bluuebunny/crossref_metadata_2025 huggingface dataset:
Three Principles for Managing Risk in the Public Interest
Authors: Nathwani Jatin , Narveson Jan
Published: May 2006

We propose three principles and a general framework of reasoning for managing risk in the public interest.Principle 1.Risks shall be managed to maximize the total expected net benefit to society—The principle that the net benefit is to be maximized across society as a whole is argued to be a sufficient and rational guide to assessing the effectiveness of efforts directed at reducing risk and thus improving health and safety. The net benefit of an activity is the excess of the totality of benefits over the totality of detriments.Principle 2.The safety benefit to be promoted is life‐expectancy—The goal is to ensure that risk mitigation efforts maximize the net benefit to society in the specific terms of length of life for all individuals. The effect of an activity on life expectancy is proposed as the proper basic measure of its net safety impact. Life expectancy is a universal measure valid for comparisons both within and among countries and can be adjusted to include health expectancy and other factors such as income levels that affect the quality of life. The impact on life expectancy allows a dispassionate accounting of the good and the bad inherent in any proposal or activity that is in the public interest but has some impact on life and health.Principle 3.Decisions for the public in regard to health and safety must be open and apply across the complete range of hazards to life and health—Systematic efforts to evaluateallthe important consequences, both direct and indirect, are required to improve the basis for risk management in society. Balancing of the detrimentsandthe benefits of any given initiative is the key aspect of the undertaking. Safety may well be an important objective in society, but it is not the only one. Thus, allocation of society's resources devoted to safety must be openly and continually appraised in light of other competing social needs because there is a limit on the resources that can be expended to save lives. Maximization of healthful life for all is judged the proper basis for managing risk in the public interest, and that this is achieved when the net of the contribution to the total saving of life exceeds the loss of life.
Updating Uncertainty in an Integrated Risk Assessment: Conceptual Framework and Methods
Authors: Brand Kevin P. , Small Mitchell J.
Published: May 2006

Bayesian methods are presented for updating the uncertainty in the predictions of an integrated Environmental Health Risk Assessment (EHRA) model. The methods allow the estimation of posterior uncertainty distributions based on the observation of different model outputs along the chain of the linked assessment framework. Analytical equations are derived for the case of the multiplicative lognormal risk model where the sequential log outputs (log ambient concentration, log applied dose, log delivered dose, and log risk) are each normally distributed. Given observations of a log output made with a normally distributed measurement error, the posterior distributions of the log outputs remain normal, but with modified means and variances, and induced correlations between successive log outputs and log inputs. The analytical equations for forward and backward propagation of the updates are generally applicable to sums of normally distributed variables. The Bayesian Monte‐Carlo (BMC) procedure is presented to provide an approximate, but more broadly applicable method for numerically updating uncertainty with concurrent backward and forward propagation. Illustrative examples, presented for the multiplicative lognormal model, demonstrate agreement between the analytical and BMC methods, and show how uncertainty updates can propagate through a linked EHRA. The Bayesian updating methods facilitate the pooling of knowledge encoded in predictive models with that transmitted by research outcomes (e.g., field measurements), and thereby support the practice of iterative risk assessment and value of information appraisals.
The SAM Framework: Modeling the Effects of Management Factors on Human Behavior in Risk Analysis
Authors: Murphy Dean M. , Paté‐Cornell M. Elisabeth
Published: May 2006

Complex engineered systems, such as nuclear reactors and chemical plants, have the potential for catastrophic failure with disastrous consequences. In recent years, human and management factors have been recognized as frequent root causes of major failures in such systems. However, classical probabilistic risk analysis (PRA) techniques do not account for the underlying causes of these errors because they focus on the physical system and do not explicitly address the link between components' performance and organizational factors. This paper describes a general approach for addressing the human and management causes of system failure, called the SAM (System‐Action‐Management) framework. Beginning with a quantitative risk model of the physical system, SAM expands the scope of analysis to incorporate first the decisions and actions of individuals that affect the physical system. SAM then links management factors (incentives, training, policies and procedures, selection criteria, etc.) to those decisions and actions. The focus of this paper is on four quantitative models of action that describe this last relationship. These models address the formation of intentions for action and their execution as a function of the organizational environment. Intention formation is described by three alternative models: a rational model, a bounded rationality model, and a rule‐based model. The execution of intentions is then modeled separately. These four models are designed to assess the probabilities of individual actions from the perspective of management, thus reflecting the uncertainties inherent to human behavior. The SAM framework is illustrated for a hypothetical case of hazardous materials transportation. This framework can be used as a tool to increase the safety and reliability of complex technical systems by modifying the organization, rather than, or in addition to, re‐designing the physical system.
An Empirical Analysis of Rock Climbers' Response to Hazard Warnings
Authors: Jakus Paul M. , Shaw W. Douglass
Published: May 2006

