Chemical characterization and health risks associated with e-cigarettes: A comprehensive review

The evolution of the cigarette industry took us from traditional to electronic cigarettes (e-cigs). These are electronic devices that produce nicotine-containing aerosols by heating a liquid (e-liquid) that contains the drug as well as other numerous compounds. Although designed to decrease the harmful effects of traditional cigarettes, little is known about the long-term health incidence of e-cigarettes. The chemical composition of e-liquids varies depending on their manufacturer, country of origin, and batches. Fundamentally, e-liquids contain glycerol, propylene glycol, water, and nicotine. However, a concerning number of toxic substances including heavy metals, nonmetals, pesticides, polycyclic aromatic hydrocarbons, volatile organic compounds, and many other molecules have been identified in them. A wide number of analytical techniques have been employed in the identification and quantitation of these chemicals in liquids as well as aerosols. This review will discuss the numerous chemical substances associated with the use of e-cigarettes, including the potential impact of these on human health. Additionally, this work will address the available analytical tools as well as promising technologies that can contribute to future toxicological characterization efforts. This review also covers some of the global regulatory policies including their challenges and loopholes.