Nicotine Exposure by Device Type among Adult Electronic Nicotine Delivery System Users in the Population Assessment of Tobacco and Health Study, 2015-2016.

Background: Previous studies have examined the characteristics of open and closed system electronic nicotine delivery system (ENDS) users, but population-level information on nicotine exposure among these users has not been available. Methods: We analyzed nicotine biomarker and survey data from Wave 3 of the Population Assessment of Tobacco and Health (PATH) study collected from October 2015 to October 2016. We identified 277 exclusive ENDS users and 468 dual cigarette and ENDS users and analyzed concentrations of nicotine and its metabolites obtained from urine samples by device type and other characteristics, such as frequency of use and e-liquid flavor. Results: Among exclusive ENDS users, open system users had higher levels of total nicotine exposure (TNE-2) than closed system users [8.8 mmol/g creatinine (95% confidence interval [CI] = 5.3-14.8 mu mol/g vs. 2.0 mu mol/g (95% CI = 0.7-5.4 mu mol/g)]. However, TNE-2 concentrations were similar when open and closed system users were stratified as daily [26.4 mu mol/g (95% CI = 20.1-34.7 mu mol/g) vs. 27.1 mu mol/g (95% CI = 16.4-44.9 mu mol/g)] and nondaily [0.5 mu mol/g (95% CI = 0.1-1.9 mu mol/g) vs. 0.2 mu mol/g (95% CI = 0.0-0.7 mu mol/g)] ENDS users. Dual users generally had higher nicotine exposure than exclusive users. Conclusions: Nicotine exposure was observed to be higher among exclusive open system ENDS users compared with closed system users, but levels were similar when users were stratified by frequency of use. Impact: These results suggest that exclusive ENDS users with similar use patterns receive comparable levels of nicotine, regardless of whether they use open or closed system devices.