Propylene glycol, a component of electronic cigarette liquid, damages epithelial cells in human small airways Respiratory Research Springer Nature Link Thirdhand Vapor from E cigarettes Damages the Lungs of Mice Thirdhand Smoke Resource Center Although research on cancer risks associated with vaping is still limited, a 2025 systematic review found substantial evidence that e cigarette exposure is associated with biomarkers reflective of cancer disease risk. This includes Former Smokers Who Vape at Greater Risk of Lung Cancer RT Can vaping cause cancer? The evidence suggests it might. The Washington Post Test Kit: Propylene Glycol in Indoor Air as an Indicator of Vaping LCS Laboratory Inc.