January 22, 2004: Study Finds That Combined Exposure To Second-Hand Smoke And Urban Air Pollutants During Pregnancy Adversely Affects Birth Outcomes

First Study To Show These Common Pollutants Interact to Increase Risk — Provides Further Evidence That Pregnant Women Should Limit Exposure To Second-Hand Smoke

New York, NY — January 22, 2004 — Combined prenatal exposure to 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 at Columbia University.

The research involved a sample of 226 infants of non-smoking African American and Dominican women in Washington Heights, Central Harlem and the South Bronx. The study examined the effect of prenatal exposure to two common urban pollutants on fetal growth. The two pollutants are second-hand smoke, also known as Environmental Tobacco Smoke (ETS), which contains hundreds of chemicals, and combustion-related pollutants known as polycyclic aromatic hydrocarbons (PAH). PAH enter the environment when combustion occurs — such as from car, truck, or bus engines, residential heating, power generation, or tobacco smoking.

The researchers compared those infants whose mothers lived during pregnancy in households where an active smoker was present to 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 today, will be published in Environmental Health Perspectives, a peer-reviewed scientific journal.

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 about a 3 percent reduction in head circumference.

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 worse school performance.

“This study shows, for the first time, that the combined effect of these two exposures is damaging to the developing fetus,” said Dr. Frederica P. Perera, Director of the Center and principal author of the study. “Pregnant women, in addition to not smoking, should be careful to limit their exposure to second-hand smoke. The results also underscore the need for sound policies to reduce both outdoor and indoor air pollution in the city.”

This study was made possible by research grants from the National Institute of Environmental Health Sciences (NIEHS), and the U.S. Environmental Protection Agency (EPA), as well as a number of generous private foundations. It 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 cockroach and mouse allergens. Other key investigators on this particular study include Dr. Virginia Rauh, Dr. Robin Whyatt, and Dr. Deliang Tang, also of the Columbia Center for Children’s Environmental Health.

Read the study online.

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