An NGO Perspective on Risk Assessment and Scientific Research

Concerns over risk assessment have been raised by Non-Government Organizations (NGO) and the environmental community for decades. In considering proposals for research in this area, it is important for both scientists and policymakers to consider the following points: (1) risk assessment as a method of policymaking is increasingly inaccessible to meaningful public participation, (2) the lack of fundamental toxicological data constrains the application of risk assessment methods more than any other factor, and (3) the importance of individual susceptibility in risk assessments must be tempered by the lack of control over individual exposures.     

Addressing Susceptibility in Microbial Pathogen Risk Assessment

As concern for vulnerable subpopulations has grown, susceptibility has become a more important element in risk assessment and management processes. However, there is little consensus on how to incorporate or model the concept effectively in microbial pathogen risk assessment (MRA). Susceptibility is fundamentally a complex concept. There are many different definitions for it, reflecting the principles and viewpoints of the fields that contribute to risk assessment. Although susceptibility needs to be addressed in every step of the risk management paradigm, it has not yet been fully integrated into risk assessment, one step within the paradigm. Many factors are involved in characterizing and modeling susceptibility, but little is known about the relationships of many of the factors and many cannot be reliably measured. Recent MRA frameworks and case studies were reviewed for their approaches to susceptibility. Themes identified included limited or no explicit conceptualization of susceptibility in the problem formulation, limited data to assess susceptibility, heavy or exclusive emphasis on susceptibility in the health effects portion of the model, primary focus on host characteristics, and little consideration of susceptibility in risk characterization. Recommendations to improve approaches to susceptibility in MRA are presented.     

Trends in Risk Assessment of Chemicals in the European Union

Current legislation in the European Union (EU) requires a risk assessment for industrial chemicals. The underlying procedures and paradigms of such EU risk assessment for new and existing chemicals are explained. The risk assessment is performed according to a harmonised methodology, laid down in the Technical Guidance Documents (TGD). Important new, technical risk assessment aspects covered in a recent revision round of the TGD are highlighted. The most prominent change in the environmental TGD part is the addition of the marine risk assessment, including a Persistent Bioaccumulation and Toxicity (PBT) assessment. In the human health part a significant change is the new data requirement for reproductive toxicity. The performance of both the risk assessment and the risk reduction phase of EU existing chemicals have been evaluated. An important conclusion was that our a priori knowledge on possible risks of chemicals is poor. The European Commission has recently launched a proposal (REACH) for drastically changing the risk management process of industrial chemicals in the EU. Major changes are a shift in responsibility from authorities to industry (including downstream users) for the safe use of chemicals, an acceleration of data collection for ‘non-assessed’ chemicals, and an authorization step for substances of very high concern.     

Use of Toxicological Data in Estimating Reference Values for Risk Assessment

A number of programs within the U.S. Environmental Protection Agency (USEPA) currently set less-than-lifetime exposure limits in addition to the chronic reference dose (RfD) and reference concentration (RfC). A review of procedures within the USEPA for setting reference values suggests that less-thanlifetime reference values should be more routinely developed and captured in the USEPA's online IRIS database where chronic RfDs and RfCs, as well as cancer slope factors, are currently available. A review of standard testing study protocols was conducted to determine what data were available for setting acute, short-term, and longer-term reference values, as well as chronic values. This review was done from the point of view of endpoints assessed for specific organ systems (both structural and functional), life stages covered by exposure and outcome, durations of exposure covered and the outcomes evaluated for each, and evaluation of latency to response and/or reversibility of effects. This review revealed a number of data gaps and research needs, including the need for an acute and/or short-term testing protocol that can be used to set acute and shortterm reference values, a strategy for when to conduct more extensive testing based on initial screening data or other information (e.g., chemical class, pharmacokinetics, mode of action), additonal standard testing guidlines protocols to allow more complete assessment of certain organ systems and life stages, development of pharmacokinetic data for different life stages, toxicity related to aging, and latency to response, particularly long-term latency as a result of developmental exposures. The implications of this review are discussed relative to characterizing hazard data for setting reference values, and the potential effects on uncertainty factors and low-dose extrapolation.     

