United States Environmental Protection Agency (USEPA) framework for ecological risk assessment (Cont.)

the decision-making, such as the Port of New York and New Jersey

(NY/NJ) Dredged Material Management Plan (DMMP) project.

The authors place an emphasis on the importance of discussion between

risk assessor and risk managers, not only in the planning stages, but

throughout the risk assessment process. Consultation between the risk

manager and risk assessor is especially important at the beginning and

end of the assessment and when the analysis plan is being developed.

b. Problem formulation phase. The first phase of an ecological risk

assessment, as described in this document, is "Problem Formulation."

This phase involves "generating and evaluating preliminary hypotheses

about why ecological effects have occurred, or may occur, from human

activities." The problem formulation serves as the basis for the rest of the

risk assessment. There are basically three products from executing this

step:

(1) Assessment end point(s).

(2) A conceptual model.

(3) An analysis plan.

Assessment end points are "explicit expressions of the actual

environmental value that is to be protected" (USEPA 1992a). These end

points should accurately reflect the ecological concern at the site and

focus the risk assessment.

Once these end points are established, a conceptual model of the

relationship between stressor(s) and the assessment end points can be

developed. The two parts of a conceptual model are a written explanation

of the predicted relationships between the stressor and assessment

endpoint (risk hypotheses) and a diagram representing the relationships

described in the written portion. Justification for the risk hypotheses, as

well as uncertainty associated with the proposed conceptual model should

be mentioned. An example of a source of uncertainty is if multiple

stressors are present at a site. Complex interactions may occur between

these stressors which the risk assessor might not predict in a risk

hypothesis.

The analysis plan in the "Problem formulation" phase should include the

types of data that will be used, the method for data treatment, the

assessment design, and level of confidence needed to make management

decisions based on available data. Different measures to evaluate risk

hypotheses should also be developed, such as measures of effect,

measures of exposure, and measures of ecosystem and receptor

characteristics. Justifications and uncertainties associated with the

analysis plan should also be included.

c. Analysis phase. The purpose of the "Analysis phase" of an ecological risk

assessment is to evaluate the data that have been collected. The

Appendix A Summary of Federal, State, and Regional Guidance