E-cigarettes have been popular since 2007 and are used by many people, including ex-smokers, smokers, and even non-smokers. This study reviewed the potential lung effects of e-cigarettes and aimed to predict long-term impacts, as there hasn’t been enough time to study long-term users. Short-term studies and laboratory models have shown that e-cigarettes can cause inflammation and reduce resistance to infections, similar to traditional cigarettes. Additionally, e-cigarettes were found to disrupt lipid processing in the body, which is unique to them. The review highlights the need for further research to fully understand the health effects of e-cigarettes and to inform regulations to mitigate potential future problems.

Abstract

Commercially available since 2007, e-cigarettes are a popular electronic delivery device of ever-growing complexity. Given their increasing use by ex-smokers, smokers and never-smokers, it is important to evaluate evidence of their potential pulmonary effects and predict effects of long-term use, since there has been insufficient time to study a chronic user cohort. It is crucial to evaluate indicators of harm seen in cigarette use, and those potentially unique to e-cigarette exposure. Evaluation must also account for the vast variation in e-cigarette devices (now including at least five generations of devices) and exposure methods used in vivo and in vitro.

Thus far, short-term use cohort studies, combined with in vivo and in vitro models, have been used to probe for the effects of e-cigarette exposure. The effects and mechanisms identified, including dysregulated inflammation and decreased pathogen resistance, show concerning overlaps with the established effects of cigarette smoke exposure. Additionally, research has identified a signature of dysregulated lipid processing, which is unique to e-cigarette exposure.

This review will evaluate the evidence of pulmonary effects of, and driving mechanisms behind, e-cigarette exposure, which have been highlighted in emerging literature, and highlight the gaps in current knowledge. Such a summary allows understanding of the ongoing debate into e-cigarette regulation, as well as prediction and potential mitigation of future problems surrounding e-cigarette use.

Authors: Lauren C Davis , Elizabeth Sapey , David R Thickett, Aaron Scott