Trends in the Development of Ecological Risk Assessment and Management Frameworks

Ecological risk assessment and management have grown from a long history of assessment and management activities aimed at improving the everyday lives of humans. The background against which ecological risk assessment and management has developed is discussed and recent trends in the development of risk assessment and management frameworks documented. Seven frameworks from five different countries are examined. All maintain an important role for science, suggest adaptive approaches to decision-making and have well-defined analytical steps. Differences in approaches toward the separation of policy and science, the preference for management over assessment, the inclusion of stakeholders, the iterative nature of the analytical cycle, the use of decision criteria and economic information suggest considerable evolution in framework design over time. Despite the changes, no consensus on the design of a framework is apparent and work remains to be done on refining an integrative framework that effectively incorporates both policy and science considerations for environmental management purposes.     

The Fox River Risk Assessment Teaching Tool

In 1999 and 2000, two environmental consulting companies independently prepared risk assessments of the Lower Fox River waste site in Wisconsin. Because the two assessments produced somewhat different risk characterizations, the Association for Environmental Health & Sciences was asked by the site's Potentially Responsible Party to form a peer review panel to critique and compare the two assessments. The panel found interesting differences between the two risk assessments and recommended that their observations, together with the two risk assessments, be made available as a Teaching Tool for persons interested in conducting human and ecological risk assessments. An accompanying CD contains these and other materials useful for teaching purposes.     

Ecological Risk Assessment and the Precautionary Principle

The Precautionary Principle, generated during the late 1980s as a unifying principle for regulating discharge of hazardous material into the North Sea, has been broadened to include a shifting of the burden of proof to the proponent of a proposed activity, adoption of a more holistic assessment process, and encompassing all environmental management decisions, not just pollution prevention activities. We argue that the Precautionary Principle remains a management philosophy, not a substitute for risk assessment. Risk assessment is a tool for organizing information used in environmental management decisions. However, increasing attention to reducing the Type II error of risk assessment studies would significantly reduce the skepticism with which many view the risk assessment process. A critical review of default assumptions used in risk assessments, inclusion of indirect effects within an ecologically relevant spatial/temporal framework, and better communication between risk assessors and risk managers also would enhance the acceptability of the process. Risk assessment can provide a sound basis for management decisions regardless of the underlying philosophies of environmental conservation or utilitarianism, but only if the inherent biases in the risk assessment assumptions are acknowledged explicitly throughout the assessment and management processes.     

An Assessment of Integrated Risk Assessment

In order to promote international understanding and acceptance of the integrated risk assessment process, the World Health Organization/International Programme on Chemical Safety (WHO/IPCS), in collaboration with the U.S. Environmental Protection Agency and the Organization for Economic Cooperation and Development, initiated a number of activities related to integrated risk assessment. In this project, the WHO/IPCS defines integrated risk assessment as a science-based approach that combines the processes of risk estimation for humans, biota, and natural resources in one assessment. This article explores the strengths and weaknesses of integration as identified up to this date and the degree of acceptance of this concept by the global risk assessment/risk management community. It discusses both opportunities and impediments for further development and implementation.

The major emerging opportunities for an integrated approach stem from the increasing societal and political pressure to move away from vertebrate testing leading to a demand for scientific integrated approaches to in vitro and in vivo testing, as well as to computer simulations, in so-called Intelligent Testing Strategies. In addition, by weighing the evidence from conventional mammalian toxicology, ecotoxicology, human epidemiology, and eco-epidemiology, risk assessors could better characterize mechanisms of action and the forms of the relationships of exposures to responses. It is concluded that further demonstrations of scientific, economic and regulatory benefits of an integrated approach are needed. As risk assessment is becoming more mechanistic and molecular this may create an integrated approach based on common mechanisms and a common systems-biology approach.     

Human Health Risk Assessment: Required Reading

Over the past 30 years, risk assessment has developed into a scientific discipline. It is critical that the next generation of risk assessors understand the history of our field, and recognize the numerous successes and failures that have taken place. This short Perspective identifies and describes specific books, monographs, and reports that are required reading for any nascent risk assessor.     

Human Health Risk Assessment at a Depleted Uranium Site

Human health risk assessments for depleted uranium are common for Department of Defense (DOD) sites since the metal has various military uses. At a training and experimental site, DU was evaluated in soil in order to make decisions regarding cleanup and future use of the site. At this site, concentrations were found to be protective of human health; DU is less toxic than uranium. Other data important to this decision were the type of receptors likely to be exposed, the amount of time spent by the receptor on-site, the acceptable yearly radiation dose, and other non-radiation associated effects to the kidney. Total uranium concentrations in soil were calculated for the 90th percentile and the 50th percentile. The highest soil concentration used as an exposure point was 3500 ug/g (90th percentile). Short exposure timeframes contributed to the risk results.     

