bluuebunny/crossref_metadata_2025 huggingface dataset:
The Cost of Compensating Asbestos Victims Under the Occupational Disease Compensation Act of 1983
Authors: Siskind Frederic B.
Published: May 2006

The potentially huge financial liability due to asbestos product suits and the resulting filings for reorganization in bankruptcy by Manville, UNR Industries, Inc., and Amatex, has become a major public policy concern. In response to the problem several bills have been introduced in the Congress to provide compensation for asbestos (and other occupational disease) victims. This paper estimates the cost of compensating asbestos victims under the provisions of the “Occupational Disease Compensation Act of 1983,” introduced by Congressman George Miller. Utilizing fatality projections from studies by Enterline, Selikoff, and Walker, and assumptions regarding likely claims filing and success rates, duration and degree of disability, and medical expenses, first year costs for this legislation are estimated to range from a low of $131 million to a high of $1.9 billion. Present value cost estimates at a 2% real discount rate range from $3 billion to $56 billion.

The paper also estimates the impact of possible modifications to the compensation provisions of the legislation. Reducing medical payments by the amount received from medicare would lower costs by 3–4%. Providing survivors with a 3‐year lump sum benefit rather than a 5‐year lump sum payment would save 20–25% as would offsetting the 5‐year lump sum by expected social security old age and disability benefits. Combining all of these changes would reduce costs by almost 50%.
Mixtures of Toxic Agents and Attributable Risk Calculations
Authors: Seiler Fritz A. , Scott Bobby R.
Published: May 2006

Calculations of attributable risks have attracted increasing interest recently. However, these efforts have been limited to mostly one agent, radiation, and no interactions with effects of other toxic agents have been taken into account. This paper outlines a generic approach to the calculation of attributable risks for an exposure to several toxic agents and interaction effects associated with them. In this calculation, the partition of interaction terms between the agents responsible is of particular importance. At present, there are no rules on how to assign equitable shares, so one methodology will be proposed and others discussed briefly. For one example of an assignment, the standard errors of the attributable risks are determined in terms of the uncertainties of the input parameters, thus setting the stage for a comparison of the different shares of responsibility.
Decision Analysis and Risk Management Decision Making: Issues and Methods
Authors: Covello Vincent T.
Published: May 2006

This paper provides an overview of decision analysis and its use in risk management decision making. The paper discusses the distinctive characteristics of decision analysis and compares these characteristics with those of its principal alternative—cost–benefit analysis. The paper also discusses each of the steps in a decision analysis and the strengths and limitations of the method.
Risks of Municipal Solid Waste Incineration: An Environmental Perspective
Authors: Denison Richard A. , Silbergeld Ellen K.
Published: May 2006

The central focus of the debate over incineration of municipal solid waste (MSW) has shifted from its apparent management advantages to unresolved risk issues. This shift is a result of the lack of comprehensive consideration of risks associated with incineration. We discuss the need to expand incinerator risk assessment beyond the limited view of incinerators as stationary air pollution sources to encompass the following: other products of incineration, ash in particular, and pollutants other than dioxins, metals in particular; routes of exposure in addition to direct inhalation; health effects in addition to cancer; and the cumulative nature of exposure and health effects induced by many incinerator‐associated pollutants. Rational MSW management planning requires that the limitations as well as advantages of incineration be recognized. Incineration is a waste‐processing—not a waste disposal—technology, and its products pose substantial management and disposal problems of their own. Consideration of the nature of these products suggests that incineration is ill‐suited to manage the municipal wastestream in its entirety. In particular, incineration greatly enhances the mobility and bioavailability of toxic metals present in MSW. These factors suggest that incineration must be viewed as only one component in an integrated MSW management system. The potential for source reduction, separation, and recycling to increase the safety and efficiency of incineration should be counted among their many benefits. Risk considerations dictate that alternatives to the use of toxic metals at the production stage also be examined in designing an effective, long‐term MSW management strategy.
A Methodology for More Efficient Tail Area Sampling with Discrete Probability Distributions
Authors: Park Sang Ryeol , Kim Tae Woon , Lee Byung Ho
Published: May 2006

Monte Carlo Method is commonly used to observe the overall distribution and to determine the lower or upper bound value in statistical approach when direct analytical calculation is unavailable. However, this method would not be efficient if the tail area of a distribution is concerned. A new method, entitled Two‐Step Tail Area Sampling, is developed, which uses the assumption of discrete probability distribution and samples only the tail area without distorting the overall distribution. This method uses a two‐step sampling procedure. First, sampling at points separated by large intervals is done and second, sampling at points separated by small intervals is done with some check points determined at first‐step sampling. Comparison with Monte Carlo Method shows that the results obtained from the new method converge to analytic value faster than Monte Carlo Method if the numbers of calculation of both methods are the same. This new method is applied to DNBR (Departure from Nucleate Boiling Ratio) prediction problem in design of the pressurized light water nuclear reactor.
The Social Amplification of Risk: A Conceptual Framework
Authors: Kasperson Roger E. , Renn Ortwin , Slovic Paul , Brown Halina S. , Emel Jacque , Goble Robert , Kasperson Jeanne X. , Ratick Samuel
Published: May 2006

