bluuebunny/crossref_metadata_2025 huggingface dataset:
Probabilistic Health Risk Assessment for Exposures to Estuary Sediments and Biota Contaminated with Polychlorinated Biphenyls, Polychlorinated Terphenyls and Other Toxic Substances
Authors: Adams Michael R. , Hanna Cynthia A. , Mayernik Janet A. , Mendez William M.
Published: May 2006

A Latin Hypercube probabilistic risk assessment methodology was employed in the assessment of health risks associated with exposures to contaminated sediment and biota in an estuary in the Tidewater region of Virginia. The primary contaminants were polychlorinated biphenyls (PCBs), polychlorinated terphenyls (PCTs), polynuclear aromatic hydrocarbons (PAHs), and metals released into the estuary from a storm sewer system. The exposure pathways associated with the highest contaminant intake and risks were dermal contact with contaminated sediment and ingestion of contaminated aquatic and terrestrial biota from the contaminated area. As expected, all of the output probability distributions of risk were highly skewed, and the ratios of the expected value (mean) to median risk estimates ranged from 1.4 to 14.8 for the various exposed populations. The 99th percentile risk estimates were as much as two orders of magnitude above the mean risk estimates. For the sediment exposure pathways, the stability of the median risk estimates was found to be much greater than the stability of the expected value risk estimates. The interrun variability in the median risk estimate was found to be +/‐1.9% at 3000 iterations. The interrun stability of the mean risk estimates was found to be approximately equal to that of the 95th percentile estimates at any number of iterations. The variation in neither contaminant concentrations nor any other single input variable contributed disproportionately to the overall simulation variance. The inclusion or exclusion of spatial correlations among contaminant concentrations in the simulation model did not significantly effect either the magnitude or the variance of the simulation risk estimates for sediment exposures.
Physiologically Based Pharmacokinetic Models in Developmental Toxicology
Authors: O'Flaherty E. J.
Published: May 2006

The kinetics of disposition of drugs and environmental chemicals will be altered as a result of the rapid and pronounced anatomic and physiologic changes that occur during pregnancy. These include changes in maternal intestinal motility, pulmonary tidal volume and minute volume, cardiac output, and renal function as well as in maternal tissue and fluid volumes and in the weight of the embryo/fetus and its developing organs. Physiologically‐based models of pregnancy are capable of taking these temporal changes into account. Several such models have been developed. They vary in their characteristics, depending on the chemical under consideration and the period of gestation of concern to the developers of the models. Several physiologically‐based models of gestation are outlined, and an example is given of the application of a physiologically‐based model of gestation to predict dose to the rat and mouse fetus.
Structural Determinants of Developmental Toxicity1
Authors: Takihi Noriyuki , Rosenkranz Herbert S. , Klopman Gilles , Mattison Donald R.
Published: May 2006

Developmental toxicity, an area of public concern, suffers from the lack of accessible, reliable, peer‐reviewed compilations of data and substantial gaps in testing. These deficits frequently make it necessary for regulatory agencies to use other toxicological end points to regulate developmental toxicants. We have utilized a database of chemicals identified as developmental toxicants in rats, mice, rabbits, and humans and an expert system which learns the association between molecular structure and biological response (Computer Automated Structure Evaluation; CASE) to explore structure‐activity relationships in developmental toxicity. Developmental toxicity was defined as death, growth retardation, or structural or functional malformations. In analyzing the data CASE selects its own molecular descriptors from a learning set of active and inactive molecules. Using randomly constructed learner and tester sets, the concordance of the predictions with the actual data was between 77 and 82%. CASE identified 13 major structural fragments associated with developmental toxicity in mice, IS in rats, 9 in rabbits, and 7 in humans. These analyses indicate that there is indeed a structural basis for developmental toxicity which may be used to predict the developmental hazard of untested or inadequately tested chemicals.
Designing Risk Communications: Completing and Correcting Mental Models of Hazardous Processes, Part I
Authors: Atman Cynthia J. , Bostrom Ann , Fischhoff Baruch , Morgan M. Granger
Published: May 2006

Many risk communications are intended to help the lay public make complex decisions about risk. To guide risk communicators with this objective, a mental models approach to the design and characterization of risk communications is proposed. Building on text comprehension and mental models research, this approach offers an integrated set of methods to help the risk communication designer choose and analyze risk communication content, structure, and organization. An applied example shows that two radon brochures designed with this approach present roughly the same expert facts as a radon brochure widely distributed by the U.S. EPA but meet higher standards on other content, structure, and organization criteria.
Database Requirements for Epidemiological Estimates of Radiation Risks in Continuously Exposed Populations
Authors: Mayya Y. S. , Joshi P. V. , Nambi K. S. V.
Published: May 2006

Using the revised risk coefficients recommended by the 1990 report of the International Commission of Radiological Protection (ICRP), computations have been made on the minimum databases required for detecting radiogenic cancer excesses from epidemiological surveys of populations exposed to low level radiations. The computations have been made separately for Indian and Western populations using their representative demographic data. The western database requirements are generally found to be about half the Indian requirement.

