atmospheric and aquatic transport processes, they are found typically in the greatest concentrations in marine and freshwater sediments near the sources of their environmental release. Most PCBs do not degrade easily in the environment and may persist for years in sediments. Furthermore, PCBs are bioaccumulated by aquatic and terrestrial organisms and thus can enter the food web. Humans and wildlife that consume contaminated organisms, such as fish, can accumulate PCBs in their tissues. Such accumulations are of concern, because they may lead to body burdens of PCBs that could have adverse health effects in humans and wildlife. PCBs can affect not only individual organisms but ultimately whole ecosystems.

The presence of PCBs in sediments might trigger several regulatory actions, such as designation of part of a water body as a hazardous waste site, possible inclusion on the U.S. Environmental Protection Agency’s (EPA’s) National Priorities List (NPL), issuance of a fish consumption advisory for some or all fish species in a water body, and restrictions on permits for navigational dredging of the sediments, among others. Of the 1,230 sites on the NPL, 535 contain PCBs, of which 122 sites have contaminated sediments. As of 1998, there were 679 fish consumption advisories for PCBs in the United States (J.Bigler, EPA, personal commun., October 12, 2000). Many NPL sites are quite large and have “hot spots” where PCB concentrations are considerably higher than those in other parts of the site. Such sites include the upper Hudson River, Commencement Bay in Washington, and New Bedford Harbor in Massachusetts.

Legitimate concerns over the potential health, environmental, economic, and social impacts of the various strategies for managing PCB-contaminated sediments have led to extensive debate among industry, regulators, communities, and other interested or affected parties on the best course of action for dealing with these sediments. The debate often focuses on certain questions: What are the immediate and the long-term (decades) human health and ecological risks associated with PCB concentrations found in various parts of a specific ecosystem? If PCB concentrations must be reduced, how much reduction is needed, and what is the best approach to achieve the reduction? What are the immediate and the long-term human health and ecological risks associated with the various processes to reduce PCB concentrations both locally and for a wider geographic area? What are the economic and social costs of various options?

THE COMMITTEE’S TASK

The challenges of managing PCB-contaminated sediments have drawn the attention of the U.S. Congress. In 1998, the U.S. House of Representatives



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