The problem formulation step of a human health or environmental risk assessment seeks to define the scope of the assessment in order to best determine the data, tools and procedures required to complete the evaluation. One outcome of this step is a conceptual model that summarizes the connections between sources or stressors, exposure pathways, human or ecological receptors and toxicological or other risk endpoints.

The Risk Assessment Formulation Tool (RAFT) was developed to help streamline the problem formulation step in the RISK21® framework by providing a fill-in-the-blanks template for a diagrammatic conceptual model and guidance in choosing its contents.

The RAFT is a Microsoft Excel®-based tool that can be used to produce Human Health Risk Assessment (HRA) or Environmental Risk Assessment (ERA) conceptual models. The conceptual model is in the form of a horizontal flow chart that describes the exposure process from source (or stressor) to receptor of concern.