For the exposures in high background radiation areas at the rate of say 5 mSv/y, the minimum required database is 121,500 person years, in the Indian case. Similarly, for Indian occupational workers exposed at the rate of say, 10 mSv/y, it is required to observe 30,000 persons for the first 40 years or 3600 persons over their entire lifetime for obtaining statistically significant results.
Opportunities and Impediments for Risk‐Based Standards: Some Views from a Workshop
Authors: Hunter Regina L. , Layton David W. , Anspaugh Lynn R.
Published: May 2006

Techniques for performing scientific risk assessments for a wide variety of chemical and radiological hazards present in the environment and workplace are available. Speakers at a workshop sponsored by the Environmental and Public/Occupational Health Standard's Steering Group addressed both the state‐of‐the‐art in risk assessment and areas of difficulty that require further research. The Steering Group concluded that within the limits of the available data, risk‐assessment techniques are a useful tool in decision‐making. In the past, many government agencies have not been effective either in listening to public concerns or in communicating technical or scientific information about risks. This has been true at all levels of government. Workshop speakers discussed some ways that government agencies can more effectively communicate with the public. The Steering Group concluded that major efforts must be made to ensure that two‐way communication takes place. Thus the results of the workshop show that effective management of risk requires both a scientific assessment of risk and a responsive consideration of the public's perception of risk. Intensive efforts must be made to ensure that effective two‐way communication takes place between members of the public and the appropriate government agencies.
Environmental Tobacco Smoke: Science vs. Rhetoric
Authors: Jinot Jennifer , Bayard Steven
Published: May 2006

After an extensive review and analysis of the scientific evidence on the respiratory health effects of passive smoking, the U.S. Environmental Protection Agency concluded that environmental tobacco smoke causes lung cancer in adult nonsmokers and increases the risk of a variety of non‐cancer respiratory disorders, especially in children. This article is a response to claims in Dr. Gio Gori's article “Policy Against Science: The Case of Environmental Tobacco Smoke,” appearing in the same issue of this journal, that such conclusions are unwarranted. This response focuses only on the respiratory health effects of environmental tobacco smoke.
Simple Relations Between Administered and Internal Doses in Compartmental Flow Models
Authors: Cox Louis Anthony
Published: May 2006

It is sometimes argued that the use of increasingly complex “biologically‐based” risk assessment (BBRA) models to capture increasing mechanistic understanding of carcinogenic processes may run into a practical barrier that cannot be overcome in the near term: the need for unrealistically large amounts of data about pharmacokinetic and pharmacodynamic parameters. This paper shows that, for a class of dynamical models widely used in biologically‐based risk assessments, it is unnecessary to estimate the values of the individual parameters. Instead, the input‐output properties of such a model–specifically, the ratio of the area‐under‐curve (AUC) for any selected output to the AUC of the input–is determined by a single aggregate “reduced” constant, which can be estimated from measured input and output quantities. Uncertainties about the many individual parameter values of the model, and even uncertainties about its internal structure, are irrelevant for purposes of quantifying and extrapolating its input‐output (e.g., dose‐response) behavior. We prove that this is the case for the class of linear, constant‐coefficient, globally stable compartmental flow systems used in many classical pharmacokinetic and low‐dose PBPK models. Examples are cited that suggest that the value of the reduced parameter representing such a system's aggregate behavior may be relatively insensitive to changes in (and hence to uncertainties about) the values of individual parameters. The theory is illustrated with a model of pharmacokinetics and metabolism of cyclophosphamide (CP), a drug widely used in cancer chemotherapy and as an immunosuppressive agent.
Variation in Cancer Risk Estimates for Exposure to Powerline Frequency Electromagnetic Fields: A Meta‐Analysis Comparing EMF Measurement Methods
Authors: Miller Michelle A. , Murphy James R. , Miller Thomas I , Ruttenber A.J.
Published: May 2006

We used meta‐analysis to synthesize the findings from eleven case‐control studies on cancer risks in humans exposed to 50‐60 Hertz powerline electromagnetic fields (EMFs). Pooled estimates of risk are derived for different EMF measurement methods and types of cancer. EMF measurement methods are classified as: wiring configuration codes, distance to power distribution equipment, spot measurements of magnetic fields, and calculated indices based on distance to power distribution equipment and historic load data. Pooled odds ratios depicting the risk of cancer by each measurement type are presented for all cancers combined, leukemia for all age groups and childhood leukemia. The wire code measurement technique was associated with a significantly increased risk for all three cancer types, while spot measures consistently showed non‐significant odds ratios. Distance measures and the calculated indices produced risk estimates which were significant only for leukemia.
A Method for Evaluating Transmission Line Magnetic Field Mitigation Strategies That Incorporates Biological Uncertainty
Authors: Adams John G. , Zhang Jun , Morgan M. Granger , Nair Indira
Published: May 2006

