Interactive Effects of Cadmium, Polychlorinated Biphenyls, and Fuel Oil on Experimentally Exposed English Sole (Parophrys vetulus)

Investigation of the interactive effects of representatives of three classes of compounds was performed, using English sole (Parophrys vetulus) as the test organism, juvenile fish were exposed orally to cadmium chloride and Aroclor 1254 (PCB), either independently or simultaneously, for a 4-wk period, followed by exposure to seawater-accommodated No. 2 diesel fuel for 2 wk. Blood was collected for analysis of serum constituents, and tissue samples were examined for histological changes. Hepatocellular necrosis, regeneration, and karyomegaly were observed. Differential lesion prevalences were observed among the exposure groups, with high proportions among cadmium-exposed fish, low proportions among PCB-exposed fish, and intermediate proportions in combination cadmium- plus PCB-exposed fish. Levels of aspartate aminotransferase activity and magnesium in the sera of these groups exhibited similar patterns. Depressed serum calcium levels in both PCB-exposed and cadmium- plus PCB-exposed groups were found after the first week, and lower serum albumin concentrations occurred in all cadmium- and PCB-exposed groups following the third week. Subsequent exposure to No. 2 diesel fuel produced few effects in any of the exposure groups. The observed antagonistic effect of Aroclor 1254 against cadmium toxicity emphasizes the importance of employing multiple as well as single contaminant exposure in toxicity studies.