Frontiers Regulation of immune checkpoints by electronic cigarette The rise of teen vaping is worrying doctors worldwide. While e cigarettes were once marketed as a safer alternative, research shows they contain nicotine, heavy metals, and cancer causing chemicals that can damage developing Generic vapes, e cigarettes. Concept background for concern over health, cancer, plastic use, environment, habit, youth, smoking, vaping. Refillable Stock Photo Alamy Genetic evidence that e cigarettes increase cancer (and other disease) risk among young adults Stanton Glantz blog