bluuebunny/crossref_metadata_2025 huggingface dataset:
The Brent Spar Controversy: An Example of Risk Communication Gone Wrong
Authors: Löfstedt Ragnar E. , Renn Ortwin
Published: May 2006

This perspective piece uses the theories and ideas of risk communication to shed light on the reasons why the proposed dumping of Brent Spar in the U.K. offshore waters caused such an international uproar. We postulate that the Brent Spar crisis is a classic example of risk communication gone wrong. Had the sinking of the storage buoy not been amplified by the media and the environmental group Greenpeace, and had not the U.K. Government nor Shell come across as distrustful it would probably have taken place without any public notice. We examine some of the main reasons why Greenpeace succeeded in its risk communication and Shell/the U.K. Government failed. We conclude with a discussion concerning some of the risk communication lessons learned from this crisis.
Estimating Health Risks from Natural Hazards Using Risk Assessment and Epidemiology
Authors: Malilay Josephine , Henderson Alden , McGeehin Michael , Flanders W. Dana
Published: May 2006

Risk assessment is the process of estimating the likelihood that an adverse effect may result from exposure to a specific health hazard. The process traditionally involves hazard identification, dose‐response assessment, exposure assessment, and risk characterization to answer “How many excess cases of disease A will occur in a population of size B due to exposure to agent C at dose level D?” For natural hazards, however, we modify the risk assessment paradigm to answer “How many excess cases of outcome Y will occur in a population of size B due to natural hazard event E of severity D?” Using a modified version involving hazard identification, risk factor characterization, exposure characterization, and risk characterization, we demonstrate that epidemiologic modeling and measures of risk can quantify the risks from natural hazard events. We further extend the paradigm to address mitigation, the equivalent of risk management, to answer “What is the risk for outcome Y in the presence of prevention intervention X relative to the risk for Y in the absence of X?” We use the preventable fraction to estimate the efficacy of mitigation, or reduction in adverse health outcomes as a result of a prevention strategy under ideal circumstances, and further estimate the effectiveness of mitigation, or reduction in adverse health outcomes under typical community‐based settings. By relating socioeconomic costs of mitigation to measures of risk, we illustrate that prevention effectiveness is useful for developing cost‐effective risk management options.
The Two‐Stage Model of Carcinogenesis: Overcoming the Nonidentifiability Dilemma
Authors: Sherman Claire D. , Portier Christopher J.
Published: May 2006

The two‐stage mathematical model of carcinogenesis has been shown to be nonidentifiable whenever tumor incidence data alone is used to fit the model (Hanin and Yakovlev, 1996). This lack of identifiability implies that more than one parameter vector satisfies the optimization criteria for parameter estimation, e.g., maximum likelihood estimation. A question of greater concern to persons using the two‐stage model of carcinogenesis is under what conditions can identifiable parameters be obtained from the observed experimental data. We outline how to obtain identifiable parameters for the two‐stage model.
Some Properties of the Hazard Function of the Two‐Mutation Clonal Expansion Model
Authors: Heidenreich Wolfgang F. , Luebeck E. Georg , Moolgavkar Suresh H.
Published: May 2006

We discuss the hazard function of the two‐mutation clonal expansion model with time‐dependent parameters, with particular emphasis on identifiability of the parameters. We explicitly construct identifiable parameter combinations, and illustrate the properties of the hazard function under perturbations of the underlying biological parameters.
An Approach for Modeling Noncancer Dose Responses with an Emphasis on Uncertainty
Authors: Price Paul S. , Keenan Russell E. , Swartout Jeffrey C. , Gillis Carol A. , Carlson‐Lynch Heather , Dourson Michael L.
Published: May 2006

This paper presents an approach for characterizing the probability of adverse effects occurring in a population exposed to dose rates in excess of the Reference Dose (RfD). The approach uses a linear threshold (hockey stick) model of response and is based on the current system of uncertainty factors used in setting RfDs. The approach requires generally available toxicological estimates such as No‐Observed‐Adverse‐Effect Levels (NOAELs) or Benchmark Doses and doses at which adverse effects are observed in 50% of the test animals (ED50s). In this approach, Monte Carlo analysis is used to characterize the uncertainty in the dose response slope based on the range and magnitude of the key sources of uncertainty in setting protective doses. The method does not require information on the shape of the dose response curve for specific chemicals, but is amenable to the inclusion of such data. The approach is applied to four compounds to produce estimates of response rates for dose rates greater than the RfD
A Unified Approach to a Class of Stochastic Carcinogenesis Models
Authors: Zheng Qi
Published: May 2006

Survival and hazard functions play a pivotal role in carcinogenesis modeling. This paper provides a unified approach to computing these two quantities by classifying a large class of carcinogenesis models from a computational point of view, and prescribes specific computational recipes according to this classification.
The Vulnerability of the Nevada Visitor Economy to a Repository at Yucca Mountain
Authors: Easterling Doug
Published: May 2006

