Introduction
The increasing popularity of electronic cigarettes (e-cigarettes) as an alternative to regular cigarettes continues to generate much controversy. This is partly because of the mixed evidence of its efficacy and safety as an effective aid for smoking cessation (Bullen et al., 2013; Huang et al., 2016; Majeed et al., 2017). Prior studies have found potential toxicants in e-cigarette liquids and vapor (Glasser et al., 2017). The use of e-cigarettes may also produce mild adverse reactions such as mouth and throat irritation (Caponnetto et al., 2012; Polosa et al., 2014). The World Health Organization (WHO) Framework Convention on Tobacco Control...