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Prediction and assessment of the aquatic toxicity of mixtures of chemicals


Surface waters and aquatic organisms are typically exposed to numerous chemicals simultaneously or in sequence. Consequently, hazard assessment in aquatic toxicology has to include rational approaches to predict possible combination effects. Different concepts allow to calculate expected toxicities of mixtures by analysis of concentration response relationships of their components.
The recent report to the Scientific Advisory Committee on Toxicology and Ecotoxicology of the EEC concluded that the concept of concentration addition provides a reasonable basis to predict combined effects of similar acting substances. It should be applied when environmental quality norms are set. However, three questions remain to be answered:
- Which criteria shall be used to classify substances as similar acting?
- Is the concept of concentration addition valid for the prediction of mixture toxicities on more complex than single species levels?
- What are reasonable predictions for combined effects of substances with dissimilar modes of action?
The objectives of the research project PREDICT are:
- to avaluate the potential of quantitative structure activity relationships (QSAR) for the prospective assessment of mixture toxicities and to optimise grouping criteria for pollutants like the list 1 chemicals of directive 76/464/EEC.
- to experimentally validate predictions made from the concept of concentration addition for similar acting substances on a periphyton multispecies community test level, and
- to compare the predictive values of the concepts of ,concentration addition and independent action for multi-component combinations of dissimilar acting substances especially for low, non-significant effect concentrations (EC1%) of the individual constituents.
D. Calamari & M. Vighi (1991),EEC contract B 6612-90-001297
mixture toxicity; prediction; aquatic toxicology.

Funding Scheme

CSC - Cost-sharing contracts


2,Loebener Strasse 2
28344 Bremen

Participants (2)

22B,carl Skottsbergs Gata 22B
413 19 Goeteborg
Università degli Studi di Milano
Via Celoria 2
20133 Milano