Tobacco-use behavior and toxicant exposure among current dual users of electronic cigarettes and tobacco cigarettes.

Electronic cigarette (e-cigarette) use continues to grow with most users reporting concurrent cigarette smoking, but few studies have focused on tobacco use and toxicant exposure among naturalistic dual-using populations. This controlled clinical laboratory study examined how dual versus exclusive use of e-cigarettes and cigarettes and no tobacco/nicotine affected behavioral, physiological, and subjective measures among current dual users. Twenty-two participants identifying as cigarette (≥ 10 cigarettes per day [CPD]) and e-cigarette (≥ 3 days/week) users of "cig-a-like" e-cigarettes completed four 5-day outpatient conditions, which differed by their own brand of products used ad libitum: (a) cigarette and e-cigarette (dual), (b) cigarette-only, (c) e-cigarette-only, and (d) no tobacco/nicotine. Primary outcomes included daily tobacco use, expired air carbon monoxide (CO), and urinary cotinine and NNAL. Linear mixed models with pairwise comparisons (Bonferroni corrected) were performed (p < .05). CPD did not differ significantly between dual and cigarette-only use, but e-cigarette use and liquid consumed increased significantly during e-cigarette-only relative to dual use. Relative to dual use, expired air CO did not differ during cigarette-only and was significantly lower during e-cigarette-only use. Urinary cotinine was significantly lower during e-cigarette-only use relative to dual and cigarette-only use, while urinary NNAL did not differ between the nicotine-containing conditions. In summary, among current dual users, e-cigarettes in combination with cigarettes did not reduce CPD relative to exclusive cigarette use or toxicant exposure relative to exclusive use of either product. However, exclusive e-cigarette use did reduce CO and cotinine, highlighting the benefits of cigarette cessation. (PsycInfo Database Record (c) 2020 APA, all rights reserved).