The relatively recent development of industries working with nanomaterials has created challenges for exposure assessment. In this article, we propose a relatively simple approach to assessing nanomaterial exposures for the purposes of epidemiological studies of workers in these industries. This method consists of an onsite industrial hygiene visit of facilities carried out individually and a description of workstations where nano-objects and their agglomerates and aggregates (NOAA) are present using a standardized tool, the Onsite technical logbook. To assess its reliability, we implemented this approach for assessing exposure to NOAA in workplaces at seven workstations which synthesize and functionalize carbon nanotubes. The prediction of exposure to NOAA using this method exhibited substantial agreement with that of the reference method, the latter being based on an onsite group visit, an expert's report and exposure measurements (Cohen kappa = 0.70, sensitivity = 0.88, specificity = 0.92). Intramethod comparison of results for exposure prediction showed moderate agreement between the three evaluators (two program team evaluators and one external evaluator) (weighted Fleiss kappa = 0.60, P = 0.003). Interevaluator reliability of the semiquantitative exposure characterization results was excellent between the two evaluators from the program team (Spearman rho = 0.93, P = 0.03) and fair when these two evaluators' results were compared with the external evaluator's results. The project was undertaken within the framework of the French epidemiological surveillance program EpiNano. This study allowed a first reliability assessment of the EpiNano method. However, to further validate this method a comparison with robust quantitative exposure measurement data is necessary.
Objectives:Economic, social, technical, and political drivers are fundamentally changing the nature of work and work environments, with profound implications for the field of occupational health. Nevertheless, researchers and practitioners entering the field are largely being trained to assess and control exposures using approaches developed under old models of work and risks.Methods:A speaker series and symposium were organized to broadly explore current challenges and future directions for the occupational health field. Broad themes identified throughout these discussions are characterized and discussed to highlight important future directions of occupational health.Findings:Despite the relatively diverse group of presenters and topics addressed, some important cross-cutting themes emerged. Changes in work organization and the resulting insecurity and precarious employment arrangements change the nature of risk to a large fraction of the workforce. Workforce demographics are changing, and economic disparities among working groups are growing. Globalization exacerbates the 'race to the bottom' for cheap labor, poor regulatory oversight, and limited labor rights. Largely, as a result of these phenomena, the historical distinction between work and non-work exposures has become largely artificial and less useful in understanding risks and developing effective public health intervention models. Additional changes related to climate change, governmental and regulatory limitations, and inadequate surveillance systems challenge and frustrate occupational health progress, while new biomedical and information technologies expand the opportunities for understanding and intervening to improve worker health.Conclusion:The ideas and evidences discussed during this project suggest that occupational health training, professional practice, and research evolve towards a more holistic, public health-oriented model of worker health. This will require engagement with a wide network of stakeholders. Research and training portfolios need to be broadened to better align with the current realities of work and health and to prepare practitioners for the changing array of occupational health challenges.
Employees who are exposed to high concentrations of microorganisms in bioaerosols frequently suffer from respiratory disorders. However, etiology and in particular potential roles of microorganisms in pathogenesis still need to be elucidated. Thus, determination of employees' antibody titers against specific occupational microbial antigens may lead to identification of potentially harmful species. Since indirect immunofluorescence (IIF) is easy to implement, we used this technique to analyze immunoreactions in human sera. In order to address disadvantageous inter-observer variations as well as the absence of quantifiable fluorescence data in conventional titer determination by eye, we specifically developed a software tool for automated image analysis. The 'Fluorolyzer' software is able to reliably quantify fluorescence intensities of antibody-bound bacterial cells on digital images. Subsequently, fluorescence values of single cells have been used to calculate non-discrete IgG titers. We tested this approach on multiple bacterial workplace isolates and determined titers in sera from 20 volunteers. Furthermore, we compared image-based results with the conventional manual readout and found significant correlation as well as statistically confirmed reproducibility. In conclusion, we successfully employed 'Fluorolyzer' for determination of titers against various bacterial species and demonstrated its applicability as a useful tool for reliable and efficient analysis of immune response toward occupational exposure to bioaerosols.