This paper reports the results of a field test of the hazard warning system used in rock climbing. The system is succinct; it differentiates between magnitudes of hazard; and it establishes a “warnings vocabulary.” The empirical hazard response models include an “individuating factor,” which influences the likelihood of injury, and the severity of injury as independent variables. The models indicate that climbers do assess a “personal” probability of injury and incorporate the hazard warning message when choosing climbing routes. Climbers of greater technical ability are more likely to climb hazardous routes, but they mitigate the likelihood of the hazardous outcome by reducing the technical difficulty of the hazardous route chosen. The response increases with the degree of hazard involved.
What Is Wrong with Criterion FN‐Lines for Judging the Tolerability of Risk?
Authors: Evans Andrew W. , Verlander Neville Q.
Published: May 2006

This paper is concerned with the intellectual framework in which judgments are made about the tolerability of so‐called societal risk. The current practical approach is based on the position of the FN‐curves representing the risks from hazardous systems in relation to criterion FN‐lines. The objections to FN‐criteria are that they can give unreasonable conclusions and that they are inconsistent. Statistical decision theory suggests an alternative and preferable rule of minimising the expected disutility, that is average harm, from accidents.
Neighborhood Quality, Environmental Hazards, Personality Traits, and Resident Actions
Authors: Greenberg Michael , Schneider Dona
Published: May 2006

A survey of 798 New Jersey residents examined relationships among residents’ neighborhood activities, perceptions of neighborhood quality, trust of experts, support for rebuilding cities and equal rights, and degree of optimism. Neighborhood activities increased with lack of trust and optimism. These personality characteristic measures were folded into multidimensional constructs that included local environmental hazards, respondents’ ratings of their previous neighborhoods, and some demographic variables. Pessimism and values that support equal rights and rebuilding cities were weakly associated with poor quality neighborhood ratings.
The Value of Improved National Exposure Information for Perchloroethylene (Perc): A Case Study for Dry Cleaners
Authors: Thompson Kimberly M. , Evans John S.
Published: May 2006

Opportunities to improve our information about risk continue to arise and lead decision makers to indirectly address the issue of the value of improved information through resource allocation decisions. Statistical decision analysis techniques provide an analytical framework for valuing information explicitly in the context of regulatory decision making. This paper provides estimates of the value of improved national estimates of perchloroethylene (perc) exposure from U.S. dry cleaners in the context of EPA's recently promulgated National Emissions Standard for Hazardous Air Pollutants (NESHAP) with emphasis on exposure information. Consistent with the NESHAP decision, we relied on EPA's technology and economic assessments. In this first cut analysis, estimates of the exposures of workers, consumers of dry cleaning services, and the general public are probabilistically characterized to reflect uncertainty about exposure and potency. We consider the net benefits of the different control options by assessing the associated changes in the total annual population risks and valuing them in monetary terms, with no constraints placed on maximum individual risks. The results suggest that the expected value of perfect information (EVPI) about potency exceeds the EVPI about exposure. Sensitivity analyses demonstrate how the choices of the valuation parameters and distributions used to characterize uncertainty in the model affect the estimates of the value of information.
Public Opposition to a Proposed Nuclear Waste Repository in Canada: An Investigation of Cultural and Economic Effects
Authors: Hine Donald W. , Summers Craig , Prystupa Mark , McKenzie‐Richer Antoinette
Published: May 2006

Residents of four northern communities were surveyed about Atomic Energy of Canada Limited's proposal to site an underground repository for high‐level nuclear waste somewhere in the Canadian Shield. Opposition to the repository was relatively strong in all communities, but was strongest among aboriginal respondents. Path analysis revealed that trust in nuclear regulators, faith in science and technology, and anticipated net costs were important mediators of this effect. Aboriginals were less trusting, exhibited less faith in science and technology, and perceived the costs associated with the repository to be higher than their nonaboriginal counterparts. No support was found for the hypothesis that, after controlling for aboriginal status, financially insecure individuals would display greater support for the nuclear waste repository than financially secure individuals. Policy implications for balancing perceived risks and siting needs are discussed.
Exploring the “Psychometric Paradigm”: Comparisons Between Aggregate and Individual Analyses
Authors: Marris Claire , Langford Ian , Saunderson Thomas , O'Riordan Timothy
Published: May 2006

