Researchers found that within a sample of 215 children monitored from birth, those children with high levels of a pollution exposure marker in their cord blood had more symptoms of attention problems and anxiety/depression at ages 5 and 7 than did children with lower exposure.
The researchers measured a biologic marker or "fingerprint" of exposure to polycyclic aromatic hydrocarbons (PAH) and other combustion-related pollutants in newborns' cord blood. When inhaled by the mother during pregnancy, these pollutants can be transferred across the placenta and bind to the DNA of the fetus, forming "adducts" in blood and other tissues and providing a biologic measure of pollutant exposure. Mothers completed a detailed assessment of their child's behavior.
In urban air, traffic emissions are a dominant source of the pollutants measured in the study. The authors accounted for other sources such as environmental tobacco smoke and diet in their analyses. None of the mothers in the study were smokers.
From here citing Frederica P. Perera, Shuang Wang, Julia Vishnevetsky, Bingzhi Zhang, Kathleen J. Cole, Deliang Tang, Virginia Rauh, David H. Phillips. PAH/Aromatic DNA Adducts in Cord Blood and Behavior Scores in New York City Children. Environmental Health Perspectives, 2011; DOI: 10.1289/ehp.1002705.