bluuebunny/crossref_metadata_2025 huggingface dataset:
Communicating Under Section 112(r) of the Clean Air Act Amendments
Authors: McNulty Patrick J. , Schaller Leon C. , Chinander Karen R.
Published: May 2006

Regulations under Section 112(r) of the 1990 Clean Air Act Amendments require fixed facilities having threshold quantities of materials on the U.S. Environmental Protection Agency's list of regulated substances to disclose to the general public the expected offsite consequences of worst‐case accidental chemical releases. This paper describes the communication practices of small firms in Delaware and New Jersey and the practical problems these facilities might encounter complying with the proposed rule. The paper reports an interesting difference between the apprehension voiced by small firms required to report worst‐case release information and the public's apparent lack of interest in such information. Unlike the difficulty expected by small firms in calculating and communicating worst‐case chemical release information, this paper includes some observations on the ability of large chemical firms to comply with the proposed requirements.
A Pharmacokinetic Study of Occupational and Environmental Benzene Exposure with Regard to Gender
Authors: Brown Elizabeth A. , Shelley Michael L. , Fisher Jeffrey W.
Published: May 2006

Using physiologically‐based pharmacokinetic (PBPK) modeling, occupational, personal, and environmental benzene exposure scenarios are simulated for adult men and women. This research identifies differences in internal exposure due to physiological and biochemical gender differences. Physiological and chemical‐specific model parameters were obtained from other studies reported in the literature and medical texts for the subjects of interest. Women were found to have a higher blood/air partition coefficient and maximum velocity of metabolism for benzene than men (the two most sensitive parameters affecting gender‐specific differences). Additionally, women generally have a higher body fat percentage than men. These factors influence the internal exposure incurred by the subjects and should be considered when conducting a risk assessment. Results demonstrated that physicochemical gender differences result in women metabolizing 23–26% more benzene than men when subject to the same exposure scenario even though benzene blood concentration levels are generally higher in men. These results suggest that women may be at significantly higher risk for certain effects of benzene exposure. Thus, exposure standards based on data from male subjects may not be protective for the female population.
Lognormal Distributions for Total Water Intake and Tap Water Intake by Pregnant and Lactating Women in the United States
Authors: Burmaster David E.
Published: May 2006

Using probability plots and Maximum Likelihood Estimation (MLE), we fit lognormal distributions to data compiled by Ershow et al. for daily intake of total water and tap water by three groups of women (controls, pregnant, and lactating; all between 15–49 years of age) in the United States. We also develop bivariate lognormal distributions for the joint distribution of water ingestion and body weight for these three groups. Overall, we recommend the marginal distributions for water intake as fit by MLE for use in human health risk assessments.
Analysis of Exogenous Components of Mortality Risks
Authors: Blinkin Victor L.
Published: May 2006

A new technique for deriving exogenous components of mortality risks from national vital statistics has been developed. Each observed death rate Dij (where i corresponds to calendar time (year or interval of years) and j denotes the number of corresponding age group) was represented as Dij=Aj+BiCj, and unknown quantities Aj, Bi, and Cj were estimated by a special procedure using the least‐squares principle. The coefficients of variation do not exceed 10%. It is shown that the term Aj can be interpreted as the endogenous and the second term BiCj as the exogenous components of the death rate. The aggregate of endogenous components Aj can be described by a regression function, corresponding to the Gompertz‐Makeham law, A(τ) =γ+β· eατ, where γ, β, and α are constants, τ is age, AττAττAj, and τj, is the value of age τ in jth age group. The coefficients of variation for such a representation does not exceed 4%. An analysis of exogenous risk levels in the Moscow and Russian populations during 1980–1995 shows that since 1992 all components of exogenous risk in the Moscow population had been increasing up to 1994. The greatest contribution to the total level of exogenous risk was lethal diseases, and their death rate was 387 deaths per 100,000 persons in 1994, i.e., 61.9% of all deaths. The dynamics of exogenous mortality risk change during 1990–1994 in the Moscow population and in the Russian population without Moscow had been identical: the risk had been increasing, and its value in the Russian population had been higher than that in the Moscow population.
Testing the Cultural Theory of Risk in France
Authors: Brenot Jean , Bonnefous Sylviane , Marris Claire
Published: May 2006

Cultural Theory, as developed by Mary Douglas, argues that differing risk perceptions can be explained by reference to four distinct cultural biases: hierarchy, egalitarianism, individualism, and fatalism. This paper presents empirical results from a quantitative survey based on a questionnaire devised by Karl Dake to measure these cultural biases. A large representative sample (N = 1022) was used to test this instrument in the French social context. Correlations between cultural biases and perceptions of 20 social and environmental risks were examined. These correlations were very weak, but were statistically significant: cultural biases explained 6%, at most, of the variance in risk perceptions. Standard sociodemographic variables were also weakly related to risk perceptions (especially gender, social class, and education), and cultural biases and sociodemographic variables were themselves inter correlated (especially with age, social class, and political outlook). The authors compare these results with surveys conducted in other countries using the same instrument and conclude that new methods, more qualitative and contextual, still need to be developed to investigate the cultural dimensions of risk perceptions. The paper also discusses relationships between perceptions of personal and residual risk, and between perceived risk and demand for additional safety measures. These three dimensions were generally closely related, but interesting differences were observed for some risk issues.
Estimation of Unit Risk for Coke Oven Emissions
Authors: Moolgavkar Suresh H. , Luebeck E. Georg , Anderson Elizabeth L.
Published: May 2006

