The air quality in and around your home may have negative effects on your child’s intelligence, according to a study by Columbia University Center for Children’s Environmental Health (CCCEH).

The study, released a week ago by the National Institute of Environmental Health Sciences (NIEHS), found that children exposed to chemical pollutants called polycyclic aromatic hydrocarbons found in the air, water, and soil scored lower on IQ tests than children with lower exposure.

Polycyclic aromatic hydrocarbons, or PAHs, are chemical pollutants that can be found in the air, water, and soil. PAHs are typically released from the burning of fossil fuels (coal, diesel, oil, gas, etc.), tobacco and other natural substances. Auto emissions are a major source of PAHs in the United States, especially in heavily trafficked urban areas.

Doctor Frederica Perera, lead author and professor of Environmental Health Sciences at Columbia University Mailman School of Public Health, compares the exposure to such pollutants to low-level lead exposure. “These findings are of concern because these decreases in IQ could be educationally meaningful in terms of school performance,” she says. “IQ is an important predictor of future academic performance.”

A child’s developing fetal and nervous system is more vulnerable than an adult’s, and PAHs have been associated with higher cancer risk, asthma, allergies, low birth weight, and a reduced head circumference. Reduced head circumference, according to CCCEH, is connected with lower cognitive functioning and academic performance. In this study, the first of its kind, researchers hoped to study the relationship of in utero PAH exposure on a child’s intelligence.
 
Participants were non-smoking black and Dominican-American women, aged 18-35, residing in Washington Heights, Harlem and South Bronx, N.Y.—areas with higher pollutant exposure. During pregnancy participants regularly completed questionnaires and were asked to wear monitors that measured PAH levels.

Researchers followed the children, measuring IQ levels at age three and again at age five using the Wechsler Preschool and Primary Scale of the Intelligence. Of the 249 children, 140 had higher than the average 2.26 n/m3 level of exposure. The mean score for all children was 98.72, with a mean score of 96.6 for children whose exposure was classified as “high” and 101.6 for children with lower exposure. Scores differed by 4.67 on the verbal and 4.31 points on the full-scale test.

Researchers will continue to follow children to age 11 to learn more about the effects of PAHs on intelligence and child development. “It should serve as a warning bell to us all,” says Linda Birnbaum, Ph.D., director of NIEHS. “We need to do more to prevent environmental exposures from harming our children.”

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