Prenatal exposure to air pollutants lowers children’s IQ.

Perera, FP, L Zhigang, R Whyatt, L Hoepner, S Wang, D Camann and V Rauh. 2009. 2009. Prenatal airborne polycyclic aromatic hydrocarbon exposure and child IQ at age 5 years. Pediatrics doi: 10.1542/peds.2008-3506.

A new study concludes that prenatal exposure to the common air pollutants – polycyclic aromatic hydrocarbons (PAHs) – can lower children’s IQ at kindergarten age.

This is the first study to show that prenatal exposure to PAH can lower children’s IQ. However, PAHs are known to adversely affect neurodevelopment, reproductive function and growth, and to cause cancer.

Polycyclic aromatic hydrocarbons (PAHs) are one of the most ubiquitous air pollutants. They are the byproduct of burning fossil fuel, tobacco and organic materials. In urban settings motor vehicle emissions are a major source of PAH pollution.

PAH emissions are regulated in developed countries. However, according to this study, children born in urban environments, such as New York city, are at high-risk for adverse developmental effects from PAH exposure.

Scientists at Columbia University's Center for Children’s Environmental Health monitored children of non-smoking black and Dominican-American women age 18 to 35 who lived in Washington Heights, Harlem or South Bronx in New York City. While pregnant, mothers wore personal air monitors to measure exposure to PAHs.

The children’s intelligence was assessed at age 5 using a standard assessment test (the Wechsler Preschool and Primary Scale of Intelligence-Revised). The average prenatal PAH exposure of children was calculated.

Children exposed to PAH levels above the average of 2.26 nanograms per cubic meter were designated as having high exposure. Full-scale and verbal IQ scores of children with high PAH exposure were 4.31 and 4.61 points lower and were significantly different statistically from the low exposure group.

Similar decreases in full-scale IQ scores have been reported for children with low-level lead exposure.