Silver emissions and their environmental impacts: a multilevel assessment.

A detailed accounting of environmental releases of silver is presented for the year 1997, based on data from Yale University's Stocks and Flows (STAF) project and other sources. The analysis is carried out for 64 countries, eight regions, and the world. From the chemical composition and receiving media of these different releases, each emission category is assigned an environmental impact score in accordance with the Indiana Relative Chemical Hazard (IRCH) ranking system. Flows are scaled by impact and land area to form an overall semiquantitative assessment of the environmental impact of silver. Of the 64 countries, the United States has the highest gross emissions for nearly all flows to the environment. On a regional basis, Asia is the largest emitter of silver directly to land and water. In major silver-producing countries, tailings tend to have the highest environmental impact of any emissions category; in nonproducing countries, it is dissipation to land (Hong Kong having the highest impact in this category). Globally, more than 13 Gg of silver are emitted annually to the environment, with that in tailings and landfills making up almost three-fourths of the total. The utility of this method for evaluating the environmental impact of other metals is explored.