A method to determine how much reduction in public exposure to power frequency magnetic fields can be obtained for different levels of investment is presented. Which if any “effects function” best describes the relationship between field exposure and biological effect is uncertain at this time. Also, in a particular context such as construction of new transmission lines there are a variety of different technologies which might be used to reduce exposure. We describe and demonstrate a method by which exposure reduction supply curves (i.e., the cost of purchasing different amounts of exposure reduction given various mitigation options) can be estimated parametrically for different exposure conditions and effects functions, and we display illustrative results.
Methods to Approximate Joint Uncertainty and Variability in Risk
Authors: Bogen Kenneth T.
Published: May 2006

As interest in quantitative analysis of joint uncertainty and interindividual variability (JUV) in risk grows, so does the need for related computational shortcuts. To quantify JUV in risk, Monte Carlo methods typically require nested sampling of JUV in distributed inputs, which is cumbersome and time‐consuming. Two approximation methods proposed here allow simpler and more rapid analysis. The first consists of new upper‐bound JUV estimators that involve only uncertainty or variability, not both, and so never require nested sampling to calculate. The second is a discrete‐probability‐calculus procedure that uses only the mean and one upper‐tail mean for each input in order to estimate mean and upper‐bound risk, which procedure is simpler and more intuitive than similar ones in use. Application of these methods is illustrated in an assessment of cancer risk from residential exposures to chloroform in Kanawah Valley, West Virginia. Because each of the multiple exposure pathways considered in this assessment had separate modeled sources of uncertainty and variability, the assessment illustrates a realistic case where a standard Monte Carlo approach to JUV analysis requires nested sampling. In the illustration, the first proposed method quantified JUV in cancer risk much more efficiently than corresponding nested Monte Carlo calculations. The second proposed method also nearly duplicated JUV‐related and other estimates of risk obtained using Monte Carlo methods. Both methods were thus found adequate to obtain basic risk estimates accounting for JUV in a realistically complex risk assessment. These methods make routine JUV analysis more convenient and practical.
Tissue Dosimetry, Pharmacokinetic Modeling, and Interspecies Scaling Factors
Authors: Andersen Melvin E. , Clewell III Harvey , Krishnan Kannan
Published: May 2006

Interspecies scaling factors (ISFs) are numbers used to adjust the potency factor (for example, the q1* for carcinogens or reference doses for compounds eliciting other toxic endpoints) determined in experimental animals to account for expected differences in potency between test animals and people. ISFs have been developed for both cancer and non‐cancer risk assessments in response to a common issue: toxicologists often determine adverse effects of chemicals in test animals and then they, or more commonly risk assessors and risk managers, have to draw inferences about what these observations mean for the human population. This perspective briefly reviews the development of ISFs and their applications in health risk assessments over the past 20 years, examining the impact of pharmacokinetic principles in altering current perceptions of the ISFs applied in these health risk assessments, and assessing future directions in applying both pharmacokinetic and pharmacodynamic principles for developing ISFs.
Canada's Health Status: A Public Health Perspective1
Authors: Wigle Donald T.
Published: May 2006

Health status assessment and disease surveillance are essential to identify and priorize health issues, to evaluate intervention programs and to plan to meet future needs for health services. Canadians currently benefit by having among the highest life expectancies at birth in the world (81 for females, 74 for males). Disability‐free life expectancies for females and males, respectively, were 10.1 and 11.3 years lower for the lowest income quintile compared to the highest. Canada's infant mortality rate in 1990 (7/1000 live births) was one of the lowest in the world but within Canada, the rate in the lowest income quintile (10.5/1000 live births) was almost double that in the highest income quintile (5.8/1000 live births). Fair or poor health was reported by 36% of adult Canadians in the lowest income category in 1990 compared to only 5% in the highest income group. The leading causes of premature death for females in 1991 were breast cancer, coronary heart disease, lung cancer, car crashes, birth defects and suicide; those for males were coronary heart disease, suicide, car crashes, lung cancer, birth defects, and AIDS. Lowest income quintile males had mortality rates at least double those for the highest income quintile for alcohol‐related conditions, violence, injuries and emphysema. Cardiovascular diseases, cancer, musculoskeletal diseases, injuries and respiratory diseases imposed the highest direct and indirect economic costs in Canada in 1986. For all of these conditions, improved prevention is possible. For example, the forecasted tobacco‐related deaths before age 70 among current male smokers age 15 will far exceed those due to car crashes, suicide, murder, AIDS, and drug abuse combined. Population aging will aggravate trends for many chronic conditions especially those with increasing incidence rates; there will be large increases in the numbers of persons with aging‐related cancers, dementias and other conditions. There is an urgent need for Canadian health jurisdictions to ensure that rational priorities, goals/objectives, strategies, and programs are in place to enhance prevention and disease control.
Interspecies Extrapolation of Physiological Pharmacokinetic Parameter Distributions
Authors: Watanabe Karen H. , Bois Frédéric Y.
Published: May 2006