Axes of Extrapolation in Risk Assessment

Extrapolation in risk assessment involves the use of data and information to estimate or predict something that has not been measured or observed. Reasons for extrapolation include that the number of combinations of environmental stressors and possible receptors is too large to characterize risks comprehensively, that direct characterization is sometimes impossible, and that the power to characterize risk in a particular situation can be enhanced by using information obtained in other similar situations. Three types of extrapolation are common in risk assessments: biological (including between taxa and across levels of biological organization), temporal, and spatial. They can be thought of conceptually as the axes of a 3-dimensional graph defining the state space of biological, temporal, and spatial scales within which extrapolations are made. Each of these types of extrapolation can introduce uncertainties into risk assessments. Such uncertainties may be reduced through synergistic research facilitated by the sharing of methods, models, and data used by human health and ecological scientists     

Using Ecological Risk Assessment Principles in a Source Water Protection Assessment

It has become increasingly common to apply ecological risk assessment (ERA) principles to watershed and regional scale environmental management. This article describes the application of watershed ERA principles to the development of a source water protection assessment and a strategic watershed management plan. The primary focus was on the protection of drinking water quality, a concern typically addressed by human health risk assessors. The approach emphasizes adaptations to the problem formulation phase of ERA (defining assessment endpoints, developing conceptual models and an analysis plan) suitable for watershed management planning in a multi-objective, multi-stressor context. Physical, chemical, and biological attributes were selected for primary drinking water quality assessment endpoints, and coupled with additional assessment endpoints relevant to other environmental and social management objectives. Conceptual models helped the planning team to better understand and communicate the multiple natural and human stressors in the watershed and the causal pathways by which they affected drinking water. The article provides an example of the types of adaptations that can make ERA principles suitable for watershed management related to human health goals, and illustrates the efficiency of integrating health and ecological assessments.     

Machinery Risk Assessment for Risk Reduction

New avenues are reviewed and discussed for preventing industrial machine-related injury by means of realistic risk evaluation and reduction processes at the design and application stages of machinery development and use. U.S. guidelines and European standards on machinery risk assessment procedures are described. Applications of risk assessment for machine-related injury risk management and teaching machine-risk control are discussed.     

Relating Ozone Uptake in Forest Trees to Risk Assessment

This paper reviews the importance of ozone uptake through plant stomata in understanding plant response to ozone and discusses challenges in quantifying ozone uptake in forest trees. Uncertainties in spatial and temporal scaling of ozone uptake from the leaf to the landscape level, insufficient monitoring of ozone in forested areas, and tremendous variability in the composition and structure of forest ecosystems of the United States prevent the current use of ozone uptake in large-scale risk assessments and regulatory decisions.     

Bioindicators Versus Biomarkers in Ecological Risk Assessment

The biomarker approach, adopted from medical toxicology, is subject to several theoretical and practical difficulties when used to address environmental problems. The problems are related to the definition that emphasizes measurement but does not specify a requirement to establish cause-effect linkages. An improved definition for a bioindicator is reviewed. The sentinel species approach is judged to be a biomarker rather than a bioindicator, and therefore of limited use for environmental risk assessment. An empirical weight of evidence approach to improve the utility of sentinel species is proposed.     

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.     

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.     

Risk Assessment: Replacing Default Options with Specific Science

The history of approaches to evaluating the hazards and risks of chemicals is briefly reviewed. The role of default options (generic approaches based on general knowledge in the absence of specific knowledge to the contrary) is discussed as a part of the risk assessment paradigm advanced by the National Academy of Science/National Research Council in 1983 and 1994. Examples are given of the impact of acquiring specific science to replace default options. An argument is made for developing specific science that would reduce uncertainty in risk assessments. Research on specific science would be guided by identified sources of uncertainty in the risk assessment process. The importance of using a research strategy that builds on human data is emphasized for validating new molecular and cellular biological assessment methods. The paper closes with a discussion of the tension between a hazard-based approach versus quantitative risk assessment in guiding risk management decisions. The former requires limited data, is qualitative, and easy to communicate, while the latter requires substantial data and is difficult to communicate. However, quantitative risk assessment provides a more rational basis for decisions on the allocation of both public and private resources for actions that will effectively minimize overall health risks to the public.