Introduction to the Special Issue on JUUL Use.

This special issue addresses key topics relating to the public health impact of the use of electronic nicotine delivery devices (ENDS), particularly JUUL-brand ENDS. Smokers smoke for nicotine, but are harmed by the byproducts of combustion. ENDS can play a role in tobacco harm reduction offering a noncombustible alternative source of nicotine for adult smokers who would otherwise continue smoking. Papers presented here estimate the prevalence of ENDS and JUUL use among young and older adults, and document the 12-month smoking trajectories of adults who purchased a JUUL Starter Kit. Overall, smoking prevalence was halved, with most smokers switching completely as dual use declined. This held for subpopulations defined by demographics and psychiatric comorbidity. For those who did not switch, most significantly reduced (50%+) their cigarette consumption. Another study reports that dependence declines as smokers switch from smoking to using JUUL. The public health potential of ENDS is undermined by use of ENDS by nonsmokers, especially underage individuals. Some smoking was reported by adult former and never smokers, with little evidence of persistent smoking, and lower risk of smoking among those using JUUL more frequently. Regarding underage use, one paper reports that technology can ensure age-verification at point of sale. Population modeling integrating impacts on diverse populations indicates that availability of ENDS is expected to avert millions of premature deaths in the US. We believe these papers make a substantial contribution to the field of tobacco science and smoking control.