Framework for Human Health Risk Assessment

The views expressed in this paper are those of the authors and do not necessarily reflect the views or policies of the USEPA. The U.S. Government has the right to retain a nonexclusive royalty-free license in and to any copyright covering this article. The U.S. Environmental Protection Agency has recognized the need to develop a framework for human health risk assessment that puts a perspective on the approaches in practice throughout the Agency. In response, the USEPA's Risk Assessment Forum has begun the process of developing a framework for human health risk assessment. This paper provides some additional background to the previous review of the framework efforts and notes the Agency's extramural efforts to begin the process of integrating and harmonizing risk assessment approaches for all human health endpoints.     

Framework for Human Health Risk Assessment

The U.S. Environmental Protection Agency has recognized the need to develop a framework for human health risk assessment that puts a perspective on the approaches in practice throughout the Agency. In response, the Agency's Risk Assessment Forum has begun the long-term process of developing a framework for human health risk assessment. The framework will be a communication piece that will lay out the scientific basis, principles, and policy choices underlying past and current risk assessment approaches and will provide recommendations for integrating/harmonizing risk assessment methodologies for all human health endpoints.     

Can Ecological Receptors Really Be At Risk?

Birds and mammals at hazardous waste sites are routinely modeled for their potential to display harmful toxicological effects as a result of their exposures to contaminants. Although standard desktop measures of the potential for toxicological endpoints to be reached commonly suggest that these receptors should be at ill health (e.g., experiencing reproductive impairment), evidence is lacking from the field that such effects are occurring. Plausibly, the excessive time lapse (frequently several decades) from contaminant release event to site ecological risk assessment, can explain the disconnect. Aided by their relatively brief life spans, these modeled ecological receptors have produced multiple generations to date and may have outbred the chemical stress. In light of the absence of observed health impacts in birds and mammals since the creation of the U.S. Environmental Protection Agency's Superfund program, there may be no need to continue assessing the health of these species. Additionally, given the very few reported instances of observed health effects at terrestrial sites, it may be prudent to replace risk assessment with impact assessment as the essence of a revamped ecological assessment process.     

Indicators for Human and Ecological Risk Assessment: A U.S. Environmental Protection Agency Perspective

Assessment of risk to public health or environmental resources requires competent characterization of stressors and corresponding effects. Because of the complexity of most stressor-response relationships, it is impossible to completely characterize all the variables, so a select set of measurements is made to reflect the most critical components. Such measurements, or indicators, are included in monitoring programs to estimate trend, stressor source, or magnitude of effects and lead to thresholds for management action or restoration. Although a wide variety of programs and program objectives exists, there are some common challenges for indicator development, including a strong link to management actions. Indicator measurements used in U.S. Environmental Protection Agency (USEPA) risk assessment activities must stem from collaboration among managers, risk assessors, scientists and stakeholders. The primary objective of the USEPA's Fifth Symposium of the National Health and Ecological Effects Research Laboratory was to improve health and ecological risk assessment through dedicated sessions that maximized interaction and discussion among these groups. Existing measurements were challenged for appropriateness, efficiency and scientific validity. Emerging science was explored for greater understanding, better interpretation, and improved methodology. A secondary objective was to uncover and exploit common indicators and supporting data for human health and ecological models.     

Overview: The future of ecological risk assessment

Risk assessment has become a popular tool to help solve ecological problems. The basic concept is not new and has been applied to diverse decision problems. The application to ecological problems, especially complex ecological problems, is fairly recent and controversial. The fundamental and most important elements of the controversy revolve around two key points: (1) a person's implicit “world view;”; and (2) the assumption of who (or what) receives the benefits and who (or what) pays the costs for ecological “decisions.”; A person's attitude toward risk assessment is, at least implicitly, defined by a world view. It is this world view that defines how each of us reacts to risk assessment applied to ecological problems. How the question of benefits and costs is defined also defines the appropriate use, if any, of ecological risk assessment. The future of ecological risk assessment will almost certainly follow the course of other analytical tools: enthusiastic support, rapid, widespread adoption and use; then disillusionment and rapid replacement with newer approaches, but with continued use for a greatly constrained set of ecological issues.     

