Arterial blood gases--from content to pressures.
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Biomedical subjects
Publications and source records attributed to M J Small.
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Home improvement is a popular activity, but one that can also involve exposure to hazardous substances. Paint stripping is of particular concern because of the high potential exposures to methylene chloride, a solvent that is a potential human carcinogen and neurotoxicant. This article presents a general methodology for evaluating the effectiveness of behavioral interventions for reducing these risks. It doubles as a model that assesses exposure patterns, incorporating user time-activity patterns and risk-mitigation strategies. The model draws upon recent innovations in indoor air-quality modeling to estimate exposure through inhalation and dermal pathways to paint-stripper users. It is designed to use data gathered from home paint-stripper users about room characteristics, amount of stripper used, time-activity patterns and exposure-reduction strategies (e.g., increased ventilation and modification in the timing of stripper application, scraping, and breaks). Results indicate that the effectiveness of behavioral interventions depends strongly on characteristics of the room (e.g., size, number and size of doors and windows, base air-exchange rates). The greatest simple reduction in exposure is achieved by using an exhaust fan in addition to opening windows and doors. These results can help identify the most important information for product labels and other risk-communication materials.
Modeling of the uncertainty of multiple input variables for a complex decision problem complicates sensitivity analysis. A method of analysis comprising stochastic simulation of the model and logistic regression of the simulated dichotomous decision variable against all of the input variables yields a direct measure of the importance of input variables to the decision. This method is demonstrated on a previously analyzed clinical decision either to continue observation or to immediately treat with anticoagulants a woman presenting with deep vein thrombosis in the first trimester of pregnancy. A relative measure of the importance of each input variable in causing a change of decision is estimated by calculating the change in the log odds attributable to variation of each input variable over its range of uncertain values compared with the total change of log odds from variation of all input variables. This method is compared with alternative measures of input variable importance, and is found to be a simple yet powerful tool for gaining quantitative insight into the nuances of a decision model.
The volatilization of volatile organic chemicals during domestic water usage can result in significant indoor air concentrations, and the subsequent inhalation of these contaminants is an important route of exposure. The magnitude of these exposures is highly dependent on the activities undertaken by the exposed individual, as well as the activities of other occupants of the home. The indoor air quality-exposure Model for the Analysis of Volatiles and Residential Indoor Air Quality (MARVIQ) was used to ascertain the impact of water-use activities on the potential contaminant dose to household members. Human time-activity patterns of various population groups were sampled from the California Air Resources Board database, applying distributions of water-use occurrence and water-use duration to each activity based on survey results. Indoor air concentrations in a sample house and the resulting potential inhalation dose to the occupants were computed for different individuals and pairs of individuals to test for exposure and coexposure effects. The simulated daily exposure is well described by a simplified equation that is a function of the amount of time the individual spends in the shower, the bath, and the bathroom; the total water usage in the home; and the fraction of time the individual is at home. These results can be used to identify high-risk populations, individuals, and households. The study also demonstrates the importance of further research on joint time-activity patterns in multiperson households for assessment of exposure and coexposure effects.
Behavioral experiments were performed on 342 subjects to determine whether behavior, which could affect the level of personal exposure, is exhibited in response to odors and labels which are commonly used for household chemicals. Potential for exposure was assessed by having subjects perform cleaning tasks presented as a product preference test, and noting the amount of cleaning product used, the time taken to complete the cleaning task, the product preference, and the exhibition of avoidance behavior. Product odor was found to affect product preference in the study with the pleasant odored product being preferred to the neutral and unpleasant products. Product odor was also found to influence the amount of product used; less of the odored products was used compared to the neutral product. The experiment also found that very few of the subjects in the study read the product labels, precluding analysis of the effect of such labels on product use. A postexperiment questionnaire on household cleaning product purchasing and use was administered to participants. The results indicate that significant gender differences exist. Women in the sample reported more frequent purchase and use of cleaning products resulting in an estimated potential exposure 40% greater than for the men in the sample. This finding is somewhat countered by the fact that women more frequently reported exposure avoidance behavior, such as using gloves. Additional significant gender differences were found in the stated importance of product qualities, such as odor and environmental quality. This study suggests the need for further research, in a more realistic use setting, on the impact of public education, labels, and product odor on preference, use, and exposure for different types of consumer products.