Ecological risk assessment description

The link between the ecological/ecotoxicological risk assessment and the risk management frameworks is demonstrated. The ecological risk assessment consists of seven interactive elements (Fig. 17). The quantitative and descriptive science used to conduct ERA (Table 5) does not answer, in a direct way, the question of what should be done to manage the risk. Science determines adversity, but the public determines acceptability (Fig. 18). But acceptable risk is a highly subjective and relative term. It is time and space-specific and depends upon definitions of quality of life and robustness of the environment. 

It is important to clearly describe and quantitatively estimate the assumptions and uncertainties involved in the evaluation, where possible. Examples include natural variability in ecological characteristics and responses and uncertainties in the test system and extrapolations. The description and analysis of uncertainty in characterization of ecological effects are combined with uncertainty analyses for the other ecological risk assessment elements during risk characterization. 

Another added feature in ecological risk assessments is the risk description component of risk characterization. In this component, the nature and intensity of effects, their spatial and temporal scale, and the potential for ecosystem recovery are all addressed. This component partially serves to identify ways to remedy effects at a site. 

Risk description has two primary elements. The first is the ecological risk summary, which summarizes the results of the risk estimation and uncertainty analysis and assesses confidence in the risk estimates through a discussion of the weight of evidence. The second element is interpretation of ecological significance, which describes the magnitude of the identified risks to the assessment endpoint. 

The major focus of the conceptual model (Figure 2) is the development of a series of working hypotheses regarding how the stressor might affect ecological components of the natural environment (NRC, 1986). The conceptual model also includes descriptions of the ecosystem potentially at risk and the relationship between measurement and assessment endpoints. 

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