According to Canadian researchers children could inherit genetic damage from a father who smokes.
They say men who smoke risk damaging their sperm and that damage is passed on in the genes of his children.
The researchers with Health Canada conducted a study in mice and found that cigarette smoke caused changes in the DNA of their sperm cells; the researchers say such mutations, called germline mutations, are known to be permanent.
Dr. Carole Yauk, a research scientist in the Mutagenesis Section of Canada's Environmental and Occupational Toxicology Division, says if inherited, these mutations persist as irreversible changes in the genetic composition of offspring.
Dr. Yauk, who led the study, points out it is now common knowledge that mothers who smoke can harm their fetuses, and this study produces evidence that fathers can potentially damage offspring long before they even meet their future partners.
For the study Yauk and her colleagues at McMaster University, studied the stem cells that produce sperm in mice exposed to cigarette smoke for either six or 12 weeks.
Males, whether mouse or man, generate a constant supply of new sperm from self-renewing spermatogonial stem cells.
Yauk and her colleagues found that the rate of Ms6-hm mutations in the smoking mice were 1.4 times higher than that of non-smoking mice at six weeks, and 1.7 times that of non-smoking mice at 12 weeks.
The researchers say 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.
The team now plan to study how altered DNA manifests itself in the children and grandchildren of male mice that are exposed to firsthand smoke.
They also plan to study the effects of secondhand smoke on male mice as well the possibility that the eggs of females are also affected by smoke.
The results of their study are published in the current issue of Cancer Research; the research was funded by the Canadian Regulatory System for Biotechnology and the Canadian Institutes of Health Research.