Three methods (multiplicative, additive, and allometric) were developed to extrapolate physiological model parameter distributions across species, specifically from rats to humans. In the multiplicative approach, the rat model parameters are multiplied by the ratio of the mean values between humans and rats. Additive scaling of the distributions is denned by adding the difference between the average human value and the average rat value to each rat value. Finally, allometric scaling relies on established extrapolation relationships using power functions of body weight. A physiologically‐based pharmacokinetic model was fitted independently to rat and human benzene disposition data. Human model parameters obtained by extrapolation and by fitting were used to predict the total bone marrow exposure to benzene and the quantity of metabolites produced in bone marrow. We found that extrapolations poorly predict the human data relative to the human model. In addition, the prediction performance depends largely on the quantity of interest. The extrapolated models underpredict bone marrow exposure to benzene relative to the human model. Yet, predictions of the quantity of metabolite produced in bone marrow are closer to the human model predictions. These results indicate that the multiplicative and allometric techniques were able to extrapolate the model parameter distributions, but also that rats do not provide a good kinetic model of benzene disposition in humans.
A Biologically‐Based Dose—Response Model for Developmental Toxicology
Authors: Leroux Brian G. , Leisenring Wendy M. , Moolgavkar Suresh H. , Faustman Elaine M.
Published: May 2006

The methods currently used to evaluate the risk of developmental defects in humans from exposure to potential toxic agents do not reflect biological processes in extrapolating estimated risks to low doses and from test species to humans. We develop a mathematical model to describe aspects of the dynamic process of organogenesis, based on branching process models of cell kinetics. The biological information that can be incorporated into the model includes timing and rates of dynamic cell processes such as differentiation, migration, growth, and replication. The dose‐response models produced can explain patterns of malformation rates as a function of both dose and time of exposure, resulting in improvements in risk assessment and understanding of the underlying mechanistic processes. To illustrate the use of the model, we apply it to the prediction of the effects of methylmercury on brain development in rats.
What Determines Trust in Information About Food‐Related Risks? Underlying Psychological Constructs
Authors: Frewer L. J. , Howard C. , Hedderley D. , Shepherd R.
Published: May 2006

Trust in risk information about food related‐hazards may be an important determinant of public reactions to risk information. One of the central questions addressed by the risk communication literature is why some individuals and organizations are trusted as sources of risk information and others are not. Industry and government often lack public trust, whereas other sources (for example, consumer organizations, the quality media, medical doctors) are highly trusted. Problematically, previous surveys and questionnaire studies have utilized questions generated by the investigators themselves to assess public perceptions of trust in different sources. Furthermore, no account of the hazard domain was made. In the first study reported here, semistructured interviewing was used to elicit underpinning constructs determining trust and distrust in different sources providing food‐related risk information (n= 35). In the second study, the repertory grid method was used to elicit the terminology that respondents use to distinguish between different potential food‐related information sources (n= 35), the data being submitted to generalised Procrustes analysis. The results of the two studies were combined and validated in survey research (n= 888) where factor analysis indicated that knowledge in itself does not lead to trust, but that trusted sources are seen to be characterised by multiple positive attributes. Contrary to previous research, complete freedom does not lead to trust—rather sources which possess moderate accountability are seen to be the most trusted.
Altruistic Preferences for Life‐Saving Public Programs: Do Baseline Risks Matter?
Authors: Van Houtven George L.
Published: May 2006

Cost‐benefit analyses of life‐saving public programs typically focus on the number of expected deaths avoided (statistical lives saved) as the metric for evaluating benefits. Although this measure of population risk is clearly important, it ignores the distribution of underlying individual risks. A similar number of lives can be saved by protecting relatively large populations with relatively low baseline risk as can be saved by protecting smaller populations faced with higher baseline risks. Should the value of saving a statistical life be sensitive to the baseline levels of risk to exposed individuals? This paper addresses this issue by focusing specifically on individuals’ altruistic values with regard to life‐saving programs. Using results from a survey, this study finds that when individuals are asked to state their preference for equally costly life‐saving programs that will only affect others’ level of risk, they prefer those that save more lives. More importantly, however, controlling for the number of lives saved, they also prefer programs that affect smaller populations facing higher levels of baseline risk. Furthermore, the results suggest that each order‐of‐magnitude increase in the level of baseline risk to others approximately doubles the altruistic value component of a statistical life saved.
An Overview of a Multimedia Benchmarking Analysis for Three Risk Assessment Models: RESRAD, MMSOILS, and MEPAS
Authors: Laniak Gerard F. , Droppo James G. , Faillace Ernest R. , Gnanapragasam Emmanuel K. , Mills William B. , Strenge Dennis L. , Whelan Gene , Yu Charley
Published: May 2006

