Emerging multisystem disease mechanisms of e-cigarette vaping on human health

Electronic cigarettes (e-cigarettes) have quickly grown from a niche smoking cessation design to a ubiquitous nicotine-delivery device, causing ever-growing debate concerning their safety and long-term health outcomes. This review critically summarizes the available evidence from current literature on the development of e-cigarette technologies, nicotine pharmacodynamics, and systemic biological effects, especially pulmonary, cardiovascular, and neurological outcomes. Although noncombustible, e-cigarette aerosols contain hazardous compounds such as nicotine, metallic particulates, and aldehyde-reactive species, which can interact with the endothelial surfaces, immune effector cells, and neuronal networks, leading to oxidative stress, inflammation, and tissue remodeling. Clinical and preclinical evidence shows that e-cigarette vaping is linked to acute and chronic pulmonary injury, endothelial dysfunction, suppressed neurodevelopment, and behavioral dysregulation in adolescents. Additionally, the so-called nicotine-free and flavored products often contain unreported toxicants and do not have standardized safety tests. The consumption trends among young people and the vulnerable have been on the increase due to unsubstantiated assumptions about its controversial harm-reduction effects and overly zealous advertising campaigns. This review will also discuss controversial issues of the harm-reduction paradigm, gaps in regulatory control, and future research areas, such as longitudinal cohort studies. An evidence-based, multidisciplinary framework is firmly needed to guide innovation, policy, and clinical practice and, as such, make sure that responses to public health are aligned with sound scientific knowledge.