RAISEBIO · Risk assessment and environmental safety affected by compound bio-availability in multiphase environments

Final Activity Report Summary - RAISEBIO (Risk assessment and environmental safety affected by compound bioavailability in multiphase environments)

The RAISEBIO project provided new approaches and advanced concepts for the determination, modelling and control of bioavailability and residue formation of chemical pollutants and environmental compounds, in particular for the analysis of effective concentrations of the compounds governing toxicity or availability for degradation in terrestrial environments. Overall eight research and development fellows were successfully recruited and their theses provided new insights, in particular related to the compound matrix interactions, analysed by two fellows, by assessment of the mobility of the compounds in complex systems. This mobility was driven by the thermodynamic activity and not by the total concentration in the system. In the field of organism compound interactions, also analysed by two fellows, it turned out that bioavailability was not a compound or matrix related property but an overall systems property. For example, the bioavailability of a toxic organic compound was different to organisms that were capable of utilising the compound instead of only being exposed to toxic effects. In addition, microbes provided strategies to enhance bioavailability, for example by transporting the compounds in fungal networks. In the field of organism matrix interactions, which was examined by two fellows, it was shown that extracellular enzymes of microorganisms were strongly affected by the matrix composition resulting in lowered overall activity but with a high stabilisation. The research resulted in a geometrical model accounting for the differential contribution of metabolically active bacteria and pollutants enabling numerical reactive transport modelling in heterogeneous pore networks. In the field of residue formation in soil systems, also analysed by two fellows, it was proven that if biodegradation in soil systems occurred, the formation of non-extractable, i.e. bound, residues could be dominated by biogenic precursor molecules and thus did not contribute to the risk related to parent compound or partly modified metabolites. In addition, general rules for the extrapolation of degradation data from degradation tests in aqueous systems to soil systems were provided, in accordance to the Organisation for Economic Cooperation and Development (OECD) guidelines 301/310, and false formation of residue by fixation of labelled carbon dioxide (CO2) after degradation of the labelled parent compounds were identified. The training operated by excellent scientists and mentors aided by associated international experts within the project resulted in highly experienced environmental scientists, who achieved comprehensive experience in their specific disciplines and a broad overview in related disciplines with certain highly specific training course in cutting edge methods, for example isotope tracer techniques, activity assessment, etc. Overall the successful training in the project resulted in improved expertise, prepared scientists with excellent career options and was the example for the design and implementation of the Helmholtz-Graduate school Higrade (http://www.higrade.ufz.de). In between, all of the fellows were invited to interviews for employment and some of them had already gotten education adequate positions in science and authorities by the time of the project completion. The results of the project significantly improved the knowledge on bioavailability, refined the predictive modelling of bioavailable concentrations in environmental systems and emphasised the role of bioavailability and residue formation issues in setting environmental quality standards in current and future European strategies of risk assessment of anthropogenic chemicals and approval procedures. The outcome of the project was anticipated to be finally laid down in 25 to 30 high ranking publications and to provide the background for establishing acceptable and realistic endpoints for microbial degradation within environmentally sound management options in accordance with the Water Framework Directive. Finally, the results related to biogenic residues were considered to be incorporated in assessment strategies for chemical by the German Environmental Protection Agency (EPA).

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