This article describes the results of a survey conducted in 2003 on methods used by different member countries within the Organization for Economic Cooperation and Development (OECD) to evaluate persistent and bioaccumulative pesticides. The objectives were to establish the differences in taking persistence (P) and bioaccumulation (B) into account in the decision-making process and to establish the influence of the assessors' subjectivity to data interpretation and data selection. Fifteen countries participated in the survey, which generated a vast amount of information on decision making, risk assessment, risk classification, and data treatment. Survey results indicated clear differences in approaches to the use of P, B, and toxicity (T) information in scientific risk assessment. Using the same data for 2 different pesticides, several OECD member countries responded differently in classifying both substances as P, B, and T. Differences in regulatory decision-making were also apparent because, based on identical classifications, several OECD member countries adopted different decisions on pesticide registration; recommendations were based, with respect to technical guidance, on data handling, training of assessors, and handling of uncertainty in risk assessment.

Decabromodiphenyl (oxide) ether (Deca) is a widely used brominated flame retardant in the United States predominantly in the hard-plastic housings of consumer electronics and in flame-retarded backing on textiles used in furniture. A child-specific exposure assessment of Deca was performed for the US Environmental Protection Agency's Voluntary Children's Chemical Evaluation Program (VCCEP). The VCCEP guidance for a tier 1 exposure assessment requires that a screening-level assessment be conducted using currently available data and conservative assumptions. For Deca, relevant exposure pathways considered were general environmental exposures (e.g., exposures to contaminated soil, dust, air, and food), breast milk exposures, inhalation of Deca-containing particulates in air, and mouthing Deca-containing consumer products. For each of these scenarios, a mid-range and upper estimate of age-appropriate intakes were calculated. The calculated intakes indicate that, despite the uncertainties, children appear to be exposed to Deca at levels at least 1 order of magnitude, with most being several orders of magnitude, below the National Academy of Sciences reference dose for Deca of 4 mg/kg/d. This analysis indicates that, using the available data, current levels of Deca in the United States are unlikely to represent an adverse health risk for children.

This article describes the results of a survey conducted in 2003 on methods used by different member countries within the Organization for Economic Cooperation and Development (OECD) to evaluate persistent and bioaccumulative pesticides. The objectives were to establish the differences in taking persistence (P) and bioaccumulation (B) into account in the decision-making process and to establish the influence of the assessors' subjectivity to data interpretation and data selection. Fifteen countries participated in the survey, which generated a vast amount of information on decision making, risk assessment, risk classification, and data treatment. Survey results indicated clear differences in approaches to the use of P, B, and toxicity (T) information in scientific risk assessment. Using the same data for 2 different pesticides, several OECD member countries responded differently in classifying both substances as P, B, and T. Differences in regulatory decision-making were also apparent because, based on identical classifications, several OECD member countries adopted different decisions on pesticide registration; recommendations were based, with respect to technical guidance, on data handling, training of assessors, and handling of uncertainty in risk assessment.

At the Third International Conference on Remediation of Contaminated Sediments, a panel discussion was held to consider how best to incorporate sediment stability assessment (SSA) results when managing risks at contaminated sediment sites. This remains a challenge to the scientific and regulatory community, especially at sites where large volumes of legacy sediment are present below layers of recent sediment of better quality, and where in-place management may be viable. Use of a suite of empirical and predictive approaches collectively to assess potential risks resulting from bed erosion has emerged as the state-of-the-art approach for SSA, yet current practice lacks consistent guidance for conducting such assessments and for dealing with and communicating implications of uncertainty. The regulatory community lacks a decision-making framework that specifically incorporates SSA results, though it is a consideration in US Environmental Protection Agency (USEPA 2002) Principles for Sediment Management. Practitioners have not consistently communicated SSA results from a risk perspective to the stakeholder community. We believe this combination of factors, especially the inconsistent framing of results in a risk context, has contributed to discounted use of sediment stability information in decision making, fostering application of the precautionary principle, where removal is viewed as a presumed conservative but more expensive approach over in-place management options. We assert that the incorporation of SSA in decision making will be improved through the use of a consistent SSA assessment framework built around the conceptual site model, incorporating multiple lines of evidence detailing the potential impacts of large, low-probability events (e.g., the 100-y storm) on exposure and risk, and the associated uncertainties. Further advocacy of this approach was realized through panel–audience discussion at the conference. The technical methods discussed are not new; rather, it is the synthesis approach emphasized here, which by providing a framework for the systematic evaluation of how SSA is best addressed from site to site, makes the results of SSA efforts more accessible and acceptable to stakeholders and decision makers.

