Cefic-lri Programme | European Chemical Industry Council

ECO 55: Assessing the Impact of Sample Collection on Microbial Population and Validity Criteria in the OECD 309 Surface Water Mineralisation Test

Principal Investigator

Dr. Odd Gunnar Brakstad
P.O Box 4762 Torgarden
N-7465 Trondheim
Tel: +47 982 43 447


Deni Ribicic, SINTEF Ocean, Trondheim, Norway, Deni.ribicic@sintef.no

Roman Netzer, SINTEF Ocean, Trondheim, Norway, roman.netzer@sintef.no

David M Brown, Ricardo Energy and Environment, UK, David.brown@ricardo.com

Chris Hughes, Ricardo Energy and Environment, UK, Chris.hughes@ricardo.com

Silke Fiebig, Noack Laboratorien GmbH, Germany, silke.fiebig@noack-lab.de

Dirk Scheerbaum, Noack Laboratorien GmbH, Germany, Dirk.scheerbaum@noack-lab.de


Biodegradation is an important removal pathway for many environmental organic contaminants and is a major determinant of both chemical persistence and chemical exposure. Guidelines for chemical hazard assessment in many regional and global regulations, such as the European chemicals regulation REACH, set thresholds for persistence in environmental compartments (e.g., degradation half-life in water) that need to be quantitatively evaluated. Furthermore, to assess chemical exposure, quantitative estimates of degradation half-lives are also required for environmental media that influence the exposure of target organisms.

This proposed project aims to address several of these specific issues by providing an in-depth assessment of inoculum quality and viability; identifying and validating more relevant reference substances that better reflect the viability of the inoculum, and providing a data-based evaluation of the test robustness and applicability at the new mandated test temperature (9°C in freshwater/12°C C in seawater). In particular, the project will provide improved guidance on surface water sample collection, storage and treatment including a scientifically defensible maximum range between water source sampling and experimental temperature and a suite of quantitative and qualitative tests that further demonstrate inoculum viability and guidance on the test validity criteria which will incorporate detailed information on selected reference chemical biodegradation rates at different temperatures. These improvements will be largely based on the principal theme of characterising the relationship between inoculum diversity, viability and performance of biodegradation with more appropriate new reference substances. Characterization of the bio-physico-chemical water sample diversity may be important to resolve inoculum variations between seasons and during changes during storage (Fuhrman et al., 2015), and at to secure the chance of competent cells in a biodegradation process (e.g. Kowalczyk et al., 2015; Ott et al., 2019). Studies of microbial community succession analyses have also proven important for understanding biodegradation processes (Ribicic et al., 2018a, b.)

The project as outlined in this proposal addresses all the objectives in the RfP and the benefits are expected to be:

1. Addressing changes in inoculum performances and defining acceptance criteria for inoculum sampling and storage/treatment;
2. Identifying reference substances which are appropriate for describing not P and P properties in the OECD309 in freshwater at 12°C and seawater at 9°C;
3. Suggesting criteria for test performance, based on the variability between experimental setups;
4. Preparing a revision of the OECD 309 Guideline based on scientific approach and through interlaboratory testing;
5. A better understanding of the implications in the regulatory context of the required change in test temperature from 20°C to 12°C /freshwater)/9°C (seawater);
6. Improved understanding of applicability domain of OECD 309 with respect to difficult test substances; and
7. Improved robustness of the OECD 309 method for regulatory application.

The project is positioned to take advantage of recent scientific developments in a consistent and coherent way and in line with persistence assessment protection goals. Thus, it is expected, that the outcome of this project will lead to significant improvements to OECD 309 tests and its applicability to a range of substance types.

Timeline: March 2021 > February 2024

LRI funding: 500 190€

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