Double Dose of Bad Air Puts Fetuses at Risk - The New York Times

January 27, 2004


Melissa P. McNamara

Combined exposure to secondhand smoke and urban air pollutants at levels
encountered in New York City can hurt fetal development, a study by the
Columbia Center for Children's Environmental Health says.

While previous research has explored the effect of secondhand smoke and
urban air pollution independently on fetuses, the study is the first to find
a significant combined effect of both pollutants on birth weight and head
circumference, two standard measures of fetal growth. Babies exposed in the
womb to both secondhand smoke and high levels of urban air pollutants had a
7 percent reduction in birth weight and a 3 percent reduction in head
circumference, scientists found, compared with babies exposed only to low
levels of urban air pollution in utero.

The study is to be published in Environmental Health Perspectives in April.
"The effects we see, reduced fetal growth and lower birth weight, have been
linked to later problems in learning and school performance in childhood,"
said Dr. Frederica P. Perera, the senior author of the study and director of
the center. "These are warning signs that we should take seriously."

The findings are noteworthy because pollutants affect the human body
simultaneously, rather than separately, as they are frequently studied, the
researchers say. The scientists also used a new approach to measure the
effects of pollutants on individual babies, by tracking the pollutants in
DNA, Dr. Perera said.

The researchers conducted the study on 214 infants of nonsmoking
African-American and Dominican women in Washington Heights, Central Harlem
and the South Bronx, the communities the center serves. Members of urban
minority groups are also at high-risk for problem births and are more likely
to be exposed to environmental contaminants. But the findings can be
generalized across race and ethnicity, the researchers say.

The researchers examined the effect of prenatal exposure to two common urban
pollutants on fetal growth - environmental tobacco smoke and
combustion-related pollutants, which enter the air from car, truck or bus
engines, residential heating and power generation.

Interviewers administered a 45-minute questionnaire to the participants
during the last trimester of pregnancy to track demographic information,
travel away from their homes in the past year, number of household members
who smoke and alcohol use in each trimester.

When the women gave birth, the researchers compared those infants whose
mothers had lived in households where a smoker was present to those whose
mothers did not by measuring DNA damage caused by the pollutants in the
umbilical cord blood of the newborns.

The findings show the combined effect of these two exposures can damage the
developing fetus, Dr. Perera said. Babies exposed to second-hand smoke and
air pollutants were, on average, half a pound (or 233 grams) lighter and
their heads were almost half an inch (10 millimeters) smaller in
circumference.

Dr. Perera said the results showed the need to improve air quality. "My
advice to pregnant women," he added, "is don't let people in your household
smoke."

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