Quote Originally Posted by OzzyOz
you'd have to smoke alot ( hundreds of pounds ); or inject Synthesized THC

Alot of THC ( suprisingly ) is burnt when you smoke a bowl; or smoke a joint

that's why vaporizers realease 4x as much thc, it does damage the THC...
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.
-MAPS/CaNORML vaporizer and waterpipe studies

CBN is an inactive cannabinoid.