|
(092) Mixture toxicity analysis of environmental chemicals. Walter, Helge1, Altenburger, Rolf1, Scholze, Martin2, Consolaro, Federica3, Gramatica, Paola3, 1 2 3 ABSTRACT- For the assessment and prediction of the toxicity of chemical mixtures, the pharmacological concept of concentration addition (CA), implying similar action of the mixture components, and the concept of independent action (IA), assuming the chemicals to act independently and in a dissimilar way, are proposed. In the course of the EU supported PREDICT project reference cases could be established demonstrating that these concepts might well be used to predict combination effects of mixtures of chemicals if the mode of action is specific and known, either strictly similarly or strictly dissimilarly acting, respectively. However, environmental exposure situations are often characterised by a multitude of heterogenous chemicals with unknown or unspecific mode of action lacking any classification presupposed by the concepts on mixture toxicity assessment. Additionally environmental factors like pH characterise milieu conditions and may consequently influence the toxicity of environmental chemicals and mixtures thereof. In this study, the EEC priority List 1 (Council Directive 76/464/EEC) was used to select components for mixture experiments. List 1 consists of heterogenous environmental chemicals with mostly unknown or unspecific modes of action. All chemicals were chemometrically classified for maximum structural dissimilarity. Expectations of the toxicity for a mixture with 11 substances at different mixture ratios were calculated allowing for pH influence and compared with experimental results. The applicability of the concepts of CA and IA to assess and predict the toxicity of environmental chemicals will be discussed with respect to pH condition. Key words: mixture toxicity, environmental chemicals, milieu condition |
