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(49-14) Mixture toxicity of marine pollutants. Meyer, Wiebke*,1, Backhaus, Thomas1, Junghans, Marion1, Scholze, Martin1, Vighi, Marco2, Grimme, L.Horst1, 1 University of Bremen, Leobenerstrasse, Bremen, Germany2 University of Milano, Piazza del Scienza 1, Milano, Italy ABSTRACT- Organisms in the marine environment are not only exposed towards single substances, but against a multitude of functionally and structurally heterogeneous chemicals. As the determination of the toxicity of all conceivable mixtures is not feasible, an alternative for the predictive hazard assessment of chemical mixtures may be to predict the expected mixture toxicity from the effects of the single compounds using the concepts of concentration addition or independent action. Concentration addition is generally considered to be valid when dealing with mixtures of similarly acting chemicals. The toxicities of mixtures entirely composed of dissimilarly acting compounds are good predictable by independent action. So far, the power of the two concepts has only been assessed with specifically "designed" mixtures: The selection of mixture components was based on known or estimated mechanisms of action and mixtures were composed of substances either entirely sharing an identical mode of action or having completely different modes of action. Furthermore, the mixture ratio was typically adjusted to the relative toxicity of the components. Here we report on the predictive power of the two aforementioned concepts for mixtures, that shall reflect a typical pollution scenario in the marine environment. The tested mixture was composed of chlorobenzenes, chlorophenols and chloroaliphatics, as well as heavy metals. The marine bacterium Vibrio fischeri was used as the test organism. The results will be discussed with respect to the applicability of concentration addition and independent action as tools for the predictive hazard assessment of environmentally realistic mixtures. Key words: combined effects, prediction of mixture toxicity, marine pollutants, Vibrio fischeri |