This article reviews the studies commissioned by the Nevada Nuclear Waste Project Office to estimate the economic impact of a high‐level nuclear waste repository at Yucca Mountain. Case studies found that visitor impacts occur for some analogous facilities, but not for others. Assessments of behavioral intent indicate that at least some economic agents would avoid visiting Nevada under repository scenarios. A third set of studies tested the risk‐aversion and negative‐imagery models of visitor decision making; people avoid visiting places associated with either a significant health risk or negative imagery, but it has yet to be shown that a repository would induce these perceptions in nearby places. In sum, the NWPO‐sponsored studies suggest the potential for visitor impacts, but do confirm that these effects will occur.
The Elaboration Likelihood Model and Communication About Food Risks
Authors: Frewer Lynn J. , Howard Chaya , Hedderley Duncan , Shepherd Richard
Published: May 2006

Factors such as hazard type and source credibility have been identified as important in the establishment of effective strategies for risk communication. The elaboration likelihood model was adapted to investigate the potential impact of hazard type, information source, and persuasive content of information on individual engagement in elaborative, or thoughtful, cognitions about risk messages. One hundred sixty respondents were allocated to one of eight experimental groups, and the effects of source credibility, persuasive content of information and hazard type were systematically varied. The impact of the different factors on beliefs about the information and elaborative processing examined. Low credibility was particularly important in reducing risk perceptions, although persuasive content and hazard type were also influential in determining whether elaborative processing occurred.
A Native American Exposure Scenario
Authors: Harris Stuart G. , Harper Barbara L.
Published: May 2006

EPA's Risk Assessment Guidance for Superfund (RAGS) and later documents provide guidance for estimating exposures received from suburban and agricultural activity patterns and lifestyles. However, these methods are not suitable for typical tribal communities whose members pursue, at least in part, traditional lifestyles. These lifestyles are derived from a long association with all of the resources in a particular region. We interviewed 35 members of a Columbia River Basin tribe to develop a lifestyle‐based subsistence exposure scenario that represents a midrange exposure that a traditional tribal member would receive. This scenario provides a way to partially satisfy Executive Order 12898 on environmental justice, which requires a specific evaluation of impacts from federal actions to peoples with subsistence diets. Because a subsistence diet is only a portion of what is important to a traditional lifestyle, we also used information obtained from the interviews to identify parameters for evaluating impacts to environmental and sociocultural qualify of life.
Risk of Extreme Events Under Nonstationary Conditions
Authors: Olsen J. Rolf , Lambert James H. , Haimes Yacov Y.
Published: May 2006

The concept of the return period is widely used in the analysis of the risk of extreme events and in engineering design. For example, a levee can be designed to protect against the 100‐year flood, the flood which on average occurs once in 100 years. Use of the return period typically assumes that the probability of occurrence of an extreme event in the current or any future year is the same. However, there is evidence that potential climate change may affect the probabilities of some extreme events such as floods and droughts. In turn, this would affect the level of protection provided by the current infrastructure. For an engineering project, the risk of an extreme event in a future year could greatly exceed the average annual risk over the design life of the project. An equivalent definition of the return period under stationary conditions is the expected waiting time before failure. This paper examines how this definition can be adapted to nonstationary conditions. Designers of flood control projects should be aware that alternative definitions of the return period imply different risk under nonstationary conditions. The statistics of extremes and extreme value distributions are useful to examine extreme event risk. This paper uses a Gumbel Type I distribution to model the probability of failure under nonstationary conditions. The probability of an extreme event under nonstationary conditions depends on the rate of change of the parameters of the underlying distribution.
Rating Threat Mitigators: Faith in Experts, Governments, and Individuals Themselves to Create a Safer World
Authors: O'Connor Robert E. , Bord Richard J. , Fisher Ann
Published: May 2006

This research explores public judgments about the threat‐reducing potential of experts, individual behavior, and government spending. The data are responses of a national sample of 1225 to mail surveys that include measures of several dimensions of public judgments about violent crime, automobile accidents, hazardous chemical waste, air pollution, water pollution, global warming, AIDS, heart disease, and cancer. Beliefs about who can best mitigate threats are specific to classes of threats. In general, there is little faith that experts can do much about violent crime and automobile accidents, moderate faith in their ability to address problems of global warming, and greater expectations for expert solutions to the remaining threats. People judge individual behavior as effective in reducing the threats of violent crime, AIDS, heart disease, and automobile accidents but less so for the remaining threats. Faith in more government spending is highest for AIDS and the other two health items, lowest for the trio of violent crime, automobile accidents, and global warming, and moderate for the remaining threats. For most threats, people are not distributed at the extremes in judging mitigators. Strong attitudinal and demographic cleavages are also lacking, although some interesting relationships occur. This relative lack of sharp cleavages and the generally moderate opinion indicate ample opportunity for public education and risk communication.
Evaluating Risk Communication: Examining Target Audience Perceptions About Four Presentation Formats for Fish Consumption Health Advisory Information
Authors: Connelly Nancy A. , Knuth Barbara A.
Published: May 2006

