A Review of Pulmonary Toxicity of Electronic Cigarettes in the Context of Smoking: A Focus on Inflammation

Abstract

The use of electronic cigarettes (e-cigs) is increasing rapidly, but their effects on lung toxicity are largely unknown. Smoking is a well-established cause of lung cancer and respiratory disease, in part through inflammation. It is plausible that e-cig use might affect similar inflammatory pathways. E-cigs are used by some smokers as an aid for quitting or smoking reduction, and by never smokers (e.g., adolescents and young adults). The relative effects for impacting disease risk may differ for these groups. Cell culture and experimental animal data indicate that e-cigs have the potential for inducing inflammation, albeit much less than smoking. Human studies show that e-cig use in smokers is associated with substantial reductions in blood or urinary biomarkers of tobacco toxicants when completely switching and somewhat for dual use. However, the extent to which these biomarkers are surrogates for potential lung toxicity remains unclear. The FDA now has regulatory authority over e-cigs and can regulate product and e-liquid design features such as nicotine content and delivery, voltage, e-liquid formulations, and flavors. All of these factors may impact pulmonary toxicity. This review summarizes current data on pulmonary inflammation related to both smoking and e-cig use, with a focus on human lung biomarkers.

Organizing pneumonia related to electronic cigarette use: A case report and review of literature

“…5,6 Another study found increase in inflammatory signalling molecules upon inhalation, in resemblance to what is seen in tobacco smoking. 9 Clinical studies evaluating the safety and risk profile of e cigarette use in humans are limited and most the current data is obtained from in vitro studies on cultured cells and in vivo experiments in animal models. The short-term in-vitro studies using cultured cells have shown that exposure to e liquid or aerosols reduces cell viability, induces cytokine production and causes oxidative stress.…”

Knowledge and attitudes towards E-cigarette use in Lebanon and their associated factors

“…In addition, it has been established that EL contains carcinogenic metals such as cadmium, chromium, nickel, lead, and manganese [15]. Flavorings in the EL, intended to appeal to consumers, also contain lung toxins like diacetyl and diketones [16]; the former of which is associated with bronchiolitis obliterans, commonly known as popcorn lung disease [17]. Toxicity is marked in all flavorings.…”

Update on the Risks of Electronic Cigarettes—Vaping

“…ECs are not entirely free of these compounds and may also contain propylene glycol, glycerol, liquid flavors, heavy metals, nicotine, and volatile organic compounds (VOCs). 6,7 Formaldehyde, a product of propylene glycol and glycerol vapor degradation, is a cancer-causing substance that may form if the EC liquid overheats or not enough liquid reaches the heating element (known as a dry puff). Formaldehyde can cause an increase in airway inflammatory markers up to 10 times more than traditional cigarettes.…”

“…Formaldehyde can cause an increase in airway inflammatory markers up to 10 times more than traditional cigarettes. 6 ECs aerosolize nicotine, and concentrations are typically between 6 to 24 mg/mL but can be as high as 100 mg/mL. 8 Online vaping and EC stores sell a variety of EC liquids, nicotine salts, and vaping liquids containing cannabidiol (CBD) and tetrahydrocannabinol (THC).…”