The Life-Cycle Approach The most important information necessary to design EPR relationships is that derived from what has been called a life-cycle approach. It is an attitude and mode of thinking that is expressed in a range of environmental assessment tools, certification systems, labelling programs, directories and databases, and green design initiatives. It is a mentality of valuation that attempts to understand the effects of a product or process from cradle to grave. In the words of Dave Wann (1996, p. 32), it responds to the quintessential question, where does [a product or substance] come from, what does it accomplish, and where is it going? While the concept is simple, this understanding does not come easily, since economic activities are in fact a complex web of relationships. It is not simply a matter of tracing a linear path from material extraction, to processing and manufacturing, to distribution, to installation and use, to disposal. All along the way there are inputs and outputs that must be consideredfor example, in the use stage of building material, the cleaning substances used and the outgassing of chemical constituents. Those substances and constituents themselves likely have multiple impacts. And every kind input or output is different, with a greater or lesser importance in the overall scheme of thing. The life-cycle approach can also be applied to social factors. All along the lifecycle, products and materials create (or eliminate) certain kinds of work; create certain kinds of social, sexual, and organizational relationships; and have specific kinds