April 24, 2006: Pregnant Mothers’ Exposure to Air Pollutants Threatens Cognitive Development In Utero

Peer-Reviewed Study Funded by EPA, National Institutes of Health Is First to Reveal Link Between Pollutants, Performance Deficits

New York, NY — April 24, 2006 — Women who are exposed to harmful air pollutants during pregnancy can give birth to children whose cognitive development has been adversely affected in utero, leading to below average performances on cognitive tests administered once they have reached age three, according to a peer-reviewed study published by the National Institute of Environmental Health Sciences in its journal Environmental Health Perspectives.

The study, which followed the development of almost 200 New York City children from before birth to age three, reveals for the first time that certain combustion-related urban air pollutants known as polycyclic aromatic hydrocarbons (PAHs) can be transmitted to developing fetuses through their mothers and cause subsequent developmental problems. Recently released by the Columbia Center for Children’s Environmental Health (CCCEH) at Columbia University’s Mailman School of Public Health, the study was funded by the U.S. Environmental Protection Agency and the National Institutes of Health.

“These findings are of concern, because compromised mental performance in the preschool years is an important precursor of subsequent educational performance deficits,” said Dr. Frederica Perera, DrPH director of the Center and lead investigator.  “Fortunately, airborne PAH concentrations can be reduced by currently available pollution controls, greater energy efficiency, and the use of alternative energy sources.”

Investigators at the Center studied a sample of 183 three-year-old children of non-smoking African-American and Dominican women residing in the Washington Heights, Central Harlem, and the South Bronx. They found that exposure during pregnancy to PAHs was linked to significantly lower scores on mental development tests and more than double the risk of developmental delay by age three.

The children were administered standardized tests of mental and psychomotor development, which revealed that those who were exposed in the womb to the highest levels of PAHs scored on average 5.7 points (6.3 percent) lower than the less exposed children; and their risk of being developmentally delayed was 2.9 times greater than that of children who had lower prenatal exposure. Both results were statistically significant. The Center will continue to follow the children’s development until ages seven and eight.

In the study, the mothers’ exposure during pregnancy to varying levels of airborne PAHs was measured by personal air monitoring. PAHs enter the environment when combustion occurs — such as from car, truck, or bus engines, residential heating, power generation, or tobacco smoking. When the mother breathes them, the pollutants can be transferred across the placenta to the fetus.

The study is part of a broader multi-year research project, “The Mothers and Children Study in New York City,” started in 1998, which examines the health effects of exposure of pregnant women and babies to indoor and outdoor air pollutants, pesticides, and allergens. Previous studies have shown that the same air pollutants that harm mental development also can adversely affect birth weight and head circumference at birth.

“Identifying and attending to developmental delays in the preschool years is likely to be cost-effective and improve cognitive development,” said Dr. Virginia Rauh, ScD, co-investigator and co-author of the study, “since the skills children bring with them to school not only affect educational outcomes but also determine how schools must spend their resources.”

The investigators controlled for other exposures that might have contributed to developmental problems such as socioeconomic factors, exposure to tobacco smoke, lead, and other environmental contaminants.

Other co-investigators on the study include Pat Kinney, Robin Whyatt, and Wei Yann Tsai.

Read the study online.

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