In 1984, based on epidemiological data on cohorts of coke oven workers, USEPA estimated a unit risk for lung cancer associated with continuous exposure from birth to 1 pg/m3 of coke oven emissions, of 6.2 × This risk assessment was based on information on the cohorts available through 1966. Follow‐up of these cohorts has now been extended to 1982 and, moreover, individual job histories, which were not available in 1984, have been constructed. In this study, lung cancer mortality in these cohorts of coke oven workers with extended follow‐up was analyzed using standard techniques of survival analysis and a new approach based on the two stage clonal expansion model of carcinogenesis. The latter approach allows the explicit consideration of detailed patterns of exposure of each individual in the cohort. The analyses used the extended follow‐up data through 1982 and the detailed job histories now available. Based on these analyses, the best estimate of unit risk is 1.5 × with 95% confidence interval = 1.2 × 10‐”1.8 X
Profiling the High Hazards Perceivers: An Exploratory Study
Authors: Hellessy Odd , Grønhaug Kjell , Kvitastein Olav
Published: May 2006

This paper raises two questions, i.e., Are some people more prone to perceive hazards than others embedded in the same dangerous working environment?, and—if so—Is it possible to find distinguishing characteristics allowing us to profile this worker segment? A survey study was conducted among catering personnel working on a drilling platform at the continental shelf in the North sea. It was observed that some people more than others perceived hazards in their working environment. By contrasting the extreme groups, i.e., the high and low hazards perceivers it was found that sociodemographics, e.g., gender, marital status, age and working experience possessed no descriptive power. However, the findings revealed that the worker segment prone to perceive high hazards also reported higher degree of burnout, anxiety and depression than did the low hazards perceivers. They (the high hazards perceivers) were also less satisfied with their stay on the platform, and they reported more health problems as well. The findings indicate that hazards perceptions of hazards go beyond mere “cold cognition,” also tapping into negatively feelings and emotional states. Theoretical and practical implications are highlighted.
The Expected Value of Information and the Probability of Surprise
Authors: Hammitt James K. , Shlyakhter Alexander I.
Published: May 2006

Risk assessors attempting to use probabilistic approaches to describe uncertaintyoften find themselves in a data‐sparse situation: available data are only partially relevant to the parameter of interest, so one needs to adjust empirical distributions, use explicit judgmental distributions, or collect new data. In determining whether ornot to collect additional data, whether by measurement or by elicitation of experts, it is useful to consider the expected value of the additional information. The expected value of information depends on the prior distribution used to represent current information; if the prior distribution is too narrow, in many risk‐analytic cases the calculated expected value of information will be biased downward. The well‐documentedtendency toward overconfidence, including the neglect of potential surprise, suggeststhis bias may be substantial. We examine the expected value of information, includingthe role of surprise, test for bias in estimating the expected value of information, and suggest procedures to guard against overconfidence and underestimation of the expected value of information when developing prior distributions and when combining distributions obtained from multiple experts. The methods are illustrated with applications to potential carcinogens in food, commercial energy demand, and global climate change.
Who Lives Near Coke Plants and Oil Refineries? An Exploration of the Environmental Inequity Hypothesis
Authors: Graham John D. , Beaulieu Nancy Dean , Sussman Dana , Sadowitz March , Li Yi‐Ching
Published: May 2006

Facility‐specific information on pollution was obtained for 36 coke plants and 46 oil refineries in the United States and matched with information on populations surrounding these 82 facilities. These data were analyzed to determine whether environmental inequities were present, whether they were more economic or racial in nature, and whether the racial composition of nearby communities has changed significantly since plants began operations. The Census tracts near coke plants have a disproportionate share of poor and nonwhite residents. Multivariate analyses suggest that existing inequities are primarily economic in nature. The findings for oil refineries are not strongly supportive of the environmental inequity hypothesis. Rank ordering of facilities by race, poverty, and pollution produces limited (although not consistent) evidence that the more risky facilities tend to be operating in communities with above‐median proportions of nonwhite residents (near coke plants) and Hispanic residents (near oil refineries). Over time, the racial makeup of many communities near facilities has changed significantly, particularly in the case of coke plants sited in the early 1900s. Further risk‐oriented studies of multiple manufacturing facilities in various industrial sectors of the economy are recommended.
Fishing in Urban New Jersey: Ethnicity Affects Information Sources, Pe ception, and Compliance
Authors: Burger Joanna , Pflugh Kerry Kirk , Lurig Lynette , Von Hagen Leigh Ann , Von Hagen Stanley
Published: May 2006

