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Print“These findings are of concern because these decreases in IQ could be educationally meaningful in terms of school performance. The good news is that we have seen a decline in air pollution exposure in our cohort since 1998.”
We already know smog makes the horizon fuzzy, but it may do the same to childrens’ brains, too. A recent study shows prenatal exposure to chemicals released when coal, diesel, oil, and gas are burned can hurt a child’s intelligence quotient. Other organic substances such as tobacco can also lower the IQ, say researchers from the Columbia Center for Children’s Environmental Health at the Mailman School of Public Health.
Researchers say children exposed to high levels of the chemicals known as polycyclic aromatic hydrocarbons in New York City had overall IQ scores that were 4.31 points lower and verbal IQ scores that were 4.67 points lower than children with less exposure to these chemicals. High levels of these hydrocarbons were defined as above the median of 2.26 nanograms per cubic meter. Motor vehicles are a major source of the hydrocarbons in urban areas.
The study, published in the journal Pediatrics, included children who were born to non-smoking Black and Dominican American women age 18 to 35, who resided in Washington Heights, Harlem, or the South Bronx in New York. The children were followed from in utero to five years of age. The mothers wore personal air monitors during pregnancy to measure exposure to the hydrocarbons and they responded to questionnaires.
At five years of age, 249children were given an intelligence test known as the Wechsler Preschool and Primary Scale of the Intelligence, which provides verbal, performance, and full-scale IQ scores. The researchers developed models to calculate the associations between prenatal hydrocarbon exposure and IQ. They accounted for other factors such as second-hand smoke exposure, lead, the mother's education, and the quality of the home caretaking environment. Study participants exposed to air pollution levels below the average were designated as having “low exposure,” while those exposed to pollution levels above the average were identified as “high exposure.” A total of 140 children were classified as having high exposure to the polycyclic aromatic hydrocarbons.
“The decrease in full-scale IQ score among the more exposed children is similar to that seen with low-level lead exposure,” Perera says. “This finding is of concern because IQ is an important predictor of future academic performance, and [the hydrocarbons] are widespread in urban environments and throughout the world. Fortunately, airborne [polycyclic aromatic hydrocarbons] concentrations can be reduced through currently available controls, alternative energy sources, and policy interventions.”
