Just seen on the news about some research on tobacco smokings effects on mutations of cells. It said that it caused irreversable mutation of dna in cells mostly in the lungs but some in the larynx,mouth and also a few in the bladder and liver. It spoke of a women who had given up smoking 17 years but had this year developed lung cancer due to the mutations caused in the past. This is a scary thing for us vapers who have give up smoking as all it does is lower the amount of DNA mutations that can cause cancerous cells from growing. The mutations may already have caused a problem which will appear in the future.