Toxicity of PCB 28 in the rat liver: a quantitative ultrastructural study

Polychlorinated biphenyls (PCBs) are persistent environmental contaminants that bioaccumulate in the food chain and thus pose a health risk to both humans and other animals. PCB 28 was administered via the diets to male and female Sprague-Dawley rats for 13 weeks in concentrations of 0.05, 0.5, 5 and 50 ppm. The chemical was mixed in corn oil and animals that served as controls received only corn oil in their diets. Use of transmission electron microscopy and stereology revealed significant (P < 0.05) elevations in the mean volume fraction (VF) of liver smooth reticulum (SER) profiles (5 and 50 ppm groups) in the females. Also, the hepatocytes of the male rats contained a significantly greater baseline VF of SER compared to those of the females. Statistically significant alterations were not detected in VP of mitochondria, rough endoplasmic reticulum, peroxisomes or lipid droplets. We estimated in Sprague-Dawley rats a no observable adverse effect level (NOAEL) of 0.5 ppm for congener 28.