A new study of the effects of combustion-related air pollutants in New York City reveals that babies in the womb are more sensitive than their mothers to DNA damage from such pollution.
Despite the protection provided by the placenta, which reduces the fetal dose to an estimated one-tenth the dose of the mother, the levels of DNA damage were similar in the newborns and their mothers. This finding is especially notable, since evidence from previous studies of laboratory rodents suggests that the fetus is more sensitive to the carcinogenic effects of the same pollutants than the adult.
The study -- the first of its kind in New York City -- was released today by the Columbia Center for Children's Environmental Health, part of the Mailman School of Public Health at Columbia University. It will be published in the June issue of Environmental Health Perspectives, a peer-reviewed scientific journal, which is available online at http://ehp.niehs.nih.gov/.
The study involved 265 pairs of mothers and newborns in New York City. The mothers were non-smoking African American or Latina women in Washington Heights, Central Harlem and the South Bronx.
The study examined the effect of prenatal exposure to combustion-related pollutants, known as polycyclic aromatic hydrocarbons (PAH), on DNA damage. PAH are carcinogenic air pollutants that cross the placenta. They enter the environment when combustion occurs -- such as from car, truck, or bus engines, residential heating, power generation, or tobacco smoking.
The researchers collected blood samples from the mothers and from the umbilical cords of the newborns and examined the presence of two key biomarkers: carcinogen-DNA adducts (previously associated with increased cancer risk) and cotinine (a measure of tobacco smoke exposure -- in this case, secondhand tobacco smoke, since the mothers were all nonsmokers). Despite the estimated 10-fold lower dose to the fetus compared to the mother, the levels of DNA damage were comparable in newborns and mothers; and cotinine levels were higher in newborns than mothers.
The study findings are consistent with results of a prior study, conducted by the Center in Krakow, Poland. However, because pollutant levels are much higher in Krakow than in New York and other American cities, it was important to determine levels of pollutant-related DNA damage in mothers and newborns at the lower concentrations seen in the United States.
"These results raise serious concern," said Dr. Frederica P. Perera, Director of the Center and the study team leader. "Fetal susceptibility to DNA damage from air pollution, including motor vehicle emissions and secondhand smoke, has important implications for cancer risk and developmental problems. And it underscores the importance of reducing levels of air pollution in our city."
A previous study by the Center, released in January 2004, found that the combination of high PAH-DNA damage and second-hand smoke, at levels found in New York City, reduces the birth weight and head circumference of newborns.
The current study was made possible by research grants from the National Institute of Environmental Health Sciences, the U.S. Environmental Protection Agency, as well as a number of generous private foundations (http://www.ccceh.org/funders.html). Other co-authors of the study include Deliang Tang, Yi-Hsuan Tu, Linda Ali Cruz, Mejico Borjas, and Robin M. Whyatt from the Center, and Tom Bernert from the Centers for Disease Control and Prevention.
The research is part of a broader, multi-year research project, "The Mothers & Children Study In New York City," started in 1998, which examines the health effects of exposure of pregnant women and babies to air pollutants from vehicle exhaust, the commercial burning of fuels, and tobacco smoking, as well as from residential use of pesticides and allergens.