This is 1 of 4 papers reporting on the results of a SETAC technical workshop titled “The Nexus Between Ecological Risk Assessment and Natural Resource Damage Assessment Under CERCLA: Understanding and Improving the Common Scientific Underpinnings,” held 18–22 August 2008 in Montana, USA, to examine approaches to ecological risk assessment and natural resource damage assessment in US contaminated site cleanup legislation known as the Comprehensive Environmental Response, Compensation, and Liability Act.

A SETAC Technical Workshop titled “The Nexus Between Ecological Risk Assessment and Natural Resource Damage Assessment Under CERCLA: Understanding and Improving the Common Scientific Underpinnings,” was held 18–22 August 2008 in Gregson, Montana, USA, to examine the linkage, nexus, and overlap between ecological risk assessment (ERA) and natural resource damage assessment (NRDA) under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Experts from a broad range of relevant scientific, legal, and policy disciplines convened to 1) ascertain the potential for improved scientific harmonization of the processes of ERA and NRDA; 2) identify where statutory, regulatory, or scientific constraints might exist that would constrain or preclude the harmonization of the 2 processes; 3) determine approaches that might overcome these constraints; and 4) recommend research or potential changes in regulatory policies that might serve to improve both processes. This is the introduction to a series of 3 papers that describe the findings and conclusions of this workshop. Although unanimity was not achieved on all technical, legal, or policy questions posed to the participants, some consensus areas did arise. First, there appear to be few if any legal constraints to using the environmental data collected for ERA or NRDA for both processes. Second, although it is important to recognize and preserve the distinctions between ERA and NRDA, opportunities for data sharing exist, particularly for the characterization of environmental exposures and derivation of ecotoxicological information. Thus, effective coordination is not precluded by the underlying science. Where a cooperative, interactive process is involved among the response agencies, the natural resource trustees, and the responsible party(s), technical, legal or regulatory constraints can be minimized. Finally, one approach that might enhance the potential applicability of data collected for the ERA is to consider ecosystem services in the development of assessment endpoints. These points are explained in greater detail in the series of papers published herein.

This is 1 of 4 papers reporting on the results of a SETAC technical workshop titled “The Nexus between Ecological Risk Assessment and Natural Resource Damage Assessment under CERCLA: Understanding and Improving the Common Scientific Underpinnings,” held 18–22 August 2008 in Montana, USA, to examine approaches to ecological risk assessment and natural resource damage assessment in US contaminated site cleanup legislation known as the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA).

Hazardous site management in the United States includes remediation of contaminated environmental media and restoration of injured natural resources. Site remediation decisions are informed by ecological risk assessment (ERA), whereas restoration and compensation decisions are informed by the natural resource damage assessment (NRDA) process. Despite similarities in many of their data needs and the advantages of more closely linking their analyses, ERA and NRDA have been conducted largely independently of one another. This is the 4th in a series of papers reporting the results of a recent workshop that explored how ERA and NRDA data needs and assessment processes could be more closely linked. Our objective is to evaluate the technical underpinnings of recent methods used to translate natural resource injuries into ecological service losses and to propose ways to enhance the usefulness of data obtained in ERAs to the NRDA process. Three aspects are addressed: 1) improving the linkage among ERA assessment endpoints and ecological services evaluated in the NRDA process, 2) enhancing ERA data collection and interpretation approaches to improve translation of ERA measurements in damage assessments, and 3) highlighting methods that can be used to aggregate service losses across contaminants and across natural resources. We propose that ERA and NRDA both would benefit by focusing ecological assessment endpoints on the ecosystem services that correspond most directly to restoration and damage compensation decisions, and we encourage development of generic ecosystem service assessment endpoints for application in hazardous site investigations. To facilitate their use in NRDA, ERA measurements should focus on natural resource species that affect the flow of ecosystem services most directly, should encompass levels of biological organization above organisms, and should be made with the use of experimental designs that support description of responses to contaminants as continuous (as opposed to discrete) variables. Application of a data quality objective process, involving input from ERA and NRDA practitioners and site decision makers alike, can facilitate identification of data collection and analysis approaches that will benefit both assessment processes. Because of their demonstrated relationships to a number of important ecosystem services, we recommend that measures of biodiversity be targeted as key measurement endpoints in ERA to support the translation between risk and service losses. Building from case studies of recent successes, suggestions are offered for aggregating service losses at sites involving combinations of chemicals and multiple natural resource groups. Recognizing that ERA and NRDA are conducted for different purposes, we conclude that their values to environmental decision making can be enhanced by more closely linking their data collection and analysis activities.

