DISCUSSION In comparison to cigarette smoke, the total yield of phenolic compounds quantified for the first time in the waterpipe smoke was at least 3 times higher than that in mainstream cigarette smoke. Variations in phenols amount between different waterpipe smoking sessions (28 < % Relative Standard Deviation < 61; Table 2) are attributed to differences in www.selleckchem.com/products/Romidepsin-FK228.html smoke production that result from natural variations in charcoal briquette burning rates, and hand-packing of the tobacco mixture in the waterpipe head. These variations are also apparent in the amounts of total particulate matter produced per session (Table 1). Furthermore, knowing that more additives and flavors are added to the ma��assel tobacco in waterpipe than cigarettes, it is expected that additives such as sugars, cellulose, and polysaccharides present at such high quantities can lead to an increase in the toxicity of the waterpipe smoke.

Toxicity could be ascribed to increase in the total particulate matter concentrations as well as the formation of more additive-related pyrolysis or combustion harmful products (i.e., formaldehyde) (Baker et al., 2004; Wertz, Kyriss, Paranjape, & Glantz, 2011; Xiaomin et al., 2012). It is also noteworthy that though phenols are highly polar and soluble in water (high Henry��s constants) (Feigenbrugel, Le Calv��, Mirabel, & Louis, 2004), and susceptible to be trapped in the water bubbler, they are apparently present in high enough quantities that there is still a lot left in the smoke reaching the mouthpiece.

Therefore, the reported yields of phenols and their derivatives represent the lower limits of their actual values in the waterpipe smoke. If reported phenol emissions are normalized by the volume of smoke inhaled or Total Particulate Matter (TPM) produced, cigarette smoke appears more toxic than waterpipe smoke. In terms of physiological/clinical relevance vis-��-vis the human body��s toxicant clearance mechanisms, however, an equally important measure could be the intake of phenols per hour of smoking, in which case the waterpipe smoking involves higher hourly phenol intake than cigarette smoking. After considering the various parameters that could be reported, phenol emissions per unit smoked would be the most relevant to the community. Those in need of toxicant concentrations per milliliter smoke or per milligram TPM can derive such values from the presented data.

CONCLUSION When heated or burned, tobacco ingredients such as cellulose, polyphenols, chlorogenic acid, and quercetin dehydrate generate phenols and their derivatives. In waterpipe smoking, the relatively low temperature of the burning tobacco mixture favors production and survival of phenol compounds; in this study we observed high yields Batimastat of hydroquinone, catechol, and methyl derivatives of catechol.