Multimedia modelers from the United States Environmental Protection Agency (EPA) and the United States Department of Energy (DOE) collaborated to conduct a detailed and quantitative benchmarking analysis of three multimedia models. The three models—RESRAD (DOE), MMSOILS (EPA), and MEPAS (DOE)—represent analytically‐based tools that are used by the respective agencies for performing human exposure and health risk assessments. The study is performed by individuals who participate directly in the ongoing design, development, and application of the models. Model form and function are compared by applying the models to a series of hypothetical problems, first isolating individual modules (e.g., atmospheric, surface water, groundwater) and then simulating multimedia‐based risk resulting from contaminant release from a single source to multiple environmental media. Study results show that the models differ with respect to environmental processes included (i.e., model features) and the mathematical formulation and assumptions related to the implementation of solutions. Depending on the application, numerical estimates resulting from the models may vary over several orders‐of‐magnitude. On the other hand, two or more differences may offset each other such that model predictions are virtually equal. The conclusion from these results is that multimedia models are complex due to the integration of the many components of a risk assessment and this complexity must be fully appreciated during each step of the modeling process (i.e., model selection, problem conceptualization, model application, and interpretation of results).
The Words of Risk Analysis
Authors: Kaplan Stan
Published: May 2006

This paper is a transcript of a talk given to a plenary session at the 1996 Annual Meeting of the Society for Risk Analysis. Its purpose is to contribute toward a single, uniformly understood language for the risk analysis community.
The Cost‐Effectiveness of Lifesaving Interventions in Sweden
Authors: Ramsberg Joakim A. L. , Sjöberg Lennart
Published: May 2006

In this article, we discuss under what conditions an estimated cost per statistical life saved can be interpreted as an implied lifevalue. Furthermore, we state optimality conditions with respect to variation in implied lifevalues. The cost‐effectiveness, together with references, are presented for 165 lifesaving interventions in Sweden. The cost‐effectiveness of interventions has been found in publicly available analyses, or in some cases been calculated by us. Several of these interventions produce net savings for society. The most expensive interventions cost several hundred million SEK, or more, per life saved. To improve the comparability of the interventions, certain criteria have been used to standardize the estimates. Still, dissimilarities in the calculation of implied life values remain and the quality of the original data is in some cases uncertain. Despite this and the fact that the interventions are not a representative sample, it is nevertheless possible to conclude that implied life values vary greatly both within and between different sectors of the Swedish society, much in the same manner as in current U.S. analyses.
Health Risks of Energy Systems
Authors: Krewitt Wolfram , Hurley Fintan , Trukenmüller Alfred , Friedrich Rainer
Published: May 2006

Health risks from fossil, renewable and nuclear reference energy systems are estimated following a detailed impact pathway approach. Using a set of appropriate air quality models and exposure‐effect functions derived from the recent epidemiological literature, a methodological framework for risk assessment has been established and consistently applied across the different energy systems, including the analysis of consequences from a major nuclear accident. A wide range of health impacts resulting from increased air pollution and ionizing radiation is quantified, and the transferability of results derived from specific power plants to a more general context is discussed.
Sample Timing and Mathematical Considerations for Modeling Breath Elimination of Volatile Organic Compounds
Authors: Pleil Joachim D. , Lindstrom Andrew B.
Published: May 2006

Real‐world exposure measurements are a necessary ingredient for subsequent detailed study of the risks from an environmental pollutant. For volatile organic compounds, researchers are applying exhaled breath analysis and the time dependence of concentrations as a noninvasive indicator of exposure, dose, and blood levels. To optimize the acquisition of such data, samples must be collected in a time frame suited to the needs of the mathematical model, within physical limitations of the equipment and subjects, and within logistical constraints. Additionally, one must consider the impact of measurement error on the eventual extraction of biologically and physiologically relevant parameters. Given a particular mathematical model for the elimination kinetics (in this case a very simple pharmacokinetic model based upon a multitenn exponential decay function that has been shown to fit real‐world data extremely well), we investigated the effects on synthetic data caused by sample timing, random measurement error, and number of terms included in the model. This information generated a series of conditions for collecting samples and performing analyses dependent upon the eventual informational needs, and it provided an estimate of error associated with various choices and compromises. Though the work was geared specifically toward breath sampling, it is equally applicable to direct blood measurements in optimizing sampling strategy and improving the exposure assessment process.
An Empirical Approach for Deriving Information on Total Duration of Exposure from Information on Historical Exposure
Authors: Price Paul S. , Scott Paul K. , Wilson Natalie D. , Paustenbach Dennis J.
Published: May 2006

