Waste-Derived Products Need a Contaminant Budget, Not Just a Carbon Footprint

Abstract Waste valorization is increasingly assessed through resource recovery, waste diversion, and carbon benefits, but these metrics may overlook contaminants inherited from waste feedstocks or generated during processing. This viewpoint article proposes contaminant budgeting as a complementary approach to carbon accounting, tracking contaminant inputs and their partitioning among recovered products, residual solids, water, air emissions, and transformed fractions. Cases involving PFAS and microplastics in biosolids illustrate that resource recovery may redistribute contaminants rather than eliminating them. Integrating contaminant budgeting with resource and carbon accounting can strengthen the environmental assessment and sustainability of waste-derived products.