Long‐term neurobehavioral effects of perinatal polychlorinated biphenyl (PCB) exposure in monkeys

In recent years, there has been growing concern about the potential long‐term neurobe‐havioral effects of perinatal polychlorinated biphenyl (PCB) exposure. We have addressed this issue in a series of studies at the Harlow Primate Laboratory. Offspring of rhesus monkeys (Macaca mulatto) exposed to commercial PCB mixtures (Aroclor 1016 or Aroclor 1248) were tested on two‐choice discrimination‐reversal learning at 1.5 years of age and on delayed spatial alternation, a spatial learning and memory task, at four to six years of age. Deficits in performance were observed on both tasks. The deficit observed on delayed spatial alternation in Aroclor 1248‐exposed monkeys was quite dramatic. The monkeys were tested for 80 test sessions, but were never able to achieve control levels of performance. This effect was observed when the monkeys were four to six years of age (young adulthood), even though they had not been exposed to PCBs since they were weaned at four months of age. The pattern of effects on both discrimination‐reversal learning and delayed spatial alternation was suggestive of damage to the prefrontal cortex.