Exposure duration is an important component in determining long‐term dose rates associated with exposure to environmental contaminants. Surveys of exposed populations collect information on individuals' past behaviors, including the durations of a behavior up to the time of the survey. This paper presents an empirical approach for determining the distribution of total durations that is consistent with the distribution past durations obtained from surveys. This approach is appropriate where the rates of beginning and ending a behavior are relatively constant over time. The approach allows the incorporation of information on the distribution of age in a population into the determination of the distribution of durations. The paper also explores the impact of “longevity” bias on survey data. A case study of the application of this approach to two angler populations is also provided. The results of the case study have characteristics similar to the results reported by Israeli and Nelson (Risk Anal. 12, 65‐72 (1992)) from their analytical model of residential duration. Specifically, the average period of time for the total duration in the entire population is shorter than the average period of time reported for historical duration in the surveyed individuals.
Risk, Media, and Stigma at Rocky Flats
Authors: Flynn James , Peters Ellen , Mertz C. K. , Slovid Paul
Published: May 2006

Public responses to nuclear technologies are often strongly negative. Events, such as accidents or evidence of unsafe conditions at nuclear facilities, receive extensive and dramatic coverage by the news media. These news stories affect public perceptions of nuclear risks and the geographic areas near nuclear facilities. One result of these perceptions, avoidance behavior, is a form of “technological stigma” that leads to losses in property values near nuclear facilities. The social amplification of risk is a conceptual framework that attempts to explain how stigma is created through media transmission of information about hazardous places and public perceptions and decisions. This paper examines stigma associated with the U.S. Department of Energy's Rocky Flats facility, a major production plant in the nation's nuclear weapons complex, located near Denver, Colorado. This study, based upon newspaper analyses and a survey of Denver area residents, finds that the social amplification theory provides a reasonable framework for understanding the events and public responses that took place in regard to Rocky Flats during a 6‐year period, beginning with an FBI raid of the facility in 1989.
Physiologically‐Based Pharmacokinetic Model for Trichloroethylene Considering Enterohepatic Recirculation of Major Metabolites
Authors: Stenner Robert D. , Merdink James L. , Fisher Jeffery W. , Bull Richard J.
Published: May 2006

Trichloroacetic acid (TCA) is major metabolite of trichloroethylene (TRI) thought to contribute to its hepatocarcinogenic effects in mice. Recent studies have shown that peak blood concentrations of TCA in rats do not occur until approximately 12 hours following an oral dose of TRI. However, blood concentrations of TRI reach maximum within an hour and are nondetectable after 2 hours.(1) The results of study which examined the enterohepatic recirculation (EHC) of the principle TRI metabolited(2) was used to develop physiologically‐based pharmacokinetic model for TRI, which includes enterohepatic recirculation of its metabolites. The model quantitatively predicts the uptake, distribution and elimination of TRI, trichloroethanol, trichloroethanol‐glucuronide, and TCA and includes production of metabolites through the enterohepatic recirculation pathway. Physiologic parameters used in the model were obtained from the literature.(3.4) Parameters for TRI metabolism were taken from Fisher et al.(5) Other kinetic parameters were found in the literature or estimated from experimental data.(2) The model was calibrated to data from experiments of an earlier study where TRI was orally administered(2) Verification of the model was conducted using data on the enterohepatic recirculation of TCEOH and TCA(2) chloral hydrate data (infusion doses) from Merdink,(1) and TRI data from Templin(l) and Larson and Bull.(1)
Estimates of per Capita Fish Consumption in the U.S. Based on the Continuing Survey of Food Intake by Individuals (CSFII)
Authors: Jacobs Helen L. , Kahn Henry D. , Stralka Kathleen A. , Phan Dung B.
Published: May 2006

This paper presents estimates of daily average per capita fish consumption by age and gender for the 48 conterminous states. The estimated consumption rates are reported for three fish habitats: freshwater/estuarine fish, marine fish, and all fish. The estimates were generated from the combined 1989, 1990, and 1991 Continuing Survey of Food Intake by Individuals (CSFII), a national food consumption survey conducted by the United States Department of Agriculture (USDA). Point and interval estimates of per capita fish consumption were generated from the empirical distribution of daily average per capita consumption. The point estimates include the mean, 50th, 75th, 90th, 95th, and 99th percentiles. Ninety percent confidence intervals are provided for the estimated mean and 90% bootstrap intervals are provided for percentile estimates. Information in a recipe file provided by USDA was used to calculate the amount of fish in recipes which contain fish. The estimated consumption rates are based on the weight of fish in its prepared or “as consumed” condition. The estimated mean consumption rate for all fish for the U.S. population of the 48 conterminous states was 15.65 grams/person/day (C.I.:14.67–16.63) of which 4.71 grams/person/day (C.I.:4.17–5.25) was freshwater/estuarine fish and 10.94 grams/person/day (C.I.: 10.14–11.73) was marine fish.
Methods for Characterizing Variability and Uncertainty: Comparison of Bootstrap Simulation and Likelihood‐Based Approaches
Authors: Frey H. Christopher , Burmaster David E.
Published: May 2006

