Elimination of PCB congeners via milk in rabbits administered Fenclor 64

A single dose of 100 mg per kg body weight of a commercial mixture of polychlorinated biphenyls (PCB), Fenclor 64 was given intraperitoneally to pregnant rabbits. The distribution in dams and foetuses and excretion in milk was investigated for six of the congeners by quantifying them in fat from maternal adipose tissue, from whole foetuses and newborn bodies and from newborn gastric contents. The cytochrome-P-450 induction after Fenclor 64 in foetuses and suckling off-spring was followed by measuring the following hepatic mixed function oxidase (MFO) activities: p-nitroanisole-demethylase, ethoxyresorufin-deethylase, ethoxycoumarin-deethylase and NADPH cytochrome-C reductase. At the 28th day of pregnancy PCB fat concentrations in foetuses were similar to those in mothers (126.4 +/- 7.1 and 152.6 +/- 28.1 micrograms/g of fat, respectively). By the 5th day of life fat concentrations in the youngs were double those of foetuses (216.81 +/- 8.12 micrograms/g) and remained high until weaning (142.2 +/- 15.5 micrograms/g at the 20th day). PCB concentrations in mothers' fat decreased during lactation (104.1 micrograms/g at the 20th day) but at the end of the experiment they were still high (95.5 micrograms/g). The cytochrome-P-450 concentration and MFO activities in young rabbits' livers from treated dams were significantly higher than controls from the 5th (P less than 0.01) to the 10th (P less than 0.01) day of life, with the exception of NADPH-cyt-C-reductase (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)