Recreational and subsistence angling are important aspects of urban culture for much of North America where people are concentrated near the coasts or major rivers. Yet there are fish and shellfish advisories for many estuaries, rivers, and lakes, and these are not always heeded. This paper examines fishing behavior, sources of information, perceptions, and compliance with fishing advisories as a function of ethnicity for people fishing in the Newark Bay Complex of the New York‐New Jersey Harbor. We test the null hypothesis that there were no ethnic differences in sources of information, perceptions of the safety of fish consumption, and compliance with advisories. There were ethnic differences in consumption rates, sources of information about fishing, knowledge about the safety of the fish, awareness of fishing advisories or of the correct advisories, and knowledge about risks for increased cancer and to unborn and young children. In general, the knowledge base was much lower for Hispanics, was intermediate for blacks, and was greatest for whites. When presented with a statement about the potential risks from eating fish, there were no differences in their willingness to stop eating fish or to encourage pregnant women to stop. These results indicate a willingness to comply with advisories regardless of ethnicity, but a vast difference in the base knowledge necessary to make informed risk decisions about the safety of fish and shellfish. Although the overall median income level of the population was in the $25,000‐34,999 income category, for Hispanics it was on the border between $15,OOO‐24,999 and $25,000‐34,999.
Estimating Noncancer Uncertainty Factors: Are Ratios NOAELs Informative?
Authors: Brand Kevin P. , Rhomberg J Lorenz , Evans John S.
Published: May 2006

The prominent role of animal bioassay evidence in environmental regulatory decisions compels a careful characterization of extrapolation uncertainties. In noncancer risk assessment, uncertainty factors are incorporated to account for each of several extrapolations required to convert a bioassay outcome into a putative subthreshold dose for humans. Measures of relative toxicity taken between different dosing regimens, different endpoints, or different species serve as a reference for establishing the uncertainty factors. Ratios of no observed adverse effect levels (NOAELs) have been used for this purpose; statistical summaries of such ratios across sets of chemicals are widely used to guide the setting of uncertainty factors. Given the poor statistical properties of NOAELs, the informativeness of these summary statistics is open to question. To evaluate this, we develop an approach to “calibrate” the ability of NOAEL ratios to reveal true properties of a specified distribution for relative toxicity. A priority of this analysis is to account for dependencies of NOAEL ratios on experimental design and other exogenous factors. Our analysis of NOAEL ratio summary statistics finds (1) that such dependencies are complex and produce pronounced systematic errors and (2) that sampling error associated with typical sample sizes (50 chemicals) is nonnegligible. These uncertainties strongly suggest that NOAEL ratio summary statistics cannot be taken at face value; conclusions based on such ratios reported in well over a dozen published papers should be reconsidered.
Cancer Risk Estimation of Genotoxic Chemicals Based on Target Dose and a Multiplicative Model
Authors: Granpth Fredrik N. , Vaca J Carlos E. , Ehrenberg Lars G. , Törnqvist Margareta Â.
Published: May 2006

A mechanistic model and associated procedures are proposed for cancer risk assessment of genotoxic chemicals. As previously shown for ionizing radiation, a linear multiplicative model was found to be compatible with published experimental data for ethylene oxide, acrylamide, and butadiene. The validity of this model was anticipated in view of the multiplicative interaction of mutation with inherited and acquired growth‐promoting conditions. Concurrent analysis led to rejection of an additive model (i.e. the model commonly applied for cancer risk assessment). A reanalysis of data for radiogenic cancer in mouse, dog and man shows that the relative risk coefficient is approximately the same (0.4 to 0.5 percent per rad) for tumours induced in the three species.

Doses in vivo, defined as the time‐integrated concentrations of ultimate mutagens, expressed in millimol X kg‐1 x h (mMh) are, like radiation doses given in Gy or rad, proportional to frequencies of potentially mutagenic events. The radiation dose equivalents of chemical doses are, calculated by multiplying chemical doses (in mMh) with the relative genotoxic potencies (in rad X mMh‐1) determined in vitro. In this way the relative cancer incidence increments in rats and mice exposed to ethylene oxide were shown to be about 0.4 percent per rad‐equivalent, in agreement with the data for radiogenic cancer.

