Assessing the Effect of Nicotine Reduction on ENDS User's Addiction and Exposures

The use of electronic nicotine delivery systems (ENDS or e-cigarettes) has reached epidemic levels among young people in the United States (US). ENDS emit toxic substances, including nicotine that irreversibly affects the developing brain and leads to dependence and increased risk of cigarette smoking initiation. Evidence indicates that young people using ENDS are likely to accelerate use and become nicotine dependent. Some of the most popular ENDS among youth (e.g. JUUL with 5% nicotine liquid) deliver in one cartridge a nicotine dose equal to an entire pack of cigarettes, and many users are unaware of this substantial exposure and the related risk of addiction. On the other hand, nicotine reduction (NR) has been considered by the US Food and Drug Administration (FDA) as an important strategy to limit the addictiveness and use of tobacco products. Now that the FDA regulates ENDS under the "deeming rule", such a strategy can be considered for these emerging tobacco products. However, the investigators still lack evidence on the expected effects of a range of NR levels on ENDS users at different stages of use trajectory. Using clinical and analytical lab methods, the investigators plan to compare among 5% nicotine ENDS users the effect of partial (3%) or total (nicotine-free, 0%) NR on users' dependence, satisfaction, clinical (e.g. BP, oximetry, lung functions, symptoms), puffing behavior, and exposure to toxicants. The investigators will recruit current ENDS users (n=120; 21-35 yrs), for a 2X2 within subject crossover lab study. The nicotine conditions (5%, 3%) or (0%,5%) x 2 times (pre-post) are the within-subject factors. Therefore, the study is divided into 2 parts, whereby the first part will be 2x2 comparing NJOY 5% and 3% to test the effects of partial nicotine reduction, and the second part will be using the NIDA Standardized Research Electronic Cigarette (SREC) for Clinical Research 5% and 0% (placebo), to test the effect of the total reduction using the same pods and juices from the same manufacturer. The investigators hypothesize that NR will be associated with less satisfaction, withdrawal suppression, and intention to use and that such an effect will be more pronounced in total compared to partial NR and among high compared to low-dependency users. The proposed studies aim to answer 3 main regulatory questions: 1) is NR a promising regulatory option to reduce ENDS addictiveness and use; 2) what is the effect of partial vs. total NR on compensatory puffing and exposure to nicotine and respiratory toxicants, and 3) what is the effect of NR on ENDS users at different stages of their use. Combined, these studies will give direct and standardized evidence on the potential of NR regulations to limit the addictiveness and use of ENDS, and to help predict any potential side effects of NR on ENDS users' exposure to harmful toxicants.