PARENT SESSION

2A - Mixture toxicity
Poster Hall
8:30 AM - Monday, 28 April 2003
Chair: Hermens, J.¹, ¹
Co-chair: Toy, R.², Backhaus, T.³, ^{2 3}

(MOP/62) Predictability of photo-enhanced PAH mixture toxicity.

Grote, Matthias¹, Walter, Helge¹, Altenburger, Rolf¹, ¹ UFZ - Centre for Environmental Research, Dept. for Chemical Ecotoxicology, Leipzig, Germany

ABSTRACT- For the assessment and the prediction of the toxicity of chemical mixtures the concepts of Concentration Addition and Independent Action are proposed. The predictive capability of these concepts has been shown for mixtures of similarly and dissimilarly action substances. Toxicity of PAHs is known to strongly depend on the light conditions in various test systems. Therefore the question is how pronounced this light influence gets with respect to the toxicity of PAH mixtures and whether the latter is predictable despite the complex mechanisms of photo-enhanced toxicity involving photomodification and photosensitisation. In this study, the influence of the light conditions on the algae toxicity of the single PAH compounds is examined. Subsequently the predictive power of the concepts is studied for PAH mixtures. Finally the assessment under realistic environmental light situations is attempted. Simulated sunlight increases the toxicity of most PAHs by one order of magnitude and more compared to standard light conditions. The mixture toxicity also strongly depends on the site specific light exposure. More than one order of magnitude may lie between the toxicity of the same mixture at different light conditions. However, it can be concluded that the concepts for mixture toxicity allow valid predictions for PAH mixtures under different light conditions if the light dependency of the single substance toxicity is taken into account although the metabolism and mode of actions of the single substances are still unclear.

Key words: PAH, mixture toxicity, phototoxicity