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

Abstract

Worldwide use of electronic cigarettes has been rapidly expanding over recent years, but the long-term effect of e-cigarette vapor exposure on human health and environment is not well established; however, its mechanism of action entails the production of reactive oxygen species and trace metals, and the exacerbation of inflammation, which are associated with potential cytotoxicity and genotoxicity. The present study examines the effects of selected liquid chemicals used in e-cigarettes, such as propylene glycol/vegetable glycerin, nicotine and flavorings, on living organisms; the data collected indicates that exposure to e-cigarette liquid has potentially detrimental effects on cells in vitro, and on animals and humans in vivo. While e-liquid exposure can adversely influence the physiology of living organisms, vaping is recommended as an alternative for tobacco smoking. The study also compares the impact of e-cigarette liquid exposure and traditional cigarette smoke on organisms and the environmental impact. The environmental influence of e-cigarette use is closely connected with the emission of airborne particulate matter, suggesting the possibility of passive smoking. The obtained data provides an insight into the impact of nicotine delivery systems on living organisms and the environment.

Addressing the challenges of E-cigarette safety profiling by assessment of pulmonary toxicological response in bronchial and alveolar mucosa models

“…While assessing and comparing the effects of E-smoke in our study with those reported in other studies, it is important to consider the exposure methods and cell lines used. In many cases, normal bronchial epithelial cells in ALI have been used but the ECIG liquid or E-smoke extract has been added in the basal medium in contrast to the E-smoke exposure in our study and in real life 16,59 . While taking into account of the nicotine concentration, majority of the studies 16,59 used nicotine concentrations between 12 and 36 mg/mL, as compared to 3 mg/mL used in this study (relevant for Sweden and European Union).…”

“…In many cases, normal bronchial epithelial cells in ALI have been used but the ECIG liquid or E-smoke extract has been added in the basal medium in contrast to the E-smoke exposure in our study and in real life 16,59 . While taking into account of the nicotine concentration, majority of the studies 16,59 used nicotine concentrations between 12 and 36 mg/mL, as compared to 3 mg/mL used in this study (relevant for Sweden and European Union). Increased proinflammatory cytokine secretion (such as IL6, CXCL8), reduced cell viability, increased oxidative stress, morphologic alteration of secretory functions, and alteration of barrier function on exposure to both high doses of non-nicotinized and nicotinized ECIG-liquid have been reported 16,59,60 .…”

“…While taking into account of the nicotine concentration, majority of the studies 16,59 used nicotine concentrations between 12 and 36 mg/mL, as compared to 3 mg/mL used in this study (relevant for Sweden and European Union). Increased proinflammatory cytokine secretion (such as IL6, CXCL8), reduced cell viability, increased oxidative stress, morphologic alteration of secretory functions, and alteration of barrier function on exposure to both high doses of non-nicotinized and nicotinized ECIG-liquid have been reported 16,59,60 . Ween et al 61 (2017) reported decreased TNF-α, IL6, and other pro-inflammatory cytokine levels on exposure to both +NIC (18 mg/mL) and −NIC apple flavored ECIG-liquids using THP-1 macrophages.…”

How effective are electronic cigarettes for reducing respiratory and cardiovascular risk in smokers? A systematic review

“…Overall, laboratory studies have demonstrated that aerosols emitted from e-cigarettes contain fewer amounts and lower concentrations of toxicants than combustible cigarettes [ 16 – 19 ]. In vitro studies and in vivo animal models also suggest lower toxicity of e-cigarette compared to combustible cigarettes [ 20 – 26 ]. While laboratory studies provide important insights into relative toxicity of e-cigarettes compared to combustible cigarettes, human studies provide further evidence of how the reduced toxicity of e-cigarettes correlates with a potential reduction of health risk among smokers who transitioned from smoking to vaping.…”

The effect of E-liquid exposure on Caenorhabditis elegans

“…Initial studies were largely epidemiological to examine the take-up of this habit and dependency in vulnerable and young people [25]. Now there is a growing body of evidence outlining potential harmful effects on inhaling E-liquid vapours [26].…”