One of the most perplexing problems in risk analysis is why some relatively minor risks or risk events, as assessed by technical experts, often elicit strong public concerns and result in substantial impacts upon society and economy. This article sets forth a conceptual framework that seeks to link systematically the technical assessment of risk with psychological, sociological, and cultural perspectives of risk perception and risk‐related behavior. The main thesis is that hazards interact with psychological, social, institutional, and cultural processes in ways that may amplify or attenuate public responses to the risk or risk event. A structural description of the social amplification of risk is now possible. Amplification occurs at two stages: in the transfer of information about the risk, and in the response mechanisms of society. Signals about risk are processed by individual and social amplification stations, including the scientist who communicates the risk assessment, the news media, cultural groups, interpersonal networks, and others. Key steps of amplifications can be identified at each stage. The amplified risk leads to behavioral responses, which, in turn, result in secondary impacts. Models are presented that portray the elements and linkages in the proposed conceptual framework.
Lottery Games and Risky Technologies: Communications About Low‐Probability/High‐Consequence Events
Authors: Mumpower Jeryl L.
Published: May 2006

There are strong structural similarities between risks from technological hazards and big‐purse state lottery games. Risks from technological hazards are often described as low‐probability, high‐consequence negative events. State lotteries could be equally well characterized as low‐probability, high‐consequence positive events. Typical communications about state lotteries provide a virtual strategic textbook for opponents of risky technologies. The same techniques can be used to sell lottery tickets or “sell” opposition to risky technologies. Eight basic principles are enumerated.
Cooperation Versus Confrontation: A Comparison of Approaches to Environmental Risk Management in Japan and the United States1
Authors: Covello Vincent T. , Kawamura Kazuhiko , Boroush Mark , Ikeda Saburo , Lynes Paul F. , Minor Michael S.
Published: May 2006

This paper compares approaches to environmental risk management in Japan and the United States. The paper includes an historical examination of two case studies of environmental risk management: synthetic detergents and lead in gasoline. In addition, the paper discusses several important differences between Japan and the United States, including (a) different attitudes toward separating environmental risk management from environmental risk assessment, and (b) different approaches toward environmental risk management. Specifically, the Japanese approach is based largely on a cooperative model of risk management, with a strong emphasis on negotiation and consensus‐building, while the U.S. approach is based largely on a confrontational model of risk management, with a strong emphasis on rigorous scientific analysis and open adverserial processes.
Decision‐Making, Time Horizons, and Risk in the Very Long‐Term Perspective
Authors: Svenson Ola , Karlsson Gunnar
Published: May 2006

Some decisions made today have far‐reaching consequences as exemplified by those concerning nuclear power and spent nuclear fuel. The investigation presented here uses a decision theoretic framework in which time horizons and the discounting of negative consequences play significant roles. The results indicated wide variations in the lengths of the planning horizons judged to be adequate not only across a number of activities, including nuclear waste management, but also across groups of subjects (e.g., engineering students, retired people, and nuclear fuel experts). The paper reports typical judgments and correlations between different variables for different groups of subjects. The differences across groups reflect potential sources of conflict, depending in part on different values and different perceptions of more or less uncertain facts. Discounting functions for negative consequences in the future were also established. A range in differences in the speed of discounting were found and illustrated. Furthermore, it was found that substantial proportions in all groups regarded negative consequences related to nuclear waste as nondiscountable. When asked about the effect of time until outcome on acceptable probability of a negative outcome, many subjects used the probability concept in an incoherent way, illustrating the great difficulty in communicating small probabilities in a long‐term risk context.
Dimensions of Risk
Authors: Hansson Sven Ove
Published: May 2006

Eight major factors of risk comparisons are presented, and the conventional reduction of the risk concept to a unidimensional format is challenged. The similarities between risk issues and other issues of the social decision process are stressed. It is concluded that risk decisions are part of the general political process, and cannot be isolated from this. Expert assessments should be presented in a way that reflects the complexity of the subject matter, instead of repressing it.
Network Evening News Coverage of Environmental Risk
Authors: Greenberg Michael R. , Sachsman David B. , Sandman Peter M. , Salomone Kandice L.
Published: May 2006

