In a study published in the online journal BMC Pediatrics, Stephen G. Grant, Ph.D., associate professor of environmental and occupational health, reports that both active maternal smoking and secondary maternal exposure result in similarly increased rates of genetic mutation that are basically indistinguishable.
"This analysis shows not only that smoking during pregnancy causes genetic damage in the developing fetus that can be detected at birth, but also that passive or secondary exposure causes just as much damage as active smoking, and it is the same kind of damage," said Dr. Grant, whose primary area of study is genotoxicity and the mechanisms of DNA repair. "These kinds of mutations are likely to have lifelong repercussions for the exposed fetus, affecting survival, birth weight and susceptibility to disease, including cancer."
This is a startlingly different conclusion than that reached by three previous studies looking at the potential effects of tobacco smoke exposure to babies in the womb, one of which Dr. Grant co-authored. The primary papers largely discounted the effects of secondary and sometimes even direct exposure through maternal smoking or produced contradictory results.
The original studies looked at mutation rates at the HPRT gene located on the X chromosome in cord blood samples from newborns. Dr. Grant's analysis pooled the studies' data, looking for frequency of induced mutation as well as the resulting molecular spectrum of mutations. In particular, the new analysis redefines the "non-smokers" used as controls to consider their second-hand exposure to tobacco smoke through other family membe