Nicotine & Tobacco Research

activates a heating device that aerosolizes cartridge fluid which is in turn delivered to the user (Flouris & Oikonomou, 2010; Pauly, Li, & Barry, 2007; Wollscheid & Kremzner, 2009). E-cigarette products vary in their cartridge contents and may have different humectants (e.g., propylene glycol, glycerin), flavorings, and various concentrations of nicotine. E-cigarettes are sold world-wide and are readily available over the Internet and in shopping malls in the United States. They are sometimes advertised to be safer than tobacco-containing products since they do not pro-duce the many chemicals found in mainstream and sidestream cigarette smoke (Cahn & Siegel, 2010; Laugesen, 2008). E-cigarettes, unlike nicotine replacement therapies such as patches and gum, are not regulated by the Food and Drug Administration (FDA) as medical devices, and little is known about their safety, quality control, aerosol delivery, and long-term health effects. The FDA questioned e-cigarette quality control and safety after finding: (a) low levels of carcinogens in cartridges, (b) con-centrations of nicotine in cartridges were not always consistent with labeling, and (c) diethylene glycol (a toxicant) in one car-tridge (Westenberger, 2009). In contrast, a study supported by an e-cigarette manufacturer concluded these products are safe since carcinogen levels are low and the aerosol contains fewer chemicals than tobacco-containing cigarette smoke (Laugesen, 2008). Poor labeling and packaging of e-cigarettes, leakiness of the cartridges, confusing nomenclature for nicotine concentra-tions, defective parts and safety features, errors in filling orders, insufficient warnings on packaging, incomplete instruction manuals, and misleading advertisements have also raised con-cern about their safety and usage (Trtchounian & Talbot, 2010). Three human studies found low levels of nicotine in the blood of e-cigarette users raising questions about their effectiveness as nicotine delivery devices (Bullen et al., 2010; Eissenberg, 2010