Effects of polychlorinated biphenyls at low dose levels in rats.

Abstract

Clophen® A-50, a commercial polychlorinated biphenyl (PCB) mixture, was administered orally to rats for six weeks at the dose levels of 2, 10, 50, 150, and 250 mg/kg. An accumulation of PCBs was found in the liver, the kidney, and in the adipose tissue of all dosed animals. The highest levels were observed in the fatty tissue, which were 10 and 40 times higher than those found in the liver and kidney, respectively. After six weeks treatment with 2 mg/kg, histopathological alterations were evident in the liver, manifest as centrolobular necroses. At the dose level of 10 mg/kg, increases were found in the liver weight and in serum cholinesterase activity. The serum bilirubin concentration and serum protein content were elevated at 50 mg/kg. The activities of serum glutamic oxalacetic transaminase (SGOT) and serum glutamic pyruvic transaminase (SGPT) however, were only increased at doses higher than 50 mg/kg. The levels of the serum lipids cholesterol and triglycerides were elevated at the doses of 2 mg and 50 mg/kg respectively. The urinary excretion of δ-aminolevulinic acid (ALA) and porphobilinogen (PBG) was enhanced at the dose levels between 50 and 250 mg/kg, whereas the urinary porphyrin levels remained unchanged. The no-effect level of repeated oral PCB administration in rats was less than 2 mg/kg.