subjects.
"We were able to deliver more-or-less equivalent amounts of THC into the bloodstream," Nature magazine quoted Abrams as saying.
According to him, the main difference between the two delivery methods was that THC seemed to be absorbed into the bloodstream faster when using the vaporisers.
"The pharmacological and physiological effects were comparable," he says.
Abrams, however, conceded that a larger study would be needed to prove that they are biologically equivalent.