ABC, CBS, and NBC's carefully crafted and expensively produced evening news broadcasts devoted 1.7% of their air time to 564 stories about man‐made environmental risks during the period from January 1984 to February 1986. Little relationship was found between amount of coverage and public health risk. Instead, the networks appeared to be using traditional journalistic determinants of news (timeliness, proximity, prominence, consequence, and human interest) plus the broadcast criterion of visual impact to determine the degree of coverage of risk issues. Government, industry, and citizens accounted for two‐thirds of the sources cited by the networks. Experts and spokespersons for environmental advocacy groups were sparsely used as sources. Given the media's need for news pegs, acute and chronic risk stories were covered differently. Acute risk stories were reported in a clearly defined cycle, peaking on the second day with on‐the‐scene reports and film‐clips of devastation. In keeping with a decrease in visual drama, later reports were shorter and emphasized legal and political considerations. Chronic risk coverage followed the release of new scientific, legal, or political information.
Transgenic Mice as Future Tools in Risk Assessment
Authors: Cordaro J. Christopher
Published: May 2006

Historically, mice have served a routine and useful purpose in the research, development, and testing of biologicals, chemicals, and drugs for efficacy, toxicity, and carcinogenic risk. The literature is replete with examples using mice to study organic compounds both in short‐term tests involving tumor initiation and promotion and in long‐term experiments dealing with fertility, reproduction, and teratology. During the past two decades, a virtual explosion of advances has occurred in modern biology that includes the discoveries of retroviruses, oncogenes, DNA restriction enzymes, nucleotide sequence analyses, and microinjection techniques. Fusion of these milestones in genetic, molecular, and cell biology with recent developments in mouse embryology has opened novel avenues and methods of experimentation as significant additions to the risk assessment armamentarium that currently uses both prokaryotes and eukaryotes. Some promising directions afforded by transgenic mice as powerful future tools in risk assessment will be summarized below.
On the Relationship Between Carcinogenicity and Acute Toxicity
Authors: Metzger Bernhard , Crouch Edmund , Wilson Richard
Published: May 2006

Parodi et al.(1) and Zeise et al.(2) found a surprising statistical correlation (or association) between acute toxicity and carcinogenic potency. In order to shed light on the questions of whether or not it is a causal correlation, and whether or not it is a statistical or tautological artifact, we have compared the correlations for the NCI/NTP data set with those for chemicals not in this set. Carcinogenic potencies were taken from the Gold et al. database. We find a weak correlation with an average value of TD50/LD50= 0.04 for the non‐NCI data set, compared with TD50/LD50= 0.15 for the NCI data set. We conclude that it is not easy to distinguish types of carcinogens on the basis of whether or not they are acutely toxic.
A Risk Assessment for Selected Lead‐Induced Health Effects: An Example of a General Methodology
Authors: Whitfield Ronald G. , Wallsten Thomas S.
Published: May 2006

The research described here is part of a larger risk assessment project to aid the U.S. Environmental Protection Agency (EPA) in its review of the primary National Ambient Air Quality Standard for lead. The methodology can be applied to many situations in which a policy decision about a toxic substance is required in the face of incomplete data. Numerical results are presented for three potentially adverse lead‐induced effects of interest to EPA: elevated erythrocyte protoporphyrin (EP), hemoglobin (Hb) decrement, and intelligence quotient (IQ) decrement.
Risk Perception and Social Acceptability of Technologies: The French Case
Authors: Bastide Sophie , Moatti Jean‐Paul , Pages Jean‐Pierre , Fagnani Francis
Published: May 2006

The authors present results of a February 1987 survey on judged frequency of mortality causes and risk perception of technologies in a representative sample of the French population. Although the French context is very different, and the impact of public controversies have been very limited on technological choices such as the nuclear energy program, strong similarities in risk perception of technologies are observed with results from U.S. surveys. Results, which could be worthwhile for other countries, suggest that risk perception is influenced by two different types of components. The first influence is the global feeling of “security” that society procures to its members. Such feeling depends on the individual's socioeconomic status, subjective state of health, and personal discomfort in daily life, and explains individual aversion to risk independently of the mortality causes or technologies involved. The second influence is the degree of perceived social legitimization of the activities involving risks. Risks of medical and transportation activities are strongly opposed to illegitimate risky behaviors (smoking, drugs, alcohol); technologies which have been an object of public debate (nuclear plants, the chemical industry, lead in gasoline) have an intermediate position reflecting the remaining uncertainties of public opinion about their risk–benefit balancing. Tentative conclusions for risk communication are proposed.
Major Hazard Information Policy in the European Community: Implications for Risk Analysis
Authors: Otway Harry , Amendola Aniello
Published: May 2006

