In this project, we therefore intend to investigate two hypotheses that should (i) help to better understand the value and information content of the existing OECD 308 protocol, and (ii) help to develop an improved test strategy for assessing persistence in sediment and surface water in a consistent and robust manner.Hypothesis 1:Advanced parameter estimation techniques such as Bayesian inference can be used to quantify uncertainty in parameter estimates derived from OECD 308 data and to incorporate additional knowledge in a transparent manner.Hypothesis 2:To obtain robust degradation data, experiments and data analysis methods need to enable disentangling (reversible and non-reversible) sorption from (bio)degradability, while clearly distinguishing between aerobic or anaerobic conditions.
To investigate hypothesis 1, the following objectives are proposed:
(1) Collation and analysis of existing data from OECD 308 and OECD 309 studies using advanced parameter estimation techniques including Markov-Chain Monte Carlo methods (Gorlitz et al., 2001; Zak et al., 2003) and Bayesian inference (Brun et al., 2001; Boys et al., 2008; Habibi et al., 2007; Purutcuoglu, Wit, 2008; Schenker et al., 2009), and additional knowledge on sorption and biodegradability as available in the literature or from estimation methods.
(2) Based on this analysis, a critical review of the information content of OECD 308 and 309 data, including a comparison of DegT50 and DT50 values against regulatory persistence criteria.
To investigate hypothesis 2, the following objectives are proposed:(3) Conduct, in parallel, OECD 308 and 309 studies- for four substances that characteristically differ in their partitioning behavior (polar, apolar) and in their biodegradability, and that are well characterized in terms of biodegradation;- using the same sediments across all experiments;- focusing on aerobic conditions (bearing in mind uncertainties of OECD 308);
– including a quantification of microbial biomass in the water and sediment phase;
– including a modified version of OECD 308 with a thinner, ideally fully aerobic sediment layer;
– including a modified version of OECD 309 with a higher sediment content;
– including a water-sediment screening tool (modified version of the ready biodegradability test OECD 301C with a sediment layer).
(4) Experimental determination of sorption coefficients (Kd, Koc) for all four substances and sediments.
(5) Analysis of data from all experiments with advanced parameter estimation techniques developed under objective (1), and the experimentally determined information on Kd and biomass concentrations.
(6) Relate results on biodegradability from OECD 308, modified OECD 308, OECD 309, modified OECD 309 and the water-sediment screening tool (modified OECD 301C) to each other and to existing literature data for these substances.
(7) Based on the results of objective (6) suggest an improved, cost-effective test strategy for persistence in the surface water and sediment on the basis of existing test strategies, e.g., the test strategies for biodegradation within the regulation of medicinal products (VICH, 2004; EMEA, 2006), biocides (EC, 1998) or pesticides (FOCUS, 1997).
Bridging across OECD 308 and 309 Data in Search of a Robust Biotransformation Indicator, by Mark Honti, Stefa, Hahn, Dieter Hennecke, Thomas Junker, Prasit Shrestha and Kathrin Fenner, Environmental Science & Technology, 2016
Simulation Studies to Explore Biodegradation in Water-Sediment Systems: From OECD 308 to OECD 309, by Prasit Shrestha, Thomas Junker, Kathrin Fenner, Stefan Hahn, Mark Honti, Rani Bakkour, Cecilia Diaz and Dieter Hennecke, Environmental Science & Technology, 2016
Improved test system to determine chemical degradation in laboratory water/sediment systems - experimental results, by Dieter Hennecke, poster abstract presented at SETAC 2014 Meeting.
New approach for active biomass measurement and dynamics of bacterial communities in sediment, by C. Diaz, poster abstract presented at SETAC 2014 Meeting.
Estimating transformation rate constants from OECD 308 data - opportunities and limitations of existing data, by Mark Honti, poster abstract presented at SETAC 2014 Meeting.
Biodegration of selected compounds in different water-sediment-systems - water-sediment screening tool (WSST) vs. simulation studies, by Thomas Junker, poster abstract presented at SETAC 2014 Meeting.
PBT-Assessment: The need for a harmonised guidance across regulations - assessment of persistence- by Caren Rauert, Sabine Duquesne, Georgia Hermann, Carsta Hufenbach, Ulrich Joehncke, Anja Kehrer, Michael Neumann, Ines Prutz, Jens Schoenfeld, Astrid Wiermann, Karen Willhaus ans Janina Woeltjen, SETAC Berlin, 2012
What is persistence? Seeking for a practical interpretation for regulatory practice by Szegedi K. and Gottesbüren B., SETAC Berlin, 2012
Water-Sediment Biodegradation: Challenges in Modeling and Screening for Pharmaceutical Transformation Products by Jon F. Ericson, SETAC Berlin, 2012
Persistence testing at the sediment-water interface: Too much effort for too little data? by Kathrin Fenner, Thomas Junker and Dieter Hennecke, presented at the 14th Cefic-LRI Annual Workshop
Developing improved strategies to assess chemical persistence at the water-sediment interface, by Kathrin Fenner, presented at the 16th Cefic-LRI Annual Workshop 2014