Our analyses suggest that values of the relative risk coefficients for genotoxic chemicals are independent of species and that relative cancer risks determined in animal tests apply also to humans. If reliable animal test data are not available, cancer risks may be estimated by the relative potency. In both cases exposure dose/target dose relationships, the latter via macromolecule adducts, should be determined.
Use of Environmental Tobacco Smoke Constituents as Markers for Exposure
Authors: LaKind Judy S. , Jenkins Roger A. , Naiman Daniel Q. , Ginevan Michael E. , Graves Carol G. , Tardiff Robert G.
Published: May 2006

The 16‐City Study analyzed for gas‐phase environmental tobacco smoke (ETS) constituents (nicotine, 3‐ethenyl pyridine [3‐EP], and myosmine) and for particulate‐phase constituents (respirable particulate matter [RSP], ultraviolet‐absorbing particulate matter [UVPM], fluorescing particulate matter [FPM], scopoletin, and solanesol). In this second of three articles, we discussthe merits of each constituent as a marker for ETS and report pair‐wise comparisons of the markers. Neither nicotine nor UVPM were good predictors for RSP. However, nicotine and UVPM were good qualitative predictors of each other. Nicotine was correlated with other gas‐phase constituents. Comparisons between UVPM and other particulate‐phase constituents were performed. Its relation with FPM was excellent, with UVPM approximately 11/2 times FPM. The correlation between UVPM and solanesol was good, but the relationship between the two was not linear. The relation between UVPM and scopoletin was not good, largely because of noise in the scopoletin measures around its limit of detection. We considered the relation between nicotine and saliva cotinine, a metabolite of nicotine. The two were highly correlated on the group level. That is, for each cell (smoking home and work, smoking home but nonsmoking work, and so forth), there was high correlation between average cotinine and 24‐hour time‐weighted average (TWA) nicotine concentrations. However, on the individual level, the correlations, although significant, were not biologically meaningful. A consideration of cotinine and nicotine or 3‐EP on a subset of the study whoseonly exposure to ETS was exclusively at work or exclusively at home showed that home exposure was a more important source of ETS than work exposure.
The Power of Perception: Health Risk Attributed to Air Pollution in anUrban Industrial Neighbourhood
Authors: Elliott Susan J. , Cole Donald C. , Krueger Paul , Voorberg Nancy , Wakefield Sarah
Published: May 2006

This paper describes a multi‐stakeholder process designed to assess thepotential health risks associated with adverse air quality in an urban industrial neighborhood. The paper briefly describes the quantitative health risk assessment conducted by scientific experts, with input by a grassroots community group concerned about the impacts of adverse air quality on theirhealth and quality of life. In this case, rather than accept the views of the scientific experts, the community used their powers of perception toadvantage by successfully advocating for a professionally conducted community health survey. This survey was designed to document, systematically and rigorously, the health risk perceptions community members associated with exposure to adverse air quality in their neighborhood. This paper describes theinstitutional and community contexts within which the research is situated as well as the design, administration, analysis, and results of the community health survey administered to 402 households living in an urban industrial neighborhood in Hamilton, Ontario, Canada. These survey results served tolegitimate the community's concerns about air quality and tohelp broaden operational definitions of ‘health.’ In addition, the resultsof both healthrisk assessment exercises served to keep issues of air quality on the localpolitical agenda. Implications of these findings for our understanding of theenvironmental justice process as well as the ability of communitiesto influence environmental health policy are discussed.
A Model of Consumers' Risk Perceptions Toward Recombinant Bovine Growth Hormone (rbGH): The Impact of Risk Characteristics
Authors: Grobe Deana , Douthitt Robin , Zepeda Lydia
Published: May 2006

This study estimates the effect risk characteristics, described as outrage factors by Hadden, have on consumers' risk perceptions toward the food‐related biotechnology, recombinant bovine growth hormone (rbGH). The outrage factors applicable to milk from rbGH treated herds are involuntary risk exposure, unfamiliarity with the product's production process, unnatural product characteristics, lack of trust in regulator's ability to protectconsumers in the marketplace, and consumers' inability to distinguish milkfrom rbGH treated herds compared to milk from untreated herds. An empirical analysis of data from a national survey of household food shoppers reveals that outrage factors mediate risk perceptions. The results support the inclusion of outrage factors into the risk perception model for the rbGH product, as they add significantly to the explanatory power of the model and therefore reduce bias compared to a simpler model of attitudinal and demographic factors. The study indicates that outrage factors which have a significant impact on risk perceptions are the lack of trust in the FDA as afood‐related information source, and perceiving no consumer benefits from farmers' use of rbGH. Communication strategies to reduce consumer risk perceptions therefore could utilize agencies perceived as more trustworthy and emphasize the benefits of rbGH use to consumers.
Challenges to the Acceptance of Probabilistic Risk Analysis
Authors: Bier Vicki M.
Published: May 2006

This paper discusses a number of the key challenges to the acceptance and aplication of probabilistic risk analysis (PRA). Those challenges include:(a) the extensive reliance on subjective judgment in PRA, requiring the development of guidance for the use of PRA in risk‐informed regulation, and possibly the development of “robust” or “reference” prior distributions to minimize the reliance on judgment; and (b) the treatment of human perfor‐mance in PRA, including not only human errorperse but also management and organizational factors more broadly. All of these areas are seen as presentinginteresting research challenges at the interface between engineering and other disciplines.
The Complementary Roles of Mitigation and Insurance in Managing Catastrophic Risks
Authors: Kleindorfer Paul R. , Kunreuther Howard
Published: May 2006

