bluuebunny/crossref_metadata_2025 huggingface dataset:
Subjective‐Probability‐Based Scenarios for Uncertain Input Parameters: Stratospheric Ozone Depletion
Authors: Hammitt James K.
Published: May 2006

Risk analysis often depends on complex, computer‐based models to describe links between policies (e.g., required emission‐control equipment) and consequences (e.g., probabilities of adverse health effects). Appropriate specification of many model aspects is uncertain, including details of the model structure; transport, reaction‐rate, and other parameters; and application‐specific inputs such as pollutant‐release rates. Because these uncertainties preclude calculation of the precise consequences of a policy, it is important to characterize the plausible range of effects. In principle, a probability distribution function for the effects can be constructed using Monte Carlo analysis, but the combinatorics of multiple uncertainties and the often high cost of model runs quickly exhaust available resources. This paper presents and applies a method to choose sets of input conditions (scenarios) that efficiently represent knowledge about the joint probability distribution of inputs. A simple score function approximately relating inputs to a policy‐relevant output—in this case, globally averaged stratospheric ozone depletion—is developed. The probability density function for the score‐function value is analytically derived from a subjective joint probability density for the inputs. Scenarios are defined by selected quantiles of the score function. Using this method, scenarios can be systematically selected in terms of the approximate probability distribution function for the output of concern, and probability intervals for the joint effect of the inputs can be readily constructed.
Appraisal of Individual Radiation Risk in the Context of Probabilistic Exposures
Authors: Bohnenblust Hans , Prêtre Serge
Published: May 2006

There exists a growing desire to base safety criteria in different fields on the same principles. The current approach by the international Commission on Radiological Protection (ICRP) to control radiation exposure touches many aspects such as social, psychological, or economic factors that are important for such principles. This paper attempts to further explore possible ways of defining a common basis for dealing with radiation risks and other safety problems. Specifically, it introduces the following issues: (1) different types of risk are judged differently. To account for this, the concept of risk categories is introduced. (2) The dimension of time may play an important role. There is a difference between an immediate death and a death occurring 20 years after exposure to radiation. Effects such as reduced quality of life after exposure and reduction of lifetime expectancy are discussed. The paper suggests to introduce an individual risk equivalent which allows to compare risks as defined in various fields. Furthermore, it suggests the use of risk acceptance criteria which depend on the different categories of risk.
Pharmacokinetic Principles for Dose‐Rate Extrapolation of Carcinogenic Risk from Genetically Active Agents
Authors: Hattis Dale
Published: May 2006

Neither experimental animal exposures nor real‐life human exposures are delivered at a constant level over a full lifetime. Although there are strong theoretical reasons why all pharmacokinetic processes must “go linear” at the limit of low dose rates, fluctuations in dose rate may produce nonlinearities that either increase or decrease actual risks relative to what would be expected for constant lifetime exposure. This paper discusses quantitative theory and specific examples for a number of processes that can be expected to give rise to pharmacokinetic nonlinearities at high dose rates–including transport processes (e.g., renal tubular secretion), activating and detoxifying metabolism, DNA repair, and enhancement of cell replication following gross toxicity in target tissues. At the extreme, full saturation of a detoxification or DNA repair process has the potential to create as much as a dose2 dependence of risk on dose delivered in a single burst, and if more than one detoxification step becomes fully saturated, this can be compounded. Effects via changes in cell replication rates, which appear likely to be largely responsible for the steep upward turning curve of formaldehyde carcinogenesis in rats, can be even more profound over a relatively narrow range of dosage. General suggestions are made for experimental methods to detect nonlinearities arising from the various sources in premarket screening programs.
DETECT
Authors: Whitfield Ronald G. , VanKuiken Jack C.
Published: May 2006

DETECT is an inexpensive, easy to use, general‐purpose, Monte Carlo simulation program for IBM and compatible personal computers. It can be used to quickly analyze fault trees or functions of random variables. DETECT provides a wide variety of input distributions to choose from and a dependency (correlation) option. The result of the analysis is a probability distribution over the variable of interest. We look forward to further improvements (e.g., graphics, full‐screen editing, ability to inspect intermediate results) that will make DETECT even more useful and attractive.
The Dependence of the Risk of Research Reactors from Their Operating Schedule–A Case Study
Authors: Kollas John G.
Published: May 2006

