Abstract
Background and aims: Completely substituting e-cigarettes (EC) for combustible tobacco cigarettes reduces exposure to toxicants and carcinogens. However, a large proportion of EC users (dual users) continue to smoke conventional cigarettes. This study aimed to compare estimated nicotine intake and e-cigarette use characteristics between exclusive EC users and dual users.Design: Web-based anonymous cross-sectional survey.Setting: France.Participants: A total of 3189 adults, current users of electronic cigarettes (EC). Data collection between 4 October 2014 and 11 November 2014.Measurements: Primary outcome: estimated nicotine intake per day (mg) from participants' reports.Secondary outcomes: duration, frequency of EC use and nicotine content of e-liquids used/day. Dual use was defined as using at least one cigarette per day while also using EC.Findings: A total of 2836 respondents reported exclusive EC use and 353 reported being dual users. Backward stepwise logistic regression showed that dual users had higher estimated combined daily nicotine intake from e-liquids and cigarettes [estimate: 2.14, standard error (SE) = 0.26, adjusted odds ratio (aOR) = 8.48, 95% confidence interval (CI) = 5.11-14.09, P < 0.001], but lower daily nicotine intake from EC (estimate: -2.14, SE = 0.26, aOR = 0.12, CI = 0.07-0.196, P < 0.001) and reported fewer months of EC use (estimate: -0.31, SE = 0.14, aOR = 0.73, CI = 0.56-0.95, P = 0.022) compared with exclusive EC users.Conclusion: Dual e-cigarette users in France may have higher nicotine intake overall than exclusive e-cigarette users, but they may take in less nicotine from their e-cigarettes.