This is 1 of 4 papers reporting on the results of a SETAC technical workshop titled “The Nexus Between Ecological Risk Assessment and Natural Resource Damage Assessment Under CERCLA: Understanding and Improving the Common Scientific Underpinnings,” held 18–22 August 2008 in Montana, USA, to examine approaches to ecological risk assessment and natural resource damage assessment in US contaminated site cleanup legislation known as the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA).

The Society of Environmental Toxicology and Chemistry (SETAC) convened an invited workshop (August 2008) to address coordination between ecological risk assessment (ERA) and natural resource damage assessment (NRDA). Although ERA and NRDA activities are performed under a number of statutory and regulatory authorities, the primary focus of the workshop was on ERA and NRDA as currently practiced in the United States under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). This paper presents the findings and conclusions of the Synthesis Work Group, 1 of 3 work groups convened at the workshop. The Synthesis Work Group concluded that the different programmatic objectives and legal requirements of the 2 processes preclude development of a single, integrated ERA/NRDA process. However, although institutional and programmatic impediments exist to integration of the 2 processes, parties are capitalizing on opportunities to coordinate technical and scientific elements of the assessments at a number of locations. Although it is important to recognize and preserve the distinctions between ERA and NRDA, opportunities for data sharing exist, particularly for the characterization of environmental exposures and derivation of ecotoxicological information. Thus, effective coordination is not precluded by the underlying science. Rather, willing participants, accommodating schedules, and recognition of potential efficiencies associated with shared data collection can lead to enhanced coordination and consistency between ERA and NRDA.

This is 1 of 4 papers reporting on the results of an SETAC technical workshop titled “The Nexus Between Ecological Risk Assessment and Natural Resource Damage Assessment Under CERCLA: Understanding and Improving the Common Scientific Underpinnings,” held 18–22 August 2008 in Montana, USA, to examine approaches to ecological risk assessment and natural resource damage assessment in US contaminated site cleanup legislation known as the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA).

Although ecological risk assessments (ERAs) and natural resource damage assessments (NRDAs) are performed under different statutory and regulatory authorities, primarily the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), as currently practiced, the activities typically overlap. ERAs performed as part of the response process (typically by the US Environmental Protection Agency [USEPA]) should be closely coordinated with the natural resource trustees' (trustees') NRDAs. Trustees should actively participate in the early stages of the remedial investigation (RI) and work with USEPA, including the potentially responsible parties (PRPs), when appropriate, to coordinate NRDA data needs with those of the RI. Close coordination can present opportunities to avoid inefficiencies, such as unnecessary resampling or duplicate data gathering, and provide the opportunity to fulfill both process requirements with a few well-designed investigations. Early identification of opportunities for practical combined assessment can save money and time as the restoration process proceeds and facilitate a cooperative resolution of the entire site's CERCLA liability. The Society of Environmental Toxicology and Chemistry (SETAC) convened an invited workshop (August 2008) to address coordination between ERA and NRDA efforts. This paper presents the findings and conclusions of the Framework Work Group, which considered technical issues common to each process, while mindful of the current legal and policy landscape, and developed recommendations for future practice.

