ABSTRACT

The environmental fate of pollutants has been an important issue at least as early as the 1960s, when environmentalists began to raise public consciousness that chemicals may ultimately travel far from their original sources. During the 1970s and 1980s, the Environmental Protection Agency (EPA) and other organizations have supported research designed to better understand, and better predict, the fate of chemicals in the environment. Computational tools, usually computer-based programs or models, were developed to help in predictions. The National Research Council (NRC) in 19833 noted that regulatory actions taken by government agencies such as EPA are based on two separate and distinct, albeit related, processes. The magnitude of this contact is determined by measuring or estimating the amount of an agent available at the exchange boundaries during some specific time. A regulatory agency such as EPA is especially interested in the point of exposure, since it is at this point that risk reduction makes the biggest impact.