The dependence of the radiological consequences of the “Demokritos” research reactor on the operating schedule of the reactor is assessed in this paper. The 5 MW reactor is located within the limits of Athens city, a large population center with over 3 million inhabitants. The consequences examined would be due to the occurrence of a postulated accident, a 20% core melt loss of coolant accident, that is also considered as the design basis accident of the reactor. Three operating schedules are taken into account: (a) a continuous operation schedule; (b) a 16 hr/day, 5 days/week schedule; and (c) the present 8 hr/day, 5 days/week operating schedule. The assessment of the source term emerges from a conservative estimation of fission product releases to the reactor operating floor, and further under the conservative assumptions of no filter mitigation, and a ground release to the environment. The results of the analysis indicate that there is a direct relation between consequences and duration of operation, the former becoming appreciable as the continuous operation limit is approached. In all cases examined, the thyroid dose and the latent thyroid health effects would be the limiting consequences.
Information Needs Concerning a Planned Waste Incineration Facility
Authors: Wiedemann Peter M. , Schütz Holger , Peters Hans Peter
Published: May 2006

Waste management has become a major environmental issue in Germany. The siting of waste incineration especially arouses strong local opposition. The study presented here is related to such a case (i.e., a planned waste incineration facility in a small West German village). The study is based on a telephone survey aimed at the information needs of the residents. Two topics are stressed: (1) the thematic relevance of the siting project as seen by the public; and (2) the residents’information needs. The results show that a majority of residents are concerned about the planned facility, and the most important topics of their information needs refer to the risks and the safety systems of the planned facility, as well as information about waste management alternatives. Furthermore, the information needs depend on the personal relevance of the issue and the perceived knowledge deficit about it. Conclusions are drawn with regard to the design of a risk communication program. Here, four groups of residents are distinguished in terms of knowledge and motivation and, thus, need to be approached in different ways.
Do Faster Rescues Save More Lives
Authors: Quon Tony K. , Laube Jan A.
Published: May 2006

The primary mission of search and rescue (SAR) is the saving of lives. To assess SAR operations from a planning perspective, one must draw a connection between operations and the number of lives saved. Our approach is to model the probability that an incident results in at least one fatality, given the response time between the time of incident occurrence and time of rescue. We show that incidents involving air crashes, capsizing, foundering, grounding and other/unknown types of incidents tended to have higher probabilities of fatalities as the response time became higher. However, other emergency types did not exhibit the same overall tendency as these did. These statistical results do not prove causality between faster response times and lower fatality incidence for the above‐mentioned emergency types. They can be used, however, for estimating the average number of fatalities for a given distribution of response time, and ultimately the marginal savings in lives for a change in the mix of resources and locations.
A Note on the Influence of Rail Defects on the Risk Associated with Shipping Hazardous Materials by Rail
Authors: McNeil Sue , Oh Sci‐Chang
Published: May 2006

Existing approaches to routing hazardous material shipments by rail recognize that track condition is an important influence, but have not included it in the risk assessment and routing models. This note explores the influence of track condition based on predictions of internal defects in the rail. The method developed predicts the expected frequency of accidents and subsequent consequences in terms of the expected number of fatalities accounting for one aspect of track condition—internal defects. It is intended to indicate the magnitude and impact of track condition. The formulation integrates models of consequences and the risk of a hazardous spill found in the literature with the frequency of accidents as a function of the number of defects. The number of defects may be based on observations or predicted as a function of the cumulative traffic. The models are used to calculate the expected number of fatalities per year for a particular route. Application of the methodology to a hypothetical route shows that the risk associated with the transportation of hazardous material shipments varies significantly with the expected number of defects in the track. Therefore, risk not only varies from route to route but over time for any section of track as the condition deteriorates.
Human Health Risks Associated with Asbestos Abatement
Authors: Chrostowski Paul C. , Foster Sarah A. , Anderson Elizabeth L.
Published: May 2006

Upperbound lifetime excess cancer risks were calculated for activities associated with asbestos abatement using a risk assessment framework developed for EPA's Superfund program. It was found that removals were associated with cancer risks to workers which were often greater than the commonly accepted cancer risk of 1 × 10−6, although lower than occupational exposure limits associated with risks of 1 × 10−3. Removals had little effect in reducing risk to school populations. Risks to teachers and students in school buildings containing asbestos were approximately the same as risks associated with exposure to ambient asbestos by the general public and were below the levels typically of concern to regulatory agencies. During abatement, however, there were increased risks to both workers and nearby individuals. Careless, everyday building maintenance generated the greatest risk to workers followed by removals and encapsulation. If asbestos abatement was judged by the risk criteria applied to EPA's Superfund program, the no‐action alternative would likely be selected in preference to removal in a majority of cases. These conclusions should only be interpreted within the context of an overall asbestos risk management program, which includes consideration of specific fiber types and sizes, sampling and analytical limitations, physical condition of asbestos‐containing material, episodic peak exposures, and the number of people potentially exposed.
The Accident Evolution and Barrier Function (AEB) Model Applied to Incident Analysis in the Processing Industries
Authors: Svenson Ola
Published: May 2006

