Passive smoking can cause genetic damage to sperm cells that may result in birth defects, miscarriages and other reproductive problems which make it difficult to father a healthy child, scientists have found.
Researchers believe that similar DNA changes in boys or men exposed regularly to passive smoke could lead to reproductive problems such as infertility or a higher risk of fathering children with congenital defects.
Scientists led by Carole Yauk, of Health Canada in Ottawa, found that when mice were exposed to the sidestream smoke from a burning cigarette, they suffered a significant increase in the number of DNA mutations within the "germ cells" of the testes which are responsible for making sperm.
"Our data suggests that paternal exposure to second-hand smoke may have reproductive consequences that go beyond the passive smoker," the researchers write in the journal Proceedings of the National Academy of Sciences.
They say their work on laboratory mice provides "compelling evidence" to support the argument that passive smoking should be regarded as a potential mutation-causing behaviour in human sperm cells.