Refinement of biodegradation tests methodologies and the proposed utility of new microbial ecology techniques

• Review of OECD biodegradation tests.
• We identify knowledge gaps regarding chemical biodegradation and highlighted lack of environmental realism.
• We indicate how to better incorporate an understanding of microbiology in laboratory studies in order to reflect processes relevant to the real world.
• Discussion on the potential challenges for industry and regulatory bodies regarding current assessment of chemical persistence.

Society׳s reliance upon chemicals over the last few decades has led to their increased production, application and release into the environment. Determination of chemical persistence is crucial for risk assessment and management of chemicals. Current established OECD biodegradation guidelines enable testing of chemicals under laboratory conditions but with an incomplete consideration of factors that can impact on chemical persistence in the environment. The suite of OECD biodegradation tests do not characterise microbial inoculum and often provide little insight into pathways of degradation. The present review considers limitations with the current OECD biodegradation tests and highlights novel scientific approaches to chemical fate studies. We demonstrate how the incorporation of molecular microbial ecology methods (i.e., ‘omics’) may improve the underlying mechanistic understanding of biodegradation processes, and enable better extrapolation of data from laboratory based test systems to the relevant environment, which would potentially improve chemical risk assessment and decision making. We outline future challenges for relevant stakeholders to modernise OECD biodegradation tests and put the ‘bio’ back into biodegradation.