Toxic compounds from heated e cigarette fluids can damage lung cells Strongest evidence yet that vaping likely causes cancer The impact of tobacco smoking and electronic cigarette vaping on salivary biomarkers. A comparative study ScienceDirect E Cigarette and Endothelial FunctionA Critical Review of Preclinical Studies Chemical Research in Toxicology Transcriptomic responses in the blood and sputum of cigarette smokers compared to e cigarette vapers Respiratory Research Springer Nature Link