The main impetus to the development of information about major industrial hazards in the European Community comes from the so‐called Seveso Directive, which defines an information network and requires the generation and transmission of information as the basis for accident prevention and risk management. This important policy development, which calls for the formal identification and analysis of major hazards and the communication of risk information to members of the public, presents new opportunities and challenges to risk analysis and research in Europe. This paper briefly reviews the accidents that gave rise to the Directive and shaped its content, and then summarizes its requirements. The status of its implementation in the EC Member States is discussed, with special emphasis given to the comparison of safety analysis practices, the Major Accident Reporting System (MARS), and risk communication. Some new research directions stimulated by the Directive are identified.
The Decline of Deference: The Political Context of Risk Communication
Authors: Laird Frank N.
Published: May 2006

Risk communication is seen as an important adjunct to the process of siting locally noxious facilities. To understand how risk communication might function in such a process, one needs to understand the political context that gives rise to public opposition to such facilities in the first place. This analysis draws on a variety of data to describe the decline of deference, a situation in which a hostile and alienated public is mobilized primarily through ad hoc voluntary organizations, and is increasingly reluctant to defer important decisions to institutional elites. Risk communication programs must be designed to offset the trends that result in the decline of deference. This conclusion differs markedly from the conventional wisdom that risk communication is merely a device for providing information to citizens so sthat they may make more rational decisions.
The Health Risks of Energy Production
Authors: Fritzsche Andrew F.
Published: May 2006

Any personal or societal activity, besides bringing us benefits, also carries some risk. Energy production and use are no exceptions. In order to judge these risks, they must be quantified, and the risks of all alternative methods of producing this energy must then be compared among each other. These risks originate in many parts of the energy cycle; they are diverse in character and involve different parts of the population. It is therefore necessary to discriminate between many aspects of risk so that only reasonably comparable categories are compared. The results of a critical analysis of the international risk literature are presented, which are applicable to power production plants as they could be built today in central European countries. This review pays special attention to the possibility of severe accidents occurring, which attract so much attention in our modern societies. It turns out that the health risks of routine nuclear energy production are lower than the risks of other energy options, particularly for the general public. The probability of a severe accident occurring is far higher for all conventional energy options. Only the renewable systems utilizing the energy of the sun and the wind are not susceptible to severe accidents.
OSHA's Permissible Exposure Limits: Regulatory Compliance Versus Health Risk
Authors: Spear Robert C. , Selvin Steve
Published: May 2006

Workplace exposures to airborne chemicals are regulated in the U.S. by the Occupational Safety and Health Administration (OSHA) via the promulgation of permissible exposure limits (PELs). These limits, usually defined as eight‐hour time‐weighted average values, are enforced as concentrations never to be exceeded. In the case of chronic or delayed toxicants, the PEL is determined from epidemiological evidence and/or quantitative risk assessments based on long‐term mean exposures or, equivalently, cumulative lifetime exposures. A statistical model was used to investigate the relation between the compliance strategy, the PEL as a limit never to be exceeded, and the health risk as measured by the probability that an individual's long‐term mean exposure concentration is above the PEL. The model incorporates within‐worker and between‐worker variability in exposure, and assumes the relevant distributions to be log‐normal. When data are inadequate to estimate the parameters of the full model, as it is in compliance inspections, it is argued that the probability of a random measurement being above the PEL must be regarded as a lower bound on the probability that a randomly selected worker's long‐term mean exposure concentration will exceed the PEL. It is concluded that OSHA's compliance strategy is a reasonable, as well as a practical, means of limiting health risk for chronic or delayed toxicants.
A Robust Measure of Uncertainty Importance for Use in Fault Tree System Analysis
Authors: Iman Ronald L. , Hora Stephen C.
Published: May 2006

The analysis of probabilistic fault trees often involves the investigation of events that contribute both to the frequency of the top event and to the uncertainty in this frequency. This paper provides a discussion of three measures of the contribution of an event to the total uncertainty in the top event. These measures are known as uncertainty importance measures. Two of these measures are new developments. Each of the measures is shown to have unique advantages and disadvantages. The three measures are based on, respectively, the expected reduction in the variance of the top‐event frequency should the uncertainty in an event be resolved, the same measure based on the log frequency, and a measure based on shifts in the quantiles of the distribution of top‐event frequency.
Assessing Exposures to Environmental Tobacco Smoke
Authors: Leaderer Brian P.
Published: May 2006

The combustion of tobacco indoors results in the emission of a wide range of air contaminants that are associated with a variety of acute and chronic health and comfort effects. Exposures to environmental tobacco smoke (ETS) are assessed for epidemiologic studies and risk assessment and risk management applications. An individual's or population's exposure to ETS can be assessed by direct methods, which employ personal air monitoring and biomarkers, and indirect methods, which utilize various degrees of microenvironmental measurements of spaces, models, and questionnaires in combination with time–activity information. The major issues related to assessing exposures to ETS are summarized and discussed, including the physical–chemical nature of ETS air contaminants, use of proxy air contaminants to represent ETS, use of biomarkers, models for estimating ETS concentrations indoors, and the application of questionnaires.
Bayesian Modeling of Initiating Event Frequencies at Nuclear Power Plants1
Authors: Hora Stephen C. , Iman Ronald L.
Published: May 2006

