The effects of electronic cigarette vapour on the lung: direct comparison to tobacco smoke

Abstract

Electronic cigarette (e-cigarette) usage in the USA has drastically increased in the past 5 years due to age restrictions on conventional cigarettes, aggressive marketing and a perception that e-cigarettes are a healthy alternative. E-cigarettes contain nicotine, water, glycerol, propylene glycol and optional flavouring. On inhalation, the device heats the ingredients into a vapour [1]. While tobacco cigarette smoke is known to cause deleterious effects on the cardiovascular system, angiogenesis and skin capillary perfusion by causing direct injury to blood vessel walls, increased platelet aggregation, microvascular thrombosis [2-4] and inflammation [5], the consequences of e-cigarette vapour exposure on the lung are still largely unexplored [6, 7]. Recently, LERNER et al. [8] reported that vapours produced by e-cigarettes and e-cigarette fluids with flavourings induced toxicity, oxidative stress and inflammatory response in human bronchial airway epithelial cells (H292) and fetal lung fibroblasts (HFL1) as well as mouse lung. GARCIA-ARCOS et al. [9] showed that the aerosolised nicotine-containing e-cigarette fluid increased airway hyperreactivity, distal airspace enlargement, mucin production, and cytokine and protease expression in mice, implying potential dangers of nicotine inhalation during e-cigarette use. The inflammatory response to e-cigarette use involved increased neutrophil activation and mucus production [10], and decreased mucociliary clearance [11]. In human embryonic and mouse neural stem cells, human pulmonary fibroblasts [12], and skin and lung cells [13], cytotoxicity of e-cigarette vapour was correlated with the number and concentration of chemicals used to flavour the fluids. We recently showed in the skin flap survival model in vivo that nicotine-containing e-cigarette vapour is just as harmful to the microcirculation as tobacco cigarette smoke [4]. In the present study, we examined whether long-term exposure to e-cigarette vapour or nicotine produce the same damaging effect on lung structure and vasculature as tobacco smoke in a rat model in vivo. 6-week-old, male Sprague Dawley rats (Envigo Laboratories, Denver, CO, USA) were divided into four groups of eight animals per group and exposed for 5 weeks as follows. 1) Room air. 2) Subcutaneous injections of (−)-nicotine ditartrate (Sigma Aldrich, St Louis, MO, USA) 2 mg•kg −1 twice daily; the amount of nicotine for injections was based on that known from previous studies to produce stable plasma nicotine levels of approximately 25 ng•mL −1 , which is compatible with plasma levels in habitual smokers [14, 15]. 3) Blu E-cigs (Classic Tobacco Flavour (Blu, Charlotte, NC, USA), containing 12 mg•mL −1 nicotine) vapour produced in a TE-2E e-cigarette smoking machine (Teague Enterprises, Davis, CA, USA); the coil temperature of the e-cigarettes was within the normal range usually used by vapers (200-250°C). Rats in this group were exposed to 48 mg nicotine per day [4]. Our experimental design, by subjecting rats to e-cigarette vapour, is a major imp...

What are the respiratory effects of e-cigarettes?

“…Thus, vaping in mice leads to rapid changes at the cell and protein levels. Of greater concern, five to 16 weeks of e-cigarette exposure induced alveolar cell apoptosis and architectural simplification suggestive of emphysema,96106 although results have not been consistent 90107. Finally, although e-cigarettes have been widely promoted as having a negligible risk of malignancy compared with smoked tobacco, exposure to e-cigarette aerosol has recently been associated with DNA damage, thought to occur via in situ metabolism of nicotine to nitrosamines 91…”

Association Between Youth Smoking, Electronic Cigarette Use, and COVID-19

“…There are a number of potential reasons why both dual use and e-cigarette use were associated with getting infected with COVID-19. Heightened exposure to nicotine and other chemicals in e-cigarettes adversely affects lung function [14], with studies showing that lung damage caused by e-cigarettes is comparable to combustible cigarettes [4,15,16]. COVID-19 spreads through repeated touching of one's hands to the mouth and face, which is common among cigarette and e-cigarette users [17].…”

A Summary of In Vitro and In Vivo Studies Evaluating the Impact of E-Cigarette Exposure on Living Organisms and the Environment

“…Interestingly, the results of the in vitro cell transformation assays, useful in assessing the carcinogenic activity of particular chemicals and complex mixtures, suggest that e-cigarettes are a better alternative to traditional cigarettes [202], the compounds in the aerosol may potentiate the genotoxic effects of tobacco carcinogens when used simultaneously with conventional smoke [203]. One such study conducted on rats demonstrates that e-cigarette exposure has a detrimental effect on pulmonary structures comparable to tobacco smoke [204].…”