Effects of prenatal PCB exposure on cognitive processing efficiency and sustained attention.

Four-year-old children exposed prenatally to polychlorinated biphenyls (PCBs), an environmental toxin, were assessed on three tasks―two designed to evaluate cognitive processing efficiency and one to evaluate sustained attention. When compared with standardized IQ tests, these tasks provided greater specificity in identifying cognitive deficits. Adapted for 4-year-old children in the present study, these paradigms demonstrated moderate levels of test-retest reliability. Prenatal exposure to PCBs was associated with less efficient visual discrimination processing and more errors in short-term memory scanning but not with sustained attention. Although much larger quantities of these contaminants are transferred postnatally via breasfeeding than prenatally across the placenta, postnatal exposure was unrelated to cognitive performance. The data link intrauterine PCB exposure to two dimensions of cognitive functioning fundamental to learning