Flavorings in Electronic Cigarettes An Unrecognized Respiratory Health Hazard? Use of electronic cigarettes (e-cigarettes), vape

nicotine delivery systems (ENDS) has increased rap-idly since their introduction in the United States in 2007, growing to a $2 billion market.1 There is contro-versy concerning the utility of ENDS as a harm reduc-tion strategy, reflecting major gaps in the emerging evidence on potential benefits and harms of the products.2-4 Although exclusive use of ENDS is gener-ally considered to be less risky for individuals than smoking combustible tobacco products, there is con-cern that their availability may both lead to dual prod-uct use (ie, ENDS and cigarettes) and reduce cessa-tion. Additionally, there is concern that ENDS may be used by nonsmoking adolescents and young adults who might not otherwise have used nicotine-delivering products, and that dual use may follow