This study develops a theoretical model for accident evolutions and how they can be arrested. The model describes the interaction between technical and human‐organizational systems which may lead to an accident. The analytic tool provided by the model gives equal weight to both these types of systems and necessitates simultaneous and interactive accident analysis by engineers and human factors specialists. It can be used in predictive safety analyses as well as in post hoc incident analyses. To illustrate this, the AEB model is applied to an incident reported by the nuclear industry in Sweden. In general, application of the model will indicate where and how safety can be improved, and it also raises questions about issues such as the cost, feasibility, and effectiveness of different ways of increasing safety.
Estimation of Maximum Tolerated Dose for Long‐Term Bioassays from Acute Lethal Dose and Structure by QSAR
Authors: Gombar Viay K. , Enslein Kurt , Hart Jeffrey B. , Blake Benjamin W. , Borgstedt Harold H.
Published: May 2006

A quantitative structure‐activity relationship (QSAR) model has been developed to estimate maximum tolerated doses (MTD) from structural features of chemicals and the corresponding oral acute lethal doses (LD50) as determined in male rats. The model is based on a set of 269 diverse chemicals which have been tested under the National Cancer Institute/National Toxicology Program (NCI/NTP) protocols. The rat oral LD50 value was the strongest predictor. Additionally, 22 structural descriptors comprising nine substructural MOLSTAC(c) keys, three molecular connectivity indices, and sigma charges on 10 molecular fragments were identified as endpoint predictors. The model explains 76% of the variance and is significant (F= 35.7) at p < 0.0001 with a standard error of the estimate of 0.40 in the log(1/mol) units used in Hansch‐type equations. Cross‐validation showed that the difference between the average deleted residual square (0.179) and the model residual square (0.160) was not significant (t= 0.98).
A Study of the Shape of Dose‐Response Curves for Acute Lethality at Low Response: A “Megadaphnia Study”
Authors: Sebaugh Jeanne L. , Wilson James D. , Tucker Michael W. , Adams William J.
Published: May 2006

Dose‐response curves were developed for the immobilization response in Daphnia magna to four toxicants. The purpose of this work was to study the effect of the form of the model and the number of concentration levels used on the estimates of typical low‐dose effective concentrations (1%, 5%, 10%). The generalized four‐parameter logistic model was used as the reference. When using 12 concentration levels, one of the logistic family two‐ or three‐parameter models was shown reliably to represent each of these various sets of dose‐response data, and to provide adequate estimates of EC01 and EC05, as well as EC10 and EC50. For two of the toxicants, an asymmetric model was required. When reducing the number of concentrations to five, the EC10 and EC50 were well estimated by the probit model, with acceptable results at the EC05 level.
Modeling Benzene Pharmacokinetics Across Three Sets of Animal Data: Parametric Sensitivity and Risk Implications
Authors: Spear Robert C. , Bois Frédéric Y. , Woodruff Tracey , Auslander David , Parker Jennifer , Selvin Steve
Published: May 2006

Typically, the uncertainty affecting the parameters of physiologically based pharmacokinetic (PBPK) models is ignored because it is not currently practical to adjust their values using classical parameter estimation techniques. This issue of parametric variability in a physiological model of benzene pharmacokinetics is addressed in this paper. Monte Carlo simulations were used to study the effects on the model output arising from variability in its parameters. The output was classified into two categories, depending on whether the output of the model on a particular run was judged to be generally consistent with published experimental data. Statistical techniques were used to examine sensitivity and interaction in the parameter space. The model was evaluated against the data from three different experiments in order to test for the structural adequacy of the model and the consistency of the experimental results. The regions of the parameter space associated with various inhalation and gavage experiments are distinct, and the model as presently structured cannot adequately represent the outcomes of all experiments. Our results suggest that further effort is required to discern between the structural adequacy of the model and the consistency of the experimental results. The impact of our results on the risk assessment process for benzene is also examined.
An Approach to Assessing the Impacts of Incident‐Free Transportation of Radioactive Materials: I. Air Transportation
Authors: Weiner Ruth F. , LaPlante Patrick A. , Hageman John P.
Published: May 2006

Annual radiation doses and risks to passengers and crew are calculated for shipments of radioactive materials in passenger aircraft under accident‐free and incident‐free conditions (i.e., under normal transportation conditions). The 1982 database developed by Sandia National Laboratories is used, and calculations are made using RADTRAN 4.0. This paper is one of two papers estimating radiological risk associated with incident‐free transportation of radioactive materials.
Planning Replacement of Natural Gas Distribution Systems Under Constraints on Acceptable Risk from Explosions
Authors: Noonan Francis
Published: May 2006

