By way of example, Lave has revisited the analysis by Hocking [see Figure 18-7] of the comparative life cycle analyses of paper and polystyrene cups (Lave et al. 1995). The task faced by Hocking-and anyone else attempting a process analysis of this type-is immense because of the vast array of direct and indirect suppliers and inputs associated with every level of the production chain from raw materials to fi nal product. Figure 20-1 is a representation of the narrow boundaries of Hocking’s analysis as determined by Lave. This restricted analysis focused on a limited set of direct suppliers. In contrast, once input-output analysis is brought to this problem, the boundary is signifi cantly wider and is represented in Figure 20-2 . Lave’s conclusions were twofold: (1) while the toxic discharges from all direct suppliers were substantial, indirect suppliers have more than twice the toxic discharges of direct suppliers; and (2) while on a per dollar, or per pound, of output, plastic generates greater toxic discharges than paperboard, on a per cup basis, paperboard generates more toxic waste than plastic. To make this comparison, Lave totaled all toxic releases to air, water, underground, and land in pounds.