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In this project, we intend to investigate two hypotheses that should (i) help better understand the value and information content of the existing OECD 308 protocol, and (ii) help 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).
Mark Honti and Kathrin Fenner. Deriving persistence indicators from regulatory watersediment studies – Opportunities and limitations in OECD 308 data. Environ Sci Technol. 2015 May 19;49(10):5879-86.
Mark Honti, Stefa, Hahn, Dieter Hennecke, Thomas Junker, Prasit Shrestha, Kathrin Fenner. Bridging across OECD 308 and 309 Data in Search of a Robust Biotransformation Indicator. Environ Sci Technol. 2016 Jul 5;50(13):6865-72.
Prasit Shrestha, Thomas Junker, Kathrin Fenner, Stefan Hahn, Mark Honti, Rani Bakkour, Cecilia Diaz, Dieter Hennecke. Simulation Studies to Explore Biodegradation in Water-Sediment Systems: From OECD 308 to OECD 309. Environ Sci Technol. 2016 Jul 5;50(13):6856-64.
Kathrin Fenner. Developing improved strategies to assess chemical persistence at the water-sediment interface. Cefic-LRI 16th Annual Workshop, November 2014, Brussels, Belgium.
Caren Rauert, Sabine Duquesne, Georgia Hermann, Carsta Hufenbach, Ulrich Joehncke, Anja Kehrer, Michael Neumann, Ines Prutz, Jens Schoenfeld, Astrid Wiermann, Karen Willhaus, Janina Woeltjen. PBT-Assessment: The need for a harmonised guidance across regulations – assessment of persistence. SETAC Europe 22nd Annual Meeting, May 2012, Berlin, Germany.
Szegedi Krisztian, Gottesbüren Bernhard. What is persistence? Seeking for a practical interpretation for regulatory practice. SETAC Europe 22nd Annual Meeting, May 2012, Berlin, Germany.
Jon F. Ericson.Water-Sediment Biodegradation: Challenges in Modeling and Screening for Pharmaceutical Transformation Products. SETAC Europe 22nd Annual Meeting, May 2012, Berlin, Germany.
Kathrin Fenner, Thomas Junker, Dieter Hennecke. Persistence testing at the sediment-water interface: Too much effort for too little data? 14th Cefic-LRI Annual Workshop, November 2012, Brussels, Belgium.
Dieter Hennecke, Angela Bauer, Shresta Prasith, Thomas Junker, Kathrin Fenner. Improved test system to determine chemical degradation in laboratory water/sediment systems – experimental results. SETAC Europe 24th Annual Meeting, May 2014, Basel, Switzerland.
Cecilia Diaz, Dieter Hennecke, Kathrin Fenner, Thomas Junker. New approach for active biomass measurement and dynamics of bacterial communities in sediment. SETAC Europe 24th Annual Meeting, May 2014, Basel, Switzerland.
Mark Honti, Kathrin Fenner. Estimating transformation rate constants from OECD 308 data – opportunities and limitations of existing data. SETAC Europe 24th Annual Meeting, May 2014, Basel, Switzerland.
Thomas Junker, Elena Heusner, Daniel Gilberg, Pedro Ferreira, Jörg Römbke, Werner Gräf, Dieter Hennecke, Kathrin Fenner. Biodegration of selected compounds in different water-sediment-systems – water-sediment screening tool (WSST) vs. simulation studies. SETAC Europe 24th Annual Meeting, May 2014, Basel, Switzerland.