Waste Transformer Oil and PCB Toxicity to Rainbow Trout

Abstract

Young rainbow trout Salmo gairdneri (starting age, 17 d) were exposed to nominal concentrations of 0, 0.38, 0.75, 1.5, 3.0, and 6.0 μg/L total polychlorinated biphenyls (PCBs) for 90 d, then held in fresh water for 60 d. Sources of PCBs were (1) waste transformer oil containing various hydrocarbons plus a 1:2 ratio of Aroclors 1254 and 1260, and (2) pure technical PCBs of the same Aroclor ratio as that in the transformer oil. Survival of fish was much lower in transformer oil than in technical PCBs at day 90. Growth was reduced at day 30 by the transformer oil, but not until day 90 at the highest concentration of technical PCBs. Fin erosion was severe and vertebra integrity was reduced in fish exposed to transformer oil but not in fish exposed to technical PCBs. Abnormal swimming behavior of fish exposed to transformer oil was attributed to reduced volume of the swim bladder. Exposures to transformer oil decreased hematocrit, and increased serum cortisol to twice that of controls and of fish exposed to technical PCBs. Exposure to either PCB source increased disease resistance of fish to flush (external) challenges of the bacterium Yersinia ruckeri, but intraperitoneal injection of Y. ruckeri caused faster mortality of fish exposed to transformer oil than of control fish or fish exposed to technical PCBs. All routes of disease exposure should be considered in contaminant-disease interactions. Disease susceptibility or any clinical endpoints measured were never more sensitive indicators of contaminant stress than those endpoints normally examined (growth and survival) in chronic toxicity studies. Because fish took up more PCBs from the technical solutions than from transformer oil, presumably due to petroleum hydrocarbons in transformer oil, environmental assessments of PCBs should include testing the form of the material that may enter the environment.