Comparison of effects of charcoal versus electric heating of waterpipe tobacco on carbon monoxide levels: Cardiovascular measures; benzene, pyrene, and nicotine uptake; and subjective reactions.

Toxicants are released from charcoal burned to heat waterpipe tobacco (WPT) and from WPT itself. This natural home setting trial tested a strategy to reduce harm of WPT use by comparing the effects of charcoal versus electric heating of WPT on outcome measures of toxicity. Fifty WPT smokers and 25 non-smokers (controls) participated. Within-subjects measures were collected in charcoal heated and in electric heated WPT smoking sessions. Pre-to-post differences in levels of ambient carbon monoxide (CO), exhaled CO, and heart rate were significantly lower when WPT was electrically heated; there were no differences for urinary biomarkers of nicotine, benzene and pyrene uptake. Comparing levels of controls to post smoking levels of urinary biomarkers of exposure to WPT indicated that electric heating of WPT versus charcoal heating did not significantly reduce exposure to the addictive drug nicotine or the toxicant pyrene, but did significantly reduce exposure to the carcinogenic compound benzene. Furthermore, we found visual evidence of charred WPT from electric sessions, suggesting excessively heated WPT. Participants reported smoking electric-heated WPT was less appealing; harsher and hurt their throat; but healthier and cleaner. To prevent negative subjective reactions from smokers and potential adverse health effects, electric heating devices should be regulated to prevent overheating and excessive thermal degradation of WPT. The findings also inform a harm reduction strategy, particularly for children living in homes of WPT smokers: smokers who use burning charcoal to heat WPT should avoid smoking indoors, as ambient CO levels proved significantly higher indoors than outdoors.