This paper examines the impact that insurance coupled with specific risk mitigation measures (RMMs) could have on reducing losses from hurricanes and earthquakes as well as improving the solvency position of insurers who provide coverage against these hazards. We first explore why relatively fewindividuals adopt cost‐effective RMMs by reporting on the results of empirical studies and controlled laboratory studies. We then investigate the impact that an RMM has on both the expected losses and those from a worst case scenario in two model cities‐Oakland (an earthquake‐prone area) and Miami/Dade County (a hurricane‐prone area) which were constructed respectively with the assistance of two modeling firms. The paper then explores three programs for forging a meaningful public‐private sector partner‐ ship: well‐enforced building codes, insurance premium reductions linked with long‐term loans, and lower deductibles on insurance policies tied to mitigation. We conclude by briefly examining four issues for future research on linking mitigation with insurance.
The Role of Performance Assessment in the Regulation of Underground Disposal of Radioactive Wastes: An International Perspective
Authors: Thompson B. G. J.
Published: May 2006

Much has been written about the development and application of quantitative methods for estimating under uncertainty the long‐term radiological performance of underground disposal of radioactive wastes. Until recently, interest has been focused almost entirely on the technical challenges regardless of the role of the organization responsible for these analyses. Now the dialogue between regulators, the repository developer or operator, and other interested parties in the decision‐making process receives increasing attention, especially in view of some current difficulties in obtaining approvals to construct or operate deep facilities for intermediate or high‐level wastes. Consequently, it is timely to consider the options for regulators’review and evaluation of safety submissions, at the various stages in the site selection to repository closure process, and to consider, especially, the role for performance assessment (PA) within the programs of a regulator both before and after delivery of such a submission. The origins and broad character of present regulations in the European Union (EU) and in the OECD countries are outlined and some regulatory PA reviewed. The issues raised are discussed, especially in regard to the interpretation of regulations, the dangers from the desire for simplicity in argument, the use of regulatory PA to review and challenge the PA in the safety case, and the effects of the relationship between proponent and regulator. Finally, a very limited analysis of the role of PA in public hearings is outlined and recommendations are made, together with proposals for improving the mechanisms for international collaboration on technical issues of regulatory concern.
Total System Performance Assessment for Waste Disposal Using a Logic Tree Approach
Authors: Kessler John H. , McGuire Robin K.
Published: May 2006

The Electric Power Research Institute (EPRI) has sponsored the development of a model to assess the long‐term, overall “performance” of the candidate spent fuel and high‐level radioactive waste (HLW) disposal facility at Yucca Mountain, Nevada. The model simulates the processes that lead to HLW container corrosion, HLW mobilization from the spent fuel, and transport by groundwater, and contaminated groundwater usage by future hypothetical individuals leading to radiation doses to those individuals. The model must incorporate a multitude of complex, coupled processes across a variety of technical disciplines. Furthermore, because of the very long time frames involved in the modeling effort (>104 years), the relative lack of directly applicable data, and many uncertainties and variabilities in those data, a probabilistic approach to model development was necessary. The developers of the model chose a logic tree approach to represent uncertainties in both conceptual models and model parameter values. The developers felt the logic tree approach was the most appropriate. This paper discusses the value and use of logic trees applied to assessing the uncertainties in HLW disposal, the components of the model, and a few of the results of that model. The paper concludes with a comparison of logic trees and Monte Carlo approaches.
Conditional Uncertainty Analysis and Implications for Decision Making: The Case of WIPP
Authors: Paté‐Cornell M. Elisabeth
Published: May 2006

Uncertainty analyses and the reporting of their results can be misinterpreted when these analyses are conditional on a set of assumptions generally intended to bring some conservatism in the decisions. In this paper, two cases of conditional uncertainty analysis are examined. The first case includes studies that result, for instance, in a family of risk curves representing percentiles of the probability distribution of the future frequency of exceeding specified consequence levels conditional on a set of hypotheses. The second case involves analyses that result in an interval of outcomes estimated on the basis of conservative assumptions. Both types of results are difficult to use because they are sometimes misinterpreted as if they represented the output of a full uncertainty analysis. In the first case, the percentiles shown on each risk curve may be taken at face value when in reality (in marginal terms) they are lower if the chosen hypotheses are conservative. In the second case, the fact that some segments of the resulting interval are highly unlikely‐or that some more benign segments outside the range of results are quite possible‐does not appear. Also, these results are difficult to compare to those of analyses of other risks, possibly competing for the same risk management resources, and the decision criteria have to be adapted to the conservatism of the hypotheses. In this paper, the focus is on the first type (conditional risk curves) more than on the second and the discussion is illustrated by the case of the performance assessment of the Waste Isolation Pilot Plant in New Mexico. For policy‐making purposes, however, the problems of interpretation, comparison, and use of the results are similar.
Resolution of the Long‐Term Performance Issues at the Waste Isolation Pilot Plant
Authors: Silva Matthew K. , Rucker Dale F. , Chaturvedi Lokesh
Published: May 2006

