A Bayesian Model and Stochastic Exposure (Dose) Estimation for Relative Exposure Risk Comparison Involving Asbestos‐Containing Dropped Ceiling Panel Installation and Maintenance Tasks

Assessing exposures to hazards in order to characterize risk is at the core of occupational hygiene. Our study examined dropped ceiling systems commonly used in schools and commercial buildings and lay‐in ceiling panels that may have contained asbestos prior to the mid to late 1970s. However, most ceiling panels and tiles do not contain asbestos. Since asbestos risk relates to dose, we estimated the distribution of eight‐hour TWA concentrations and one‐year exposures (a one‐year dose equivalent) to asbestos fibers (asbestos f/cc‐years) for five groups of workers who may encounter dropped ceilings: specialists, generalists, maintenance workers, nonprofessional do‐it‐yourself (DIY) persons, and other tradespersons who are bystanders to ceiling work. Concentration data (asbestos f/cc) were obtained through two exposure assessment studies in the field and one chamber study. Bayesian and stochastic models were applied to estimate distributions of eight‐hour TWAs and annual exposures (dose). The eight‐hour TWAs for all work categories were below current and historic occupational exposure limits (OELs). Exposures to asbestos fibers from dropped ceiling work would be categorized as “highly controlled” for maintenance workers and “well controlled” for remaining work categories, according to the American Industrial Hygiene Association exposure control rating system. Annual exposures (dose) were found to be greatest for specialists, followed by maintenance workers, generalists, bystanders, and DIY. On a comparative basis, modeled dose and thus risk from dropped ceilings for all work categories were orders of magnitude lower than published exposures for other sources of banned friable asbestos‐containing building material commonly encountered in construction trades.     

Employment expectations and the costs of migration

This paper analyses the employment and migration expectations and the perceived costs and returns to migration of a group of workers who have recently lost their employment due to the closure of the major employer in a small rural community. A model of migration decision-making is developed and data relating to this are presented. The contingent valuation approach is used to estimate the losses associated with a move away from the area. The results of an attempt to estimate the complete migration model are described. Finally, the likely approach to the issue of migration under these particular circumtances is discussed.     

Community councils as a medium for public participation: a case study in Grampian region

Planning authorities in Scotland are obliged to consult the public before finalising policies and proposals to be included in their development plans. Community councils are intended to operate as ‘the voice of a neighbourhood’ and this paper analyses an attempt by a regional planning authority to use community councils as a vehicle for consulting the public in the preparation of a structure plan for a rural area. The paper concludes that the attempt was unsuccessful because the community councils were not clear about the role they were expected to play; nor were they adequately prepared for their role. The authors believe, however, that the involvement of community councils has potential for promoting greater public participation in the preparation of development plans.     

Psychosocial correlates and depression in Vietnamese adolescents

This paper reports findings on depression in a sample of 38 Vietnamese adolescents. Hierarchical regression analysis was conducted to examine the empirical use of psychosocial variables and stressful life event measures in predicting depression. Self-esteem (Esteem) and SLEs scales were entered in blocks and explained for 68 percent of the total variance in depression (CES-D scale). Esteem accounts for 30 percent of the overall variance. The SLE block contributes another 39 percent above and beyond in the prediction of depression. Death, PTSD, and Peer stress scales were significant predictors (p<.01). The mean CES-D depression score was 16.32 (SD=10.95). A cutoff score of 16 was used to classify those adolescents who were depressed from those who were not depressed (Radloff, 1977).     

Expressing imprecision in probabilistic knowledge

Summary The representation of imprecise knowledge in probabilistic expert systems is investigated. It is argued that Bayesian statistics offers a multitude of models and methods that may be employed to express probabilistic knowledge by first and second order probability distributions. Distributions offer a much richer repertoire to express uncertainty that point probabilities. Special attention is payed to Dirichletian weights of evidence in discrete systems and to predictons and inverse predictions in linear regression. Approximate methods for non-conjugate distributions and for incomplete data are discussed. An important property of imprecision in complex systems is that it explodes rapidly when the conclusions are derived from long chains of premises. Thus, imprecision is a pruning criterion is a pruning criterion in complex knowledge systems. This research was supported by the Fonds zur F?rderung der wissenschftlichen Forschung, Vienna.     

Modelling the management of underground water assets

Central to the activities of any industry is the modernization of its assets. This paper describes the application of statistical methods to the asset management plan of a large water company. A model for the underground assets is given in detail, and the extensive computations required are illustrated. A Bayesian model shows the consequences of various policy options and provides realistic measures of the uncertainty connected with them.     

Testing for space-time clusters of unknown size

The Knox test is widely used in epidemiology to test for infection or contagion, which is indicated by an excess of cases that are close both in space and time. Often, however, the values of the space and time critical parameters that define 'closeness' are unknown. An exact test is proposed for this situation, its computer implementation is described and examples of its use on published data sets are given. Other possible applications of the method adopted here are discussed. This is an example of a test where nuisance parameters are absent under H0, and where the distribution of the test statistic can be found numerically.     

History of sexual abuse and parental alcohol misuse: Risk,outcomes and protective factors in adolescents

This study examined the school performance, suicidal involvement, disordered eating behaviors, pregnancy risk and chemical use of teenagers with a history of sexual abuse or parental alcohol misuse and found that they had higher rates of these adverse outcomes than among a comparison group of teenagers without such background risk factors. Adolescents with dual-risk background reported higher levels of suicide risk, disordered eating, sexual behaviors and chemical abuse than teenagers with only one background risk factor. Among index group members, protective factors against these adverse outcomes included a high degree of religiosity and the ability to discuss problems with family or friends. Risk factors that increased the likelihood of adverse outcomes included depression, perceived substance use in school and worries about family financial security.The first author was supported in the preparation of this article by a grant from the Lois and Samuel Silberman Fund of New York.     

Testing a theoretical model of adolescent sexual behavior among rural families in poverty

This was a study of 357 adolescents, aged 13 to 17 years, who resided in a family receiving AFDC in 10 rural counties in Arkansas. The study had a twofold purpose: 1) to examine what elements of social control, social learning, and strain theories predicted 3 measures of sexual behavior; and 2) to test an integrated theoretical model with 2-stage least squares regression to see if it fit the data on the 3 measures of sex. The measures of sexual behavior were frequency of sexual intercourse in the past year, number of sexual partners in the past year, and number of sexual partners in lifetime. Bivariate analyses revealed that the consistent predictors of the 3 measures of sex were age, gender, attachment to mother, beliefs, parental supervision and punishment, family and friend support, frustration, and use of rationalizations. The theoretical model that fit all measures of sex showed that bonding influences sexual behavior through frustration, and that age, gender and rationalizations directly impact behavior.