The “psychometric paradigm” developed by Slovic, Fischhoff, and Lichtenstein was a landmark in research about public attitudes toward risks. One problem with this work, however, was that (at least initially) it did not attempt to distinguish between individuals or groups of people, except “experts” vs. “lay people.” This paradigm produced a “cognitive map” of hazards, and the assumption seemed to be that the characteristics identified were inherent attributes of risk. This paper examines the validity of this assumption. A questionnaire survey similar to those designed by Slovic et al. was conducted, but the data were analyzed at both the aggregate level, using mean scores, and at the level of individuals (N= 131 Norwich residents). The results reported here demonstrate that (1) individuals vary in their perception of the same risk issue; (2) individuals vary in their rating of the same risk characteristics on the same risk issue; and (3) some of the strong intercorrelations observed between risk characteristics at the aggregate level are not supported when the same data are analysed at the level of individuals. Despite these findings, the relationship between risk characteristics and risk perceptions inferred by the psychometric paradigm did hold true at the level of individuals, for most—but not all—of the characteristics. In particular, the relationship between “lack of knowledge to those exposed” and risk perceptions appears to be a complex one, a finding which has important implications for risk communication strategies.
Using GIS in Risk Analysis: A Case Study of Hazardous Waste Transport
Authors: Lovett Andrew A. , Parfitt Julian P. , Brainard Julii S.
Published: May 2006

This paper provides an illustration of how a geographic information system (GIS) can be used in risk analysis. It focuses on liquid hazardous waste transport and utilizes records archived by the London Waste Regulatory Authority. This data source provides information on the origin and destination of each waste stream, but not the route followed during transport. A GIS was therefore employed to predict the paths used, taking into account different routing criteria and characteristics of the available road network. Details were also assembled on population distribution and ground‐water vulnerability, thus providing a basis for evaluating the potential consequences of a waste spillage during transport. Four routing scenarios were implemented to identify sections of road which consistently saw heavy traffic. These simulations also highlighted that some interventions could lead to risk tradeoffs rather than hazard mitigation. Many parts of the research would not have been possible without a GIS, and the study demonstrates the considerable potential of such software in environmental risk assessment and management.
Methyl tert Butyl Ether Systemic Toxicity
Authors: Clary John J.
Published: May 2006

In male F344 rats exposed in a chronic inhalation study to methyl tertiary butyl ether (MTBE) a treatment related increase in severity of chronic nephropathy and mortality and an increase in hyaline droplets in the kidney were noted. Liver weights were increased in both rats and mice but no histological lesions other than hypertrophy are seen. Transient CNS effects but no indications of permanent nervous system effects were noted. MTBE is not a reproductive or developmental hazard. MTBE is rapidly absorbed. MTBE with some metabolite, tertiary butyl alcohol (TBA) and a little CO2, are excreted in the air. The urinary excretion products in animals are TBA metabolites, while in humans the urinary excretion products are MTBE and TBA. A comparison of the systemic responses of the possible metabolites TBA and formaldehyde indicate that they are not responsible for toxicity associated with MTBE, except that TBA may be partially responsible for the kidney effects reported. Animals and humans are similar in the uptake and excretion though with some differences in metabolism of MTBE. This supports the use of the animal data as a surrogate for humans.
An Analysis of the Health Benefits Associated with the Use of MTBE Reformulated Gasoline and Oxygenated Fuels in Reducing Atmospheric Concentrations of Selected Volatile Organic Compounds
Authors: Spitzer Hugh L.
Published: May 2006

To assess the health benefits gained from the use of cleaner burning gasoline, an analysis was conducted of changes in the atmospheric concentration of eight VOCs: acetaldehyde, benzene, 1,3‐butadiene, ethylbenzene, formaldehyde, POM, toluene, and xylenes resulting from the use of reformulated gasoline and oxyfuel containing the additive MTBE. Modeled ambient air concentrations of VOCs were used to assess three seasonally‐based scenarios: baseline gasoline compared to (a) summer MTBE:RFG, (b) winter MTBE:RFG, and (c) MTBE oxyfuel. The model predicts that the addition of MTBE to RFG or oxyfuel will decrease acetaldehyde, benzene, 1,3‐butadiene and POM, but increase formaldehyde tailpipe emissions. The increased formaldehyde emissions, however, will be offset by the reduction of formaldehyde formation in the atmosphere from other VOCs. Using a range of plausible risk estimates, the analysis predicts a positive health benefit, i.e., a decline in cancer incidence associated with use of MTBE:RFG and MTBE oxyfuel. Using EPA cancer risk estimates, reduction in 1,3‐butadiene exposure accounts for the greatest health benefit while reduction of benzene exposure accounts for the greatest health benefits based on alternative risk estimates. An analysis of microenvironment monitoring data indicates that most exposures to VOCs are significantly below levels of concern based on established margin‐of‐safety standards. The analysis does suggest, however, that health effects associated with short‐term exposures to acetaldehyde and benzene may warrant further investigation.
Causality Assessment of the Acute Health Complaints Reported in Association with Oxygenated Fuels
Authors: Balter Nancy J.
Published: May 2006

