Ecological Risk Assessment

The four major components of the ERA paradigm are problem formulation, exposure assessment, effects assessment, and risk characterization (Anderson and Albert 1998; Suter et al. 2000; USEPA 1992, 1997, 1998a). An ERA begins with problem formulation. Activities occurring during this phase include definition of the goals and spatial and temporal scale of the ERA, development of a SCM, selection of endpoint and nonhuman receptor species selection, and preliminary identification of contaminants of potential concern. Exposure assessment and effects assessment follow and can be performed simultaneously. Exposure assessment evaluates the fate, transport, and transformation of chemicals in the environment, and quantitative uptake and intake of these substances in receptor organisms. Effects assessment establishes the relationship between exposure levels and toxic effects in receptors. Risk characterization is the last step in the ERA and is where exposure and toxic effect information are combined to describe the likelihood of adverse effects in receptors. Many of the evaluation criteria needed to evaluate an ERA are identical to those already presented for human health risk assessment (HHRA). This section focuses primarily on the unique aspects of ERAs and does not repeat material covered under HHRA that applies to both subjects.