Toxicity of four oil dispersants to some animals from the Baltic Sea

Four oil dispersants of interest for practical use in the Baltic Sea were tested as regards toxicity to animals from the littoral zone of the same area. The dispersants tested were Corexit 7664, Berol TL-188, Berol TL-198, all water-base dispersants, and BP 1100-X, an oil-base dispersant. Two species of fish, two species of bivalves and two species of crustaceans were tested. Significant differences in toxicity were found between the water-base dispersants at concentrations above 1700 ppm. Below this concentration there were no significant differences. The dispersants contain similar surfactants in similar concentrations, but differ with respect to types and amount of solvent. The observed differences at high concentrations are, therefore, argued to be connected chiefly to differences between these solvents. Differences in toxicity to different animal types were found between the water-base dispersants and the oil-base dispersants. The toxicity of Corexit 7664 was (96h LC₅₀ approximate values): fish, 1000 ppm; bivalves, 2000 ppm; crustaceans, 10,000 ppm. The toxicity order was strikingly reversed for BP 1100-X: crustanceans, 150 ppm; bivalves, 2000 ppm; fish, 10,000 ppm. This difference in toxicity for different animal types is suggested to be connected mainly to differences in the chemical character of the outer layer of the body surface of the animals.