摘要: Material flows of heavy metals and other toxic chemicals are of great concern for companies, regulators, researchers and society at large. Understanding how and why we use these toxic chemicals can help us to use them more efficiently. In this thesis I develop a mixed-unit, input-output life-cycle assessment model (MUIO-LCA) capable of tracking cadmium, lead, nickel, and zinc flows among roughly 500 sectors of the US economy.Flows of cadmium, lead, nickel and zinc commodities are modeled using data provided by the US Geological Survey (USGS) by adding sectors to national input-output accounts developed by the US Bureau of Economic Analysis (BEA). First an aggregate, summary level model based on the BEA 12 by 12 sector monetary inputoutput tables is introduced and used to explain the method. Then a detailed model is constructed by augmenting the detailed BEA 1997 Benchmark Input-Output …