|
2A - Mixture toxicity (MOP/82) mixture toxicity of heavy metals to lemna minor under conditions of simultaneous and sequential exposure. Drost, Wiebke1, Backhaus, Thomas1, Grimme, L. Horst1, 1 Institute of Cellbiology, Biochemistry and Biochemistry, University Bremen, Bremen, Germany ABSTRACT- Risk assessment of toxic chemicals usually focuses on the investigation of pure single compounds although ecosystems are exposed to a multitude of pollutants, either simultaneously or sequentially. Due to the high spatial and temporal variability of the amounts of the individual toxicants, an experimental effect assessment of all conceivable mixtures is not feasible. Predictive approaches using informations on the toxicities of individual compounds may allow an estimation of the overall toxicity of a given chemical mixture. Two models, concentration addition and independent action, can be used for such purpose. Concentration addition is based on the assumption that all components of a mixture share a common site of action. For components acting on different sites of action the independent action concept is used. The presented study investigated the toxicity of heavy metals to the duckweed Lemna minor. The overall mixture toxicities of the heavy metals were determined under conditions of simultaneous and sequential exposure. The predictive power of both models for these situations will be presented and discussed. Key words: mixture toxicity, heavy metal, simultanous, sequential |
