Real, as opposed to rhetorical, progress toward improved environmental management in the future is likely to depend increasingly on the availability o f detailed knowledge o f the specific physical and chemical processes that occur in the production and use o f goods. Whether the optimum environ­ mental management strategy is to concentrate on regulation and enforce­ ment-as at present-or to alter the price structure so as to eliminate or com pensate for market failures, as many econom ists would advocate, it quickly becom es apparent that one cannot expect simply to put an absolute stop to all waste discharges that may have a deleterious effect on the environment. The awkward fact is that all materials that are con­ verted to useful goods eventually outlive their usefulness and becom e waste products.1 The same is true o f energy. These are simple consequences o f the basic physical laws o f conservation, even though they seem to be somewhat at odds with the traditional language (at least) o f econom ics, where one speaks o f “final” consumption as though the physical sub­ stances involved actually disappeared. Obviously, they do not.