An empirical hierarchical Bayesian unification of occupational exposure assessment methods.

In occupational exposure assessment of airborne contaminants, exposure levels can either be estimated through repeated measurements of the pollutant concentration in air, expert judgment or through exposure models that use information on the conditions of exposure as input. In this report, we propose an empirical hierarchical Bayesian model to unify these approaches. Prior to any measurement, the hygienist conducts an assessment to generate prior distributions of exposure determinants. Monte-Carlo samples from these distributions feed two level-2 models: a physical, two-compartment model, and a non-parametric, neural network model trained with existing exposure data. The outputs of these two models are weighted according to the expert's assessment of their relevance to yield predictive distributions of the long-term geometric mean and geometric standard deviation of the worker's exposure profile (level-1 model). Bayesian inferences are then drawn iteratively from subsequent measurements of worker exposure. Any traditional decision strategy based on a comparison with occupational exposure limits (e.g. mean exposure, exceedance strategies) can then be applied. Data on 82 workers exposed to 18 contaminants in 14 companies were used to validate the model with cross-validation techniques. A user-friendly program running the model is available upon request.

Comparison of indices proposed as criteria for assigning skin notation

OBJECTIVES: Skin notations are used as a hazard identification tool to flag chemicals associated with a potential risk related to transdermal penetration. The transparency and rigorousness of the skin notation assignment process have recently been questioned. We compared different approaches proposed as criteria for these notations as a starting point for improving and systematizing current practice. METHODS: In this study, skin notations, dermal acute lethal dose 50 in mammals (LD(50)s) and two dermal risk indices derived from previously published work were compared using the lists of Swiss maximum allowable concentrations (MACs) and threshold limit values (TLVs) from the American Conference of Governmental Industrial Hygienists (ACGIH). The indices were both based on quantitative structure-activity relationship (QSAR) estimation of transdermal fluxes. One index compared the cumulative dose received through skin given specific exposure surface and duration to that received through lungs following inhalation 8 h at the MAC or TLV. The other index estimated the blood level increase caused by adding skin exposure to the inhalation route at kinetic steady state. Dermal-to-other route ratios of LD(50) were calculated as secondary indices of dermal penetrability. RESULTS: The working data set included 364 substances. Depending on the subdataset, agreement between the Swiss and ACGIH skin notations varied between 82 and 87%. Chemicals with a skin notation were more likely to have higher dermal risk indices and lower dermal LD(50) than chemicals without a notation (probabilities between 60 and 70%). The risk indices, based on cumulative dose and kinetic steady state, respectively, appeared proportional up to a constant independent of chemical-specific properties. They agreed well with dermal LD(50)s (Spearman correlation coefficients -0.42 to -0.43). Dermal-to-other routes LD(50) ratios were moderately associated with QSAR-based transdermal fluxes (Spearman correlation coefficients -0.2 to -0.3). CONCLUSIONS: The plausible but variable relationship between current skin notations and the different approaches tested confirm the need to improve current skin notations. QSAR-based risk indices and dermal toxicity data might be successfully integrated in a systematic alternative to current skin notations for detecting chemicals associated with potential dermal risk in the workplace. [Authors]

Le partage du savoir dans les arts du soin : mélanges en l'honneur de Marco Vannotti

La circularité relationnelle du savoir-être : l'enseignement post-grade selon une perspective systémique / Marco Vannotti - La passion de transmettre : une lecture platonicienne en hommage à M. Vannotti / Michèle Gennart - «Apprendre à coopérer pour apprendre» : la construction des échanges coopératifs / Olivier Real del Sarte - Apprendre à traiter les enfants battus : la transformation de l'intervenant / Stefano Cirillo - Fin de thérapie / Ferenc Rakoczy - La transmission du savoir psychiatrique à la Policlinique Médicale Universitaire : les liaisons dangereuses / Christian Marin - Entre transmission et acquisition des savoirs : le poids de la parole / Brikela Sulstarova - La volonté de faire sens en médecine : clinique, intersubjectivité, et reconnaissance / Francesco Panese - Médecine et rationalité / Jean Starobinski

Exposure models in Switzerland: an overview of the present situation

A survey was undertaken among Swiss occupational health and safety specialists in 2004 to identify uses, difficulties, and possible developments of exposure models. Occupational hygienists (121), occupational physicians (169), and safety specialists (95) were surveyed with an in depth questionnaire. Results obtained indicate that models are not used very much in practice in Switzerland and are reserved to research groups focusing on specific topics. However, various determinants of exposure are often considered important by professionals (emission rate, work activity), and in some cases recorded and used (room parameters, operator activity). These parameters cannot be directly included in present models. Nevertheless, more than half of the occupational hygienists think that it is important to develop quantitative exposure models. Looking at research institutions, there is, however, a big interest in the use of models to solve problems which are difficult to address with direct measurements; i. e. retrospective exposure assessment for specific clinical cases and prospective evaluation for new situations or estimation of the effect of selected parameters. In a recent study about cases of acutepulmonary toxicity following water proofing spray exposure, exposure models have been used to reconstruct exposure of a group of patients. Finally, in the context of exposure prediction, it is also important to report about a measurement database existing in Switzerland since 1991. [Authors]

A randomized controlled trial of the effectiveness of a Computer-Assisted Cognitive Remediation (CACR) program in adolescents with psychosis or at high risk of psychosis: Short term and long term outcomes

The present study investigates the short- and long-term outcomes of a computer-assisted cognitive remediation (CACR) program in adolescents with psychosis or at high risk. 32 adolescents participated in a blinded 8-week randomized controlled trial of CACR treatment compared to computer games (CG). Clinical and neuropsychological evaluations were undertaken at baseline, at the end of the program and at 6-month. At the end of the program (n = 28), results indicated that visuospatial abilities (Repeatable Battery for the Assessment of Neuropsychological Status, RBANS; P = .005) improved signifi cantly more in the CACR group compared to the CG group. Furthermore, other cognitive functions (RBANS), psychotic symptoms (Positive and Negative Symptom Scale) and psychosocial functioning (Social and Occupational Functioning Assessment Scale) improved signifi cantly, but at similar rates, in the two groups. At long term (n = 22), cognitive abilities did not demonstrated any amelioration in the control group while, in the CACR group, signifi cant long-term improvements in inhibition (Stroop; P = .040) and reasoning (Block Design Test; P = .005) were observed. In addition, symptom severity (Clinical Global Improvement) decreased signifi cantly in the control group (P = .046) and marginally in the CACR group (P = .088). To sum up, CACR can be successfully administered in this population. CACR proved to be effective over and above CG for the most intensively trained cognitive ability. Finally, on the long-term, enhanced reasoning and inhibition abilities, which are necessary to execute higher-order goals or to adapt behavior to the ever-changing environment, were observed in adolescents benefi ting from a CACR.