Usefulness of overnight pulse oximeter as the sleep assessment tool to assess the 6-year risk of road traffic collision: evidence from the Taiwan Bus Driver Cohort Study.

Background: In order to support health service organizations in arranging a system for prevention of road traffic collisions (RTC), it is important to study the usefulness of sleep assessment tools. A cohort study was used to evaluate the effectiveness of subjective and objective sleep assessment tools to assess for the 6-year risk of both first RTC event only and recurrent RTC events. Methods: The Taiwan Bus Driver Cohort Study (TBDCS) recruited 1650 professional drivers from a large bus company in Taiwan in 2005. The subjects were interviewed in person, completed the sleep assessment questionnaires and had an overnight pulse oximeter survey. Moreover, this cohort of drivers was linked to the National Traffic Accident Database (NTAD) and researchers found 139 new RTC events from 2005 to 2010. Primary outcomes were traffic collisions from NTAD, nocturnal oxygen desaturation index (ODI) from pulse oximeter, Pittsburg sleeping quality score, Epworth daytime sleepiness score, Snore Outcomes Survey score and working patterns from questionnaires. A Cox proportional hazards model and an extended Cox regression model for repeated events were performed to estimate the hazard ratio for RTC. Results: The RTC drivers had increased ODI4 levels (5.77 ± 4.72 vs 4.99 ± 6.68 events/h; P = 0.008) and ODI3 levels (8.68 ± 6.79 vs 7.42 ± 7.94 events/h; P = 0.007) in comparison with non-RTC drivers. These results were consistent regardless of whether ODI was evaluated as a continuous or a categorical variable. ODI4 and ODI3 levels increased the 6-year RTC risks among professional drivers even after adjusting for age, education, history of cardiovascular disease, caffeine intake, sleeping pills used, bus driving experience and shift modes. Moreover, there was an increased trend for ODI between the stratification of the number of RTCs in comparison with the non-RTC group. In the extended Cox regression models for repeated RTC events with the Anderson and Gill intensity model and Prentice-Williams-Petersen model, measurement of ODI increased hazards of the subsequent RTC events. Conclusion: This study showed that an increase in the 6-year risk of RTC was associated with objective measurement of ODI for a sign of sleep-disordered breathing (SDB), but was not associated with self-reported sleeping quality or daytime sleepiness. Therefore, the overnight pulse oximeter is an effective sleep assessment tool for assessing the risk of RTC. Further research should be conducted regarding measures to prevent against SDB among professional drivers.

Obstructive sleep apnea rather than diabetes or obesity associated with proteinuria in late mid-aged male workers: a decision tree analysis.

BACKGROUND: Both proteinuria and obstructive sleep apnea (OSA) are associated with cardiovascular events and consequent mortality. To examine whether age, OSA, diabetes, and obesity are potential predictors of proteinuria, a data-driven analysis was performed to delineate a potential categorical classification algorithm. METHODS: In this cross-sectional community-based cohort study, demographic data, blood pressure, serum biochemical analyses, proteinuria via single dipstick urinalysis, and overnight polysomnographies were measured in 300 males with sedentary work styles. RESULTS: Sixty-one (20.3 %) of all these participants had proteinuria. Logistic regression analysis showed that glycated hemoglobin (HbA1c), duration of arterial oxygen saturation <90 %, age, and log high-sensitivity C-reactive protein, but not apnea-hypopnea index (AHI), were responsible for 16.7 % of the variance of proteinuria's presence. A decision tree analysis showed that subjects over 49 years old had a higher risk for proteinuria than those subjects of 49 years old, or less. In the over 49-year-old group, subjects with an AHI >21 events/h had a higher risk for proteinuria; whereas in the 49-year-old and less group, subjects with HbA1c >7 %, or with HbA1c ≤7, and body mass index (BMI) >27.4 kg/m(2) had a higher risk for proteinuria than their counterparts. CONCLUSIONS: AHI was the major determinant responsible for the presence of proteinuria in late mid-aged male workers, while HbA1c and BMI were found in the junior subgroup. By algorithmic analysis, this study provides a comprehensive hierarchical model for better understanding of the correlates of proteinuria and sleep apnea.

