Residual effects of polychlorinated biphenyls on adult nonhuman primates and their offspring.

After 18 mo of consuming a diet containing 2.5 and 5.0 ppm PCB (Aroclor 1248), during which they and their offspring experienced marked alterations in physical status, female rhesus monkeys were placed on a control diet for 1 yr. During this year there was a decided improvement in their general body health and reproductive capabilities. Infants born to these animals were small at birth and during their postnatal life developed signs of PCB intoxication similar to those observed in their siblings born during the period of PCB exposure. These data indicate that the residual effects of low-level ingestion of PCBs by nonhuman primates persist for over 1 yr after discontinuation of exposure. There are also indications that the fetal and neonatal monkeys born to PCB-exposed mothers are more severely affected for a longer period than are the adult female monkeys.