In some areas where oxygenated fuel programs have been implemented, there have been widespread complaints of non‐specific health effects attributed to the gasoline. There are a number of hypotheses that can account for this apparent association. This paper examines the hypothesis that the use of oxy‐fuel (either oxygenated gasoline or reformulated gasoline) results in exposure of the general population to one or more chemicals at concentrations that cause toxicologic injury. Although several oxygenates can be used in oxy‐fuels, this analysis focuses on MTBE because it is the most widely used oxygenate and because the database of relevant toxicologic data is greatest for this oxygenate. The causal assessment is based on an evaluation of the qualitative and quantitative plausibility that oxygenated fuel‐related exposures have toxicological effects, and the epidemiologic studies that directly test the hypothesis that the use of oxygenated fuels causes adverse health effects. The plausibility that chemical exposures related to oxy‐fuel use cause toxicological effects is very low. This determination is based on consideration of the exposure‐response and time‐action profiles for relevant toxicological effects of MTBE in animals, experimental MTBE exposure studies in humans, and the possibility that the addition of MTBE to gasoline results in toxicologically significant qualitative and/or quantitative changes in gasoline‐related exposures. Similarly, the epidemiologic studies of oxy‐fuel exposed cohorts do not support a causal relationship between oxy‐fuel use and adverse health effects. Although the data are insufficient to rule the possibility of unique sensitivity in a small segment of the population, the strength of the evidence and the availability of other more plausible explanations for the health complaints reported in association with oxy‐fuels support a high degree of confidence in the conclusion that MTBE‐containing oxygenated fuels are not the cause of acute toxicity in the general population.
The Dynamics of Risk Perception: How Does Perceived Risk Respond to Risk Events?
Authors: Rogers George O.
Published: May 2006

This paper examines the relationship between perceived risk and experience. This research addresses the processes by which people learn about risk and choose among real life prospects with associated uncertainties, risks and benefits. By comparing the impact of acute risk events with that of chronic risk events on public perception of risk during and after the events, this research focuses on the learning processes that characterize what kinds of risk events alter the perception of risk. Comparing materialized hazards at existing facilities with the risks associated with potential facilities, this research addresses risk choices among real life prospects. This study uses a classic pre‐post quasi‐experimental design. Surveys conducted in the Spring of 1992 on perceived and acceptable risk in Odessa and La Porte, Texas were conducted prior to risk events. Respondents from that survey were re‐interviewed in the Spring of 1993 after the risk events to form a panel design. This paper analyzes the affect of risk events on perceived risk and the implications of these experiences for public policy concerning technological risk. The empirical results suggest that the social processes that construct and maintain risk in the public eye are at least as important as, if not more important than, the physical and psychological dimensions of risk.
Dynamic Risk Management Systems: Hybrid Architecture and Offshore Platform Illustration
Authors: Paté‐Cornell M.‐Elisabeth , Regan Peter J.
Published: May 2006

This paper describes and illustrates the architecture of computer‐based Dynamic Risk Management Systems (DRMS) designed to assist real‐time risk management decisions for complex physical systems, for example, engineered systems such as offshore platforms or medical systems such as patient treatment in Intensive Care Units. A key characteristic of the DRMSs that we describe is that they are hybrid, combining the powers of Probabilistic Risk Analysis methods and heuristic Artificial Intelligence techniques. A control module determines whether the situation corresponds to a specific rule or regulation, and is clear enough or urgent enough for an expert system to make an immediate recommendation without further analysis of the risks involved. Alternatively, if time permits and if the uncertainties justify it, a risk and decision analysis module formulates and evaluates options, including that of gathering further information. This feature is particularly critical since, most of the time, the physical system is only partially observable, i.e., the signals observed may not permit unambiguous characterization of its state. The DRMS structure is also dynamic in that, for a given time window (e.g., 1 day or 1 hour), it anticipates the physical system's state (and, when appropriate, performs a risk analysis) accounting for its evolution, its mode of operations, the predicted external loads and problems, and the possible changes in the set of available options. Therefore, we specifically address the issue of dynamic information gathering for decision‐making purposes. The concepts are illustrated focusing on the risk and decision analysis modules for a particular case of real‐time risk management on board offshore oil platforms, namely of two types of gas compressor leaks, one progressive and one catastrophic. We describe briefly the DRMS proof‐of‐concept produced at Stanford, and the prototype (ARMS) that is being constructed by Bureau Veritas (Paris) based on these concepts.
Deliberation: Integrating Analytical Results into Environmental Decisions Involving Multiple Stakeholders
Authors: Apostolakis George E. , Pickett Susan E.
Published: May 2006

