Ecological Models for Risk Assessment/Risk Management

The goal of this study is an integrated ecological risk assessment process through the use of models, test data, and other available information that will include all environmental concerns and participants in the risk analysis process. In the regulatory context, ecological models provide a close relationship between risk assessment and management. Our sequential modeling framework is a way of addressing ecological risk with definition and consistency without sacrificing accuracy. It demonstrates the difference between uncertainty and variability and the assumptions about systems, and it links data and the impacts of regulatory concern. Uncertainty and variability are a part of risk analysis and assessment and of the choice/decision process. Assumptions of risk analysis introduce both variability and uncertainty to the alternatives among which regulators must choose. Our method employs two comparable ecological risk assessment models that give two estimates for toxic effects from a chemical of known concentration. The two curves resulting from the models delineate areas on a graph that indicate acceptable, uncertain, and unacceptable levels of effect. These predictions are based on the probability of an adverse effect defined by a critical risk level set to reflect a concern level. The regulator can make a choice based on graphs that show areas of adverse effects on biota, uncertainty about the effects, and small chance of adverse effects. With these methods it is possible to communicate the chance and quality of a risk to the nontechnical regulator. The framework for the models accommodates the transition from simple to complex analysis. When models do not violate the assumptions of the bioassay, they function to meet the functional goals of risk analysis. Our models of systems are based on knowledge of the structure and function of biological communities. The Tripartite Decision Model (TDM) by Anderson and Morison (1988) allows the communication of risk in a graphical form.