Limitations of multimedia models for use in environmental decision making

The United States currently is engaged in a complex, multi-billion dollar e ffort to cleanup a legacy of both privately- and federally-owned hazardous waste sites. Decisions regarding the best approach for remediation of these sites often are based on the analysis of potential risks to human health a nd the environment. A cornerstone of such analysis is the frequent use of c omputerized multimedia environmental transport models, to evaluate the larg e quantities of information necessary to understand the present and future implications of contamination at a site. One barrier to wide-spread use of this analytical procedure is the view that results obtained using computer models are highly dependent on user input, and therefore, subject to manipu lation. It is widely recognized that for decisions to be both credible and implementable, the public must have confidence in both the scientific basis for judgments involved and the decision processes employed (NRC, 1983). Ou r purpose in this article is to overview the difficulties associated with a pplication of multimedia models to real world problems and the contribution these models can make to technically sound estimates of exposure and risk.