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 is 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 will be discussed at an international expert workshop in 2019.

Laboratory experiments will be performed for a set of selected test substances to verify the impact of ‘enhancements’ (i.e. extended test duration and 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 rated as non-persistent under environmental conditions based on ready biodegradability test results. In addition, the use of an alternative inoculum (e.g. river water) will be investigated and so-called combination tests with parallel determination of different endpoints (e.g. O2 consumption and CO2 evolution) will be performed. In total, approximately 20 tests will be conducted.

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