Natural gas distribution systems in the United States were developed primarily in the first half of this century, utilizing materials such as cast iron and then steel. Over time, cast iron and steel pipe sections became weak from corrosion and are subject to failure which in turn can lead to explosions and possible injury and loss of life. Gas utilities maintain system integrity through repair‐replacement programs where pipe sections are prioritized for replacement in any given year through cost‐benefit analysis; however, the total annual amount to be budgeted for replacement is left to engineering judgment. This approach has left some utilities vulnerable to criticism that their current replacement rate on cast iron pipe is not great enough and that public safety is being compromised. This paper addresses the problem situation by formulating a linear programming replacement decision model which augments cost‐benefit analysis with explicit constraints on acceptable risk to human life from fire/explosion. The model is illustrated for a hypothetical utility.
Structure and Parameterization of Pharmacokinetic Models: Their Impact on Model Predictions
Authors: Woodruff Tracey J. , Bois Frédéric Y. , Auslander David , Spear Robert C.
Published: May 2006

There has been an increasing interest in physiologically based pharmacokinetic (PBPK)models in the area of risk assessment. The use of these models raises two important issues: (1)How good are PBPK models for predicting experimental kinetic data? (2)How is the variability in the model output affected by the number of parameters and the structure of the model? To examine these issues, we compared a five‐compartment PBPK model, a three‐compartment PBPK model, and nonphysiological compartmental models of benzene pharmacokinetics. Monte Carlo simulations were used to take into account the variability of the parameters. The models were fitted to three sets of experimental data and a hypothetical experiment was simulated with each model to provide a uniform basis for comparison. Two main results are presented: (1)the difference is larger between the predictions of the same model fitted to different data se1ts than between the predictions of different models fitted to the dame data; and (2)the type of data used to fit the model has a larger effect on the variability of the predictions than the type of model and the number of parameters.
Statistical Design for Sampling and Analysis of Animal Populations for Chemical Contamination
Authors: Beauchamp John J. , McCarthy John F. , Rosenblatt David H. , Shugart Lee R.
Published: May 2006

A strategy for sampling of animal tissues and a statistical approach for analyzing data on body burdens of a parent chemical and its metabolites is presented such that the data may be evaluated in relation to the detection limit(s)of the analytical techniques used and the criterion levels established for acceptable tissue concentrations.
Bivariate Distributions for Height and Weight of Men and Women in the United States
Authors: Brainard Jennifer , Burmaster David E.
Published: May 2006

For the U.S. population, we fit bivariate distributions to estimated numbers of men and women aged 18‐74 years in cells representing 1 in. intervals in height and 10 lb intervals in weight. For each sex separately, the marginal histogram of height is well fit by a normal distribution. For men and women, respectively, the marginal histogram of weight is well fit and satisfactorily fit by a lognormal distribution. For men, the bivariate histogram is satisfactorily fit by a normal distribution between the height and the natural logarithm of weight. For women, the bivariate histogram is satisfactorily fit by two superposed normal distributions between the height and the natural logarithm of weight. The resulting distributions are suitable for use in public health risk assessments.
An Analysis of the Uncertainties in Estimates of Radon‐Induced Lung Cancer
Authors: Puskin Jerome S.
Published: May 2006

A recent report by the National Academy of Sciences estimates that the radiation dose to the bronchial epithelium, per working level month (WLM)of radon daughter exposure, is about 30% lower for residential exposures than for exposures received in underground mines. Adjusting the previously published BEIRIV radon risk model accordingly, the unit risk for indoor exposures of the general population is about 2.2 x 10‐4 lung cancer deaths (lcd)/WLM. Using results from EPA's National Residential Radon Survey, the average radon level is estimated to be about 1.25 pCi/L, and the annual average exposure about 0.242 WLM. Based on these estimates, 13,600 radon‐induced lcd/yr are projected for the United States. A quantitative uncertainty analysis was performed, which considers: statistical uncertainties in the epidemiological studies of radon‐exposed miners; the dependence of risk on age at, and time since, exposure; the extrapolation of risk estimates from mines to homes based on comparative dosimetry; and uncertainties in the radon daughter levels in homes and in the average residential occupancy. Based on this assessment of the uncertainties in the unit risk and exposure estimates, an uncertainty range of 7000‐30000 led/yr is derived.
Microenvironmental Analysis of Residential Exposure to Chromium‐Laden Wastes in and Around New Jersey Homes
Authors: Lioy P.J. , Freeman N.C.G. , Wainman T. , Stern A.H. , Boesch R. , Howell T. , Shupack S.I.
Published: May 2006

The purpose of this study was to identify the significant microenvironments that can lead to chromium exposure in Hudson County, New Jersey residential settings near or on soil contaminated with chromium waste. Measurements were made in indoor air, outdoor air, and house dust. Surface dust was found to be the best index of potential Cr exposure. The values of Cr in Hudson County household dust ranged from 3.25‐320 ng/cm2 in wipe samples and 1.0‐12 ng/cm2 in vacuum samples. Elevated Cr in household dust was found to be related to residential locations near large chromium waste sites, household cleaning habits, and house renovation activities. Outdoor Cr air levels were similar to those obtained in other urban areas at these seasons of the year, approximately 5‐7 ng/m3. Comparisons with measurements of the Cr levels in urine found that the elevated Cr in dust was associated with elevated excretion of Cr. Site‐specific Cr differences in household dust suggest different sources and routes of exposure. Within the total group of homes in the present study, Cr in household dust was the major influence on household exposure.
IMES: A System for Identifying and Evaluating Computer Models for Exposure Assessment2
Authors: Pardi Richard R.
Published: May 2006