The Waste Isolation Pilot Plant (WIPP) is a geological repository for disposal ofU.S. defense transuranic radioactive waste. Built and operated by the U.S. Departmentof Energy (DOE), it is located in the Permian age salt beds in southeastern New Mexico at a depth of 655 m. Performance assessment for the repository's compliance with the 10,000‐year containment standards was completed in 1996 and the U.S. Environmental Protection Agency (EPA) certified in 1998 that the repository meets compliance with the EPA standards 40 CFR 191 and 40 CFR 194. The Environmental Evaluation Group (EEG) review of the DOE'S application for certification identified a number of issues. These related to the scenarios, conceptual models, and values of the input parameters used in the calculations. It is expected that these issues will be addressed and resolved during the first 5‐year recertification process that began with the first receipt of waste at WIPP on March 26, 1999, and scheduled to be completed in March 2004.
Risk Perception in Context: The Savannah River Site Stakeholder Study
Authors: Williams Bryan L. , Brown Sylvia , Greenberg Michael , Kahn Mokbul A.
Published: May 2006

Environmental managers are increasingly charged with involving the public in the development and modification of policies regarding risks to huma health and the environment. Involving the public in environmental decision making first requires a broad understanding of how and why the public perceives various risks. The Savannah River Stakeholder Study was conducted withthe purpose of investigating individual, economic, and social characteristics of risk perceptions among those living near the Savannah River Nuclear Weapons Site. A number of factors were found to impact risk perceptions among those living near the site. One's estimated proximity to the site and relative river location surfaced as strong determinants of risk perceptions among SRS residents. Additionally, living in a quality neighborhood and demonstrating a willingness to accept health risks for economic gain strongly abated heightened risk perceptions.
Quantifying Uncertainty in a Risk Assessment Using Human Data
Authors: Fayerweather William E. , Collins James J. , Schnatter A. Robert , Hearne F. Terry , Menning Reo A. , Reynefr Daniel P.
Published: May 2006

A call for risk assessment approaches that better characterize and quantify uncertainty has been made by the scientific and regulatory community. This paper responds to that call by demonstrating a distributional approachthat draws upon human data to derive potency estimates and to identify and quantify important sources of uncertainty. The approach is rooted in the science of decision analysis and employs an influence diagram, a decision tree, probabilistic weights, and a distribution of point estimates of carcinogenic potency. Its results estimate the likelihood of different carcinogenicrisks (potencies) for a chemical under a specific scenario. For this exercise, human data on formaldehyde were employed to demonstrate the approach. Sensitivity analyses were performed to determine the relative impact of specific levels and alternatives on the potency distribution. The resulting potency estimates are compared with the results of an exercise using animal data on formaldehyde. The paper demonstrates that distributional risk assessment is readily adapted to situations in which epidemiologic data serve as the basis for potency estimates. Strengths and weaknesses of the distributional approach are discussed. Areas for further application and research are recommended.
Cancer Dose‐Response Modeling of Epidemiological Data on Worker Exposures to Aldrin and Dieldrin
Authors: Sielken Robert L. , Bretzlaff Robert S. , Valdez‐Flores Ciriaco , Stevenson Donald E. , de Jong Geed
Published: May 2006

The paper applies classical statistical principles to yield new tools for risk assessment and makes new use of epidemiological data for human riskassessment. An extensive clinical and epidemiological study of workers engaged in the manufacturing and formulation of aldrin and dieldrin provides occupational hygiene and biological monitoring data on individual exposures over the years of employment and provides unusually accurate measures of individual lifetime average daily doses. In the cancer dose‐response modeling, each worker is treated as a separate experimental unit with his own unique dose. Maximum likelihood estimates of added cancer risk are calculated for multistage, multistage‐Weibull, and proportional hazards models. Distributional characterizations of added cancer risk are based on bootstrap and relative likelihood techniques. The cancer mortality data on these male workerssuggest that low‐dose exposures to aldrin and dieldrin do not significantlyincrease human cancer risk and may even decrease the human hazard rate for all types of cancer combined at low doses (e.g., 1μg/kg/day). The apparent hormetic effect in the best fitting dose‐response models for this data set is statistically significant. The decrease in cancer risk at low doses ofaldrin and dleldrin is in sharp contrast to the U.S. Environmental Protection Agency's upper bound on cancer potency based on mouse liver tumors. The EPA's upper bound implies that lifetime average daily doses of 0.0000625 and 0.00625 pμg/kg body weight/day would correspond to increased cancer risks of 0.000001 and O.OOO1, respectively. However, the best estimate from the Pernis epidemiological data is that there is no increase in cancer risk in these workers at these doses or even at doses as large as 2 μg/kg/day.
Parameter Uncertainty and Variability In Evaluative Fate and Exposure Models
Authors: Hertwich Edgar G. , McKone Thomas E. , Pease William S.
Published: May 2006

