BEAM: Bridging effect assessment of mixtures to ecosystem situations and regulation. EU-FP5thEVK1-1999-000552000-2003

Environmental Quality Standards are typically set up for individual chemicals. Nevertheless, natural environments are not exposed to individual chemicals but to complex mixtures of chemicals of various origin (e.g. industry, agriculture, urban sewage). Therefore, there is the need for developing procedures capable to derive Environmental Qual-ity Standards for mixtures of chemicals likely to occur in the environment. The BEAM pro-ject aims at (a) achieving more realism in the analysis of ecosystem multiple exposure and combined effect situations; (b) to provide new mixture toxicity assessment tools and (c) to explore the options for implementation of mixture toxicity assessment into regulation. In this case, a “priority mixture” is not necessarily a mixture of “priority chemicals”, but a combination of chemicals that can be often discharged together by relevant typologies of hu-man activities. Procedures for assessing exposure to mixtures of different origin (agricultural, industrial, urban) are proposed by BEAM. The effects of a mixture can be predicted by the two conceptual models of Concentration Ad-dition (CA), applicable to chemicals with the same mode of action, and Independent Action (IA), applicable to chemicals with different mode of action. Both concepts make use of in-formations on the toxicities of all the individual mixture components, which implies, that the composition of the mixture has to be known qualitatively as well as quantitatively. Experimental results of BEAM, and of the previous project PREDICT show that, when deal-ing with standard single species assays, CA typically predicts a higher mixture toxicity in comparison with IA.