Although IMES is apparently a marriage of independently developed modules, the blend is nearly seamless‐there are only minor differences in “feel” between the three modules. IMES is well organized and easy to use. There are help screens at every stage in each module. Selection is efficient‐queries rarely take more than a few seconds on a 386 machine before a report can be generated. There are a few pitfalls in model selection which are difficult to avoid. Improper classification is one of them. For example, IMES lists MINTEQ as a multimedia model. It would be more appropriate from this reviewer's perspective to classify MINTEQ as a geo‐chemical model (for which this version of IMES has no classification category.)One minor concern is that in two modules (Selection and Validation)IMES queries the operator “Do you really want to exit?” or “Exit?” when one simply wants to go back one level in the screening process. It would be less disconcerting to be consistently presented (as is done in the Uncertainty module)with a pop‐up menu selection like “Do you want to return to the previous screen?”

IMES was an ambitious undertaking that resulted in a useful and important contribution to Exposure Assessment Model community.
Poorer Is Riskier
Authors: Graham John D. , Chang Bei‐Hung , Evans John S.
Published: May 2006

To examine the relationship between economic well being and health status, two economic concepts were explored: the permanent‐income hypothesis and the transitory‐income hypothesis. A regression analysis of time‐series mortality data for the period of 1950‐1988 was conducted. The regression results indicated that the total mortality rate is negatively associated with permanent income and positively associated with the transitory income. Results are also reported for the 8 major causes of death in the United States. The implications for risk analysis are discussed.
Risk, Statistical Inference, and the Law of Evidence: The Use of Epidemiological Data in Toxic Tort Cases
Authors: Brannigan Vincent M. , Bier Vicki M. , Berg Christine
Published: May 2006

Toxic torts are product liability cases dealing with alleged injuries due to chemical or biological hazards such as radiation, thalidomide, or Agent Orange. Toxic tort cases typically rely more heavily than other product liability cases on indirect or statistical proof of injury. There have been numerous theoretical analyses of statistical proof of injury in toxic tort cases. However, there have been only a handful of actual legal decisions regarding the use of such statistical evidence, and most of those decisions have been inconclusive. Recently, a major case from the Fifth Circuit, involving allegations that Benedectin (a morning sickness drug) caused birth defects, was decided entirely on the basis of statistical inference. This paper examines both the conceptual basis of that decision, and also the relationships among statistical inference, scientific evidence, and the rules of product liability in general.
The Application of Bioassays in Risk Assessment of Environmental Pollution
Authors: Lyne T.B. , Bickham J.W. , Lamb T. , Gibbons J.W.
Published: May 2006

Increased contamination of the environment by toxic chemicals has resulted in the need for sensitive assays to be used in risk assessment of polluted sites. Traditional tests are useful to detect and measure concentrations of chemicals in the environment and in tissues. However, physicochemical assays possess deficiencies that impair their use in evaluating complex environmental contamination. We have developed cytogenetic procedures, including chromosomal, micronucleus, and flow cytometric assays, to assess the mutagenic damage of petrochemicals and low‐level radioactivity on indigenous terrestrial and aquatic wildlife populations. These procedures are sensitive to the perturbation of DNA that results from exposure to mutagenic contaminants in both field and laboratory studies. The use of natural populations of animals in biomonitoring, combined with traditional chemical assays, will ultimately provide sufficient information to estimate the risk to human health and environmental quality from anthropogenic pollution.
The Risks of Using Nuclear Energy Sources in Space: Some Lay Activists’Perceptions
Authors: Maharik Michael , Fischhoff Baruch
Published: May 2006

A combination of directive and nondirective techniques was used to study the mental models of 30 lay activists regarding the risks of nuclear energy sources in space. Respondents’perceptions were compared with an “expert model” of the processes generating and controlling these risks, in terms of both the substance of their beliefs and several statistical measures of their performance. These analyses revealed a complex pattern of strengths and weaknesses. Their details are used to derive recommendations for formulating messages about these risks.
Trust as a Determinant of Opposition to a High‐Level Radioactive Waste Repository: Analysis of a Structural Model
Authors: Flynn James , Burns William , Mertz C.K. , Slovic Paul
Published: May 2006

