Nicotine in E-cigarette smoke: cancer culprit?

Tobacco smoke's harmful effects are well-known; the harmful effects of tobacco smoke have been well-investigated. Nicotine in tobacco smoke contributes to the pathogenesis of various conditions, such as lung cancer, coronary artery disease and asthma. A decade ago, a seemingly safer alternative to tobacco cigarettes was introduced- the E-cigarette. However, studies have found that E-cigarette smoke (ECS) not only induces DNA damage but also reduces DNA repair activity via BER and NER pathways. Further research conducted with cells damaged by Ultra-Violet (UV) light or hydrogen peroxide (H2O2) indicates that ECS can function as a comutagen; nicotine can amplify mutagenic activity by merging with other mutagens. The downstream metabolites derived from nicotine found in ECS put E-cigarette smokers at a higher risk for developing lung or bladder cancers or heart disease than their non-smoking counterparts. Overall, these findings are instrumental in our understanding of the harmful effects of ECS.