Chemical research in toxicology
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Chem. Res. Toxicol. · Nov 2001
ReviewA consideration of the role of gas/particle partitioning in the deposition of nicotine and other tobacco smoke compounds in the respiratory tract.
Tobacco smoke is an aerosol that contains both gaseous and suspended particulate material (PM). The particles are largely liquid droplets containing a wide variety of condensed organic compounds. Each compound in the smoke will partition between the gas and PM phases and will always seek a state of gas/particle equilibrium. ⋯ This conclusion is consistent with (1) the gas-sampling denuder results obtained by Philip Morris in which significant tobacco smoke nicotine was observed to deposit in acid-coated denuder tubes, with more depositing when the cigarette tobacco blend was treated with ammonia; (2) the view that the sensory "impact" exhibited by some tobacco smokes is caused by the deposition of gaseous nicotine in the pharynx; (3) the observed throat irritation caused by nicotine inhalers; and (4) the high overall respiratory tract deposition efficiencies for nicotine of 0.9 and greater that have been reported for some cigarette smokes. The available information combines to create a picture of nicotine in cigarette smoke that contradicts the traditional view that cigarette smoke PM is typically acidic, with little free-base nicotine typically present in the smoke PM phase. Government agencies interested in establishing a framework for the testing and monitoring of nicotine delivery may wish to consider requiring the measurement and publication of the PM-phase alpha(fb) values for the cigars and cigarettes marketed in their jurisdictions.