Organization of Literature

Over 200 articles were selected in the areas of risk assessment, risk management, risk communictation, relationship of risk to regulation, as well as general introductory articles giving the reader a backgound in understanding risk concepts.

The outline of how the articles were organized is shown below.

Risk Assessment will include the phases necessary to characterize a site and the risks the site can present to biologic receptors (including human and ecologic) on and off site. Risk Management will start with the definition of potential options, the process by which an option is selected, the remedy implemented, and stewardship of the site.

Site characterization defines the site and its geological attributes, its contents (structures, contaminants, etc.), its occupants (including non-human), its function, and its relevance to the area and region. Contamination is often a key issue at sites, and the extent and hazardous nature of contaminants, and their pathway to receiving populations/ecologies can influence potential risks, land use options, methods and degree of risk management, and the realistic nature of envisioned end states linked to anticipated land use scenarios.

Once the relevant details and more regional view of a site have been described, it is usually possible to develop a Risk Characterization. This step includes the consideration of whether the toxicants are in a form that is available to enter the receptor (human or ecologic) and be biologically absorbed and active. The type of toxicologic (and epidemiologic) response that is known to occur as a function of the dose received is characterized to describe, as best possible, the degree of risk that might exist for different exposure scenarios. While risks for certain outcomes can be estimated for different exposures, the degree of uncertainty associated with the dose-response estimate also needs to be understood. Other considerations in the Risk Characterization stage include the identification of groups or populations that could be at highest risk – either because of predispositions (genetic, prior disorders, lifestyles, etc.) or because of greater exposures (dietary patterns, etc.). Ecological issues also must be considered, and the issues of endangered species can be important both ecologically and politically. Sentinel responses are either specific biological changes that are characteristic or unique responses to a particular exposure or are early indicators of responses to that exposure. There is a growing interest regarding these types of responses and their role in surveillance and monitoring systems. Finally, there are always issues regarding low (and high) doses – specific for the substance – and whether measurements and estimates of dose and response can be verified and are relevant.

Risk Management. The steps of defining and selecting options, putting in place a remedy, and maintaining stewardship after remedy all fit under this phase. Land use decisions are often influenced by the initial state of risk, realistic land use options, the feasibility of risk reduction remedial goals and remediation options, and the relationship of these factors to both stewardship requirements (and negotiated agreements) and economics. The option selection process includes a balancing of risks that might exist for different groups (workers, public health, ecology) and at different times (present, during remediation, residual risk). An interplay of the noted variables (and others) will influence both land use and remedial option selection. The literature relevant to some aspects of this process is not as robust it is for other steps, since only recently has serious scholarship been focused on this process.

Remedy implementation may include activities aimed at removal of waste, may implement a range of engineering systems, often includes a set of institutional controls, and establishes a plan for needed monitoring, inspections and maintenance. The documentation and subsequent tracking of actions and results requires the establishment of information management systems – which could include mapping to picture changing status of sites and foster communication with stakeholders. Of course, the provision and maintenance of resources requires the establishment of appropriate financial instruments. Adequate stewardship includes the maintenance of institutional and engineering controls as well as adequate information management, monitoring to assess the long term effectiveness of the remedy, and on going risk communication.

Risk Communication. A vast literature exists on risk communication. Out of a long use of relevant publications, we selected two references (Carnes et al, and Chess and Purcell) for initial reading, with full text available in Appendix 3. We focused on actual examples of risk communication as well as the concepts of what constitutes successful risk communication.

Relationship of Risk to Regulation. Literature that relates to the development of a solid risk assessment is, by itself, of potential value for planning purposes. However, the use of risk concepts and information by the public and by the regulatory community is critical to its eventual role in risk management and in the viability of an end state planning model. Therefore, a final, but important, section of the literature search was to identify publications that have addressed the evolving role of risk and risk methods in regulatory policies and applications is the final concept covered by the compendium of articles.

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  • Concepts in Peer Reviewed Literature for a Risk-based End States Cleanup Program