Young Blonde Girl With A Water Pipe Bong Wearing A Red Necklace On The Old Fashioned Couch

However, a 2000 NORML-MAPS cannabis study found that "water pipes filter out more psychoactive THC than they do other tars, thereby requiring users to smoke more to reach their desired effect". In the study, smoke from cannabis supplied by the NIDA was drawn through a number of smoking devices and analyzed. This study looked at the tar to cannabinoid ratio in the gas outputted by various bongs, as well as unfiltered and filtered joints, and vaporizers. The results showed that only vaporizers produced a better tar to cannabinoid ratio than unfiltered joints, but that within the cannabinoids produced, even vaporizers warped the ratio of THC (the psychoactive component of the smoke) to CBN (capable of producing medical benefits but is not psychoactive) in favor of CBN. This showed an unfiltered joint had the best tar to THC ratio of all, and bongs were actually seriously detrimental in this respect.
MAPS also reviewed a study that examined the effects and composition of water-filtered and non-filtered cannabis and tobacco smoke. It found that when alveolar macrophages were exposed to unfiltered smoke, their ability to fight bacteria was reduced, unlike exposure to water-filtered smoke. It also found substantial epidemiological evidence of a lower incidence of carcinoma among tobacco smokers who used water-pipes, as opposed to cigarettes, cigars, and regular pipes. "It appears that water filtration can be effective in removing components from cannabis smoke that are known toxicants... The effectiveness of toxicant removal is related to the smoke's water contact area."
Specially designed water pipes, incorporating particulate filters and gas-dispersion frits, would likely be most effective in this regard; the gas-dispersion frit serves to break up the smoke into very fine bubbles, thereby increasing its water-contact area." These frits are commonly referred to as "diffusers" for the way that they diffuse (or disperse) the smoke as it exits the downstem, and usually consist of small holes or slats at the end of the downstem. This study suggests that a bong's smoke is less harmful than unfiltered smoke.