There is a growing sense of urgency among scientists and environmental policy-makers concerning the need for improving the scientific foundation supporting international regulations for identifying and evaluating persistent, bioaccumulative, and toxic (PBT) substances and persistent organic pollutants (POPs) in the environment. The current national and international regulations define PBTs and POPs in terms of fairly strict criteria that are based on the state of the science in the late 1970s and early 1980s. Since then, an evolution in the state of the science has produced new insights into PBT substances and an array of new methods to identify PBT chemicals. The development of regulatory criteria has not kept up with the rapid development in environmental chemistry and toxicology, and as a result, scientists often find themselves in the situation where guidance on PBT and POPs criteria is limited and, in some respects, out of date. With this background, a Society of Environmental Toxicology and Chemistry (SETAC) Pellston Workshop brought together experts from academia, government, and industry to reach consensus on the significance of advancements in our understanding of the behavior and potential impact of POPs and PBTs in the environment, the current understanding of the state of the science, as well as recommendations for policy-makers to improve and coordinate national and international regulations on this issue. The workshop builds on the outcome of a previous Pellston workshop, held in 1998, which focused on the evaluation of persistence and long-range transport of organic chemicals in the environment, and is linked to other recent Pellston workshops, among them the Tissue Residue Approach for Toxicity Assessment workshop held in 2007. The results of this workshop are conveyed in a series of 9 articles, published in this issue of Integrated Environmental Assessment and Management, and describe the coordination of science, regulation, and management needed to more effectively achieve a common goal of managing chemicals on our planet.

This article represents 1 of 9 articles generated from a Society of Environmental Toxicology and Chemistry (SETAC) Pellston Workshop entitled Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs, (January 2008, Florida, USA). The workshop objectives were to develop guidance and recommendations on the evaluation of substances fulfilling PBT and POP criteria, using scientific information, such as experimental and monitoring data and computer models.

Environmental persistence is an important property that can enhance the potential of a chemical substance to exert adverse effects and be transported to remote environments. The persistence of organic compounds is governed by the rates at which they are removed by biological and chemical processes, such as biodegradation, hydrolysis, atmospheric oxidation, and photolysis. The persistence workgroup in a recent Society of Environmental Toxicology and Chemistry (SETAC) Pellston workshop (Pensacola, FL, USA, January 2008) focused on evaluating persistence of organic compounds in environmental media (air, water, soil, sediment) in terms of their single-medium degradation half-lives. The primary aim was to provide guidance to authors and reviewers of chemical dossiers for persistent organic pollutants (POPs) and persistent, bioaccumulative, and toxic substances (PBTs) proposed for action. A second objective was to provide a summary of the current state of the science with respect to POP fate assessment. Assessing the persistence of chemical substances in the environment is not straightforward. A common misconception is that, like many chemical properties, environmental persistence is an inherent property of the substance and can be readily measured. In fact, rates of degradation of a substance in the environment are determined by a combination of substance-specific properties and environmental conditions. This article addresses how persistence can be evaluated based on an assortment of supporting information. Special attention is given to several critical issues, including transformation products, nonextractable residues, and treatment of uncertainty and conflicting data as part of a weight-of-evidence assessment.

This paper represents 1 of 9 papers generated from a SETAC Pellston Workshop entitled “Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs,” (January 2008, Florida, USA). The workshop objectives were to develop guidance and recommendations on the evaluation of substances fulfilling PBT and POP criteria, using scientific information such as experimental and monitoring data, and computer models.

