Molecular Health Effects of Electronic Cigarettes.

Electronic cigarettes (e-cigarettes) have emerged as a prevalent substitute for conventional cigarettes, garnering perceptions of being a safer option for health. Nicotine addicts use e-cigarettes to cease smoking. These products have also become common among young people because of their taste, smell, and attractive appearance. However, accumulating experimental and clinical evidence indicates that e-cigarette use is not risk-free. The inhalation of e-cigarette aerosols exposes users and their non-using peers to a complex mixture of chemical compounds, including aldehydes, heavy metals, and flavoring agents, many of which possess pro-oxidative and pro-inflammatory properties. This review summarizes and critically analyzes current evidence on the molecular and cellular mechanisms underlying the biological effects of e-cigarette aerosols. Particular attention is given to excessive production of reactive oxygen species, mitochondrial dysfunction, DNA damage, and the activation of redox-sensitive signaling pathways, including NF-κB and NRF2. These molecular alterations may trigger acute and, with prolonged exposure, chronic oxidative stress and inflammation, which in turn can affect gene expression, protein function, and metabolic pathways. While molecular and experimental studies often demonstrate adverse biological responses to e-cigarette aerosols, the translation of these findings into long-term clinical outcomes remains an area of ongoing investigation.