Variability arises due to differences in the value of a quantity among different members of a population. Uncertainty arises due to lack of knowledge regarding the true value of a quantity for a given member of a population. We describe and evaluate two methods for quantifying both variability and uncertainty. These methods, bootstrapsimulation and a likelihood‐based method, are applied to three datasets. The datasetsinclude a synthetic sample of 19 values from a Lognormal distribution, a sample of nine values obtained from measurements of the PCB concentration in leafy produce, and asample of five values for the partitioning of chromium in the flue gas desulfurization system of coal‐fired power plants. For each of these datasets, we employ the two methods to characterize uncertainty in the arithmetic mean and standard deviation, cumulative distribution functions based upon fitted parametric distributions, the 95th percentile of variability, and the 63rd percentile of uncertainty for the 81st percentile of variability. The latter is intended to show that it is possible to describe anypoint within the uncertain frequency distribution by specifying an uncertainty percentile and a Variability percentile. Using the bootstrap method, we compare results based upon use of the method of matching moments and the method of maximum likelihood for fitting distributions to data. Our results indicate that with only 5‐19 data pointsas in the datasets we have evaluated, there is substantial uncertainty based upon random sampling error. Both the boostrap and likelihood‐based approaches yield comparable uncertainty estimates in most cases.
Geographical Dimensions and Correlates of Trust
Authors: Greenberg Michael R. , Williams Bryan
Published: May 2006

A sample of 323 residents of New Jersey stratified by neighborhood quality (excellent, good, fair, poor) was gathered to determine if trust in science and technology to protect public health and environment at the societal scale was associated with trust of the local officials, such as the mayor, health officer, developers, mass media, and legislators who are guardians of the local environment. Societal (trust of science and technology) and neighborhood (mayor, health officer) dimensions of trust were found. These societal and neighborhood trust dimen‐sions were weakly correlated. Respondents were divided into four trust‐of‐authority groups: high societal‐high neighborhood, low societal‐low neighborhood, high societal‐low neigh‐borhood, and low societal‐high neighborhood. High societal‐high neighborhood trust re‐spondents were older, had lived in the neighborhoods for many years, were not troubled much by neighborhood or societal environmental threats, and had a strong sense of control over their environment. In strong contrast, low societal‐low neighborhood trust respondents were relatively young, typically had lived in their present neighborhood for a short time, were troubled by numerous neighborhood and societal environmental threats, did not practice many personal public health practices, and felt little control over their environment.
Factors in Exposure Assessment: Ethnic and Socioeconomic Differences in Fishing and Consumption of Fish Caught along the Savannah River
Authors: Burger Joanna , Stephens Warren L. , Boring C. Shane , Kuklinski Michelle , Gibbons J. Whitfield , Gochfeld Michael
Published: May 2006

South Carolina has issued fish consumption advisories for the Savannah River based on mercury and radionuclide levels. We examine differences in fishing rates and fish consumption of 258 people interviewed while fishing along the Savannah River, as a function of age, education, ethnicity, employment history, and income, and test the assumption that the average consumption of fish is less than the recreational value of 19 kg/year assumed by risk assessors. Ethnicity and education contributed significantly to explaining variations in number of fish meals per month, serving size, and total quantity of fish consumed per year. Blacks fished more often, ate more fish meals of slightly larger serving sizes, and consumed more fish per year than did Whites. Although education and income were correlated, education contributed most significantly to behavior; people who did not graduate from high school ate fish more often, ate more fish per year, and ate more whole fish than people who graduated from high school. Computing consumption of fish for each person individually indicates that (1) people who eat fish more often also eat larger portions, (2) a substantial number of people consume more than the amount of fish used to compute risk to recreational fishermen, (3) some people consume more than the subsistence level default assumption (50 kglyear) and (4) Blacks consume more fish per year than Whites, putting them at greater risk from contaminants in fish. Overall, ethnicity, age, and education contributed to variations in fishing behavior and consumption.
Methods for Detecting and Estimating Population Threshold Concentrations for Air Pollution‐Related Mortality with Exposure Measurement Error
Authors: Cakmak Sabit , Burnett Richard T. , Krewski Daniel
Published: May 2006