The Intersection of Independent Lies: Increasing Realism in Ecological Risk Assessment

In 1966, Levins presented a philosophical discussion on making inference about populations using clusters of models. In this article we provide an overview of model inference in ecological risk assessment, discuss the benefits and trade-offs of increasing model realism, show the similarities and differences between Levins' model clusters and those used in ecological risk assessment, and present how risk assessment models can incorporate Levins' ideas of truth through independent lies. Two aspects of Levins' philosophy are directly relevant to risk assessment. First, confidence in our interpretation of risk is increased when multiple risk assessments yield similar qualitative results. Second, model clusters should be evaluated to determine if they maximize precision, generality, or realism or a mix of the three. In the later case, the evaluation of each model will differ depending on whether it is more general, precise, or realistic relative to the other models used. We conclude that risk assessments can be strengthened using Levins' idea, but that Levins' caution that model outcome should not be mistaken for truth is still applicable.     

Integration of Environmental Indicators for the U.S. Mid-Atlantic Region

The Mid-Atlantic Integrated Assessment (MAIA) Project began in 1994 as a partnership between the U.S. Environmental Protection Agency's (USEPA's) Region III Office and the Office of Research and Development. This multiyear initiative was envisioned to: (1) improve the quality of environmental science and promote the use of sound science in environmental decision-making; (2) characterize the condition of ecological resources; and (3) report on the progress toward environmental goals through a series of State-of-the-Region reports. These reports are produced using a coordinated, integrated approach that is carried out at four levels of increasing sophistication and complexity. Results indicate that the condition of individual ecological resources can be determined with existing indicators. The results from MAIA are being communicated in a manner that is understood by environmental managers as evidenced by their use in environmental management decision-making. The application of ecological indicators needs to be coupled with an appropriate sampling design to ensure that the measurements made in the environment can be used to address the relevant questions. Multiresource indicators, those that synthesize information on individual ecological resources, are of high priority for research     

Genomics: Applications,Challenges, and Opportunities for the U.S. Environmental Protection Agency

Genomics information has great potential to enhance assessment of risks to human health and the environment. Although understanding genomic responses with respect to adverse ecological and human health outcomes is not, as yet, established, it is important to consider the likely future impacts of genomics technologies on risk assessment and decision-making. Four areas are identified as those likely to be influenced by the generation of genomics information within, and the submission of such information to, the U.S. Environmental Protection Agency (USEPA): risk assessment, prioritization of contaminants and contaminated sites, monitoring, and reporting provisions. For each of these risk assessment and regulatory applications, representative activities are presented to illustrate the application. Three major challenges for the USEPA associated with genomics are also identified in the areas of research, technical development, and capacity. The USEPA's initial activities to address these challenges are discussed. The Agency recognizes it must be prepared to use genomics information, and that many scientific, policy, ethical, and legal concerns will need to be addressed. The USEPA also recognizes it is essential to continue to collaborate with other federal agencies, academia, the regulated community, and other stakeholders in order to benefit from ongoing advances in genomics in the wider scientific and regulatory communities.     

城市生态风险评价研究进展

随着城市化发展和城市人居环境的恶化,城市生态风险越来越受到关注,但尚缺乏有关城市生态风险评价的深入系统研究.本文依据城市生态学原理及生态风险评价框架从驱动力、风险源、风险受体与评价终点,以及生态风险综合评价方法等方面对城市生态风险评价研究进行综述.指出城市经济社会活动类型与程度是城市生态风险产生的主要驱动力;城市生态系统不同等级功能实体和城市整体是城市生态风险评价中的风险受体;城市生态风险评价终点包括城市生态系统结构、过程、功能要素,以及城市整体水平的性质和功能变化;耦合了社会经济需求的生态系统模型是城市生态风险评价方法的发展方向.未来城市生态风险评价研究应明确生态风险管理具体目标,确定综合性评价终点,建立多指标评价体系和综合评价方法.     

A Regional Multiple Stressor Risk Assessment of the Codorus Creek Watershed Applying the Relative Risk Model

The relative risk model (RRM) used in Port Valdez, AK, and in Oregon's Willamette/McKenzie Watershed was applied to the Codorus Creek Watershed in south central Pennsylvania. The assessment evaluated the relative risk model for its applicability for ranking ecological risks within the Codorus Creek Watershed. The Codorus Creek Watershed approach included ranking stressors and habitats for regions within the watershed. Geographical Information Systems were vital in compiling and comparing stressor and habitat spatial data from regions in the watershed. The risk of ecological impacts to degrade assessment endpoints were calculated and ranked by quantitatively determining the interactions of the stressors and habitats as defined in the conceptual site model. Uncertainty assessment was conducted and the impact upon the relative ranks and risk conclusions evaluated. To determine regional risks, risk management information was gathered identifying areas to be protected, areas of high stress, and areas where additional information is needed. The results supported the applicability of the RRM and suggested areas and stressors for restoration efforts in the Codorus Creek Watershed. Two critical sets of conclusions were drawn from the assessment. First, in the Codorus Creek Watershed, the most significant stressor is agriculture land use, the most significantly impacted endpoint is water quality, and the most vulnerable habitats are those for macroinvertebrates and warm-water fish. Second, this risk assessment demonstrates the feasibility of using the RRM for assessing risk from multiple stressors on habitats with multiple assessment endpoints in an eastern watershed.     

