E Cigarettes and Vaping OHSU E cigarettes Found to Cause Change in Mouth Bacteria Which Could Lead to Gum Disease or Oral Cancer Respiratory Therapy Scientists Warn: Vaping Likely Causes Cancer Many students believe that vaping harmless, which is far from the truth. Vape pens can contain potentially harmful substances such as chemicals linked to lung disease, cancer causing chemicals, heavy metals such as Understanding Vaping and Lung Cancer: Risks and Insights