The association between daily fluctuations in ambient particulate matter and daily variations in nonaccidental mortality have been extensively investigated. Although it is now widely recognized that such an association exists, the form of the concentration‐response model is still in question. Linear, no threshold and linear threshold models have been most commonly examined. In this paper we considered methods to detect and estimate threshold concentrations using time series data of daily mortality rates and air pollution concentrations. Because exposure is measured with error, we also considered the influence of measurement error in distinguishing between these two completing model specifications. The methods were illustrated on a 15‐year daily time series of nonaccidental mortality and particulate air pollution data in Toronto, Canada. Nonparametric smoothed representations of the association between mortality and air pollution were adequate to graphically distinguish between these two forms. Weighted nonlinear regression methods for relative risk models were adequate to give nearly unbiased estimates of threshold concentrations even under conditions of extreme exposure measurement error. The uncertainty in the threshold estimates increased with the degree of exposure error. Regression models incorporating threshold concentrations could be clearly distinguished from linear relative risk models in the presence of exposure measurement error. The assumption of a linear model given that a threshold model was the correct form usually resulted in overestimates in the number of averted premature deaths, except for low threshold concentrations and large measurement error.
Democratizing Risk Management: Successful Public Involvement in Local Water Management Decisions
Authors: McDaniels Timothy L. , Gregory Robin S. , Fields Daryl
Published: May 2006

This paper discusses a successful public involvement effort that addressed and resolved several highly controversial water management issues involving environmental and flood risks associated with an electrical generation facility in British Columbia. It begins with a discussion of concepts for designing public involvement, summarizing research that indicates why individuals and groups may find it difficult to make complex choices. Reasons for public involvement, and the range of current practices are discussed. Next, four principles for designing group decision process are outlined, emphasizing decision‐aiding concepts that include “value‐focused thinking” and “adaptive management.” The next sections discuss the Alouette River Stakeholder Committee process in terms of objectives, participation, process, methods for structuring values and creating alternatives, information sources, and results. Discussion and conclusions complete the paper.
Uncertainty in Comparative Risk Analysis for Threatened Australian Plant Species
Authors: Burgman Mark A. , Keith David A. , Walshe Terry V.
Published: May 2006

Australian state and federal agencies use a broad range of methods for setting conservation priorities for species at risk. Some of these are based on rule sets developed by the International Union for the Conservation ofNature, while others use point scoring protocols to assess threat. All of them ignore uncertainty in the data. In this study, we assessed the conservation status of 29 threatened vascular plants from Tasmania and New South Wales using a variety of methods including point scoring and rule‐based approaches. In addition, several methods for dealing with uncertainty in the data were applied to each of the prioritysetting schemes. The results indicatethat the choice of a protocol for setting priorities and the choice of the way in which uncertainty is treated may make important differences to the resulting assessments of risk. The choice among methods needs to be rationalized within the management context in which it is to be applied. These methods are not a substitute for more formal risk assessment.
Simultaneous Analysis of Individual and Aggregate Responses in Psychometric Data Using Multilevel Modeling
Authors: Langford Ian H. , Marris Claire , McDonald Annë‐Lise , Goldstein Harvey , Rasbash Jon , O'Riordan Tim
Published: May 2006

Psychometric data on risk perceptions are often collected using the method developed by Slovic, Fischhoff, and Lichtenstein, where an array of risk issues are evaluated with respect to a number of risk characteristics, such as how dreadful, catastrophic or involuntary exposure to each risk is. The analysis of these data has often been carried out at an aggregate level, where mean scores for all respondents are compared between risk issues. However, this approach may conceal important variation between individuals, and individual analyses have also been performed for single risk issues. This paper presents a new methodological approach using a technique called multilevel modelling for analysing individual and aggregated responses simultaneously, to produce unconditional and unbiased results at both individual and aggregate levels of the data. Two examples are given using previously published data sets on risk perceptions collected by the authors, and results between the traditional and new approaches compared. The discussion focuses on the implications of and possibilities provided by the new methodology.
A Decision Theory Perspective on the Disposal of High‐Level Radioactive Waste
Authors: Garrick B. John , Kaplan Stan
Published: May 2006

In this paper the problem of high‐level nuclear waste disposal is viewed as a five‐stage, cascaded decision problem. The first four of these decisions having essentially been made, the work of recent years has been focused on the fifth stage, which concerns specifics of the repository design. The probabilistic performance assessment (PPA) work is viewed as the outcome prediction for this stage, and the site characterization work as the information gathering option. This brief examination of the proposed Yucca Mountain repository through a decision analysis framework resulted in three conclusions: (1) A decision theory approach to the process of selecting and characterizing Yucca Mountain would enhance public understanding of the issues and solutions to high‐level waste management; (2) engineered systems are an attractive alternative to offset uncertainties in the containment capability of the natural setting and should receive greater emphasis in the design of the repository; and (3) a strategy of “waste management” should be adopted, as opposed to “waste disposal,” as it allows for incremental confirmation and confidence building of a permanent solution to the high‐level waste problem.