A Risk-Management Strategy for PCB-Contaminated Sediments (2001) / Chapter Skim
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Executive Summary
Executive Summary
Pages 1-16
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The identification, quantification, and risk assessments are complicated by these changes in the composition of the PCB mixtures. Numerous bodies of water in the United States contain PCB-contaminated sediments that pose current and potential future risks.
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Many PCB-contaminated sediment sites are large, measured in acres or miles—or in tons of sediment. The sheer volume and mass of PCB-contaminated sediments at these sites makes the application of any remediation option a difficult task.
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· For a few selected sites and using the framework, estimate human and ecological risks associated with each ofthe specified remediation approaches for contaminated sediments containing PCBs in light ofthe availability, costs, and effectiveness of the various approaches. · Where applicable, recommend areas for future research.
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The committee is aware that many readers expect this report to recommend remediation options that are most suitable for reducing the risks associated with PCB-contaminated sediments or on the options that would be most applicable to specific sites. However, the committee strongly believes that making such recommendations is not appropriate, because selection of remediation options must be based on numerous site-specific factors that require evaluation by all affected parties, including local communities and federal and state regulatory agencies.
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The framework developed by the Presidential/Congressional Commission on Risk Assessment and Risk Management provides a good foundation that should be used to assess the broad range of risks associated with PCB-contaminated sediments and the various management options for a site.
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· Pilot scale testing of innovative technologies, such as biodegradation and in situ active treatment caps, to assess their effectiveness and applicability to various sites. · The impact of continuing PCBs releases and global environmental cycling on site-specific risk assessments.
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These risks shouldinclude societal, cultural, and economic impacts as well as human health and ecological risks. The committee found that the risks from PCB-contaminated sediments extend beyond traditional human health and ecological risk assessments as practiced by EPA and other regulatory agencies.
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Because an understanding of the risks posed by PCB-contaminated sediments extends to community values and concerns beyond traditional scientific and technical considerations, the involvement of the affected parties, including the local communities and others who might be affected by the contamination and potential remediation activity, is integral to a successful management process. These affected parties, particularly community groups, should be treated as partners in all stages of the nskmanagement process and have access to the resources necessary to allow their participation in this process.
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Although several of these frameworks are useful for conducting standard health and ecological risk assessments, the committee sought a framework that is inclusive of the broader range of risks that are associated with PCB-contaminated sediments. In addition, the committee sought a framework that would be applicable both to newly identified sites and to sites where the management process is already in progress.
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in recent years, there has been important progress in the scientific understanding ofthe human health and ecological effects of PCBs and their environmental dynamics. Risk assessments based on the original PCB mixture that entered the environment are not sufficient determinants of either the persistence and toxicity of the weathered PCB mixture present in the sediment or the risks to humans and the ecosystem posed by the weathered mixture.
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Traditional human health and ecological risk assessments are based on the analysis of the hazards and the potential for exposures to the chemical in the environment. For this purpose, exposure models can be used to describe all relevant PCB-exposure pathways from the contaminated sediments through the aquatic food web and to specific organisms.
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The development of a successful risk-management strategy at a site requires a combination of technical and nontechnical options. Technical options include source control, dredging, capping, and bioremediation; nontechnical options include natural attenuation and institutional controls (e.g., fish consumption advisories or covenants)
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See Chapter 7 for a description of in situ capping in Hamilton Harbor, Lake Ontario. Other innovative in situ treatments, such as enhanced biological degradation and active treatment caps, are still in the experimental stage and are not yet practical options for remediating PCB-contaminated sediments.
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Therefore, these residual risks must be considered when comparing in situ versus ex situ management options. The optimal risk-management strategy to be chosen for a particular site depends upon site-specific factors and conditions, such as sediment depth, currents, ecosystems, extent of contamination, and cocontaminants, as well as local social, legal, cultural, and economic considerations.
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measure ambient exposures to PCBs to protect human health; (2) monitor PCB releases to water and PCB concentrations in either wild-caught or caged fish and other aquatic organisms in an effort to minimize ecological risks; and (3)
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Short-term and Tong-term assessments ofthe efficacy ofthe risk-management strategy require carefully planned and adequately funded monitoring. Information gathered from assessments of completed and ongoing management projects should be used in the risk assessments, and within the riskmanagement framework, to inform decisions about remediation options and management strategies for other sites.
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