The National Research Council has recommended the use of an analytic/deliberative decision making process in environmental restoration decisions that involve multiple stakeholders. This work investigates the use of the results of risk assessment and multiattribute utility analysis (the “analysis”) in guiding the deliberation. These results include the ranking of proposed remedial action alternatives according to each stakeholder's preferences, as well as the identification of the major reasons for these rankings. The stakeholder preferences are over a number of performance measures that include the traditional risk assessment metrics, e.g., individual worker risk, as well as programmatic, cultural, and cost‐related impacts. Based on these results, a number of proposals are prepared for consideration by the stakeholders during the deliberation. These proposals are the starting point for the formulation of actual recommendations by the group. In our case study, these recommendations included new remedial action alternatives that were created by the stakeholders after an extensive discussion of the detailed analytical results.
Utilizing Third‐Party Inspections for Preventing Major Chemical Accidents
Authors: Er Jweeping , Kunreuther Howard C. , Rosenthal Isadore
Published: May 2006

This paper proposes using certified third parties, coupled with Model Risk Management Programs (Model RMPs), to implement EPA's Proposed Rule on the prevention of chemical accidental releases. We concentrate on the insurance aspects of this third‐party approach and show that it could enable insurers to more cost‐effectively provide coverage against the risks of chemical accidental releases. The third‐party approach may also signal the facility's safety and reduce the enforcement costs of regulations.
Informational Regulation of Environmental Risks
Authors: Kleindorfer Paul R. , Orts Eric W.
Published: May 2006

This paper examines the law and economics of informational regulation (IR) of environmental risks. Informational regulation here means regulation which provides to affected stakeholders information on the operations of regulated entities, usually with the expectation that such stakeholders will then exert pressure on these entities to comply with regulations in a manner which serves the interests of stakeholders. As such, IR reinforces and augments direct regulatory monitoring and enforcement through third‐party monitoring and incentives. The paper provides two contrasting frameworks, from law and economics, to analyze the costs and benefits likely to arise from IR and concludes with a discussion of the appropriate scope of IR as a substitute for and complement of traditional environmental regulation and law.
Impact of Hazardous Substances Regulations on Small Firms in Delaware and New Jersey
Authors: Schaller Leon C. , McNulty Patrick J. , Chinander Karen R.
Published: May 2006

Regulations under the 1990 Amendments to the Clean Air Act impose significant requirements on firms handling hazardous chemicals. The nature of the regulations would suggest that small firms, because of limited resources and other structural limitations, would experience more difficulty complying with the regulations than large firms. To understand the difficulties imposed by the regulations on small firms, we interviewed ten small firms in Delaware and New Jersey, states with existing hazardous regulations similar to those being considered by the U.S. Environmental Protection Agency, and evaluated their responses to state regulations. The impacts of the environmental regulations on the firms and on the risk levels of their businesses are discussed. Propositions for research into small firms compliance are developed. Possible means for reducing the regulatory burden on small firms while enhancing regulatory effectiveness are suggested.
A Probabilistic Framework for the Reference Dose (Probabilistic RfD)
Authors: Swartout Jeffrey C. , Price Paul S. , Dourson Michael L. , Carlson‐Lynch Heather L. , Keenan Russell E.
Published: May 2006

Determining the probabilistic limits for the uncertainty factors used in the derivation of the Reference Dose (RfD) is an important step toward the goal of characterizing the risk of noncarcinogenic effects from exposure to environmental pollutants. If uncertainty factors are seen, individually, as “upper bounds” on the dose‐scaling factor for sources of uncertainty, then determining comparable upper bounds for combinations of uncertainty factors can be accomplished by treating uncertainty factors as distributions, which can be combined by probabilistic techniques. This paper presents a conceptual approach to probabilistic uncertainty factors based on the definition and use of RfDs by the US. EPA. The approach does not attempt to distinguish one uncertainty factor from another based on empirical data or biological mechanisms but rather uses a simple displaced lognormal distribution as a generic representation of all uncertainty factors. Monte Carlo analyses show that the upper bounds for combinations of this distribution can vary by factors of two to four when compared to the fixed‐value uncertainty factor approach. The probabilistic approach is demonstrated in the comparison of Hazard Quotients based on RfDs with differing number of uncertainty factors.
A Comparison of Methods for Estimating the Benchmark Dose Based on Overdispersed Data from Developmental Toxicity Studies
Authors: Fung Karen Y. , Marro Leonora , Krewski Daniel
Published: May 2006

Developmental anomalies resulting from prenatal toxicity can be manifested in terms of both malformations among surviving offspring and prenatal death. Although these two endpoints have traditionally been analyzed separately in the assessment of risk, multivariate methods of risk characterization have recently been proposed. We examined this and other issues in developmental toxicity risk assessment by evaluating the accuracy and precision of estimates of the effective dose (ED05) and the benchmark dose (BMD05) using computer simulation. Our results indicated that different variance structures (Dirichlet‐trinomial and generalized linear model) used to characterize overdispersion yielded comparable results when fitting joint dose response models based on generalized estimating equations. (The choice of variance structure in separate modeling was also not critical.) However, using the Rao‐Scott transformation to eliminate overdispersion tended to produce estimates of the ED05 with reduced bias and mean squared error. Because joint modeling ensures that the ED05 for overall toxicity (based on both malformations and prenatal death) is always less than the ED05 for either malformations or prenatal death, joint modeling is preferred to separate modeling for risk assessment purposes.
What Should Be the Implications of Uncertainty, Variability, and Inherent “Biases”/“Conservatism” for Risk Management Decision‐Making?1
Authors: Hattis Dale , Anderson Elizabeth L.
Published: May 2006