For the identification and assessment of persistent, bioaccumulative, and toxic (PBT) chemicals and persistent organic pollutants (POPs), overall persistence (P_ov) and long-range transport potential (LRTP) are important indicators. In this article, we first give an overview of methods to determine P_ov and LRTP and discuss the influence of multimedia partitioning of semivolatile organic chemicals (SOCs) on P_ov and LRTP. Next, we summarize the most important features of various multimedia fate and transport models that can be used to calculate P_ov and LRTP. Complementary to environmental fate models, field data provide important empirical information about the spatial distribution and time trends of SOC concentrations in the environment. We discuss the role of field data in the estimation of P_ov and LRTP and give an overview of important field studies showing the levels and trends of various groups of chemicals in different parts of the world. Then, we address key topics in the field of PBT and POP assessment that require further research, such as the formation of transformation products, the influence of atmospheric aerosols on the degradation and transport of SOCs, and the effect of long-range transport by ocean currents. In addition, we describe the most important types of uncertainty associated with estimates of P_ov and LRTP, which are mainly uncertainty of chemical property data and uncertainty of the design of environmental fate models. Finally, we illustrate the characterization of SOCs in terms of P_ov and LRTP with the example of the consensus model for P_ov and LRTP Tool that is provided by the Organization for Economic Cooperation and Development.

This paper represents 1 of 9 papers generated from a SETAC Pellston Workshop entitled “Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs,” (January 2008, Florida, USA). The workshop objectives were to develop guidance and recommendations on the evaluation of substances fulfilling PBT and POP criteria, using scientific information such as experimental and monitoring data, and computer models.

Mandated efforts to assess chemicals for their potential to bioaccumulate within the environment are increasingly moving into the realm of data inadequacy. Consequently, there is an increasing reliance on predictive tools to complete regulatory requirements in a timely and cost-effective manner. The kinetic processes of absorption, distribution, metabolism, and elimination (ADME) determine the extent to which chemicals accumulate in fish and other biota. Current mathematical models of bioaccumulation implicitly or explicitly consider these ADME processes, but there is a lack of data needed to specify critical model input parameters. This is particularly true for compounds that are metabolized, exhibit restricted diffusion across biological membranes, or do not partition simply to tissue lipid. Here we discuss the potential of in vitro test systems to provide needed data for bioaccumulation modeling efforts. Recent studies demonstrate the utility of these systems and provide a “proof of concept” for the prediction models. Computational methods that predict ADME processes from an evaluation of chemical structure are also described. Most regulatory agencies perform bioaccumulation assessments using a weight-of-evidence approach. A strategy is presented for incorporating predictive methods into this approach. To implement this strategy it is important to understand the “domain of applicability” of both in vitro and structure-based approaches, and the context in which they are applied.

This paper represents 1 of 9 papers generated from a SETAC Pellston Workshop titled “Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs” (January 2008, Florida, USA). The workshop objectives were to develop guidance and recommendations on the evaluation of substances fulfilling PBT and POP criteria, using scientific information such as experimental and monitoring data, as well as computer models.

A primary consideration in the evaluation of chemicals is the potential for substances to be absorbed and retained in an organism's tissues (i.e., bioaccumulated) at concentrations sufficient to pose health concerns. Substances that exhibit properties that enable biomagnification in the food chain (i.e., amplification of tissue concentrations at successive trophic levels) are of particular concern due to the elevated long-term exposures these substances pose to higher trophic organisms, including humans. Historically, biomarkers of in vivo chemical exposure (e.g., eggshell thinning, bill deformities) retrospectively led to the identification of such compounds, which were later categorized as persistent organic pollutants. Today, multiple bioaccumulation metrics are available to quantitatively assess the bioaccumulation potential of new and existing chemicals and identify substances that, upon or before environmental release, may be characterized as persistent organic pollutants. This paper reviews the various in vivo measurement approaches that can be used to assess the bioaccumulation of chemicals in aquatic or terrestrial species using laboratory-exposed, field-deployed, or collected organisms. Important issues associated with laboratory measurements of bioaccumulation include appropriate test species selection, test chemical dosing methods, exposure duration, and chemical and statistical analyses. Measuring bioaccumulation at a particular field site requires consideration of which test species to use and whether to examine natural populations or to use field-deployed populations. Both laboratory and field methods also require reliable determination of chemical concentrations in exposure media of interest (i.e., water, sediment, food or prey, etc.), accumulated body residues, or both. The advantages and disadvantages of various laboratory and field bioaccumulation metrics for assessing biomagnification potential in aquatic or terrestrial food chains are discussed. Guidance is provided on how to consider the uncertainty in these metrics and develop a weight-of-evidence evaluation that supports technically sound and consistent persistent organic pollutant and persistent, bioaccumulative, and toxic chemical identification. Based on the bioaccumulation information shared in 8 draft risk profiles submitted for review under the United Nations Stockholm Convention, recommendations are given for the information that is most critical to aid transparency and consistency in decision making.

