Scientists have found that smoking a pack a day of cigarettes can cause 150 damaging changes to a smoker's lung cells each year.
The findings come from a study of the devastating genetic damage, or mutations, caused by smoking in various organs in the body. Publishing in the journal Science on Nov. 3, the researchers said the findings show a direct link between the number of cigarettes smoked in a lifetime and the number of mutations in the DNA of cancerous tumors.
The highest mutation rates were seen in lung cancers, but tumours in other parts of the body — including the bladder, liver and throat — also had smoking-associated mutations, they said. This explains why smoking also causes many other types of cancer beside lung cancer.