Information format can influence the extent to which target audiences understand and respond to risk‐related information. This study examined four elements of risk information presentation format. Using printed materials, we examined target audience perceptions about: (a) reading level; (b) use of diagrams vs. text; (c) commanding versus cajoling tone; and (d) use of qualitative vs. quantitative information presented in a risk ladder. We used the risk communication topic of human health concerns related to eating noncommercial Great Lakes fish affected by chemical contaminants. Results from the comparisons of specific communication formats indicated that multiple formats are required to meet the needs of a significant percent of anglers for three of the four format types examined. Advisory text should be reviewed to ensure the reading level is geared to abilities of the target audience. For many audiences, a combination of qualitative and quantitative information, and a combination of diagrams and text may be most effective. For most audiences, a cajoling rather than commanding tone better provides them with the information they need to make a decision about fish consumption. Segmenting audiences regarding information needs and communication formats may help clarify which approaches to take with each audience.
Risk Perception by Offshore Oil Personnel During Bad Weather Conditions
Authors: Rundmo Torbjørn , Sjöberg Lennart
Published: May 2006

This article presents the results of analyses of employee subjective risk assessments caused by platform movements on an offshore oil installation in the Norwegian sector of the North Sea. The results are based on a self‐completion questionnaire survey conducted among 179 respondents covering three shifts on the platform. The data collection was carried out during the spring of 1994. A minority expressed worry due to platform movements. A greater proportion of the personnel stated worry about the construction of the platform. The personnel were more unsafe when they assessed their own safety attitudes with regard to specific potentially hazardous consequences of platform movements. Two approaches aimed at modeling worry and concern caused by platform movements were tested. The models were the mental imagery approach and the rationalistic approach. The rationalistic and mental imagery models fitted equally well. Implications of the results for risk communication are discussed.
Judgments of Personal and Environmental Risks of Consumer Products—Do they Differ?
Authors: Schütz Holger , Wiedemann Peter M.
Published: May 2006

Many psychometric studies have investigated judgments concerning personal risks from technologies, activities or consumer products, but only a few studies have included judgments of risk to the environment. Thus, little is known about this aspect of environmental risk perception, and whether it differs from personal risk perception. This study investigates risk judgments for 30 consumer products of various types such as herbal remedies, mobile telephones, genetically engineered drugs, or garden pesticides. A survey was conducted in two German cities: Leipzig and West Berlin. In total, 408 subjects evaluated the consumer products with regard to personal and environmental risk (and other risk‐related aspects) and whether they would recommend the product to others. The findings show statistically significant differences between the mean values of perceived personal risk and environmental risk for most products. Despite these differences, the rank order of mean personal risk and environmental risk judgments for the products is quite similar. However, separate analyses for each product reveal that correlations between perceived personal and environmental risk vary strongly across products. Multiple regression analyses with personal and environmental risk judgments as predictors and product recommendation as criterion, run separately for each consumer product, show that it is mainly the judgment of perceived personal risk that explains product recommendation. Perceived risk to the environment adds little explanatory power. The study also explores differences in judgments of personal and environmental risk with regard to two sociodemographic variables: location (former East Germany vs. West Germany) and gender. Differences in both types of risk judgments are found with regard to location but not for gender.
Target Levels—Tools for Prevention
Authors: Niemelä Raimo I. , Rantanen Jorma , Kiilunen Mirja K.
Published: May 2006

Although occupational exposure limits are sought to establish health‐based standards, they do not always give a sufficient basis for planning an indoor air climate that is good and comfortable for the occupants in industrial work rooms. This paper considers methodologies by which the desired level, i.e., target level, of air quality in industrial settings can be defined, taking into account feasibility issues. Risk assessment based on health criteria is compared with risk‐assessment based on “Best Available Technology” (BAT). Because health‐based risk estimates at low concentration regions are rather inaccurate, the technology‐based approach is emphasized. The technological approach is based on information on the prevailing concentrations in industrial work environments and the benchmark air quality attained with the best achievable technology. The prevailing contaminant concentrations are obtained from a contaminant exposure databank, and the benchmark air quality by field measurements in industrial work rooms equipped with advanced ventilation and production technology. As an example, the target level assessment has been applied to formaldehyde, total inorganic dust and hexavalent chromium, which are common contaminants in work room air.
A Probabilistic Approach for Deriving Acceptable Human Intake Limits and Human Health Risks from Toxicological Studies: General Framework
Authors: Slob W. , Pieters M. N.
Published: May 2006

