Co-occurring Change in Electronic Nicotine Delivery System (ENDS) and Cigarette Harm Perceptions and Use in Young Adults.

Introduction: Use of electronic nicotine delivery systems (ENDS) may contribute to cigarette use and nicotine addiction by shifting perceptions and norms around tobacco, but little is known about whether or how ENDS use and norms are related to cigarette use and norms, particularly among young adults. This study tested two potential mechanisms by which END use may facilitate cigarette use: decreasing tobacco harm perceptions (desensitization) and increasing favorability of tobacco use (renormalization).

Method: Analyses included data from 2187 young adults in a longitudinal panel who reported any ENDS or combustible cigarette use at ages 21, 23, or 26. The sample was 53.6% male, 19.3% Hispanic, and 68.0% white. Parallel process latent growth models were fitted to test how change in ENDS use and harm perceptions about ENDS use co-occurred with change in cigarette use and harm perceptions about cigarette use across a 6-year period from ages 21, 23, and 26 (years 2014-2019).

Results: When ENDS harm perceptions decreased and ENDS use increased, cigarette harm perceptions decreased and favorability of cigarettes increased. Decreases in ENDS harm perception were differentially associated with likelihood of transition to cigarette use (an increase) and frequency of use when it occurred (a decrease).

Conclusions: Changing tobacco harm perceptions and favorability are two processes by which ENDS use may underlie transitions to cigarette use. Tobacco prevention messaging should emphasize the potential harms of ENDS use that could occur through shifting tobacco perceptions, especially among young adults who are not already frequent cigarette smokers.

Implications: Increasing favorability of ENDS (and increased ENDS use) may generalize to combustible cigarettes. Continued use of ENDS can increase risk of cigarette use when this exposure desensitizes nonsmoking young adults from the dangers of smoking and renormalizes pro-tobacco attitudes. Findings suggest that prevention messaging around tobacco products should emphasize the potential harms of ENDS use (including the increased likelihood of cigarette use after initiating ENDS), especially among young adults who are not already frequent cigarette smokers.