Consciousness Cafe - Entheogens and Psychedelic Cultural Transmissions

A post on another list alerted me to this 1996 MAPS study: http://www.ukcia.org/research/pipes.htm

This study found that, per quantity of THC, vaporizers (especially the hot plate variety) did the best of delivering the best ratio of THC to tar. Second to that was the unfiltered joint. Finally, water pipes and bongs performed the worst.

Some good quotes:

In the meantime, the easiest way for most smokers to avoid harmful smoke toxins may be simply to smoke stronger marijuana.

AND

Joints and Waterpipes

Surprisingly, the unfiltered joint outperformed all devices except the vaporizers, with a ratio of about 1 part cannabinoids to 13 parts tar. This disturbingly poor ratio may be explained by the low potency of the NIDA-supplied marijuana used in the study, which was around 2.3%.

Disappointingly, waterpipes performed uniformly worse than the unfiltered joint. The least bad waterpipe, the bong, produced 30% more tar per cannabinoids than the unfiltered joint. Ironically, the pipe with the electric mixer scored by far the worst of any device. This suggests that water filtration is actually counterproductive, apparently because water tends to absorb THC more readily than noxious tars. Like the waterpipes, the cigarette filter also performed worse than the unfiltered joint, by about 30%. Researchers speculate this is because cannabinoids are exceptionally sticky and adhere to other solids. Hence, any filtration system that picks up particulates is likely also to screen out cannabinoids.