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Prenatal exposure to both second-hand smoke and combustion-related pollutants, at levels currently found in New York City, adversely affects the size and weight of newborns, according to a study by the Columbia Center for Children's Environmental Health, part of the Mailman School of Public Health.

The study is the first to explore these exposures in combination, which is noteworthy because pollutants affect the human body simultaneously, rather than separately as they are frequently studied. The results are of concern because previous studies have linked reduced fetal growth with later problems in learning or poor school performance.

Dr. Frederica P. Perera, professor of environmental health sciences at the Mailman School and director of the center, led the study, which involved 226 infants of non-smoking African-American and Dominican women in Washington Heights, central Harlem and the South Bronx.

The study examined the effects of prenatal exposure to two common urban pollutants — second-hand smoke, also known as environmental tobacco smoke (ETS), which contains hundreds of toxic chemicals, and combustion-related pollutants known as polycyclic aromatic hydrocarbons (PAH) — on fetal growth. These substances enter the environment as a byproduct of combustion from car, truck, or bus engines, residential heating, power generation, or tobacco smoke.

The researchers compared those infants whose mothers lived during pregnancy in households where a smoker was present with those whose mothers did not. They measured DNA damage from PAH in the umbilical cord blood of the newborns — providing an individual biomarker of PAH exposure and susceptibility to PAH. The results of the study, released Jan. 22, will be published in Environmental Health Perspectives, a peer-reviewed scientific journal, and are available online at

The study found a significant combined effect of ETS and PAH on birth weight and head circumference — two standard measures of fetal growth. Specifically, it found that babies with both prenatal exposure to ETS and high levels of PAH/DNA damage had about a 7 percent reduction in birth weight and a 3 percent reduction in head circumference.

Other key investigators were Dr. Virginia Rauh, associate professor of clinical public health; Dr. Robin Whyatt, assistant professor of clinical environmental health; and Dr. Deliang Tang, assistant professor of clinical environmental health. All are also part of the Center for Children's Environmental Health.

This study was made possible by research grants from the National Institute of Environmental Health Sciences and the U.S. Environmental Protection Agency, as well as a number of private foundations ( It is part of a broader, multi- year research project, "The Mothers & Children Study in New York City," begun 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 smoke, as well as from residential use of pesticides and cockroach and mouse allergens.