Probabilistic risk assessments (PRAs) of nuclear power plants proceed by modeling potential accident sequences at the plant of interest. These hypothesized accident sequences begin with initiating events. A very important initiating event phenomenon is the loss of off‐site power (LOSP). This is the interruption of the preferred power supply to the essential and nonessential switchgear buses resulting in the use of emergency power supplies. If off‐site power is not restored in a reasonable period of time, emergency backup sources of AC and DC power may subsequently fail, resulting in a possible core meltdown. Industry data show 63 LOSP incidents in the operating history of nuclear plants in the United States. Two Bayesian models for the frequency of incidents of LOSP are presented. One model assumes that all nuclear power generating stations share a common incidence rate for LOSP, and a posterior distribution is found for the mean incidence rate for all plants. The second model assumes that the incidence rates for individual plants belong to a superpopulation of incidence rates. Under this model the incidence rate for each plant is unique, but related to the incident rate of all other plants through the superpopulation. These models provide a vehicle for incorporating initiating event uncertainty into PRAs.
A Simple Formula for Calculating the “Mass Density” of a Lognormally Distributed Characteristic: Applications to Risk Analysis
Authors: Finkel Adam M.
Published: May 2006

Statements such as “80% of the employees do 20% of the work” or “the richest 1% of society controls 10% of its assets” are commonly used to describe the distribution or concentration of a variable characteristic within a population. Analogous statements can be constructed to reflect the relationship between probability and concentration for unvarying quantities surrounded by uncertainty. Both kinds of statements represent specific usages of a general relationship, the “mass density function,” that is not widely exploited in risk analysis and management. This paper derives a simple formula for the mass density function when the uncertainty and/or the variability in a quantity is lognormally distributed; the formula gives the risk analyst an exact, “back‐of‐the‐envelope” method for determining the fraction of the total amount of a quantity contained within any portion of its distribution. For example, if exposures to a toxicant are lognormally distributed with σin x= 2, 50% of all the exposure is borne by the 2.3% of persons most heavily exposed. Implications of this formula for various issues in risk assessment are explored, including: (1) the marginal benefits of risk reduction; (2) distributional equity and risk perception; (3) accurate confidence intervals for the population mean when a limited set of data is available; (4) the possible biases introduced by the uncritical assumption that extreme “outliers” exist; and (5) the calculation of the value of new information.
Protective Responses to Household Risk: A Case Study of Radon Mitigation
Authors: Doyle James K. , McClelland Gary H. , Schulze William D. , Elliott Steven R. , Russell Glenn W.
Published: May 2006

This study analyzes the effectiveness of a mass‐media radon information and testing campaign conducted in the Washington, D.C. area in the winter of 1988. Although an impressive number of test kits (approximately 100,000) were sold, the ultimate mitigation rates resulting from the campaign were extremely low. Analyses show that low mitigation rates cannot be explained by postulating that people's responses to radon are insensitive to the level of objective risk. They may instead be due to characteristics of the protective response required to reduce radon risk. Radon may be thought of as one of a family of household risks which have risk response profiles that make them particularly difficult for people to manage and remediate. Traditional information campaigns for such risks are likely to be ineffective; instead, they may require regulatory strategies or programs which provide active guidance and assistance.
Risk Prevention and Policy‐Making in Automatic Systems
Authors: Goossens Louis H.J.
Published: May 2006

Accidents with automatic production systems are reported to be on the order of one in a hundred or thousand robot‐years, while fatal accidents are found to occur one or two orders of magnitude less frequently. Traditions in occupational safety tend to seek for safety targets in terms of zero severe accidents for automatic systems. Decision‐making requires a risk assessment balancing potential risk reduction measures and costs within the cultural environment of a production company. This paper presents a simplified procedure which acts as a decision tool. The procedure is based on a risk concept approaching prevention both in a deterministic and in a probabilistic manner. Eight accident scenarios are shown to represent the potential accident processes involving robot interactions with people. Seven prevention policies are shown to cover the accident scenarios in principle. An additional probabilistic approach may indicate which extra safety measures can be taken against what risk reduction and additional costs. The risk evaluation process aims at achieving a quantitative acceptable risk level. For that purpose, three risk evaluation methods are discussed with respect to reaching broad consensus on the safety targets.
Applications of Probabilistic Risk Assessments: The Selection of Appropriate Tools1
Authors: Linnerooth‐Bayer Joanne , Wahlström Björn
Published: May 2006

