In Utero Exposure To Urban Air Pollutants Can Increase Risk

The study will be published online Monday, April 24, 2006, and can be accessed at the following URL: http://www.ehponline.org/docs/2006/9084/abstract.html.

Investigators at the Center studied a sample of 183 three-year-old children of non-smoking African-American and Dominican women residing in the neighborhoods of Washington Heights, Central Harlem, and the South Bronx. They found that exposure during pregnancy to combustion-related urban air pollutants known as polycyclic aromatic hydrocarbons (PAHs) were linked to significantly lower scores on mental development tests and more than double the risk of developmental delay at age three. Such delay in cognitive development is indicative of greater risk for performance deficits in language, reading, and math in the early school years.

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. Following inhalation by the mother, the pollutants can be transferred across the placenta to reach the fetus. Children were tested at age three using a standardized test of mental and psychomotor development.

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.

"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."

"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."

In this study, the children who were exposed in the womb to the highest levels of PAHs scored on average 5.7 points (6.3%) lower on cognitive tests 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 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.

The study was made possible by funding from the National Institute of Environmental Health Sciences, the U.S. Environmental Protection Agency, as well as a number of private foundations.

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