extent to which materials currently regarded as wastes might be used as raw materials.
We will begin with a brief examination of the total quantities of material circulating through the waste cycles. We will then focus on a series of metals, tracking their flows as wastes and comparing the waste mass and concentration level of recycled wastes, discarded wastes, and virgin raw materials.
Mapping the flows of more than 12 billion tons of industrial and postconsumer waste is a challenging task. Part of the challenge is integrating information from many diverse sources of data. For example, more than a dozen national sources of data on industrial wastes are available (Eisenhauer and Cordes, 1992), but each covers only a portion of industrial waste generation. Each was collected over a different time period and each considers a different subset of waste generators. Despite these difficulties, each of the data sources provides a unique perspective on industrial waste streams and can be useful. The main focus in this paper will be on just a few of these inventories, most notably the National Hazardous Waste Survey and, to a much lesser extent, the Toxic Release Inventory and