A socio-Economic Assessment of Metal Use as It Relates to the Planning of a Metal Recycling System

Abstract

In this papaer, a new paradigm of socio-academic study of the relationship between utility of metals and the hazards associated with their disposal has been proposed. An attempt to establish this theory is to be made in the following study which will be referred to as a "socio-metallic study" and conducted under the following heading : 1) A study of the socio-economic assessment of metal use. 2) A study of the social cost of discarded metals. 3) A study of the optimal design of a metal recycling system. The characteristics of the change of lead use structure in Japan relating to waste problems after the Second World War has been summarized as follows : 1) The useful life of lead has been shortened from more than 11 years in 1955 to about 5.5 years in 1980. 2) The demand for lead for various unrecyclable uses amounts to 35% of the total demand for lead in 1980, increasing from 20% in 1955. 3) The total amounts of lead having a potential environmental impact for the period from 1960 to 1978 is estimated 1, 194, 000 tons by a new prediction method of the amount of waste using Duhamel integration. The result of the survey on the composition and heavy metals content of wastes in the sampled incineration factory show that the total amount of each heavy metal in the above wastes is as follows : cadmium, 2.2kg/day ; copper, 81kg/day ; lead, 59kg/day ; and zinc, 119kg/bay. Cadmium is mainly derived from plastics, copper from metal goods lead from mixed unrecognizable wastes, plastics, and glass, and zinc from mixed unrecognizable wastes, plastics and metal goods. The contribution rate of heavy metals to the above wastes is influenced by their respective uses. Thefore, the program of use and disuse of metals should be prepared carefully. The amount of discharged and dissipated lead into the environment is estimated about 2, 171g/year per capita from the above survey result. This value approximates roughly the estimated amount of discharged lead by using the new prediction method mentioned above. Therefore, it can be concluded that the new predction method is appropriate for the application of a materials balance approach to waste problems. The increased amounts of used metals have involved many types of social cost in the field of the environment. The estimated social cost (prevention cost) derived from metal use is 25.5yen/year per capita. However, the estimated social loss derived from dissipated metal, the economic value of which it is very difficult to estimate in monetary terms, seems to be much more than the social cost estimated above. Therefore, if we were to collect such dissipated metal and treat them adequately, the total cost of metal management would be too high to estimate. This fact suggests we should draw up a recycling plan based upon the estimate of both ex ante social cost and ex post social cost.