The human toxicity potential, a weighting scheme used to evaluate toxicemissions for life cycle assessment and toxics release inventories, is based on potential dose calculations and toxicity factors. This paper evaluatesthe variance in potential dose calculations that can be attributed to the uncertainty in chemical‐specific input parameters as well as the variabilit in exposure factors and landscape parameters. A knowledge of the uncertainty allows us to assess the robustness of a decision based on the toxicity potential; a knowledge of the sources of uncertainty allows us to focus our resources if we want to reduce the uncertainty. The potential dose of 236 chemicals was assessed. The chemicals were grouped by dominant exposure route, and a Monte Carlo analysis was conducted for one representative chemical in each group. The variance is typically one to two orders of magnitude. For comparison, the point estimates in potential dose for 236 chemicals span ten orders of magnitude. Most of the variance in the potential dose is due to chemical‐specific input parameters, especially half‐lives, although exposure factors such as fish intake and the source of drinking water can be important for chemicals whose dominant exposure is through indirect routes. Landscape characteristics are generally of minor importance.
On Modeling Correlated Random Variables in Risk Assessment
Authors: Haas Charles N.
Published: May 2006

Monte Carlo methods in risk assessment are finding increasingly widespread application. With the recognition that inputs may be correlated, the incorporation of such correlations into the simulation has become important. Most implementations rely upon the method of Iman and Conover for generating correlated random variables. In this work, alternative methods using copulas are presented for deriving correlated random variables. It is further shown that the particular algorithm or assumption used may have a substantial effect on the output results, due to differences in higher order bivariate moments.
Mossin's Theorem for Upper‐Limit Insurance Policies
Authors: Schlesinger Harris
Published: May 2006

Abstract

Although Mossin's Theorem (“full insurance with a fair premium and less‐than‐full coverage with a proportional premium loading”) is well known for the classes of coinsurance contracts and for deductible‐insurance contracts, it has not been proven for the class of upper‐limit insurance contracts. This article provides a proof for this case.
Ink Jet Printing of Microdot Arrays of Mesostructured Silica
Authors: Mougenot M. , Lejeune M. , Baumard J. F. , Boissiere C. , Ribot F. , Grosso D. , Sanchez C. , Noguera R.
Published: May 2006

We report a process for preparing microdot arrays of SiO2 from a tetraethoxysilane precursor containing either a cationic (CTAB) or non‐ionic surfactant. Controlling the ink jet deposition parameters and precursor hydrolysis made it possible to obtain mesoporous silica with a Pm3n cubic structure, using CTAB, or an Fmmm orthorhombic structure, using a non‐ionic surfactant. The addition of hydrophobic organosilane F3C(CF2)5CH2CH2Si(OC2H5)3 leads to the most regular and best‐defined three‐dimensional microdot array with a constant diameter of 155 μm and a regular space of 250 μm.
Use of dental hygienists and returns to scale in child dental care in Norway
Authors: Wang Nina J.
Published: May 2006

Abstract The purpose of this study was to investigate, in the provision of dental care for children, technically and economically efficient combinations of dentists and dental hygienists and to study returns to scale by analyzing production functions. Data from 137 dental health clinics were analyzed. Output was registered as the number of 3–18‐yr‐old children to whom the clinic delivered complete dental care. Resource input was registered as hours spent by dentists, denial hygienists and dental assistants to deliver care to the children. The average clinic that employed dental hygienists used one hygienist hour per three dentist hours for child dental care. It would save dentist time, but not costs, to extend the use of hygienists. Increased use of dental hygienists might be economically efficient if the work distribution between the personnel groups were changed, for example, by delegating more examinations and preventive care to hygienists. There were technical opportunities for further substitution of dental hygienists for dentists both by introducing dental hygienists in the clinics that only used dentists in child dental care and by extending use of hygienists in clinics that already employed hygienists. This study found no productivity gain from centralizing treatment of children in large dental clinics.
Subjectively reported oral health status in an adult population
Authors: Locker David , Miller Yasmin
Published: May 2006

Abstract This study describes the subjectively reported oral health status of an adult population aged 18 yr and over. The study used measures of the functional, social and psychological impact of oral disorders, originally developed for surveys of older adults, and aimed to determine whether or not they were sensitive to the oral health concerns of younger adults. It compared four age groups (18–29 yr: 30–49 yr: 50–64 yr: 65 yr and over) in terms of the following subjective oral health indicators: ability to chew, problems speaking, oral and facial pain: other oral symptoms: problems eating: problems with communication‐social relations; limitations in activities of daily living and worry and concern. The initial hypothesis that few younger subjects would report the kinds of problems documented by these indicators was not supported. On all measures except ability to chew, younger subjects were as likely to be compromised by oral conditions as older subjects.
Tooth spaces in and prosthetic treatment received by the middle‐aged and the elderly in Hong Kong
Authors: Corbet Esmonde F. , Lo Edward C. M.
Published: May 2006