Probabilistic risk assessment (PRA) is an important methodology for assessing the risks of complex technologies. This paper discusses the strengths and weaknesses of PRA. Its application is explored in three different settings: adversarial policy processes, regulatory/licensing procedures, and plant safety audits. It is concluded that PRA is a valuable tool for auditing safety precautions of existing or planned technologies, especially when it is carried out as an interactive process involving designers and plant personnel who are familiar with actual, everyday operations. PRA has not proven to be as well‐suited in providing absolute risk estimates in public‐policy debates concerning the acceptability of a technology, or for the licensing and regulatory procedures. The reasons for this are discussed.
Public Perception of the Risks of Floods: Implications for Communication
Authors: Lave Tamara R. , Lave Lester B.
Published: May 2006

Floods in the U.S. kill an average of 162 people each year and cause $3.4 billion in property damage. Flood control programs have been successful in lowering, but not eliminating, the risks to lives and property. Since the late 1960s, the federal government has emphasized flood insurance as a primary tool for improving location and flood‐proofing decisions, as well as for reimbursing flood losses. Since only 12.7% of houses in flood plain areas are covered by flood insurance, the program has been ineffective. We interviewed people living in three communities that had recently been flooded. Most people had little knowledge of the cause of floods or what could be done to prevent damage. People who work and who are better educated know more and are more likely to have flood insurance. Current government publications about flood risks are not likely to be understood by those at risk. There is little effective communication about the nature and magnitude of the risks and what individuals can do to protect their lives and property and lower their financial risks. The risk management program should both emphasize communication and enforcement of the current law requiring people at risk who hold federally funded loans to be insured.
Predicting EPA's Forthcoming CO Standards in Light of New Clinical Evidence
Authors: Graham John D. , Holtgrave David R.
Published: May 2006

For the past several years, the EPA has been monitoring clinical studies on the adverse health effects of heart patients’exposure to carbon monoxide. This paper examines the impact of three such studies (including the multi‐center CO study organized by the Health Effects Institute) on the forthcoming EPA standards for carbon monoxide. Eleven peer‐nominated specialists with expertise in environmental science and public policy were interviewed according to a specific protocol. Overall, the experts felt that the HEI study would receive greater weight than the other two studies in the regulatory process for a variety of technical reasons. Weighting each expert opinion equally, we conclude that there is about a 0.69 probability that the CO standards will be retained at their present levels, a 0.28 probability that the standards will be tightened, and a 0.03 probability that the standards will be relaxed. When asked to imagine that the HEI data were never collected and then asked to reassess their probability judgments, the mean probability judgment that the standards will be relaxed rose to 0.11, while the mean probability judgment that the standards will be tightened fell to 0.20. A modest degree of variability in expert opinion is reported in the paper. While the HEI study may receive relatively great weight in the regulatory process, it increases only slightly the probability that EPA's CO standards will be changed.
Risk Analysis of a Gas‐Processing Complex in India
Authors: Garg R. K. , Khan A. A.
Published: May 2006

ONGC's Hazira Gas‐Processing Complex (HGPC) consists of facilities for receiving natural gas along with associated condensate from an off‐shore field at a rate of 20 MMN M3 per day. After separating the condensate, which is processed in condensate fractionation units, the gas is processed through various steps to recover LPG and to reduce its dew point to less than 5°C in order to make it suitable for transportation over long distances. The acid gas recovered during the gas‐sweetening step is processed to obtain sulphur. The major products manufactured at HGPC therefore are lean sweet gas, LPG, NGL, and sulphur. The Oil and Natural Gas Commission awarded the assignment on Hazard Study and Risk Analysis of their Hazira Gas‐Processing Complex (HGPC) to the Council of Scientific and Industrial Research (CSIR) in association with the Netherlands Organisation for Applied Scientific Research (TNO). The scope of this assignment covered a number of closely related and fully defined activities normally encountered in this type of work. Identification of hazards through the most appropriate methods, assigning frequency of occurrence of major unwanted incidents, quantification and assessment of probable damage to plant equipment, environment, human and animal life due to an unexpected event, and evaluation of various methods for reducing risk, together constituted the methodology for this assignment. Detailed recommendations aimed at reducing risk and enhancing reliability of plant and machinery were made. This article gives an overview of the assignment.
Additive and Multiplicative Relative Risk in the Two‐Stage Clonal Expansion Model of Carcinogenesis
Authors: Kodell Ralph L. , Krewski Daniel , Zielinski Jan M.
Published: May 2006