The use of uncertainty factors in the standard method for deriving acceptable intake or exposure limits for humans, such as the Reference Dose (RfD), may be viewed as a conservative method of taking various uncertainties into account. As an obvious alternative, the use of uncertainty distributions instead of uncertainty factors is gaining attention. This paper presents a comprehensive discussion of a general framework that quantifies both the uncertainties in the no‐adverse‐effect level in the animal (using a benchmark‐like approach) and the uncertainties in the various extrapolation steps involved (using uncertainty distributions). This approach results in an uncertainty distribution for the no‐adverse‐effect level in the sensitive human subpopulation, reflecting the overall scientific uncertainty associated with that level. A lower percentile of this distribution may be regarded as an acceptable exposure limit (e.g., RfD) that takes account of the various uncertainties in a nonconservative fashion. The same methodology may also be used as a tool to derive a distribution for possible human health effects at a given exposure level. We argue that in a probabilistic approach the uncertainty in the estimated no‐adverse‐effect‐level in the animal should be explicitly taken into account. Not only is this source of uncertainty too large to be ignored, it also has repercussions for the quantification of the other uncertainty distributions.
Lay Understanding of Synergistic Risk: The Case of Radon and Cigarette Smoking
Authors: Hampson Sarah E. , Andrews Judy A. , Lee Michael E. , Foster Lyn S. , Glasgow Russell E. , Liechtenstein Edward
Published: May 2006

The combination of radon and smoking produces a synergistic risk of lung cancer. Lay understanding of this risk was examined from the perspectives of mental models theory, the psychometric approach to risk perception, and optimistic bias. As assessed by interview, participants (N= 50) had more extensive mental models for the risks of smoking than for the risks of radon or the combination of radon and smoking; 32% knew little or nothing about radon. Despite reading an informational brochure, their risk‐perception ratings of the three hazards showed no perception of the synergy between smoking and radon risk, although the combined hazard was rated as less familiar but more controllable than the average of the single hazards (p < .01). No evidence of optimistic bias for the health consequences of radon, or the combination of radon and smoking was observed. Participants appeared to be combining the single‐hazard risks subadditively to arrive at their combined‐hazard risk perceptions. Further research on the integration of perceived risks would be beneficial for designing optimal communications about synergistic risk.
Hormesis: A Highly Generalizable and Reproducible Phenomenon With Important Implications for Risk Assessment
Authors: Calabrese Edward J. , Baldwin Linda A. , Holland Charles D.
Published: May 2006

From a comprehensive search of the literature, the hormesis phenomenon was found to occur over a wide range of chemicals, taxonomic groups, and endpoints. By use of computer searches and extensive cross‐referencing, nearly 3000 potentially relevant articles were identified. Evidence of chemical and radiation hormesis was judged to have occurred in approximately 10oO of these by use of a priori criteria. These criteria included study design features (e.g., number of doses, dose range), dose‐response relationship, statistical analysis, and reproducibility of results. Numerous biological endpoints were assessed, with growth responses the most prevalent, followed by metabolic effects, reproductive responses, longevity, and cancer. Hormetic responses were generally observed to be of limited magnitude with an average maximum stimulation of 30 to 60 percent over that of the controls. This maximum usually occurred 4‐ to 5‐fold below the NOAEL for a particular endpoint. The present analysis suggests that hormesis is a reproducible and generalizable biological phenomenon and is a fundamental component of many, if not most, dose‐response relationships. The relatively infrequent observation of homesis in the literature is believed to be due primarily to experimental design considerations, especially with respect to the number and range of doses and endpoint selection. Because of regulatory considerations, most toxicologic studies have been carried out at high doses above the low‐dose region where the hormesis phenomenon occurs.
Task Analysis for Industrial Work Process from Aspects of Human Reliability and System Safety
Authors: Yu Fan‐Jang , Hwang Sheue‐Ling , Huang Yu‐Hao
Published: May 2006

In the design, development, and manufacturing stage of industrial products, engineers usually focus on the problems caused by hardware or software, but pay less attention to problems caused by “human error,” which may significantly affect system reliability and safety. Although operating procedures are strictly followed, human error still may occur occasionally. Among the influencing factors, the inappropriate design of standard operation procedure (SOP) or standard assembly procedure (SAP) is an important and latent reason for unexpected results found during human operation. To reduce the error probability and error effects of these unexpected behaviors in the industrial work process, overall evaluation of SOP or SAP quality has become an essential task. The human error criticality analysis (HECA) method was developed to identify the potentially critical problems caused by human error in the human operation system. This method performs task analysis on the basis of operation procedure. For example, SOP, analyzes the human error probability (HEP) for each human operation step, and assesses its error effects to the whole system. The results of the analysis will show the interrelationship that exists between critical human tasks, critical human error modes, and human reliability information of the human operation system. To identify the robustness of the model, a case study of initiator assembly tasks was conducted. Results show that the HECA method is practicable in evaluating the operation procedure, and the information is valuable in identifying the means to upgrade human reliability and system safety for human tasks.
Risk Perceptions, General Environmental Beliefs, and Willingness to Address Climate Change
Authors: O'Connor Robert E. , Bard Richard J. , Fisher Ann
Published: May 2006