Abstract The purpose of this study was to describe the state of the dentition of middle‐aged and elderly Chinese in Hong Kong in terms of teeth present, tooth spaces, and prosthetic treatment received. In an oral health survey conducted in 1991 in Hong Kong, a sample of 372 35–44‐yr‐olds and 537 noninstitutionalized 65–74‐yr‐olds was interviewed and clinically examined. In all dentate subjects, each tooth was scored for the presence/absence of that tooth, a tooth space of 5.5 mm which had not been treated, or the presence of a denture or pontic replacing that tooth. Each denture was assessed according to a set of criteria. None of the 35–44‐yr‐olds were edentulous and the mean number of teeth present was 27.5. About 40% of the third molars and about 35% of the mandibular first molars were missing. For only 1% of the missing teeth had space closure resulted in missing teeth not being recorded as tooth spaces or treated tooth spaces. Overall, 72% of the 35–44‐yr‐olds had no prosthesis. 17% had a bridge or bridges, 12% had a denture or dentures, and 1% had both. Of the 65–74‐yr‐olds, 12% were edentulous, and the dentate subjects had a mean number of 17 teeth present. About 70% of the molars were missing. Overall, only 29% of the elderly had no prosthesis, 52% had a denture or dentures, 33% had a bridge or bridges, and 13% had both. Only 35% and 28%, respectively, of the middle‐aged and elderly denture wearers had no complaint about their dentures. There were more assessed problems in the dentures of the elderly than in those of the younger adults, over one‐third of the partial dentures and half of the mandibular complete dentures being unstable and unretentive.
Oral health care needs among the middle‐aged and the elderly in Hong Kong
Authors: Lo Edward C. M. , Corbet Esmonde F. , Holmgren Christopher J.
Published: May 2006

Abstract A sample of 372 35–44‐yr‐olds and 537 noninstitutionalized 65–74‐yr‐olds were clinically examined in an oral health survey of Hong Kong Chinese conducted in 1991. The examination procedures and diagnostic criteria for assessing restorative and extraction treatment need followed those recommended by the World Health Organization. The Community Periodontal Index‐based periodontal treatment needs involving index teeth or their replacements were computed from separate clinic scores for maximum probing depth, presence of calculus, and bleeding after probing. A set of criteria for assessing prosthodontic treatment need was specially laid down for this survey. Examiners were calibrated before the survey, and the interexaminer reliability was found to be generally good. Besides reporting the various individual normative treatment need items in the traditional way, the present analysis used some holistic treatment‐need categories which may have manpower‐requirement implications for the classification of subjects. All dentate subjects surveyed required some treatment. Only 6% of the elderly, all edentulous, required denture work only. Of the 35–44‐yr‐olds, 42% needed scaling and oral hygiene instruction only, which could be provided by dental hygienists. The treatment needs of the vast majority of the middle‐aged and the elderly (mainly scaling; simple fillings; and extractions, dentures, or both) could be easily handled by general dentists. Only about one‐fifth of the subjects in both age groups required some complex care such as endodontics, crowns, and advanced periodontal treatment, which could be delivered by senior dentists or dentists with specialist training.
Evaluation of aesthetics for the different classifications of the Tooth Surface Index of Fluorosis
Authors: Clark D. Christopher
Published: May 2006

Abstract The prevalence of dental fluorosis for children both from fluoridated and non‐fluoridated communities has increased dramatically in some regions of North America. This study evaluated the aesthetics of dental fluorosis for school‐aged children from a reference population of 1131 children. The methodology from the Social Acceptability Scale of Occlusal Conditions (SASOC), part of the Dental Aesthetics Index (DAI), was used to assess fluorosis‐related aesthetics. Pairs of semantic differentiated adjectives adapted from SASOC were used to rate fifty 35 mm slides of anterior teeth. Sampling of children from the different categories of the Tooth Surface Index of Fluorosis (TSIF) on anterior permanent teeth was weighted to permit sufficient numbers of slides for the different classifications of the TSIF. Each slide was presented to a stratified random sample of pairs of parents and children who were participants in the original study. A convenience sample of dental professionals was also included. Analysis compared different classifications of “affected” slides (non‐zero TSIF scores), with the mean aesthetic score computed from all “non‐affected” slides (TSIF=0). Results from children, parents, and professionals showed that there were highly significant differences between ratings of low and high TSIF scores. The only non‐significant differences were between TSIF 4 and TSIF 5 & 6, which all three groups did not distinguish, as well as TSIF 1 versus TSIF 2 & 3, which children could not distinguish.