Toxicology studies with a high-boiling lubricating oil (Esstic 46 CF) used in a hydroelectric generating station

A spill of approximately 1,000 gallons of lubricating oil occurred at Manitoba Hydro's Great Falls generating station on the Winnipeg River. The spill prompted an investigation of the toxicity of this oil to fish. The first test of the Esstic 46 CF oil was a gas chromatographic separation of the components in order to identify hydrocarbons. Results showed that the oil did not contain low-boiling aliphatic or aromatic compounds, therefore, the toxicity was expected to be low. Several oil-in-water emulsions were prepared by mixing oil and water in a blender at different ratios of oil to water, up to a maximum of 500 ppm. Fish were fed this emulsion twice weekly. More than half the fish survived the tests. More fish died at the two highest exposure concentrations. The fish seemed healthy at the end of the exposure with only a small thickening of gills from the two highest oil/water ratios. It was concluded that Esstic 46 CF oil was not acutely toxic to fish under these exposure conditions. Some damage resulted, but the effects were mild compared to other oils. 10 refs., 4 tabs., 4 figs