This paper represents 1 of 9 papers generated from a SETAC Pellston Workshop entitled “Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs,” (January 2008, Florida, USA). The workshop objectives were to develop guidance and recommendations on the evaluation of substances fulfilling PBT and POP criteria, using scientific information such as experimental and monitoring data, and computer models.

Scientists from academia, industry, and government reviewed current international regulations for the screening of commercial chemicals for bioaccumulation in the context of the current state of bioaccumulation science. On the basis of this review, several recommendations were proposed, including a scientific definition for “bioaccumulative substances,” improved criteria for the characterization of bioaccumulative substances (including the trophic magnification factor and the biomagnification factor), novel methods for measuring and calculating bioaccumulation properties, and a framework for screening commercial chemicals for bioaccumulative substances. The proposed framework for bioaccumulation screening improves current practices by reducing miscategorization, making more effective use of available bioaccumulation data that currently cannot be considered, reducing the need for animal testing, providing simpler and cheaper test protocols for animal studies in case animal studies are necessary, making use of alternative testing strategies, including in vitro and in silico metabolic transformation assays, and providing a scientific foundation for bioaccumulation screening that can act to harmonize bioaccumulation screening among various jurisdictions.

This paper represents 1 of 9 papers generated from a SETAC Pellston Workshop entitled “Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs,” (January 2008, Florida, USA). The workshop objectives were to develop guidance and recommendations on the evaluation of substances fulfilling PBT and POP criteria, using scientific information such as experimental and monitoring data and computer models.

The Stockholm Convention on Persistent Organic Pollutants (POPs) recognized that POPs resist degradation, undergo long-range transport, and accumulate in remote ecosystems. The Stockholm Convention also acknowledged that indigenous communities, particularly in the Arctic, were at risk because of the biomagnification of POPs and contamination of their traditional foods. This recognition was largely based on environmental monitoring data and demonstrates the need to have adequate guidance on data collection and use. Although long-range transport, persistence, and bioaccumulation models are important for screening potential POPs and for assessing human exposure, environmental measurement data are needed to confirm predictions. Indeed the Stockholm Convention (Annex E) requires monitoring data for assessing “exposure in local areas and, in particular, as a result of long-range environmental transport.” However, there is relatively little guidance available on the most appropriate environmental measurement approaches, particularly for new candidate POPs, and on how to create a weight of evidence based on such data. We provide guidance on how to assess existing data that have been generated by monitoring programs and individual studies on the exposure of top predators and humans to candidate or potential POPs, as well as considerations for collecting new additional data. Our overall recommendation for assessing exposure in humans and top predators is to use or obtain direct measurements of the compound of concern from a significantly and uniquely exposed population (indigenous populations, remote populations), as well as data demonstrating biomagnification within food webs and time trends if possible. These data must be from the appropriate sample matrix type, collected and analyzed using accepted methodologies, reviewed for quality assurance, and interpreted correctly in order to be used to assess exposure.

This paper represents 1 of 9 papers generated from a SETAC Pellston Workshop entitled “Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs,” (January 2008, Florida, USA). The workshop objectives were to develop guidance and recommendations on the evaluation of substances fulfilling PBT and POP criteria, using scientific information such as experimental and monitoring data, and computer models.

