Science

Soot from traffic exhaust lowers IQ

by William Atkins

Friday, 11 January 2008

According to a recent Harvard Univesity study, the more exposure children have to black carbon (soot) from traffic fumes, the worse they do in intelligence tests.

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Shakira Franco Suglia and her colleagues at Harvard University (Cambridge, Massachusetts) studied two hundred two children, with an average age of 9.7 years plus/minus 1.7 years, from the Boston, Massachusetts area. The study was conducted from 1986 to 2001.

They found that the intelligence quotient (IQ) of children living in areas with more traffic fumes level had IQs, or intelligence levels, which were three points below that of children living in areas with less exhaust fumes. The children were given two intelligence tests: The Wide Range Assessment of Memory and Learning and the Kaufman Brief Intelligence Test.

The researchers took into account sociodemographic factors such as blood lead level, birth weight, and other such factors within the study. However, in all cases within the results, they found decreased levels of intelligence and memory in the children exposed more to traffic fumes, specifically the black carbon found in exhaust fumes.

Black carbon (BC) is a type of carbon that is produced, in the form of soot, by the incomplete combustion of fossil fuels.

In summary, the groups stated within the abstract of their paper: “Higher levels of black carbon predicted decreased cognitive function across assessments of verbal and nonverbal intelligence and memory constructs.”

Their results imply that soot is just as harmful as lead and other toxic substances that cause damage to learning by damaging the brain’s functions.

The paper, entitled “Association of Black Carbon with Cognition among Children in a Prospective Birth Cohort Study,” was presented online on November 15, 2007, in The American Journal of Epidemiology.

The paper was authored by Suglia, along with her associates: A. Gryparis (Department of Applied Mathematics, University of Crete (Greece)), R.O. Wright and J. Schwartz (both from the Department of Environmental Health, Harvard School of Public Health (Boston), and Channing Laboratory, Brigham and Women’s Hospital and Harvard Medical School), and R.J. Wright (Channing Laboratory, Brigham and Women’s Hospital and Harvard Medical School, and Department of Society, Human Development and Health, Harvard School of Public Health (Boston)).

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