to reduce the volume of existing contaminated sediment, a goal that does not necessarily reduce risk.

Therefore, in consideration of what the committee heard during the public sessions, particularly with respect to the need for a collaborative and iterative process to manage a broad range of risk, the committee determined that a framework was necessary to provide a consistent structure to assess the risks from PCB contamination and the risks associated with the various technologies and options that might be used to clean up a site. The framework should be risk-based and applicable to a variety of sites, where risks can range from obvious and short term to less evident and decades long. The framework should also be able to build upon many of the methods and procedures developed by the regulatory agencies, but it should go beyond the traditional human-health and ecological risk-assessment processes, such as those in the EPA’s Risk Assessment Guidance for Superfund (RAGS) (EPA 1989).

As discussed in Chapter 1, the Committee on Remediation of PCB-Contaminated Sediments was given the task of selecting and refining such a scientific risk-based framework for assessing the remediation alternatives for exposure of humans and other organisms to PCBs in contaminated sediments.

RISK-MANAGEMENT FRAMEWORK

PCB-contaminated sediments threaten ecosystems, marine resources, and human health and can have significant impacts on affected communities. Any decision regarding the specific choice of a risk management strategy for a contaminated sediment site must be based on careful consideration of the advantages and disadvantages of available options and a balancing of the various risks, costs, and benefits associated with each option.

The committee appreciates that more than one risk-assessment and risk-management framework has been developed and can be effective in assessing and managing a variety of activities (e.g., NRC 1983, 1994, 1996; EPA 1998b, 1999). Furthermore, some of these assessment procedures are mandated by various laws and regulations. The committee reviewed several of these frameworks and found that, although useful for specific situations, generally they are not applicable to the variety of sites and situations where PCB-contaminated sediments are an issue. One of the earliest risk-assessment frameworks was that developed by the National Research Council (NRC) in 1983 in Risk Assessment in the Federal Government: Managing the Process. This risk-assessment and risk-management paradigm (Figure 3–1) institutionalized risk assessment for many government regulatory agencies. This paradigm begins with field and laboratory research and data collection on health effects, extrapolation methods, exposure estimates, and population characterization. These



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