Research results showing a significant association between decreased intellectual functioning at 9-years of age among children exposed to prenatally to high levels of polychlorinated biphenyls (PCBs) compared to those with lower level exposures were recently reported by researchers at the Center for Neurobehavioral Effects of Environmental Toxics and the Environmental Research Center at the State University of New York at Oswego.

Details of the findings were published in the October 2008 Edition of Environmental Health Perspectives and were authored by Paul Stewart and colleagues. The study evaluated the association between PCBs and intelligence among a group of 156 children in Oswego, New York who have been tracked as part of the longitudinal study focused on the relationship between prenatal PCB exposure and cognitive development. All children included in the latest phase of the research had cord blood and placental tissue taken at or around the time of birth and were available for intelligence testing when they were nine years of age.

Researchers found that there was a linear relationship between PCB concentration in placental tissue and decreased intelligence even after controlling for several maternal and infant characteristics and other exposures including methylmercury and lead. Children in the most  highly exposed group had overall intelligence scores that were on average, six to seven points lower than those with the lowest levels of exposure. Verbal intelligence scores were especially low in the highly exposed group compared to the lowest where children who were more highly exposed had verbal intelligence scores that were about nine points lower than the least exposed group.
 

References

1. Stewart PW, Lonky E, Reihman, Pagano J, Gump BB, Darvill T. The Relationship between Prenatal PCB Exposure and Intelligence (IQ) in 9-Year-Old Children. Envirnmental Health Perspectives 2008; 116 (10): 1416-22.

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