Risk Assessment Role in Dredged Material Risk Management Process

Risk Assessment Role in Dredged Material Risk

Management Process

Risk assessment alone cannot compel a decision at a dredged material

management site. In those cases where the dredged material manager chooses to

apply risk assessment, he or she should consider it as part of a larger risk analysis

process which includes risk management. In prior considerations of risk

management, the USACE (1995b) views this process as a function of several

factors: risk and uncertainty, cost, schedule, value of resources protected, regulatory

requirements, political, economic, technical feasibility, environmental justice/equity.

The role of the risk assessment in this general process is to provide realistic

assessments, not hypothetical or highly conservative assessments that provide no

meaningful risk information to decision makers. Within the risk management

process, the risk assessment contributes most readily to the evaluation of

alternatives.

The Framework Document (USEPA/USACE 1992) provides comprehensive

guidance on identifying, screening, and selecting "reasonable" dredged material

disposal alternatives. The primary, although not exclusive, considerations when

evaluating disposal alternatives are effectiveness, implementability, and cost.

Risk Assessment Format

There are numerous program-specific documents which describe the formal

components of a risk assessment and details of conducting assessment within the

constraints of the program. The dredged material manager should recognize that

there are several general components included in risk assessments, based on an

USEPA framework (USEPA 1992a) and recently published USEPA guidelines

USEPA 1998). These components address the initial questions indicated earlier.

The risk assessment process has five general components (Figure 1).

a. Hazard identification/problem formulation. Hazard identification is the

process of determining whether exposure to a contaminant can cause an

increase in the incidence of a particular human health (e.g., cancer, birth

defect, etc.) or ecological (e.g., reproductive, lethal, etc.) effect. In

ecological risk assessment, the selection of receptors begins in this section,

but is a process which will continue into the Exposure Assessment.

b. Exposure assessment. An exposure assessment estimates the magnitude of

actual and/or potential human or ecological exposure to a contaminant of

concern, the frequency and duration of exposure, and the pathways of

exposure for human and ecological receptors. This is the major step in the

development of scenarios, and the decisions made during the exposure

assessment will be critical to the ultimate estimate of risk. To address

concerns of stakeholders, it is important that this aspect of scenario

development be a cooperative effort early in the risk assessment process.

An important component of exposure assessment is the selection of

Chapter 1 Overview of Ecological and Human Health Risk