This paper is a challenge from a pair of lifelong technical specialists in risk assessment for the risk‐management community to better define social decision criteria for risk acceptance vs. risk control in relation to the issues of variability and uncertainty. To stimulate discussion, we offer a variety of “straw man” proposals about where we think Variability and uncertainty are likely to matter for different types of social policy considerations in the context of a few different kinds of decisions. In particular, we draw on recent presentations of uncertainty and variability data that have been offered by EPA in the context of the consideration of revised ambient air quality standards under the Clean Air Act.
Reliability Analysis for Hazardous Waste Treatment Processes
Authors: Water Robert D. , Parker Frank L.
Published: May 2006

The reliability of a treatment process is addressed in terms of achieving a regulatory effluent concentration standard and the design safety factors associated with the treatment process. This methodology was then appliedto two aqueous hazardous waste treatment processes: packed tower aeration and activated sludge (aerobic) biological treatment. The designs achieving 95 percent reliability were compared with those designs based on conventional practice to determine their patterns of conservatism. Scoping‐level treatment costs were also related to reliability levels for these treatment processes. The results indicate that the reliability levels for the physicalkhemical treatment process (packed tower aeration) based on the deterministic safety factors range from 80 percent to over 99 percent, whereas those for the biological treatment process range from near 0 percent to over 99 percent, depending on the compound evaluated. Increases in reliability per unit increase in treatment costs are most pronounced at lower reliability levels(less than about 80 percent) than at the higher reliability levels (greaterthan 90 percent, indicating a point of diminishing returns. Additional research focused on process parameters that presently contain large uncertainties may reduce those uncertainties, with attending increases in the reliability levels of the treatment processes.
Distribution of Exposure Concentrations and Doses for Constituents of Environmental Tobacco Smoke
Authors: LaKind Judy S. , Ginevan Michael E. , Naiman Daniel Q. , James Anthony C. , Jenkins Roger A. , Dourson Michael L. , Felter Susan P. , Graves Carol G. , Tardiff Robert G.
Published: May 2006

The ultimate goal of the research reported in this series of three articles is to derive distributions of doses of selected environmental tobacco smoke (ETS)‐related chemicals for nonsmoking workers. This analysis uses data from the 16‐City Study collected with personal monitors over the course of one workday in workplaces where smoking occurred. In this article, we describe distributions of ETS chemical concentrations and the characteristicsof those distributions (e.g., whether the distribution was log normal for agiven constituent) for the workplace exposure. Next, we present population parameters relevant for estimating dose distributions and the methods used for estimating those dose distributions. Finally, we derive distributions of doses of selected ETS‐related constituents obtained in the workplace for people in smoking work environments. Estimating dose distributions providedinformation beyond the usual point estimate of dose and showed that the preponderance of individuals exposed to ETS in the workplace were exposed at the low end of the dose distribution curve. The results of this analysis include estimations of hourly maxima and time‐weighted average (TWA) doses of nicotine from workplace exposures to ETS (extrapolated from 1 day to 1 week) and doses derived from modeled lung burdens of ultraviolet‐absorbing particulate matter (UVPM) and solanesol resulting from workplace exposures to ETS (extrapolated from 1 day to 1 year).
Heuristic‐Systematic Information Processing and Risk Judgment
Authors: Trumbo Craig W.
Published: May 2006

The heuristic‐systematic information processing model (HSM) holds that individuals will use one or both of these modes of information processing when attempting to evaluate information in order to arrive at a judgment. Systematic processing is defined by effortful scrutiny and comparison of information, whereas heuristic processing is defined by the use of cues to amve more easily at a judgment. Antecedents to the two processing modes include information sufficiency, motivation, and self‐efficacy. Structural equation modeling is used to examine competing configuration of this model and to evaluate the model as appropriate for predicting risk judgment. The model also is evaluated across three groups that vary with respect to their level of concern. These analyses are executed within a case study involving an epidemiological investigation of a suspected cancer cluster. The analysis confirms the HSM's theoretically proposed structure and shows it to be a useful vehicle for evaluating risk judgment. In the overall analysis, antecedent variables generally function as specified by theory. Systematic processing is predicted by greater motivation. Heuristic processing is predicted by information sufficiency. Self‐efficacy is a significant predictor of both processing modes. And heuristic processing is shown to be associated with judgment of less risk. However, when the analysis is contrasted across three groups (those concerned about cancer, not concerned and uncertain) it is shown that the model is significantly more robust for the uncertain group. This finding may have implications for the use of the HSM in risk research specifically, and in field research generally.
“How Exposed Is Exposed Enough?” Lay Inferences About Chemical Exposure
Authors: MacGregor Donald G. , Slovic Paul , Malmfors Torbjorn
Published: May 2006

