Quality appraisal of household recycling influences research found evidence was mostly insufficient for drawing conclusions

Research on recycling behaviour and its influences is critical to supporting public policy efforts to mitigate the negative effects of waste. However, recent reviews have raised concerns about the quality of recycling research. Despite this, no previous reviews have conducted quality appraisals. This is partly because validated appraisal tools have typically been developed for intervention reviews in the health/medicine fields, creating difficulties applying to behaviour influence reviews in environmental fields. This update of a previous systematic review aims to fill this gap. We developed and piloted a novel quality appraisal framework tailored to interdisciplinary reviews of influences on recycling behaviours. Application of the novel framework to 118 recycling papers highlighted a lack of strongly-rated evidence, particularly for causal claims and operationalisation of behaviour. Specifically, over 80% of papers contained insufficient causal evidence, while 90% contained insufficient or cautious evidence of influence on actual behaviour. Only four papers (1%) produced strong evidence across both measures, allowing compelling confidence in their conclusions. Lack of quality evidence undermines the ability of remaining papers (and the body of literature as a whole) to draw strong conclusions about what factors have causal influence on actual recycling behaviour. This has implications for how well the field can guide interventions to improve recycling outcomes. To strengthen future research, this review identifies feasible instances of better practice to increase quality of evidence. Implementing such recommendations could increase the field's confidence in what influences household recycling. The quality appraisal framework may also be of interest for other pro-environmental behaviours.