Fate and exposure modeling has not, thus far, been explicitly used in the risk profile documents prepared for evaluating the significant adverse effect of candidate chemicals for either the Stockholm Convention or the Convention on Long-Range Transboundary Air Pollution. However, we believe models have considerable potential to improve the risk profiles. Fate and exposure models are already used routinely in other similar regulatory applications to inform decisions, and they have been instrumental in building our current understanding of the fate of persistent organic pollutants (POP) and persistent, bioaccumulative, and toxic (PBT) chemicals in the environment. The goal of this publication is to motivate the use of fate and exposure models in preparing risk profiles in the POP assessment procedure by providing strategies for incorporating and using models. The ways that fate and exposure models can be used to improve and inform the development of risk profiles include 1) benchmarking the ratio of exposure and emissions of candidate chemicals to the same ratio for known POPs, thereby opening the possibility of combining this ratio with the relative emissions and relative toxicity to arrive at a measure of relative risk; 2) directly estimating the exposure of the environment, biota, and humans to provide information to complement measurements or where measurements are not available or are limited; 3) to identify the key processes and chemical or environmental parameters that determine the exposure, thereby allowing the effective prioritization of research or measurements to improve the risk profile; and 4) forecasting future time trends, including how quickly exposure levels in remote areas would respond to reductions in emissions. Currently there is no standardized consensus model for use in the risk profile context. Therefore, to choose the appropriate model the risk profile developer must evaluate how appropriate an existing model is for a specific setting and whether the assumptions and input data are relevant in the context of the application. It is possible to have confidence in the predictions of many of the existing models because of their fundamental physical and chemical, mechanistic underpinnings and the extensive work already done to compare model predictions and empirical observations. The working group recommends that modeling tools be applied for benchmarking PBT and POPs according to exposure–emissions relationships and that modeling tools be used to interpret emissions and monitoring data. The further development of models that combine fate, long-range transport, and bioaccumulation should be fostered, especially models that will allow time trends to be scientifically addressed in the risk profile.

This paper represents 1 of 9 papers generated from a SETAC Pellston Workshop titled “Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs” (January 2008, Florida, USA). The workshop objectives were to develop guidance and recommendations on the evaluation of substances fulfilling PBT and POP criteria, using scientific information such as experimental and monitoring data, as well as computer models.

Characterization of “significant adverse ecotoxicological effects” of persistent organic pollutants (POPs) presents particular challenges. In the various international conventions on POPs and persistent, bioaccumulative, and toxic substances, guidance on classification is not detailed and, in some cases, is unclear. This paper focuses on several key issues in relation to selection of assessment endpoints, use of appropriate effect measures, and uncertainty in the face of limited data. Because POPs are persistent and bioaccumulative, measures of effect should be based not on concentrations in environmental matrices but rather on residues in the body of the organism or in tissues that are causally linked to adverse responses. To obtain these data, currently used toxicity testing methods may need to be modified or substantiated by toxicokinetic information to ensure that substances with POP-like properties are adequately characterized. These data can be more easily matched to environmental monitoring measurements of body or tissue residues for the purposes of assessing whether adverse effects occur in the environment. In the face of persistence and accumulation in the food chain, and considering the extent and suitability of available data, a suitable policy on the use of uncertainty factors may need to be applied when making judgments about toxicity. This paper offers guidance that can be used to identify candidate POPs that have the potential to cause significant adverse effects in the ecosystem.

This article summarizes discussions at the SETAC Pellston Workshop on “Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs” and provides an overview of other articles from that workshop that are also published in this issue. Identification of persistent, bioaccumulative, and toxic substances (PBTs) and persistent organic pollutants (POPs) and evaluation of their impact are more complicated than those for other chemicals and remain a challenge. The main reason for this is that PBT substance and POP assessment is associated with higher uncertainty and generally requires more data. However, for some data-rich PBTs and POPs, that identification and assessment of impact are feasible has been clearly demonstrated. New scientific developments and techniques are able to significantly increase the certainty of the various elements of PBT and POP assessment, and the current scientific literature provides many successful and illustrative examples that can be used as methodologies to build on. Applying multiple approaches for assessment is advisable, because it will reduce uncertainty and may increase confidence and improve the quality of decision-making.