The research reported here examines the relationship between risk perceptions and willingness to address climate change. The data are a national sample of 1225 mail surveys that include measures of risk perceptions and knowledge tied to climate change, support for voluntary and government actions to address the problem, general environmental beliefs, and demographic variables. Risk perceptions matter in predicting behavioral intentions. Risk perceptions are not a surrogate for general environmental beliefs, but have their own power to account for behavioral intentions. There are four secondary conclusions. First, behavioral intentions regarding climate change are complex and intriguing. People are neither “nonbelievers” who will take no initiatives themselves and oppose all government efforts, nor are they “believers” who promise both to make personal efforts and to vote for every government proposal that promises to address climate change. Second, there are separate demographic sources for voluntary actions compared with voting intentions. Third, recognizing the causes of global warming is a powerful predictor of behavioral intentions independent from believing that climate change will happen and have bad consequences. Finally, the success of the risk perception variables to account for behavioral intentions should encourage greater attention to risk perceptions as independent variables. Risk perceptions and knowledge, however, share the stage with general environmental beliefs and demographic characteristics. Although related, risk perceptions, knowledge, and general environmental beliefs are somewhat independent predictors of behavioral intentions.
Sensitivity of Concentration and Risk Predictions in the PRESTO and MMSOILS Multimedia Models: Regression Technique Assessment
Authors: Mills William B. , Lew Christine S. , Hung Cheng Y.
Published: May 2006

This paper describes the application of two multimedia models, PRESTO and MMSOILS, to predict contaminant migration from a landfill that contains an organic chemical (methylene chloride) and a radionuclide (uranium‐238). Exposure point concentrations and human health risks are predicted, and distributions of those predictions are generated using Monte Carlo techniques. Analysis of exposure point concentrations shows that predictions of uranium‐238 in groundwater differ by more than one order of magnitude between models. These differences occur mainly because PRESTO simulates uranium‐238 transport through the groundwater using a one‐dimensional algorithm and vertically mixes the plume over an effective mixing depth, whereas MMSOILS uses a three‐dimensional algorithm and simulates a plume that resides near the surface of the aquifer.

A sensitivity analysis, using stepwise multiple linear regression, is performed to evaluate which of the random variables are most important in producing the predicted distributions of exposure point concentrations and health risks. The sensitivity analysis shows that the predicted distributions can be accurately reproduced using a small subset of the random variables. Simple regression techniques are applied, for comparison, to the same scenarios, and results are similar. The practical implication of this analysis is the ability to distinguish between important versus unimportant random variables in terms of their sensitivity to selected endpoints.
Trust, Emotion, Sex, Politics, and Science: Surveying the Risk‐Assessment Battlefield
Authors: Slovic Paul
Published: May 2006

Risk management has become increasingly politicized and contentious. Polarized views, controversy, and conflict have become pervasive. Research has begun to provide a new perspective on this problem by demonstrating the complexity of the concept “risk” and the inadequacies of the traditionalview of risk assessment as a purely scientific enterprise. This paper argues that danger is real, but risk is socially constructed. Risk assessment is inherently subjective and represents a blending of science and judgmentwith important psychological, social, cultural, and political factors. In addition, our social and democratic institutions, remarkable as they are in many respects, breed distrust in the risk arena. Whoever controls the definition of risk controls the rational solution to the problem at hand. Ifrisk is defined one way, then one option will rise to the top as the most cost‐effective or the safest or the best. If it is defined another way, perhaps incorporating qualitative characteristics and other contextual factors, one will likely get a different ordering of action solutions. Definingrisk is thus an exercise in power. Scientific literacy and public education are important, but they are not central to risk controversies. The public is not irrational. Their judgments about risk are influenced by emotion and affect in a way that is both simple and sophisticated. The same holds true for scientists. Public views are also influenced by worldviews, ideologies, and values; so are scientists' views, particularly when they are working at the limits of their expertise. The limitations of risk science, the importance and difficulty of maintaining trust, and the complex, sociopolitical nature of risk point to the need for a new approach‐one that focuses upon introducing more public participation into both risk assessment and risk decision making in order to make the decision process more democratic, improve the relevance and quality of technical analysis, and increasethe legitimacy and public acceptance of the resulting decisions.
Vehicle Emission Unit Risk Factors for Transportation Risk Assessments*
Authors: Biwer Bruce M. , Butler James P.
Published: May 2006

