Exposure to pollution can lower IQ
Exposure to air pollution in the womb can significantly reduce a child's IQ, according to a study conducted by researchers from the Mailman School of Public Health in New York and published in the journal Pediatrics.
The researchers conducted the experiment on pregnant, non-smoking black and Dominican American women between the ages of 18 and 35 who were living in the New York City neighborhoods of Harlem, South Bronx or Washington Heights. The participants wore personal air monitors during pregnancy, providing the researchers accurate data on the women's exposure to a class of air pollutants known as polycyclic aromatic hydrocarbons (PAHs). The participant's children were then subjected to standardized IQ tests at age five.
"These results provide evidence that environmental PAHs at levels encountered in New York City air can affect children's IQ adversely," the researchers concluded.
PAHs are produced by the burning of fossil fuels and other organic materials, including tobacco. The major source of PAH pollution in urban areas is automobile exhaust.
The researchers found that after adjusting for other factors that might affect IQ, children of mothers who had high PAH exposure during pregnancy had IQ scores an average of 4.31 points lower than children of mothers with lower exposure. The difference in verbal IQ scores was even higher, with children of high-exposure mothers scoring an average of 4.61 points lower. This IQ difference is equivalent to that seen in children with low-level lead exposure.