Fraunhofer Institute for Molecular Biology and Applied Ecology IME
Chemicals of Unknown or Variable composition, Complex reaction products or Biological materials (UVCBs) pose major challenges in their environmental risk assessment, e.g., in the REACH approval framework. The challenges include practical testing, chemical analysis as well as the final assessment of studies.
Fraunhofer IME has long-term experience with difficult-to-test substances such as UVCBs. We have developed streamlined and solution-oriented testing strategies to cope with the various challenges of UVCBs. These solutions are adapted to the individual challenges of all environmental risk assessment study types offered at Fraunhofer IME, including aquatic and terrestrial ecotoxicity, environmental fate, bioaccumulation and accompanying chemical analysis.
Characterization
Information about the composition of a UVCB often is a key to successful and meaningful environmental risk assessment. Fraunhofer IME offers various techniques for structure elucidation such as NMR, suspect and non-target screening via liquid chromatography-high-resolution mass spectrometry (LC-HRMS) or gas chromatography-tandem mass spectrometry (GC-MS/MS). Additionally, physico-chemical parameters such as solubility (OECD test guideline (TG) 105), log KOW (OECD TGs 107, 117, 123), pKa (OECD TG 112), or surface tension can be determined at Fraunhofer IME to further characterize a UVBC.
Inorganic UVCBs or inorganic constituents can further be characterized via ICP-MS, GC-ICP-MS, LC-ICP-MS or ICP-OES.
For polymeric UVCBs, additional methods are available including SEC/GPC-RI, Flow-FFF-MALS-RI-UV, Pyrolysis-GC-MS or DLS.
Application techniques and modified test designs
Especially in the context of chemicals with difficult to test properties like poor water solubility (for aqueous tests) and volatility, Fraunhofer IME has experience with different application techniques like WAF, column generated application, passive dosing and headspace passive dosing.
In particular, for higher tiered biodegradation testing Fraunhofer IME has worked on the development of modified test setup (Shrestha et al., 2019) (Shrestha et al., 2023) for testing hydrophobic and volatile chemicals, Fraunhofer IME together with its partners Fraunhofer ITEM and DTU (Technical university of Denmark) are currently working on a development of an OECD guidance document for biodegradation testing of difficult to test chemicals including UVCB´s, a project funded by ECHA.
Additionally, bioinformatic expertise is available in-house if modelling of e.g. substance properties of UVCB constituents is necessary to choose the test design.
Chemical analysis
Comprehensive and quantitative analytical data is crucial for assessing the meaningfulness of environmental risk assessment studies and is often required by regulatory authorities. To cope with the structural complexity and knowledge gaps of UVCBs, Fraunhofer IME developed streamlined workflows to address the individual challenges of each UVCB and each study design.
The methods available for quantification of UVCBs are for example LC-MS/MS, LC-HRMS, GC-MS/MS, GC-MS, GC-FID, GC-ICP-MS, LC-ICP-MS, ICP-MS or ICP-OES.
Assessment
Ecotoxicologically relevant substances in UVCBs or mixtures thereof can be investigated based on their molecular effects using 3R-compliant biological non-target methods. To this end, guideline tests such as OECD 201, 202, or 236 are combined with non-targeted OMICs methods (transcriptomics, proteomics) to capture and evaluate the molecular fingerprints of potential adverse effects. This applies both to UVCBs as a whole and to their fractions.
For aquatic ecotoxicological studies, Fraunhofer IME developed a concept for categorization of UVCBs to streamline and facilitate chemical analysis, application approaches, and data interpretation (see poster “UVCB Categorization for Ecotoxicity Testing”).
