A study in mice shows that cigarette smoke caused changes in the DNA of sperm cells, the researchers said in this week's issue of the journal Cancer Research. Such mutations, know as germline mutations, are known to be permanent.
"If inherited, these mutations persist as irreversible changes in the genetic composition of offspring," said Carole Yauk of Health Canada's Environmental and Occupational Toxicology Division, who led the study.
"We have known that mothers who smoke can harm their fetuses, and here we show evidence that fathers can potentially damage offspring long before they may even meet their future mate."
Yauk and colleagues studied the stem cells that produce sperm in mice exposed to cigarette smoke for either six or 12 weeks. All male mammals continuously produce sperm.
They found 1.7 times as many DNA mutations in the cells of the smoke-exposed mice as in those of the unexposed mice after 12 week, and 1.4 times as many mutations after six weeks.
"This suggests that damage is related to the duration of exposure, so the longer you smoke the more mutations accumulate and the more likely a potential effect may arise in the offspring," Yauk said.