The elimination and estimated half-lives of specific polychlorinated biphenyl congeners from the blood of female monkeys after discontinuation of daily dosing with aroclor® 1254

The levels of thirty polychlorinated biphenyl congeners in the blood of female rhesus monkeys, previously dosed with Aroclor 1254 for over six years, were monitored every two weeks during the first year and monthly during the subsequent two years after dosing was discontinued. Both blood lipid and polychlorinated biphenyl congener levels generally declined during this post dosing period. The percent distribution of the PCB congeners during the post dosing period remained relatively constant with more than half of all polychlorinated biphenyls consisting of the monoorthochlorine substituted biphenyls. The contribution of the mono-orthochlorine substituted biphenyls was significantly different for one out of three monkeys in two of the three dose groups, during the post dosing period. Half-life estimations for nine of the congeners ranged from 0.3–7.6 years.