Users' Handbook supplement to the Guidance Document for developing and assessing Adverse Outcome Pathways

This document is a supplement to the Guidance Document for developing and assessing Adverse Outcome Pathways (AOPs). It provides focused and practical instructions for both AOP developers and reviewers and is intended to assist in identifying, organising and evaluating critical information on key events (KEs) as well as linkages between KEs within the AOP (i.e. AOP development).  It also provides explicit guidance on how to assess the weight of evidence (WoE) supporting the overall AOP and its relevance for life stage, sex and taxonomy (i.e. AOP evaluation). This handbook is not intended to provide a review or summary of the literature informing the AOP concept. Instead, it focuses on practical aspects of AOP development and assessment.It has been developed by a subgroup of the OECD Extended Advisory Group for Molecular Screening and Toxicogenomics (EAGMST).