Residents in the State of Nevada hold strong opinions about the federal government's proposal to site the nation's first high‐level radioactive waste repository at Yucca Mountain. The model developed in this study is designed to examine the relationship between public perceptions of risk, trust in risk management, and potential economic impacts of the current repository program using a confirmatory multivariate method known as covariance structure analysis. The data used to test the model was collected in a 1989 statewide survey of Nevada residents. The results indicate that, for a statewide sample, perceptions of potential economic benefits do not have a significant role in predicting support or opposition to the repository program. On the other hand, risk perceptions and the level of trust in repository management are closely related to each other and to positions on Yucca Mountain. Trust directly influences risk perceptions which, in turn, have a direct effect on the attitude toward the repository, and an indirect effect through perceived stigma effects.
The Organizational Links Between Risk Communication and Risk Management: The Case of Sybron Chemicals Inc.
Authors: Chess Caron , Saville Alex , Tamuz Michal , Greenberg Michael
Published: May 2006

The risk communication literature is rife with prescriptions about how organizations should interact with various publics. However, little attention has been paid to the organizational adjustments that may be necessary for corporations to heed this advice. The primary question we explore is: What do companies do internally to increase the effectiveness of their communication externally? In this article, we explore relationships between risk management and risk communication and then suggest the organizational factors that may link the two. We present five propositions dealing with relationships between risk communication and risk management derived from an in‐depth case study of an exemplary risk communication program. We discuss the implications of this case study for further research.
Effects of Increased Auto Safety Belt Use Levels on Fatalities
Authors: Latimer Eric A.
Published: May 2006

To reduce the annual toll of highway deaths, more than 30 states have passed laws mandating the use of safety belts. All have been effective at raising safety belt use; equipped with different provisions and enforced with unequal care, however, they have done so to different degrees. The article estimates the relationship between attained belt use and fatalities averted. Monthly 1982‐1986 fatality, collision, belt use, and other data from 64 areas in nine states were collected, then analyzed using a Poisson multiple regression model. The analysis indicates that an increase in belt use from 14‐40% averts about 13% of fatalities; a more pronounced increase to 50% averts about 18%. An increase from 50‐75% averts about 16% of remaining fatalities. Three significant conclusions emerge. First, previous estimates appear to have understated, in general, the overall effectiveness of belt use laws. Second, the benefits of programs to boost safety belt use in this country from its current level of about 50% to up to 75%, estimated on the basis of more direct evidence from U.S. data than previously available, appear to be very large. Third, Poisson and other multiple regression models including explicit allowance for other causal factors can usefully complement other statistical approaches in traffic safety studies.
Cancer Risk Assessment with Intermittent Exposure
Authors: Murdoch Duncan J. , Krewski Daniel , Wargo John
Published: May 2006

Applications of methods for carcinogenic risk assessment often focus on estimating lifetime cancer risk. With intermittent or time‐dependent exposures, lifetime risk is often approximated on the basis of a lifetime average daily dose (LADD). In this article, we show that there exists a lifetime equivalent constant dose (LECD)which leads to the same lifetime risk as the actual time‐dependent exposure pattern. The ratio C= LECD/LADD then provides a measure of accuracy of risk estimates based on the LADD, as well as a basis for correcting such estimates. Theoretical results derived under the classical multistage model and the two‐stage birth‐death‐mutation model suggest that the maximum value of C, which represents the factor by which the LADD may lead to underestimates of risk, will often lie in the range of 2‐ to 5‐fold. The practical application of these results is illustrated in the case of astronauts subjected to relatively short‐term exposure to volatile organics in a closed space station environment, and in the case of the ingestion of pesticide residues in food where consumption patterns vary with age.
The Market Response to the Sioux City DC‐10 Crash
Authors: Barnett Arnold , Menighetti John , Prete Matthew
Published: May 2006

The 1989 DC‐10 crash at Sioux City, Iowa presented a rare instance in which a potential threat to safety was both (i) intensely publicized over a short period and (ii) also amenable to the unobtrusive measurement of the market reaction it evoked. As such, it allowed a useful case study of the extent and duration of behavior change caused by a frightening event. Using reservations data from travel agencies in five states, this paper estimates the short‐term effects of the Sioux City crash on passenger willingness to fly the DC‐10. The data suggest that, in the first few weeks after the crash, more than one third of travelers who would normally have booked DC‐10 flights chose instead to fly other aircraft. Within 2 months of the disaster, however, DC‐10 bookings rebounded to within 10% of the level that would have been expected had the Sioux City crash not occurred. At no time, apparently, did the airlines that operate DC‐10s use their “yield‐management” computer pricing systems unofficially to lower DC‐10 fares relative to those on other types of plane.
Monte Carlo Techniques for Quantitative Uncertainty Analysis in Public Health Risk Assessments
Authors: Thompson Kimberly M. , Burmaster David E. , Crouch3 Edmund A.C.
Published: May 2006