The concept of exposure is central to chemical risk assessment and plays an important role in communicating to the public about the potential healthrisks of chemicals. Research on chemical risk perception has found some indication that the model lay people use to judge chemical exposure differs from that of toxicologists, thereby leading to different conclusions aboutchemical safety. This paper presents the results of a series of studies directed toward developing a model for understanding how lay people interpret the concept of chemical exposure. The results indicate that people'sbeliefs about chemical exposure (and its risks) are based on two broad categories of inferences. One category of inferences relates to the nature inwhich contact with a chemical has taken place, including the amount of a chemical involved and its potential health consequences. A second category ofinferences about chemical exposure relates to the pragmatics of languageinterpretation, leading to beliefs about the motives and purposes behind chemical risk communication. Risk communicators are encouraged to consider how alternative models of exposure and language interpretation can leadto conflicting conclusions on the part of the public about chemical safety.
Human Interindividual Variability in Parameters Related to Health Risks
Authors: Hattis Dale , Banati J Prerna , Goble Rob , Burmaster David E.
Published: May 2006

This paper reviews existing data on the variability in parameters relevant for health risk analyses. We cover both exposure‐related parameters andparameters related to individual susceptibility to toxicity. The toxicity/susceptibility data base under construction is part of a longer term research effort to lay the groundwork for quantitative distributional analyses of non‐cancer toxic risks. These data are broken down into a variety of parameter types that encompass different portions of the pathway from external exposure to the production of biological responses. The discrete steps in this pathway, as we now conceive them, are:

Contact Rate (Breathing rates per body weight; fish consumption per bodyweight)

Uptake or Absorption as a Fraction of Intake or Contact Rate

General Systemic Availability Net of First Pass Elimination and Dilutionvia Distribution Volume (e.g., intial blood concentration per mg/kg of uptake)

Systemic Elimination (half life or clearance)

Active Site Concentration per Systemic Blood or Plasma Concentration

Physiological Parameter Change per Active Site Concentration (expressed as the dose required to make a given percentage change in different people, or the dose required to achieve some proportion of an individual's maximum response to the drug or toxicant)

Functional Reserve Capacity‐Change in Baseline Physiological Parameter Needed to Produce a Biological Response or Pass a Criterion of Abnormal Function

Comparison of the amounts of variability observed for the different parameter types suggests that appreciable variability is associated with the final step in the process‐differences among people in “functional reserve capacity.” This has the implication that relevant information for estimatingeffective toxic susceptibility distributions may be gleaned by direct studies of the population distributions of key physiological parameters in people that are not exposed to the environmental and occupational toxicants thatare thought to perturb those parameters. This is illustrated with some recent observations of the population distributions of Low Density Lipoprotein Cholesterol from the second and third National Health and Nutrition Examination Surveys.
Performance Assessments of Nuclear Waste Repositories: A Dialogue on Their Value and Limitations
Authors: Ewing Rodney C. , Tierney Martin S. , Konikow Leonard F. , Rechard Rob P.
Published: May 2006

Performance Assessment (PA) is the use of mathematical models to simulate the long‐term behavior of engineered and geologic barriers in a nuclear waste repository; methods of uncertainty analysis are used to assess effects of parametric and conceptual uncertainties associated with the model system upon the uncertainty in outcomes of the simulation. PA is required by the U.S. Environmental Protection Agency as part of its certification process for geologic repositories for nuclear waste. This paper is a dialogue to explore the value and limitations of PA. Two “skeptics” acknowledge the utility of PA in organizing the scientific investigations that are necessary for confident siting and licensing of a repository; however, they maintain that the PA process, at least as it is currently implemented, is an essentially unscientific process with shortcomings that may provide results of limited use in evaluating actual effects on public health and safety. Conceptual uncertainties in a PA analysis can be so great that results can be confidently applied only over short time ranges, the antithesis of the purpose behind long‐term, geologic disposal. Two “proponents” of PA agree that performance assessment is unscientific, but only in the sense that PA is an engineering analysis that uses existing scientific knowledge to support public policy decisions, rather than an investigation intended to increase fundamental knowledge of nature; PA has different goals and constraints than a typical scientific study. The “proponents” describe an ideal, sixstep process for conducting generalized PA, here called probabilistic systems analysis (PSA); they note that virtually all scientific content of a PA is introduced during the model‐building steps of a PSA, they contend that a PA based on simple but scientifically acceptable mathematical models can provide useful and objective input to regulatory decision makers. The value of the results of any PA must lie between these two views and will depend on the level of knowledge of the site, the degree to which models capture actual physical and chemical processes, the time over which extrapolations are made, and the proper evaluation of health risks attending implementation of the repository. The challenge is in evaluating whether the quality of the PA matches the needs of decision makers charged with protecting the health and safety of the public.
Stringency of Workplace Air Contaminant Exposure Limits: A Case Study of OSHA Risk Management
Authors: Hakes Jahn K.
Published: May 2006

