Several models, tools and methods have been published in the past 20 years to include bioavailability in risk assessment and several OECD member countries already have developed frameworks and published guidance documents for taking metal specificities into account in environmental risk assessment. The aim of the current guidance is not to replace the aforementioned frameworks or guidance documents, but rather, to provide an overarching framework on how to apply these tools depending on which data are actually available/needed to assess the bioavailability of the metal under scrutiny. Further harmonisation of these approaches and methodology, where appropriate, over the different OECD countries is recommended and could facilitate a more worldwide application and the Mutual Acceptance of Data since using common assessment approaches may help comparing and exchanging data sets, which could result in significant resource savings.