Most public health risk assessments assume and combine a series of average, conservative, and worst‐case values to derive a conservative point estimate of risk. This procedure has major limitations. This paper demonstrates a new methodology for extended uncertainty analyses in public health risk assessments using Monte Carlo techniques. The extended method begins as do some conventional methods—with the preparation of a spreadsheet to estimate exposure and risk. This method, however, continues by modeling key inputs as random variables described by probability density functions (PDFs). Overall, the technique provides a quantitative way to estimate the probability distributions for exposure and health risks within the validity of the model used. As an example, this paper presents a simplified case study for children playing in soils contaminated with benzene and benzo(a)pyrene (BaP).
Distribution and Expected Time of Residence for U.S. Households
Authors: Israeli Miron , Nelson Christopher B.
Published: May 2006

For risk assessments, the average current residence time (time since moving into current residence) has often been used as a surrogate for the average total residence time (time between moving into and out of a residence). Since the distributions of the two quantities are not necessarily the same, neither are their averages. Housing surveys provide current residence time data; total residence times must, therefore, be inferred. By modeling the moving process, the total residence time distribution can be estimated from current residence time data. Using 1985 and 1987 U.S. housing survey data, distributions and averages for both current and total residence times were calculated for several housing categories. The average total residence time calculated for all U.S. households, 4.6 (se= 0.6) years, is less than half the average current residence time, 10.6 (se= 0.1) years.
The Nevada Initiative: A Risk Communication Fiasco
Authors: Flynn James , Slovic Paul , Mertz C. K.
Published: May 2006

The U.S. Congress has designated Yucca Mountain, Nevada as the only potential site to be studied for the nation's first high‐level nuclear waste repository. People in Nevada strongly oppose the program, managed by the U.S. Department of Energy. Survey research shows that the public believes there are great risks from a repository program, in contrast to a majority of scientists who feel the risks are acceptably small. Delays in the repository program resulting in part from public opposition in Nevada have concerned the nuclear power industry, which collects the fees for the federal repository program and believes it needs the repository as a final disposal facility for its high‐level nuclear wastes. To assist the repository program, the American Nuclear Energy Council (ANEC), an industry group, sponsored a massive advertising campaign in Nevada. The campaign attempted to assure people that the risks of a repository were small and that the repository studies should proceed. The campaign failed because its managers misunderstood the issues underlying the controversy, attempted a covert manipulation of public opinion that was revealed, and most importantly, lacked the public trust that was necessary to communicate credibly about the risks of a nuclear waste facility.
The Health Impact of Major Nuclear Accidents: The Case Of Greece
Authors: Kollas John G.
Published: May 2006

An assessment of the radiological consequences that would result for the population of Greece from postulated major nuclear accidents in the Kozloduy nuclear power station in Bulgaria is performed. Kozloduy lies at a distance of 225 km from the northern borders of Greece and contains six reactors, all of the Russian WWER type. The postulated accidents that are classified as level 7 accidents on the International Nuclear Event Scale, involve significant releases of radioactive materials into the environment, and widespread health and environmental effects. The analysis is performed by the MACCS code. The estimated consequences are compared to the corresponding actual impact of the Chernobyl accident in Greece. The results of the analysis indicate that, under the conservative assumptions adopted, the radiological consequences of the most severe accidents considered would be about 1.5 orders of magnitude larger than the actual radiological consequences of the Chernobyl accident.
Risk Assessment of Virus in Drinking Water
Authors: Haas Charles N. , Rose Joan B. , Gerba Charles , Regli Stig
Published: May 2006

The reevaluation of drinking water treatment practices in a desire to minimize the formation of disinfection byproducts while assuring minimum levels of public health protection against infectious organisms has caused it to become necessary to consider the problem of estimation of risks posed from exposure to low levels of microorganisms, such as virus or protozoans, found in treated drinking water. This paper outlines a methodology based on risk assessment principles to approach the problem. The methodology is validated by comparison with results obtained in a prospective epidemiological study. It is feasible to produce both point and interval estimates of infection, illness and perhaps mortality by this methodology. Areas of uncertainty which require future data are indicated.
An Alternative Approach to the Modeling of Probability Distributions
Authors: Chan S.Y. Jimmy
Published: May 2006

This note suggests the use of Bézier curves to model probability distributions on computers. This represents an approach completely different from the current practice, which mostly employs parametric families or piece‐wise polynomials. The Bézier curves combine simplicity and flexibility with an easy manipulation method, allowing more accurate curves to be modeled to data.
Some Criteria for Evaluating Risk Messages
Authors: Weinstein Neil D. , Sandman Peter M.
Published: May 2006

