Berlin I, et al. - Researchers compared exclusive electronic cigarettes (EC) users and dual users regarding their estimated nicotine intake and e-cigarette use characteristics. They conducted a web-based anonymous cross-sectional survey among 3,189 adults who were current users of EC. Exclusive EC use was reported by 2,836 respondents and dual-use was reported by 353 respondents. Overall, dual e-cigarette users vs exclusive e-cigarette users may report higher nicotine intake, however, their e-cigarettes contributed to less nicotine intake.