Types of Integration in Risk Assessment and Management,And Why They Are Needed

Risk-based decision making requires that the decision makers and stakeholders are informed of all risks that are potentially significant and relevant to the decision. The International Programme on Chemical Safety of the World Health Organization has developed a framework for integrating the assessment of human health and ecological risks. However, other types of integration are needed to support particular environmental decisions. They are integration of exposure and effects, of multiple chemicals and other hazardous agents, of multiple routes of exposure, of multiple endpoints, multiple receptors, multiple spatial and temporal scales, a product's life cycle, management alternatives, and socioeconomics with risk assessment. Inclusion of all these factors in an integrated assessment could lead to paralysis by analysis. Therefore, it is important that assessors be cognizant of the decision process and that decision makers and those who will influence the decision (stakeholders) be involved in planning the assessment to ensure that the degree of integration is necessary and sufficient.     

Extrapolation in Human Health and Ecological Risk Assessments: Proceedings of a Symposium

A symposium was conducted in April 1998 by the U.S. Environmental Protection Agency's National Health and Environmental Effects Research Laboratory (NHEERL) to explore issues of extrapolation in human health and ecological risk assessments. Over the course of three and one half days, leading health and ecology experts presented and discussed research methods and approaches for extrapolating data among taxa and across levels of biological organization, through time, and across spatial scales. The intended result of this symposium was enhanced interaction among a diverse array of scientists, policymakers, and risk assessors to promote identification of approaches for reducing the uncertainties of extrapolation in risk assessment.     

Integrated Risk Assessment — Results from an International Workshop

The World Health Organization's International Programme on Chemical Safety and international partners have developed a framework for integrated assessment of human health and ecological risks and four case studies. An international workshop was convened to consider how ecological and health risk assessments might be integrated, the benefits of and obstacles to integration, and the research and mechanisms needed to facilitate implementation of integrated risk assessment. Using the case studies, workshop participants identified a number of opportunities to integrate the assessment process. Improved assessment quality, efficiency, and predictive capability were considered to be principal benefits of integration. Obstacles to acceptance and implementation of integrated risk assessment included the disciplinary and organizational barriers between ecological and health disciplines. A variety of mechanisms were offered to overcome these obstacles. Research recommendations included harmonization of exposure characterization and surveillance methods and models, development of common risk endpoints across taxa, improved understanding of mechanisms of effect at multiple scales of biological organization, and development of methods to facilitate comparison of risks among endpoints.     

Finding A Niche for Soil Microbial Toxicity Tests in Ecological Risk Assessment

Soil microbial toxicity tests are seldom used in ecological risk assessments or in the development of regulatory criteria in the U.S. The primary reason is the lack of an explicit connection between these tests and assessment end-points. Soil microorganisms have three potential roles with respect to ecological assessment endpoints: properties of microbial communities may be end-points; microbial responses may be used to estimate effects on plant production; and microbial responses may be used as surrogates for responses of higher organisms. Rates of microbial processes are important to ecosystem function, and thus should be valued by regulatory agencies. However, the definition of the microbial assessment endpoint is often an impediment to its use in risk assessment. Decreases in rates are not always undesirable. Processes in a nutrient cycle are particularly difficult to define as endpoints, because what constitutes an adverse effect on a process is dependent on the rates of others. Microbial tests may be used as evidence in an assessment of plant production, but the dependence of plants on microbial processes is rarely considered. As assessment endpoints are better defined in the future, microbial ecologists and toxicologists should be provided with more direction for developing appropriate microbial tests.     