Time location analysis for exposure assessment studies of indoor workers based on active RFID technology.

In this article, we describe the development of a radio frequency identification exposure monitoring system (RFEMS) suitable for tracking and identifying workers' locations in indoor workplaces. Five workers in southern Taiwan wore the RFEMS integrated into their equipment vests. Location and exposure data were transferred to data analysis software for visualization and tabular analysis in real-time. Data were grouped into seven task activity location categories to determine the time spent and percentage reception in each location. The RFEMS could also synchronously indicate the surrounding conditions using various sensors. Additional experiments were focused on locating of boundaries and determining the instrument stability, power sustainability, and reception efficiency in typical environments. The RFEMS instruments provided adequate range for locating (typically ca. 6-45 m in each zone), allowing us to locate subjects within distinct microenvironments and to distinguish between the activities of a variety of workers, the average time activity pattern (TAP) recording deviation for both human observations and RFEMS was ca. 0.21-1.57%. Power consumption experiments revealed that the system could be sustained for more than 124 h. A pilot field test indicated that the RFEMS offers a new level of accuracy for direct quantification of time activity patterns in exposure assessments of indoor workers over long periods of time.

Assessment of airborne and dermal exposure to 2-ethoxyethyl acetate in an occupational environment.

BACKGROUND: Because of its chemical-physical properties, 2-ethoxyethyl acetate (EEAc) can penetrate through the skin. However, no actual occupational environmental studies or empirical dermal exposure measurements have been performed. METHODS: Twenty workers from a commercial label silk screening shop were recruited and they completed a questionnaire of demographic information. Environmental monitoring of EEAc exposure via respiratory and dermal routes was performed for five consecutive working days. RESULTS: Airborne EEAc concentration was over the permissible exposure limit of 5 ppm in 90% of the participants. The dermal EEAc concentration was highest on the palms. The EEAc concentration correlated with skin exposure level (P < 0.001). The dermal EEAc concentrations in individuals who did not wear gloves were higher than in those who wore gloves. CONCLUSIONS: EEAc on the skin is strongly associated with airborne EEAc. Wearing impermeable gloves during high-risk tasks (cleaning process) can reduce EEAc dermal exposure on the palms.

Exposure and health-risk assessment of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) for sinter plant workers.

This study was set out to assess polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) exposures and health-risk impact posed on sinter plant workers. One sinter plant located in southern Taiwan was selected and their workers were divided into four exposure groups based on their work tasks, including raw material charging workers, sintering grate workers, shredding workers, and others. Results show that their mean total PCDD/F and the corresponding total I-TEQ exposure levels shared the same trend as: shredding workers>others>sintering grate workers>raw material charging workers. For all selected exposure groups, their PCDD/F exposures were dominated by the particle phase contents. Congener profiles of the gaseous+particle phase PCDD/Fs were found with more fractions of high chlorinated congeners than low chlorinated congeners. The lifetime average daily doses (LADDs) and their resultant excess cancer risks (ECRs) found for sinter plant workers were higher than those residents living at the residential area and rural area, but were lower than those living at the nearby of the selected sinter plant, urban area, industrial area. Considering ECRs of the sinter plant workers were still higher than 10(-6) suggesting the need for adopting proper control measurements for reducing workers' PCDD/F exposures, particularly for those sinter zone workers.

The development and regulation of occupational exposure limits in Taiwan.