The effects of exposure to two carcinogens are explored within the context of the two‐stage clonal expansion model of carcinogenesis. This biologically based model provides a useful framework for the quantitative description of carcinogenesis, and for defining carcinogenic agents that act as initiators, promoters, and completers. This paper addresses the combined effects of simultaneous lifetime exposure to two carcinogens as well as nonoverlapping partial lifetime exposure to each agent. Whereas the age‐specific relative risk for exposure to two initiators or two completers is additive, a multiplicative relative risk model holds for exposure to an initiator and a completer, or to a promoter and a completer. Exposure to two promoters yields supra‐multiplicative relative risk. Exposure to an initiator and promoter leads to multiplicative and supra‐multiplicative relative risks for simultaneous lifetime and nonoverlapping partial lifetime exposures, respectively. Although departures from the additive relative risk model may thus occur at moderate to high doses, conditions are identified under which additivity will provide a good approximation to the joint risk at low doses. The methods of analysis used in this paper can also be used to determine the joint effects of exposure to two carcinogens which may affect more than one stage (initiation, promotion, completion) of the process of carcinogenesis. In general, the joint effects of exposure to such agents depends on the relative magnitude of the effects on individual stages.
Mathematical Modeling of Reproductive and Developmental Toxic Effects for Quantitative Risk Assessment
Authors: Kodell Ralph L. , Howe Richard B. , Chen James J. , Gaylor David W.
Published: May 2006

A new mathematical dose‐response model for reproductive and developmental risk assessment is proposed. The model includes the possibility of an exposure threshold as well as a litter‐size effect. Correlation of responses of offspring from the same litter is taken into account through the use of the beta‐binomial distribution. Confidence limits for low‐dose extrapolation are based on the asymptotic distribution of the likelihood ratio. An empirical comparison of the proposed procedure to that of Rai and Van Ryzin(1) demonstrates the improvement that can be achieved with the new procedure.
Risk to Groundlings of Death Due to Airplane Accidents: A Risk Communication Tool
Authors: Goldstein Bernard D. , Demak Michele , Northridge Mary , Wartenberg Daniel
Published: May 2006

During the period 1975‐85 in the United States the 70 year lifetime risk of dying from being hit by an airplane when the individual is on the ground was 4.2 per million people. In contrast to many other risks used for comparison purposes, risk to those on the ground from an airplane crash is not a function of our own skills; is not optional; provides no benefit to anyone involved; and is not an act of nature. As a risk comparison tool it also has the useful characteristics of being something about which we can agree that regulatory action, such as control of airplane use and traffic, is warranted; but that no significant change in personal behavior, such as living in the basement to protect against dying from a plane hitting the home, is commensurate with the extent of risk.
Determination of Less‐Than‐Lifetime Exposures to Point Source Emissions
Authors: Price Paul S. , Sample James , Strieter Robert
Published: May 2006

This paper presents a method of estimating long‐term exposures to point source emissions. The method consists of a Monte Carlo exposure model (PSEM or Point Source Exposure Model) that combines data on population mobility and mortality with information on daily activity patterns. The approach behind the model can be applied to a wide variety of exposure scenarios. In this paper, PSEM is used to characterize the range and distribution of lifetime equivalent doses received by inhalation of air contaminated by the emissions of a point source. The output of the model provides quantitative information on the dose, age, and gender of highly exposed individuals. The model is then used in an example risk assessment. Finally, future uses of the model's approach are discussed.
The Causal Sequence of Risk Communication in the Parkfield Earthquake Prediction Experiment
Authors: Mileti Dennis S. , Fitzpatrick Colleen
Published: May 2006

A model of public perception and response to communication about natural hazards risk was constructed. It was estimated on data from samples of households in three communities at risk in the Parkfield earthquake prediction experiment. Estimated model parameters revealed consistent conclusions. Communicated risk information that was reinforced through additional communications and/or social cues precipitated an interactive personal search for more information; personal definitions of risk and what to do emerged; and these social constructions directed how the public responded. Perceived risk only indirectly impacted public action through information searching. This suggests that searching behavior should intervene between perception of risk and response in the theory of public risk communication.
Runaway Reactions, Their Courses, and the Methods to Establish Safe Process Conditions
Authors: Gustin Jean Louis
Published: May 2006

The purpose of this paper is to describe the various process deviations which can cause a runaway reaction to occur, and to discuss the experimental information necessary for risk assessment, the choice of a safe process, and the mitigation of the consequences of the runaway reaction. Ten typical hazardous process situations have been identified, considering various modes of initiation, homogeneous and heterogeneous, Arrhenius, and autocatalytic reactions. Each possible hazardous process deviation is illustrated by examples from the process industry and/or relevant experimental information obtained from laboratory experiments.
Risk Assessment for Aflatoxin B1: A Modeling Approach
Authors: Wu‐Williams Anna H. , Zeise Lauren , Thomas Duncan
Published: May 2006