Quantitative prediction of the erodibility of muds and mud–sand mixtures is, at present, seldom possible without resorting to direct measurements, preferably in situ. A variety of devices and protocols have been developed for erosion testing, but a considerable degree of uncertainty remains with regard to the accuracy and comparability of the resulting data. This paper argues that differences in experimental protocols and data analysis procedures are a major contributing factor to uncertainty in estimates of sediment erodibility. In particular, the likelihood of a time-dependent erosion rate response under typical erosion testing conditions means that the time history of applied forcing and the chosen protocols for analyzing and interpreting data directly affect derived erosion parameters. Several straightforward ways to address this problem are suggested, including standardization of experimental design and data analysis protocols, explicit recognition and adoption of appropriate erosion model(s), and allowing for potential time/depth changes in erodibility. Experimentalists should also archive and share erosion-test time series, not just derived parameters, so that data sets may be reanalyzed within a different framework if necessary. An example is presented from an intercomparison experiment between the Virginia Institute of Marine Sciences Sea Carousel and the University of Maryland Center for Environmental Science Microcosm System, carried out in the upper Chesapeake Bay (Maryland, USA) in May 2002. Derived parameters appear to be incompatible when the data are analyzed using different procedures, but real similarities and differences are readily apparent when the data are analyzed using the same procedures.

Confined aquatic disposal (CAD) cells are increasingly becoming the selected option for the management of unacceptably contaminated sediments. CAD cells are selected as the preferred alternative because this approach provides an acceptable compromise when cost, logistics, regulatory acceptance, environmental risk, and perception of various alternatives are considered. This preference for CAD cells often occurs even when other alternatives with similar risk reduction and less cost, such as an open water capping alternative, are considered as options. This paradox is largely a result of subjective factors that affect regulatory acceptance such as public perceptions.

There are many experimental methods currently utilized to measure sediment erodability and stability. When utilizing any of the available methods or devices to characterize erodability, one must understand the inherent uncertainty associated with each technique in relation to the application or expected measurement need. In addition, while some uncertainties are unique to a particular measurement device or technique, other uncertainties arise from variation in sediment conditions or properties. Several widely used devices and techniques are discussed with respect to their uncertainties and applicability for certain measurements. Finally, suggestions will be made on how to reduce uncertainty and manage it in model development.

The application of mathematical models to a sediment stability study is presented, with an emphasis on using models as a component of an effort to develop, refine, and potentially validate a conceptual site model (CSM) for sediment transport at a study site. The utility of mathematical models is discussed, in which the modeling framework consists of linked hydrodynamic, sediment transport, and contaminant fate and transport models. Benefits and drawbacks of empirically based mechanistic models are presented. An approach for integrating modeling analyses into the development, refinement and validation of a CSM is provided. This approach focuses on a phased study that combines modeling and data-based analyses to test hypotheses related to the CSM and sediment stability. Uncertainty in modeling results is a primary concern in sediment stability studies, and issues related to model uncertainty are discussed. Finally, communication of modeling results to stakeholders is addressed.

This paper summarizes discussion among the 7 authors who served on an expert panel at the Third Battelle International Conference on Remediation of Contaminated Sediments held in New Orleans, Louisiana, USA, in January 2005. In this article, the authors review how sediment management decisions are currently made and address the question of how management decisions should be made in the future. It is arguably the case that sediment remediation presents greater challenges and more complexity than traditional land-based clean-ups. Although understanding of these challenges and complexities has grown over the last 25 y, there has been, until recently, relatively little innovation in the approaches used to manage the environmental risks posed by contaminated sediments. New methods that facilitate a more rigorous analysis of the multiple criteria considered in decision making have been developed. These methods, collectively known as multicriteria decision analysis (MCDA), coupled with the use of comparative-risk assessment and cost/benefit analysis, are proposed as an effective, efficient, and credible foundation for evaluating remedy alternatives at contaminated sediment sites.

Management strategies for addressing contaminated sediments can include a wide range of actions, ranging from no action, to the use of engineering controls, to the use of more aggressive, intrusive activities related to removing, containing, or treating sediments because of environmental or navigation considerations. Risk assessment provides a useful foundation for understanding the environmental benefits, residual hazards, and engineering limitations of different remedy alternatives and for identifying or ranking management options. This article, part of a series of panel discussion papers on sediment remediation presented at the Third International Conference on Remediation of Contaminated Sediments held 20–25 January 2005 in New Orleans, Louisiana, USA, reviews 2 types of risk that deserve careful consideration when evaluating remedy alternatives. The evaluation of remedy implementation risks addresses predominantly short-term engineering issues, such as worker and community health and safety, equipment failures, and accident rates. The evaluation of residual risks addresses predominantly longer-term biological and environmental issues, such as ecological recovery, bioaccumulation, and relative changes in exposure and effects to humans, aquatic biota, and wildlife. Understanding the important pathways for contaminant exposure, the human and wildlife populations potentially at risk, and the possible hazards associated with the implementation of different engineering options will contribute to informed decision making with regard to short- and long-term effectiveness, implementability, and potential environmental hazards.

