Section III: Newer/Popular Tobacco Products Aimed at Younger Smoker

E-Cigarettes: Promise or Peril?

The present study addresses the need to synthesize the findings in the current literature on e-cigarette use cessation.

PubMed, MEDLINE, and EMBASE databases were searched in November 2022 to systematically review studies focused on intentions, attempts, and successful e-cigarette use cessation. Three authors independently reviewed the full-texts of the initial pool of potentially eligible articles. Narrative data synthesis was conducted, and the risk of bias was evaluated.

A total of 12 studies were selected for review, 7 of which were experimental and 5longitudinal. The majority of the studies focused on participants' intentions to quit e-cigarette use. The experimental studies varied in sample size, intervention type, and length of participant follow-up. Findings across the experimental studies were mixed, with only one full-fledged trial having examined cessation as an outcome. The experimental studies that assessed cessation outcomes utilized mobile technology as an intervention tool. Results from longitudinal studies indicated sociodemographic characteristics (gender, race/ethnicity), vaping frequency, and cigarette smoking status as predictors of intentions, attempts and e-cigarette use cessation.

This review highlights the current paucity of methodologically rigorous research on e-cigarette use cessation. Our findings suggest that vaping cessation programs that employ mobile health technology to provide personalized cessation services may help promote intentions, attempts, and e-cigarette use cessation. Limitations of the current studies on vaping cessation include small sample sizes, heterogeneous cohorts that limit comparisons, and inconsistent ways of assessing vaping cessation. Future research needs to test long-term intervention effects using experimental and prospective designs among representative samples.

The use of electronic cigarettes (e-cigs) is rapidly increasing worldwide and is promoted as a smoking cessation tool. The impact of traditional cigs on human health has been well-defined in both animal and human studies. In contrast, little is known about the adverse effects of e-cigs exposure on human health. This review summarizes the impact of e-cigs exposure on different organ systems based on the rapidly expanding recent evidence from experimental and human studies. A number of growing studies have shown the adverse effects of e-cigs exposure on various organ systems. The summarized data in this review indicate that while e-cigs use causes less adverse effects on different organs compared to traditional cigs, its long-term exposure may lead to serious health effects. Data on short-term organ effects are limited and there is no sufficient evidence on long-term organ effects. Moreover, the adverse effects of secondhand and third hand e-cigs vapour exposure have not been thoroughly investigated in previous studies. Although some studies demonstrated e-cigs used as a smoking cessation tool, there is a lack of strong evidence to support it. While some researchers suggested e-cigs as a safer alternative to tobacco smoking, their long-term exposure health effects remain largely unknown. Therefore, more epidemiological and prospective studies including mechanistic studies are needed to address the potential adverse health effects of e-cigs to draw a firm conclusion about their safe use. A wide variation in e-cigs products and the lack of standardized testing methods are the major barriers to evaluating the existing data. Specific regulatory guidelines for both e-cigs components and the manufacturing process may be effective to protect consumer health.

It is currently understood that tobacco smoking is a major cause of pulmonary disease due to pulmonary/lung inflammation. However, due to a highly dynamic market place and an abundance of diverse products, less is known about the effects of e-cigarette (E-cig) use on the lung. In addition, varieties of E-cig liquids (e-liquids), which deliver nicotine and numerous flavor chemicals into the lungs, now number in the 1000s. Thus, a critical need exists for safety evaluations of these E-cig products.

Herein, we employed a “2-stage in vivo screening platform” (zebrafish to mouse) to assess the safety profiles of e-liquids. Using the zebrafish, we collected embryo survival data after e-liquid exposure as well as neutrophil migration data, a key hallmark for a pro-inflammatory response. Our data indicate that certain e-liquids induce an inflammatory response in our zebrafish model and that e-liquid exposure alone results in pro-inflammatory lung responses in our C57BL/6J model, data collected from lung staining and ELISA analysis, respectively, in the mouse. Thus, our platform can be used as an initial assessment to ascertain the safety profiles of e-liquid using acute inflammatory responses (zebrafish, Stage 1) as our initial metric followed by chronic studies (C57BL/6J, Stage 2).

Concerns have been raised regarding e-cigarette use as a potential stepping-stone to marijuana use. Based on Kandel’s gateway hypothesis, this study investigated if e-cigarette use could lead to marijuana use by testing two hypotheses with a longitudinal national U.S. adult sample, including (1) primary hypothesis: e-cigarette use is a gateway to marijuana use; and (2) falsification hypothesis: marijuana use is not a gateway to e-cigarette use.

Adults were extracted from the Population Assessment of Tobacco and Health Study Waves 1–3 (2013–2016). For primary hypotheses, based on baseline e-cigarette use statuses, three study groups were defined, and three logistic regressions were conducted to examine associations between baseline e-cigarette use and follow-up marijuana use initiation, reinitiation, and persistence, respectively. Similarly, for falsification hypotheses, three additional study groups were defined, and three logistic regressions were conducted to examine associations between baseline marijuana use and follow-up e-cigarette use behaviors.

Baseline e-cigarette use was associated with marijuana use initiation and reinitiation (ORs = 2.08, 1.37, respectively, both ps < .05) but not persistence at follow-up. Additionally, baseline marijuana use was associated with only e-cigarette use initiation (OR = 2.23, p < .01) but not reinitiation or persistence at follow-up.

Findings partially support the gateway hypothesis that e-cigarette use could be a steppingstone to marijuana use reinitiation among the U.S. adults. The mechanisms and behavioral characteristics, such as etiological and psychosocial factors, that may pertain to the progression from e-cigarette use to reinitiation of other substance use should be further investigated to inform effective behavioral, educational, and policy interventions.