A case study applying pathway-oriented thinking to problem formulation for planning a systematic review.

•We developed a conceptual model to guide problem formulation of a systematic review.•The model helps framing PECO questions in a broad chemical risk assessment context.•The model can serve as a decision and prioritization tool through the entire review.•The model can serve to lay out the methodological foundation of a systematic review.•Pathway-oriented approaches can be easily combined with evidence-based methods.