土壤污染生态毒性效应评价研究进展

随着社会经济的高度发展,人类活动加剧,我国土壤污染问题突出,不仅威胁人体健康,同时也严重威胁动植物及微生物的安全,生态安全问题不容忽视。但是我国土壤污染风险管控目前主要关注人体健康,对生态系统的关注较少,缺乏土壤污染生态风险评估技术指南及基于生态风险的土壤环境质量基准及标准。准确评价土壤污染生态毒性效应,是制定土壤环境质量标准、实现生态风险评估及预警与管控的重要基础。针对土壤污染生态毒性效应评价问题,分别对土壤污染生态毒性效应特征、评价方法、评价终点、暴露-效应关系构建、生态毒性效应外推,以及群落水平与复合污染生态毒性效应评价等方面的关键问题展开了讨论,指出目前土壤污染生态毒性效应评价主要是基于单物种的急性毒性测试,利用个体和亚个体水平的指示物作为评价终点,缺乏针对群落及生态系统高水平评价终点的生态毒性效应评价方法,定量评价污染物尤其是复合污染物对土壤生物群落及生态系统的影响,是土壤污染生态毒性效应评价的关键问题和难点问题。建议今后重点开展以下3方面的工作1)群落及生态系统水平评价终点的筛选;2)土壤污染生态毒性效应环境影响因子识别及影响机制研究;3)土壤复合污染联合毒性效应定量评价及...     

The Concept of Data Utility in Health Risk Assessment: A Multi-Disciplinary Perspective

Human and ecological health risk assessments and the decisions that stem from them require the acquisition and analysis of data. In agencies that are responsible for health risk decision-making, data (and/or opinions/judgments) are obtained from sources such as scientific literature, analytical and process measurements, expert elicitation, inspection findings, and public and private research institutions. Although the particulars of conducting health risk assessments of given disciplines may be dramatically different, a common concern is the subjective nature of judging data utility. Often risk assessors are limited to available data that may not be completely appropriate to address the question being asked. Data utility refers to the ability of available data to support a risk-based decision for a particular risk assessment. This article familiarizes the audience with the concept of data utility and is intended to raise the awareness of data collectors (e.g., researchers), risk assessors, and risk managers to data utility issues in health risk assessments so data collection and use will be improved. In order to emphasize the cross-cutting nature of data utility, the discussion has not been organized into a classical partitioning of risk assessment concerns as being either human health- or ecological health-oriented, as per the U.S. Environmental Protection Agency's Superfund Program.     

Ecological Indicators in Risk Assessment: Workshop Summary

Ecological indicators can be defined as relatively simple measurements that relay scientific information about complex ecosystems. Such indicators are used to characterize risk in ecological risk assessment (ERA) and to mark progress toward resource management goals. In late 1997, scientists from the U.S. Environmental Protection Agency and from the Chemical Manufacturers Association (CMA) held a workshop to explore opportunities for collaborative research and scientific exchange on the development and application of ecological indicators. Several scientific challenges were identified as they relate to problem formulation, exposure and effects assessment, and risk characterization. Chief among these were a better understanding of multiple stressors (both chemical and non-chemical), characterization of reference sites and natural variability, extrapolation of measures to ecologically relevant scales, development of comprehensive, ecosystem-based models that incorporate multiple stressors and receptors, and a consistent system for evaluating ecological indicators.     

Use of the reference dose in risk characterization of drinking water contaminants

Regulatory decisions should be made in the most expert and informed way since they are precipitated by real and perceived threats to public health, under the glare of public scrutiny. The development of environmental regulations require a three‐step paradigm, collectively called risk analysis. This paper will address the risk assessment practices required under the Safe Drinking Water Act (SDWA) Amendments of 1986 to determine a Maximum Contaminant Level Goal (MCLG, nonenforceable health goal) which should result in no known or anticipated health effects, and allows adequate margin of safety. The end product of this risk assessment, risk characterization, and risk management encompassing control options and nonrisk analysis are combined to derive the Maximum Contaminant Level (MCL, enforceable standard). Furthermore, this paper discusses the U.S. Environmental Protection Agency's efforts in exploring new and improved noncancer risk assessment approaches providing the basis for MCLGs for the protection of human health.     

Framework for the Integration of Health and Ecological Risk Assessment

The World Health Organization's International Programme on Chemical Safety (IPCS), the Organization for Economic Cooperation and Development (OECD), and the U.S. Environmental Protection Agency have developed a collaborative partnership to foster integration of assessment approaches for human health and ecological risks. This paper presents the framework developed by that group. Integration provides coherent expressions of assessment results, incorporates the interdependence of humans and the environment, uses sentinel organisms, and improves the efficiency and quality of assessments relative to independent human health and ecological risk assessments. The paper describes how integration can occur within each component of risk assessment, and communicates the benefits of integration at each point. The goal of this effort is to promote the use of this internationally accepted guidance as a basis for harmonization of risk assessment.