The long-term goal of monitored natural recovery (MNR) is to achieve ecological recovery of biological endpoints in order to protect human and ecological health. Insofar as ecological recovery is affected by surface-sediment–contaminant concentrations, the primary recovery processes for MNR are natural sediment burial and contaminant transformation and weathering to less toxic forms. This paper discusses the overall approach for effective implementation of MNR for contaminated sediment sites. Several lines of evidence that may be used to demonstrate natural recovery processes are summarized, including documentation of source control; evidence of contaminant burial; measurement of surface sediment mixing depths and the active sediment benthic layer; measurement of sediment stability; contaminant transformation and weathering; modeling sediment transport, contaminant transport, and ecological recovery; measuring ecological recovery and long-term risk reduction; knowledge of future plans for use and development of the site; and watershed and institutional controls. In general, some form of natural recovery is expected and should be included as part of a remedy at virtually all contaminated sediment sites. Further, MNR investigations and an understanding of natural recovery processes provide cost-effective information and support the evaluation of more aggressive remedies such as capping, dredging, and the use of novel amendments. The risk of dredging or capping may be greater than the risk of leaving sediments in place at sites where capping or dredging offer little long-term environmental gain but pose significant short-term risks for workers, local communities, and the environment.

As contaminated sediment sites in freshwater and marine environments come under increasing scrutiny, and the importance of these sites with regard to ecological and human health is better understood, the number of contaminated sediment sites requiring risk characterization and management is increasing. Risk reduction must be the long-term goal of all sediment management practices. Risk management strategies in aquatic environments focus on mitigating potential exposure pathways for contaminants that may pose an ecological or human health risk over time. Sediment management practices include dredging (“environmental dredging”), capping, monitored natural recovery, and combinations of these generic response actions. A Remedy Effectiveness Panel was selected to identify and discuss the key issues associated with the performance of these generic response actions for contaminated sediments. The panel convened in New Orleans on 26 January 2005 at Battelle's Third International Conference on the Remediation of Contaminated Sediments and made 3 presentations on response actions to conference attendees followed by an open dialog between attendees and panel members. This article introduces the 3 generic response actions, identifies key topics from the open dialog and presents opinions expressed, and provides a summary and observations.

The European Union has adopted several environmental directives, strategies, recommendations, and agreements that require a shift from local- or regional-based regulations to more ecosystem-based, holistic environmental management. Over the next decade, environmental management in Europe is likely to focus more on biological and ecological conditions rather than physical and chemical conditions, with ecosystem health at the center of regulation and management decision making. Successful implementation of this new ecosystem management and strategic assessment process in Europe will require the integration of regulatory and technical information and extensive collaboration from among European Union member countries, between agencies, and across disciplines to an unprecedented degree. It will also require extensive efforts to adapt current systems of environmental assessment and management to the basin and ecosystem level, across media and habitats, and considering a much broader set of impacts on ecosystem status than is currently addressed in most risk assessments. This will require the understanding, integration, and communication of economic, ecological, hydrological, and other processes across many spatial and temporal scales. This article discusses these challenges and describes some of the research initiatives that will help achieve integrated ecosystem management in Europe.

The selection of appropriate assessment endpoints is a basic element of an ecological risk assessment, especially at regional or watershed scales. Because ecological services often are tied to specific species, the risk to populations is a critical endpoint and feature of ecological risk assessments. The first item is a discussion of the replacement of population-level risk assessment with the construct of a population-scale assessment endpoint. Next, the criteria that are currently used for assessment endpoints are reviewed and evaluated for utility in an ecological risk assessment. Following this examination, assessment endpoints from a number of regional-scale ecological risk assessments are compared. The outcome of this evaluation is that population-scale assessment endpoints are important expressions of the valued components of ecological structures. Finally, a few recommendations for the selection of assessment endpoints at a population scale are listed.

Current uncertainties in our understanding of ecosystems require shifting from optimization-based management to an adaptive management paradigm. Risk managers routinely make suboptimal decisions because they are forced to predict environmental response to different management policies in the face of complex environmental challenges, changing environmental conditions, and even changing social priorities. Rather than force risk managers to make single suboptimal management choices, adaptive management explicitly acknowledges the uncertainties at the time of the decision, providing mechanisms to design and institute a set of more flexible alternatives that can be monitored to gain information and reduce the uncertainties associated with future management decisions. Although adaptive management concepts were introduced more than 20 y ago, their implementation has often been limited or piecemeal, especially in remedial decision making. We believe that viable tools exist for using adaptive management more fully. In this commentary, we propose that an adaptive management approach combined with multicriteria decision analysis techniques would result in a more efficient management decision-making process as well as more effective environmental management strategies. A preliminary framework combining the 2 concepts is proposed for future testing and discussion.