A note on scrap in the 1992 U.S. input-output tables

Introduction
A key concern of industrial ecology and life cycle analysis is the disposal and recycling of
scrap. One might conclude that the U.S. input-output tables are appropriate tools for analyzing
scrap flows. Duchin, for instance, has suggested using input-output analysis for industrial
ecology, indicating that input-output economics can trace the stocks and flows of energy and
other materials from extraction through production and consumption to recycling or disposal.
Lave and others use input-output tables to design life cycle assessment models for studying
product design, materials use, and recycling strategies, even with the knowledge that these tables
suffer from a lack of comprehensive and detailed data that may never be resolved.
Although input-output tables can offer general guidance about the interdependence of
economic and environmental processes, data reporting by industry and the economic concepts
underlying these tables pose problems for rigorous material flow examinations. This is
especially true for analyzing the output of scrap and scrap flows in the United States and
estimating the amount of scrap that can be recycled. To show how data reporting has affected the
values of scrap in recent input-output tables, this paper focuses on metal scrap generated in
manufacturing. The paper also briefly discusses scrap that is not included in the input-output
tables and some economic concepts that limit the analysis of scrap flows.