Toxicity of 2,2',4,4',5,5'-hexachlorobiphenyl in the rat liver: an electron microscope study

Morphological effects on the liver of Sprague-Dawley rats administered orally 2,2',4,4',5,5'-hexachlorobiphenyl (PCB), congener #153, were analyzed. Treatment diets were prepared by dissolving the congener in 4% corn oil. Ten animals of either sex in each group were placed on the respective diets that contained 50, 500, 5,000, or 50,000 ppb congener. Ten animals of each sex served as the control that had only the oil added to the diets. Thirteen weeks after the onset of dosing, the animals were euthanized and liver samples were obtained from the animals and prepared for electron microscopy. Animals exposed to the congener showed (in a dose-related manner) a marked increase in smooth endoplasmic reticulum profiles, and in the number of lipid droplets in many parenchymal cells. Mitochondrial abnormalities such as dumbbell shapes, and in others, the cristae that were oriented parallel to the long axis of the organelle were present. The magnitude of morphologic alterations did not reveal gender differences. The results indicate mild hepatotoxicity of the congener in the rat.