The occupational exposure limits (OELs) in Taiwan was promulgated in 1974 and has been revised five times since then. Many of the OELs were adopted from the most recent ACGIH TLVs and US OSHA PELs. A total of 483 chemicals were listed in the current Taiwan OELs Standard. The procedures of OELs development in Taiwan include the IOSH organized a recommended exposure limits (RELs) Committee to select the target chemicals and to recommend the RELs through literature review based on the health effects in the first stage, then, the CLA put policy needs, economical and technical feasibility into consideration and set up the final OELs at the second stage. A standard operation manual of RELs Committee has been developed. Based on our experience, several issues including the participation of representatives from a comprehensive spectrum, communication/education and training/enforcement, continuous collection of the local exposure data and health hazard information, use of health risk assessment, consideration of economic, and technical feasibility, as well as the globalization and information and experience sharing are critical in developing the appropriate OELs. Three examples including benzene, crystalline silica, and 2-methoxy ethanol are given to demonstrate the operation of system.

Exposure assessment of organic solvents for aircraft paint stripping and spraying workers.

The main objective of this study is to investigate the personal or area exposure of organic solvents during paint stripping and paint spraying. Three aircraft paint stripping/spraying workplaces in Taiwan were selected, and the Council of Labor Affairs and NIOSH recommended sampling/analytical methods used in this study. Activated charcoal tubes were used to investigate the personal and area exposure concentration of organic solvents in paint stripping and paint spraying operations. During aircraft paint stripping, experiment results show that methylene chloride personal exposure concentration at the ground area, 42.01+/-31.86 ppm, is higher than that at the working platform 4 M high above the ground, 20.41+/-11.43 ppm. Exposure concentration of methylene chloride in the initial paint stripping operation stage of every workplace is over the PEL (50 ppm) set by the Taiwan Council of Labor Affairs. Corrective actions are needed. During paint spraying, concentrations of all organic solvents were found to be below the PEL of OSHA.

Using exposure prediction rules for exposure assessment: an example on whole-body vibration in taxi drivers.

BACKGROUND: It is often difficult and expensive to make direct measurements of an individual's occupational or environmental exposures in large epidemiologic studies. METHODS: In this study, we used information collected in validation studies to develop a prediction rule for assessing exposure in a study with no direct measurement. We established a prediction rule through mixed-effect modeling of direct measurement data and information on observable exposure predictors and their interactions. Specifically, we used 383 measures of whole-body vibration from 247 professional taxi drivers and attempted to quantify vibration exposures for individuals in a large study on low back pain. RESULTS: Using the "jackknife method," we found that our prediction rule had an acceptably low relative prediction error of 11% (95% confidence interval-10-12%). Implementing the prediction rule would result in measurement errors independent of low back pain and of all identified and observable predictors of whole-body vibration. We applied the predicted levels to compute each person's daily exposure, and found a strong association between the predicted daily whole-body vibration exposure and prevalence of low back pain. This supported the construct validity of the exposure prediction rule. CONCLUSIONS: The predictive and construct validity of our prediction rule suggests that this general statistical approach can be useful in other occupational settings to improve the quality of exposure assessment.

Exposure to fine particulate matter (PM2.5) among highway toll station workers in taipei: direct and indirect exposure assessment.

In this study, the authors assessed occupational exposure to PM2.5 among 47 highway toll station workers in Taipei, Taiwan. The subjects were monitored for 10 days to assess integrated 8-hr fine particulate matter (PM2.5) breathing zone concentration. Researchers constructed a microenvironment-time-concentration matrix and applied direct and indirect approaches to assess cumulative exposure. Mean PM2.5 concentration for workers in the truck and bus lanes was 308 microg/m3 (SD = 115.5 microg/m3), substantially higher compared with cash-payment car lanes (mean 115, SD = 41.8, p < 0.001) and ticket-payment car lanes (mean 109, SD = 48.7, p < 0.001). Concentration per vehicle in the truck and bus lanes was 6.4 and 3.7 times higher, respectively, than that of ticket- or cash-payment car lanes. Mean cumulative exposure for the 10-day period was 4,900-13,407 microg/m3.hr, with a mean of 8,019 microg/m3.hr (SD = 2,375.3). Indirect and direct concentrations were strongly correlated (r2 = .61, F(1,125); p = 0.000). The results of this study show that personal exposure to PM2.5 can be reliably estimated using indirect approaches.