Political context may play a large role in influencing the efficiency of environmental and health regulations. This case study uses data from a 1989 update of the Occupational Safety and Health Administration (OSHA) Permissible Exposure Limits (PELS) program to determine the relative effects of legislative mandates, costly acquisition of information by the agency, and pressure applied by special interest groups upon exposure standards. The empirical analysis suggests that federal agencies successfully thwart legislative attempts to limit agency discretion, and that agencies exercise bounded rationality by placing greater emphasis on more easily obtained information. The 1989 PEL were less significantly related to more costly information, contained “safety factors” for chemicals presenting relatively more ambiguous risks, and the proposed standard stringencies showed evidence of beinginfluenced by vying industry and labor interests.
Individual Prior Information in a Physiological Model of 2H8‐Toluene Kinetics: An Empirical Bayes Estimation Strategy
Authors: Vicini Paolo , Pierce Crispin H. , Dills Russell L. , Morgan Michael S. , Kalman David A.
Published: May 2006

Physiologically‐based toxicokinetic (PBTK) models are widely used to quantify whole‐body kinetics of various substances. However, since they attempt to reproduce anatomical structures and physiological events, they have ahigh number of parameters. Their identification from kinetic data alone is often impossible, and other information about the parameters is needed to render the model identifiable. The most commonly used approach consists of independently measuring, or taking fom literature sources, some of the parameters, fixing them in the kinetic model, and then performing model identification on a reduced number of less certain parameters. This results in a substantial reduction of the degrees of freedom of the model. In this study, we show that this method results in final estimates of the free parameters whose precision is overestimated. We then compared this approach with an empirical Bayes approach, which takes into account not only the mean value, but also the error associated with the independently determined parameters. Blood and breath 2H8‐ toluene washout curves, obtained in17 subjects, were analyzed with a previously presented PBTK model suitable for person‐specific dosimetry. Model parameters with the greatest effect onpredicted levels were alveolar ventilation rate QPC, fat tissue fraction VFC, blood air partition coefficient Kb, fraction of cardiac output to fat Qa/co and rate of extrahepatic metabolismVmax.p. Differences in the measured and Bayesian‐fitted values of QPC, VFc and Kb were significant (p < 0.05), andthe precision of the fitted values Vmax.p and Qa/co went from 11 ± 5% to 75 ± 170% (NS) and from 8 ± 2% to 9 ± 2% (p < 0.05) respectively. The empirical Bayes approach did not result in less reliable parameter estimates: rather, it pointed out that the precision of parameter estimates can be overly optimistic when other parameters in the model, eitherdirectly measured or taken from literature sources, are treated as known without error. In conclusion, an empirical Bayes approach to parameter estimation resulted in a better model fit, different final parameter estimates, and more realistic parameter precisions.
The Liquidity Demand for Corporate Property Insurance
Authors: Hau Arthur
Published: May 2006

Abstract

This article suggests that liquidity may be an important reason for a corporation to purchase property insurance. A model of a risk‐neutral producer facing an endogenously determined risk of property damage under an output contract that penalizes underproduction is formulated to exemplify such a real need of liquidity. Under the output contract, the producer may purchase full unfavorable property insurance even when postloss financing is available. Surprisingly, the conclusion may still hold when the cost of postloss financing equals that of long‐term capital, provided that the rate of underproduction penalty is sufficiently high. Similar conclusions apply when postloss financing is replaced by planned internal reserve (self‐insurance) that may be invested in the short run at an interest rate that is lower than the long‐term cost of capital. When the capital market is perfect, however, the holding of planned internal reserve eliminates the purchase of actuarially unfavorable property insurance.
A Shortcut Way of Pricing Default Risk Through Zero‐Utility Principle
Authors: Tibiletti Luisa
Published: May 2006

Abstract

Pricing the default risk is a hot challenge for every risk manager. The problem is tackled in the framework of the zero‐utility principle. According to Pratt (1964), an approximation of the risk premium should be proportional to the Arrow–Pratt absolute risk aversion coefficient and the variance. Is that still true as a default risk is concerned? The answer appears to be negative, because the variance does not look to be an appropriate tool for asymmetrical risk. On the other hand, fear of ruin coefficient and probability of default are proved to be well‐tailored tools for a preliminary pricing. Bid and ask price approximations are both elicited and a necessary condition for risk exchange set out.