Seven criteria are presented for use in evaluating communications designed to explain the magnitude of a risk. The criteria are: (1) comprehension (Does the audience understand the content of the communication?); (2) agreement (Does the audience agree with the recommendation or interpretation contained in the message?); (3) dose‐response consistency (Do people facing a higher dose of a hazard perceive the risk as greater and/or show a greater readiness to take action than people exposed to a lower dose of this hazard?); (4) hazard‐response consistency (Do people facing a hazard that is higher in risk perceive the risk as greater and/or show a greater readiness to take action than people exposed to a hazard that is lower in risk?); (5) uniformity (Do audience members exposed to the same level of risk tend to have the same responses to this risk?); (6) audience evaluation (Does the audience judge the message to have been helpful, accurate, clear, etc.?); and (7) types of communication failures (When different types of failures are possible, are the failures that occur generally of the more acceptable variety?). Each of these criteria is illustrated with data collected in a test of message formats designed to explain the risk presented by radon gas in a home.
Demographic Influences on Risk Perceptions
Authors: Savage Ian
Published: May 2006

Over the past 15 years, psychologists have empirically investigated how people perceive technological, consumer, and natural hazards. The psychometric‐attitudes to risk being summarized by three factors: “dread,” whether the risk is known, and personal exposure to the risk. The results have been used to suggest that certain types of hazards are viewed very differently from other hazards. The purpose of this paper is somewhat different, in that it investigates whether individual demographic characteristics influence psychometric perceptions of risk. This paper makes use of a large, professionally conducted, survey of a wide cross‐section of the residents of metropolitan Chicago. One thousand adults were interviewed in a random‐digit dial telephone survey, producing a useable dataset of about 800. Data on the three risk factors mentioned above were obtained on 7‐point scales for four common hazards: aviation accidents, fires in the home, automobile accidents, and stomach cancer. The survey also collected demographic data on respondents’age, schooling, income, sex, and race. Regressions were then conducted to relate the demographic characteristics to risk perceptions. Some strong general conclusions can be drawn. The results suggest that women, people with lower levels of schooling and income, younger people, and blacks have more dread of hazards. The exception being age‐related illnesses which, not unnaturally, are feared by older people. Unlike previous literature, we cannot substantiate the argument that these groups of people are less informed about hazards and thus less accepting of them. The most likely leading explanation of the relationship between demographic factors and dread of a hazard is the perceived personal exposure to the hazard. People with greater perceived exposure to a hazard are more fearful.
Baseline Risk and Preference for Reductions in Risk‐to‐Life
Authors: Horowitz John K. , Carson Richard T.
Published: May 2006

The typical model of individual attitudes toward risk‐to‐life suggests that an individual's willingness to pay for a reduction in mortality risk increases with the baseline risk. The higher‐baseline hypothesis has been the subject of several empirical tests but results have so far been mixed. Using survey evidence, we present a situation in which subjects do prefer to reduce risks for which the baseline is higher. This finding is robust to several alternative explanations. Survey responses reflect subjects’concerns about government effectiveness in risk reduction, environmental effects associated with the various hazards, and other idiosyncratic elements of the risks; however, these concerns appear to occur in addition to, not in lieu of, the preference to reduce higher risks.
An Enforceable Indoor Air Quality Standard for Environmental Tobacco Smoke in the Workplace1
Authors: Repace James L. , Lowrey Alfred H.
Published: May 2006

Environmental tobacco smoke (ETS)has recently been determined by U.S. environmental and occupational health authorities to be a human carcinogen. We develop a model which permits using atmospheric nicotine measurements to estimate nonsmokers’ETS lung cancer risks in individual workplaces for the first time. We estimate that during the 1980s, the U.S. nonsmoking adult population's median nicotine lung exposure (homes and workplaces combined)was 143 micrograms (μg)of nicotine daily, and that most‐exposed adult nonsmokers inhaled 1430 μg/day. These exposure estimates are validated by pharmacokinetic modeling which yields the corresponding steady‐state dose of the nicotine metabolite, cotinine. For U.S. adult nonsmokers of working age, we estimate median cotinine values of about 1.0 nanogram per milliliter (ng/ml)in plasma, and 6.2 ng/ml in urine; for most‐exposed nonsmokers, we estimate cotinine concentrations of about 10 ng/ml in plasma and 62 ng/ml in urine. These values are consistent to within 15% of the cotinine values observed in contemporaneous clinical epidemiological studies. Corresponding median risk from ETS exposure in U.S. nonsmokers during the 1980s is estimated at about two lung cancer deaths (LCDs)per 1000 at risk, and for most‐exposed nonsmokers, about two LCDs per 100. Risks abroad appear similar. Modeling of the lung cancer mortality risk from passive smoking suggests that de minimis [i.e., “acceptable” (10‐6)], risk occurs at an 8‐hr time‐weighted‐average exposure concentration of 7.5 nanograms of ETS nicotine per cubic meter of workplace air for a working lifetime of 40 years. This model is based upon a linear exposure‐response relationship validated by physical, clinical, and epidemiological data. From available data, it appears that workplaces without effective smoking policies considerably exceed this de minimis risk standard. For a substantial fraction of the 59 million nonsmoking workers in the U.S., current workplace exposure to ETS also appears to pose risks exceeding the de manifestos risk level above which carcinogens are strictly regulated by the federal government.