How bad are e‐cigarettes? What can we learn from animal exposure models?

Abstract

Electronic cigarettes divide opinions. Some consider them key to reducing smoking incidence while others are concerned over potential for detrimental health consequences. It will take many years to identify the health consequences of e-cigarette use if we rely only upon human data. However, there is a growing body of work using rodent models that inform on these potential toxicities. These studies have focused upon the pulmonary, cardiovascular and central nervous systems. Observations include perturbations of pro-inflammatory, pro-fibrotic and oxidative stress markers, sometimes together with DNA damage and downregulation of DNA repair and antioxidant enzymes. However, the markers affected are often different between studies. A more consistent observation has been the increase in airway hyperresponsiveness, a characteristic of asthma, on exposure to electronic cigarettes, across mouse strains, sex and ages. Detrimental effects in this and other susceptible animal models such as the apolipoprotein E knockout mouse model of atherosclerosis, suggest greater risk where there is an existing predisposition. Other adverse reactions, including weight loss, oxidative stress and angiogenesis, are reported in animal studies with nicotine-containing devices. These effects remain less severe than cigarette smoke, where investigated. Animal studies have identified therefore that e-cigarettes are potentially hazardous,

Electronic Cigarettes and Asthma: What Do We Know So Far?

“…This means that EC users vaping VG-based flavored liquids at higher power output settings may be at increased risk for − OH exposures and related health consequences, such as asthma [ 33 ]. Apart from oxidative stress agents, EC has been shown to promote disorders in pro-inflammatory and pro-fibrotic markers, DNA damage and dysfunction of DNA repair and antioxidant enzymes, which participate in lung disease pathogenesis, such as asthma [ 34 ]. Long non-coding RNAs (lncRNAs), which are involved in cell proliferation and differentiation, intracellular communication, and steroid metabolism in lung pathologies, including asthma, have also been found altered after exposure to EC vapor [ 35 ].…”

“…Furthermore, patients who recovered from electronic vapor acute lung injury (EVALI), a condition more commonly observed in asthmatic patients, exhibited chronic irreversible airflow obstruction, markedly abnormal 129 Xe MRI ventilation heterogeneity, abnormal lung clearance index and oscillometry measures and decreased diffusing capacity of the lung for carbon monoxide (DLCO), all persistent after their discharge [ 48 , 49 ]. Studies in animals with allergen-induced airway disease demonstrated not only increased airway hyperresponsiveness after EC vapor inhalation, but also increase in mucus and airway wall thickening which are hallmark features of allergic asthma [ 34 , 39 , 50 , 51 ].…”

Vaping in Asthmatic Adolescents: Time to Deal with the Elephant in the Room

“…This is associated with an increase in mucus production and airway wall thickening. Th2-type inflammation has been confirmed by the detection of increased Th2 cytokine production, such as IL-4, IL-5, and IL-13, along with the presence of allergen-specific Inge [38][39][40][41].…”

Impact of Electronic Cigarette Exposure on the Testes of Adult Male Albino Rat and the Role of Cessation: Histopathological and Biochemical study

“…There is an increasing tendency of inducing these possible toxicities in experimental animals, particularly rodents, resulting in a balanced assessment of both the value and limitations of E-cigs. Animal studies have demonstrated that E-cigs are potentially harmful but still less severe than cigarette smoke [10]. However, these hazards involve many body systems including the pulmonary [11], cardiovascular [12], hepatic and metabolic [13], and central nervous systems [14].…”