Cigarette smoke may cause a catastrophic disruption of the chromosomes in human eggs that can lead to miscarriage, researchers say.
The researchers found nicotine and cadmium, another component of cigarette smoke, in the fluid that surrounds maturing eggs just before they are fertilized.
Smokers produce immature eggs, said Maria Teresa Zenzes, a geneticist at Toronto General Hospital. Those eggs have twice the appropriate number of chromosomes, and they produce highly abnormal fetuses that nearly always result in miscarriages, she said.
The study offers a possible explanation for why women who smoke are more likely to have miscarriages, Zenzes reported at the annual meeting this week of the American Society of Human Genetics.
In a separate study, researchers said Friday that a chromosome abnormality associated with lymphoma is 3.6 times as common in heavy smokers as it is in non-smokers, possibly explaining why that form of cancer is roughly three times as common in heavy smokers as in non-smokers.
"When any tissue comes in contact with cigarette smoke, you get a myriad of changes," said one of the authors of the lymphoma study, Douglas Bell, a molecular biologist at the National Institute of Environmental Health Sciences in Research Triangle Park, N.C.
The study is part of a new field of research attempting to find genetic changes associated with smoking. These changes could explain why smoking causes so many kinds of cancer, Bell said.
Mary-Claire King, an epidemiologist and geneticist at the University of California at Berkeley, said the studies were important because they showed new ways that smoking could cause genetic aberrations, even before conception.