When the transportation risk posed by shipments of hazardous chemical and radioactive materials is being assessed, it is necessary to evaluate therisks associated with both vehicle emissions and cargo‐related risks. Diesel exhaust and fugitive dust emissions from vehicles transporting hazardous shipments lead to increased air pollution, which increases the risk of latent fatalities in the affected population along the transport route. The estimated risk from these vehicle‐related sources can often be as large or larger than the estimated risk associated with the material being transported. In this paper, data from the U.S. Environmental Protection Agency's Motor Vehicle‐Related Air Toxics Study are first used to develop latent cancer fatality estimates per kilometer of travel in rural and urban areas forall diesel truck classes. These unit risk factors are based on studies investigating the carcinogenic nature of diesel exhaust. With the same methodology, the current per‐kilometer latent fatality risk factor used in transportation risk assessments for heavy diesel trucks in urban areas is revised and the analysis expanded to provide risk factors for rural areas and all diesel truck classes. These latter fatality estimates may include, but are not limited to, cancer fatalities and are based primarily on the most recent epidemiological data available on mortality rates associated with ambient air PM‐10 concentrations.
A Quantitative Analysis of Factors Affecting PELs and TLVs for Carcinogens
Authors: Smith Jeffrey S. , Mendeloff John M.
Published: May 2006

For carcinogens, this paper provides a quantitative examination of the roles of potency and weight‐of‐evidence (WOE) in setting permissible exposure limits (PELs) at the U.S. Occupational Safety and Health Administration (OSHA) and threshold limit values (TLVs) at the private American Conference of Governmental Industrial Hygienists (ACGIH). On normative grounds, both of these factors should influence choices about the acceptable level of exposures. Our major objective is to examine whether and in what ways these factors have been considered by these organizations. A lesser objective is to identify outliers, which might be candidates for further regulatory scrutiny. Our sample (N=48) includes chemicals for which EPA has estimated a unit risk as a measure of carcinogenic potency and for which OSHA or the ACGIH has a PEL or TLV. Different assessments of the strength of the evidence of carcinogenicity were obtained from EPA, ACGIH, and the International Agency for Research on Cancer. We found that potency alone explains 49% of the variation in PELs and 62% of the variation in TLVs. For the ACGIH, WOE plays a much smaller role than potency. TLVs set by the ACGIH since 1989 appear to be stricter than earlier TLVs. We suggest that this change represents evidence that the ACGIH had responded to criticisms leveled at it in the late 1980s for failing to adopt sufficiently protective standards. The models developed here identify 2‐nitropropane, ethylene dibromide, and chromium as having OSHA PELs significantly higher than predicted on the basis of potency and WOE.
Molecular Minerals™: Lyophillic Colloids for Ceramists
Authors: Riman R. E. , Kumar G. A. , Banerjee S. , Brennan J. G.
Published: May 2006

This paper will focus on a novel class of inorganic compounds that we term as molecular minerals™ (MMs). MMs are clusters of ceramic fragments encapsulated with organic ligands. These compounds can be crystallized from solution as molecular single crystals and have well‐defined crystal structures that can be described with X‐ray diffraction methods. Most importantly, the ceramic clusters are perfectly monodisperse, and conventional synthetic techniques can be applied to facilitate control of size and composition. The organic encapsulate imparts solubility in organic solvents and polymers. More importantly, the solubility is thermodynamically driven to form a single‐phase system. Thus, unlike nanoparticles, the stability of clusters in solution is spontaneous rather than kinetically derived. A critical tool for creating MMs is a firm understanding of the fundamental issues governing cluster structure and stability. We have demonstrated a unique synthetic approach to these materials, capable of creating materials with oxo, sulfido, selenido, or tellurido ligands, whose ceramic fragment size can currently be varied from about 0.5 to 2 nm. Both homometallic and heterometallic lanthanide (Ln) complexes incorporating the group 12 metals Zn, Cd, and Hg have been prepared. Relative to prior work on metal organic or organometallic Ln complexes, MMs have unprecedented luminescent properties in terms of emission wavelength, emission intensity, and quantum efficiency. These materials match or exceed the luminescent properties of ceramics, glasses, and nanomaterials, while having the additional advantage of polymer solubility. Solubility facilitates the preparation of transparent molecular mineral nanocomposites that can be fabricated as bulk polymers, fibers, and films.
Longterm visual prognosis in Usher syndrome types 1 and 2
Authors: Sadeghi André M. , Eriksson Kristina , Kimberling William J. , Sjöström Anders , Möller Claes
Published: May 2006

Purpose:  To estimate the age at diagnosis of retinitis pigmentosa and to determine visual acuity deterioration, visual field impairment and the frequency of cataracts in Usher syndrome types 1 and 2.

Methods:  We carried out a retrospective study of 328 affected subjects with Usher syndrome types 1 and 2. Study subjects were divided into seven different age groups by decade. Data were analysed using descriptive statistics, general linear model anova and survival analysis.