The data generated by Yeh et al. on hepatitis B virus, aflatoxin, and primary hepatocellular carcinoma (PHC)in Southern Guangxi, China was used to evaluate the cancer potency of aflatoxin. We examined model fits to these data to explore whether hepatitis B virus (HBV)and aflatoxin intake act together to affect PHC rates in an additive, multiplicative, or interactive fashion, using relative and excess risk model forms. Purely additive models fit the data poorly. Fitted models were checked for plausibility by comparing predictions for the U.S. population with actual PHC incidence rates in the United States, and parameter stability was evaluated. The multiplicative relative risk and the interactive excess risk models provided satisfactory descriptions of the Yeh et al. data and U.S. PHC rates. There is about an eight‐fold difference in the potency estimate for aflatoxin under the multiplicative relative risk (5.7 (mg/kg‐day)‐1)and interactive excess risk models (45.6 mg/kg‐day)‐1). The assumptions and limitations of the various models are discussed.
Concordance of Carcinogenic Response between Rodent Species: Potency Dependence and Potential Underestimation
Authors: Piegorsch Walter W. , Carr Gregory J. , Portier Christopher J. , Hoel David G.
Published: May 2006

The use of average qualitative concordance between two bioassay endpoints is considered, with emphasis directed at agreement between rats and mice from results of long‐term carcinogenicity studies. It is noted that concordance varies as a function of the underlying potency or toxicity of the chemicals over which the averaging is performed. Thus, the averaging process dilutes large observed concordances from potent chemicals, and possibly inflates lower observed concordances from weakly active chemicals. Stratification over some measure of potency is suggested as a method for taking these effects into account. Statistical simulations of concordance analyses limited to low‐potency ranges are employed to examine the concordance measure in greater detail. It is seen that at low potencies, observed concordance is consistently underestimated, reaching maximum levels of only about 80%.
Risk Assessment for Aflatoxin: III. Modeling the Relative Risk of Hepatocellular Carcinoma
Authors: Hoseyni Mohammad S.
Published: May 2006

Estimates have been made of the cancer potency of aflatoxin exposure among the U.S. population. Risk modeling is used to assess the dose‐response relationship between aflatoxin exposure and primary liver cancer, controlling for hepatitis B virus (HBV), based on data provided by the Yeh et al. study in China.(1) A relative risk model is proposed as a more appropriate alternative to the additive (“absolute” risk) model for transportation of risk coefficients between populations with different baseline rates. Several general relative risk models were examined; the exponential model provided the best fit. The Poisson regression method was used to fit the relative risk model to the grouped data. The effects of exposure to aflatoxin (AFB1) and hepatitis B infection were both found to be statistically significant. The risk of death from liver cancer for those exposed to AFB1 relative to the unexposed population, increases by 0.05% per ng/kg/day exposure of AFB1 (p<0.001). The results also indicated a 25‐fold increase in the risk of death from liver cancer among those infected with hepatitis B virus, relative to noncarriers (p<0.0001). With a hepatitis prevalence rate of 1%, the aflatoxin intake level associated with liver cancer lifetime excess risk of 1 × 10−5 for the U.S. population was estimated as 253 ng/day, based on a liver cancer baseline rate of 3.4 /100,000/yr.
Extending the Stochastic Two‐Stage Model of Carcinogenesis to Include Self‐Regulation of the Nonmalignant Cell Population
Authors: Anthony Cox Louis
Published: May 2006

One of the challenges of introducing greater biological realism into stochastic models of cancer induction is to find a way to represent the homeostatic control of the normal cell population over its own size without complicating the analysis too much to obtain useful results. Current two‐stage models of carcinogenesis typically ignore homeostatic control. Instead, a deterministic growth path is specified for the population of “normal” cells, while the population of “initiated” cells is assumed to grow randomly according to a birth‐death process with random immigrations from the normal population. This paper introduces a simple model of homeostatically controlled cell division for mature tissues, in which the size of the nonmalignant population remains essentially constant over time. Growth of the nonmalignant cell population (normal and initiated cells) is restricted by allowing cells to divide only to fill the “openings” left by cells that die or differentiate, thus maintaining the constant size of the nonmalignant cell population. The fundamental technical insight from this model is that random walks, rather than birth‐and‐death processes, are the appropriate stochastic processes for describing the kinetics of the initiated cell population. Qualitative and analytic results are presented, drawn from the mathematical theories of random walks and diffusion processes, that describe the probability of spontaneous extinction and the size distribution of surviving initiated populations when the death/differentiation rates of normal and initiated cells are known. The constraint that the nonmalignant population size must remain approximately constant leads to much simpler analytic formulas and approximations, flowing directly from random walk theory, than in previous birth‐death models. As in other stochastic models, our analysis implies that individual susceptibility to carcinogens affecting the second (malignant) transformation rate should follow an age‐dependent frequency distribution in a population of initially identical individuals; hence, individual risks are heterogeneous even in the absence of individual differences in exposure patterns or pharmacokinetics. A theoretical formula is developed for the approximate frequency distribution of individual susceptibilities in a population exposed to a simple initiator/ delay/completor regimen.