TOXICITY OF PCB-105 IN THE RAT-LIVER - AN ULTRASTRUCTURAL AND BIOCHEMICAL-STUDY

PCB 105 (2,3,3',4,4'-pentachlorobiphenyl) congener was fed to weanling Sprague-Dawley rats in a diet combined with 4% corn oil. The animals were distributed randomly into 10 groups, each of which contained 10 m ales and 10 females, and rats in 8 groups received diets containing PC B at concentrations of 0.05, 0.5, 5, and 50 ppm. Animals in the other 2 groups served as controls. After 13 weeks, the animals were humanely killed and liver samples were obtained and prepared for transmission electron microscopy. Ultrastructural alterations revealed in the hepat ocytes of animals fed the PCB included smooth endoplasmic reticulum pr oliferation, atypical mitochondrial cristae, and augmentation of perox isome numbers (in animals fed high PCB concentrations). Biochemical al terations were estimated by using hepatic microsomal pentoxyresorufin- O-dealkylase (PROD) and ethoxyresorufin-O-deethylase (EROD) activities . A dose-dependent increase in EROD and PROD activities was discovered ; only in the animals of highest PCB dose group, however, was EROD fou nd to be significant (p < .05). Based on our previous work, this conge ner is relatively less toxic than PCB 126, 118, and 153 and is similar in toxicity to 156.