Results:  Retinitis pigmentosa was diagnosed significantly earlier in subjects with Usher syndrome type 1 than in those with type 2. Visual acuity was significantly more impaired in affected subjects with Usher syndrome type 1 than in those with type 2 from 50 years of age onwards. Survival analysis revealed a significant difference in visual field loss (≤ 10 degrees) between the two groups, with type 2 subjects tending to be more impaired, while comparison indicated no significant differences between the groups in any of the other visual field categories. Cataract was found to be generally more common in Usher syndrome type 1 than type 2.

Conclusions:  Progressive loss of visual acuity and visual field begins to be substantial between the second and third decades of life in both Usher types. The rate of degeneration varies between individuals in both groups. The data are useful for the counselling of affected subjects with Usher syndrome types 1 and 2.
A meta‐analysis of durability data on conventional fixed bridges
Authors: Creugers Nico H. J. , Käyser Arnd F. , van't Hof Martin A.
Published: May 2006

Abstract A meta‐analysis was performed on the dental literature since 1970, presenting clinical data of conventional bridges. 42 publications were found that contained durability data of conventional fixed bridges. These publications dealt with 33 different samples. According to the exclusion criteria 26 studies were excluded for the meta‐analysis. The data of 4118 conventional bridges were analyzed. The calculated overall survival rate was 74.0 ± 2.1% after 15 yr.
Prediction of the need for bitewing radiography in detecting caries in the primary dentition
Authors: Roeters F. J. M. , Verdonschot E. H. , Bronkhorst E. M. , van't Hof M. A.
Published: May 2006

Abstract In recent literature some controversy has been reported regarding the prescription of bitewing radiography for caries diagnosis, particularly in children. While the low prevalence of caries justified the decision not to take radiographs, it has also been reported that the benefits of detecting slowly progressing, clinically undetectable lesions could outweigh the “costs” of radiography. It was the aim of this study to investigate whether specific risk factors could predict the presence of additional dentinal lesions (ADL) in the primary dentition on radiographs which could not be detected by visual inspection. Bitewing radiographs were taken in 182 children aged 5 yr. Risk factors for ADL were identified and appropriate rating scales were designed. Sensitivities, specificities and relative risks expressing the relation between scale values and ADL were computed for each of the risk factors and direct and stepwise discriminant analyses were performed. The results indicate that particularly the presence of lactobacilli and mutans streptococci in saliva and the detection of three or more discolored enamel lesions or dentinal lesions were good predictors of ADL. It is suggested that these risk factors be used in the timing of bitewing radiography in children with a primary dentition.
Chinese health beliefs and oral health practices among the middle‐aged and the elderly in Hong Kong
Authors: Lim L. P. , Schwarz Eli , Lo Edward C. M.
Published: May 2006

Abstract The purpose of this paper was to study possible relationships between traditional Chinese health beliefs and health practices in adult Chinese in a modernized society. The study populations comprised 398 35–44‐yr‐old and 559 65–74‐yr‐old Hong Kong Chinese. The respondents were categorized into three groups with weak, moderate, or strong Chinese beliefs on the basis of interview questions on the causes of gum disease. Chinese preventive practices and Chinese pain practices were defined according to respondents' reported use of recommended traditional cures. Questions on generally accepted oral practices were phrased in terms of frequency of daily brushing of teeth, use of toothpicks the previous day, and whether or not teeth were flossed the previous day. Around one‐third of the respondents had weak, almost one‐half had moderate, and around one‐quarter expressed strong Chinese health beliefs. No significant differences in Chinese health beliefs were found between men and women in either age group, or between the age groups. In the 35–44 age group, more of those with a higher education were in the “weak” Chinese health belief category, whereas, conversely, more of those with a lower education expressed stronger Chinese health beliefs (P<0.05). Women in both age groups reported significantly more frequent brushing. Toothpicks were used by around three‐quarters of both age groups, but flossing was extremely rare. Chinese preventive practices were reported significantly more frequently by those in the older group who held strong Chinese health beliefs than those with moderate or weak beliefs, whereas the trend in the younger group was not significant. Chinese pain practices were reported very infrequently. Chinese health beliefs did not correlate with use variables. In the older group, Chinese health beliefs correlated strongly with preventive practices and with knowledge.
Periodontal attachment loss among adults aged 60+ in South Australia
Authors: Slade Gary Douglas , Spencer Andrew John
Published: May 2006

