Toxicity of PCB 156 in the rat liver: an ultrastructural and biochemical study.

PCB 156 (2,3,3',4,4',5-hexachlorobiphenyl) congener was given to weanling Sprague-Dawley rats in diets prepared by mixing it in 4% corn oil. The animals were placed in eight groups, each comprising 10 males or females and received diets that contained 0.01, 0.1, 1, 10 ppm PCB; in addition, two control groups of rats of each gender were given diets mixed with corn oil. Thirteen weeks after commencement of dosing, animals were euthanized and liver specimens were harvested and prepared for transmission electron microscopy. Hepatocyte architectural alterations comprised augmentation of smooth reticulum profiles and mitochondria with unorthodox cristae in animals regardless of gender from 1 and 10 ppm groups. Hepatic microsomal aminopyrine-N-demethylase was elevated significantly in both genders at highest (10 ppm) congener concentration. Based on our previous work, PCB 156 is estimated to be more toxic than PCB 153 or 28 in terms of liver morphologic expressions.