Further development of simple test systems for the evaluation of potential PBT substances: How to bridge the gap between screening tests and complex studies?

The first aim of the project was to assess whether the existing OECD test guidelines for ready biodegradability of chemicals (OECD test guidelines 301 A–D and 310) can be harmonized. The gained insights were discussed at an international expert workshop in April 2019.

Laboratory experiments were performed for five test substances to verify the impact of enhancements (an extended test duration and an increased test vessel size) on the results of ready biodegradability tests. These modifications of the test procedure are allowed according to the technical guidance documents for chemical safety assessment under REACH, if a compound cannot be classified as non-persistent under environmental conditions based on ready biodegradability test results. In addition, the use of an alternative inoculum (final effluent from a sewage treatment plant) was investigated and so-called combination tests with parallel determination of different endpoints (e.g. O2 consumption, CO2 evolution, DOC removal) were performed. In total, 20 experiments were conducted.

The results of the experiments were compared with results from ready biodegradability tests strictly performed according to the test guidelines. A proposal for an ‘enhanced ready biodegradation test’ guideline was developed. Moreover, it was illustrated how the results from ‘enhanced ready biodegradation tests’ could be used in the context of the persistence assessment under REACH.

For additional information, see the project report:

Gartiser, S., Brunswik-Titze, A., Flach, F., Junker, T. (2023). Further development of screening tests for the evaluation of potential PBT substances. UBA-Texte 10/2023.

Detailed information on the practical testing is provided in the following publication:

Gartiser, S., Brunswik-Titze, A., Flach, F., Junker, T., Sättler, D., Jöhncke, U. (2022). Enhanced ready biodegradability screening tests for the evaluation of potential PBT substances. Science of the Total Environment 833:155134.

Last update: January 2023