Correlation of PCB body burden with behavioral toxicology in monkeys.

Eight monkeys fed 2.5 ppm PCB in their daily diet conceived, delivered and nursed five infants, three of which survived past weaning at four months of age. PCB residues in fat in the surviving infants at 8, 10 1/2, and 23 months of age declined linearly when plotted as log concentration versus time (first order clearance), and these functions extrapolated to presumed peak PCB levels of 21, 114, and 123 microgram/g fat (ppm) at 4 months of age. Behavioral tests on these three infants and four normal controls revealed hyperlocomotor activity at 6 and 12 months of age correlated with peak PCB body burdens. Higher peak PCB body burdens also were correlated with increased errors in five of nine learning tasks conducted between 8 and 24 months of age. Point estimates of zero-effect levels of PCB body burdens ranged around 21 ppm, although it was clear that even the monkey carrying only 21 ppm PCBs at four months of age exhibited some behavioral deficits persisting through the final testing at 24 months of age.