Abstract This study aimed to provide oral epidemiological data describing periodontal destruction among older adults in South Australia. A cross‐sectional survey design was employed and periodontal assessments were made among 801 persons aged 60+ drawn at random from the non‐institutionalized population. Measurements of pocket depth (PD) and gingival recession (GR) were made at three sites on all teeth and used to compute loss of attachment (LOA). An average of 17 teeth per person were measured. LOA of 4+mm at one or more sites was observed among 89.1% of persons. A mean of 78.1% of sites per person had LOA of 2 +mm (extent) and the mean LOA at sites with LOA of 2 +mm was 3.09 mm (severity). Extent and severity were greater for males and for persons aged 80+ yr. Extent was virtually identical for mesio‐buccal and disto‐lingual sites, while severity was virtually identical for mid‐buccal and disto‐lingual sites. Patterns of GR and PD varied according to the jaw and type of tooth. Maxillary first and second molars had the greatest mean LOA, and the majority of LOA in the maxilla was due to PD. In the mandible there was less variation in LOA among anterior and posterior teeth, and LOA tended to be more equally divided between GR and PD. Levels of periodontal destruction of South Australia were broadly similar to results from North American studies of older adults which have used full‐mouth periodontal assessments.
Prevalence and severity of dental fluorosis in a Mexican community with above‐optimal fluoride concentration in drinking water
Authors: Irigoyen Maria E. , Molina Nelly , Luengas Isabel
Published: May 2006

Abstract The purpose of this study was to determine the prevalence and severity of dental fluorosis in children living in a community at 2066 m above sea level. The water fluoride concentration of this community was 2.8 ppm. The population selected encompassed 10–12‐yr‐old schoolchildren who were life‐long residents of the area. The modified Dean Index was used to estimate the severity of fluorosis. A total of 93 children participated in the study. They all showed evidence of dental fluorosis. Fifty‐seven percent had moderate fluorosis, and 19% severe fluorosis. The high prevalence and severity of fluorosis in the population examined emphasized the need to study the factors determining denial fluorosis in Mexican communities.
Perception of dental and other individual problems: adolescents versus young adults
Authors: Assink M. H. J. , Verhey J. G. C. , Hoogstraten J. , Goedhart H.
Published: May 2006

Abstract The importance of dental problems in comparison with general health problems and psychological problems was judged by 642 adolescents. The methods used were paired comparison and direct ranking of nine stimuli. Adolescents were quite consistent in their choices. The agreement within the group was statistically significant. Adolescents judged dental problems as less important than general health problems and as more important than psychological problems. The correlation between the methods of paired comparison and direct ranking was high. The results were compared retrospectively with findings from a study of 51 older subjects. Adolescents and adults did not differ much from each other except for the ordering of the nine problems. Adults ranked dental problems as the least important.
Restorative treatment decisions from bitewing radiographs ‐ performance of dental epidemiologists and general dental practitioners
Authors: Downer Martin C. , Kay Elizabeth J.
Published: May 2006

Abstract The object of the study was to compare the performance of a group of eight trained and standardized dental epidemiologists making restorative treatment decisions with that of a group of 20 general dental practitioners. Both groups read the same set of 15 pairs of simulated bitewing radiographs. For each approximal tooth surface image, the examiners were asked to record on a six‐point rating scale the confidence with which they would or would not place a restoration. A histological gold standard was available, based on microscopic evaluation of sections of the extracted teeth used for study. The reference criterion was “caries into dentine”. The only statistically significant differences in performance between the two groups were at the “definitely” plus “probably” restore rating level. For the proportions of correct decisions out of all treatment decisions at this level, the epidemiologists scored 89% compared with 86% for the practitioners (P<0.01) while for Youden's J index, the corresponding values were 0.44 and 0.34 (P<0.05). The findings suggest that the benefits in improved performance from examiner training may be small.
Demand for and utilization of dental services among Hong Kong employees with and without dental benefit coverage
Authors: So Frankie Hon Ching , Schwarz Eli
Published: May 2006

Abstract The objectives of the present study were to investigate the effects of employer‐provided dental benefits on the pattern of demand for and utilization of denial services among Hong Kong employees and to analyse whether employees' awareness about an existing denial benefit programme influenced their denial service demand and utilization. Staff from 11 selected companies with and without dental benefits responded to questionnaires concerning their personal factors, demand for dental services, and utilization of denial services and about their awareness of their dental benefit coverage. Overall response rate was 67%. The socio‐demographic characteristics of those respondents who were covered and those who were not were similar. Forty per cent of the covered respondents were not aware of their dental benefit coverage, so analysis was performed with three groups of respondents, covered and aware, covered and unaware, and uncovered. A larger proportion of employees in the “aware” group had visited a dentist in the previous 12 months and had visited a dentist for asymptomatic reasons. The “aware” group reported more “low expenditure” items and less “high expenditure” items. Those who were aware of their dental benefit coverage irrespective of the type of scheme reported a significantly higher demand than those who were not aware of their coverage. Demand and utilization of the covered, but unaware, group was more similar to the uncovered group than lo the “aware” group. Coverage per se had no apparent effect on the demand for dental services. Further studies will be necessary lo establish that higher dental care demand and utilization induced by third party schemes also leads to improved oral health.