We read with interest the job-exposure matrix ( JEM) by van Oyen et al. (2015), a study to which we contributed unpublished dust measurements. We wish to make a number of observations regarding the paper. We begin by noting that exposure limits for asbestos were first recommended in Australia well before 1964. In 1945, the State of Victoria adopted a ceiling standard of 5 million particles per cubic foot (mppcf) into regulations (Victoria, 1945), while the 5 mppcf standard was adopted nationally [as an 8-h time-weighted average (TWA)] in 1960 (National Health and Medical Research Council, 1960). The various Australian states adopted regulations based on the membrane filter haphazardly over the 1970s. We agree with the authors that the estimated annual average exposures in AsbJEM appear very low, and that there is some similarity to full-shift exposures that can be found elsewhere in the literature. However, we also take the view that the results of any exposure reconstruction should ‘make sense’ (Armstrong et al., 2009). In our opinion, the exposure estimates for some of the job titles in AsbJEM do not make sense, in that the cumulative exposure for a lifetime of work in some job titles is not consistent with the many cases of asbestos-related disease we have encountered in workers with those job titles. For example, according to AsbJEM: the cumulative exposure for a boilermaker who spent their entire working life in the power supply industry Editorial Note. Letters to the Editor are peer reviewed to ensure that the arguments are reasonable and clearly expressed. However, letters may express a particular opinion rather than a balanced interpretation. Authors of papers commented on are invited to reply, but neither the journal nor peer reviewers should be assumed to support the arguments made.
Masks are often worn in healthcare settings to prevent the spread of infection from healthcare workers (HCWs) to patients. Masks are also used to protect the employee from patient-generated infectious organisms but poor compliance can reduce efficacy. The aim of this study was to examine the factors influencing compliance with the use of medical and cloth masks amongst hospital HCWs.HCWs compliance with the use of medical and cloth masks was measured over a 4-week period in a randomized controlled trial in Vietnam. HCWs were instructed to record their daily activities in diary cards. Demographic, clinical, and diary card data were used to determine the predictors of compliance and the relationship of compliance with infection outcomes.Compliance rates for both medical and cloth masks decreased during the 4 weeks: medical mask use decreased from 77 to 68% (P < 0.001) and cloth masks from 78 to 69% (P < 0.001). The presence of adverse events (adjusted RR 0.90, 95% CI 0.85-0.95), and performing aerosol-generating procedures (adjusted RR 0.78, 95% CI 0.73-0.82) were negatively associated with compliance, while contact with febrile respiratory illness patients was positively associated (adjusted RR 1.14, 95% CI 1.07-1.20). Being compliant with medical or cloth masks use (average use ≥70% of working time) was not associated with clinical respiratory illness, influenza-like illness, and laboratory-confirmed viral infection.Understanding the factors that affect compliance is important for the occupational health and safety of HCWs. New strategies and tools should be developed to increase compliance of HCWs. The presence of adverse events such as discomfort and breathing problems may be the main reasons for the low compliance with mask use and further studies should be conducted to improve the design/material of masks to improve comfort for the wearer.
OBJECTIVES:To efficiently and reproducibly assess occupational diesel exhaust exposure in a Spanish case-control study, we examined the utility of applying decision rules that had been extracted from expert estimates and questionnaire response patterns using classification tree (CT) models from a similar US study. METHODS:First, previously extracted CT decision rules were used to obtain initial ordinal (0-3) estimates of the probability, intensity, and frequency of occupational exposure to diesel exhaust for the 10 182 jobs reported in a Spanish case-control study of bladder cancer. Second, two experts reviewed the CT estimates for 350 jobs randomly selected from strata based on each CT rule's agreement with the expert ratings in the original study [agreement rate, from 0 (no agreement) to 1 (perfect agreement)]. Their agreement with each other and with the CT estimates was calculated using weighted kappa (κ w) and guided our choice of jobs for subsequent expert review. Third, an expert review comprised all jobs with lower confidence (low-to-moderate agreement rates or discordant assignments, n = 931) and a subset of jobs with a moderate to high CT probability rating and with moderately high agreement rates (n = 511). Logistic regression was used to examine the likelihood that an expert provided a different estimate than the CT estimate based on the CT rule agreement rates, the CT ordinal rating, and the availability of a module with diesel-related questions. RESULTS:Agreement between estimates made by two experts and between estimates made by each of the experts and the CT estimates was very high for jobs with estimates that were determined by rules with high CT agreement rates (κ w: 0.81-0.90). For jobs with estimates based on rules with lower agreement rates, moderate agreement was observed between the two experts (κ w: 0.42-0.67) and poor-to-moderate agreement was observed between the experts and the CT estimates (κ w: 0.09-0.57). In total, the expert review of 1442 jobs changed 156 probability estimates, 128 intensity estimates, and 614 frequency estimates. The expert was more likely to provide a different estimate when the CT rule agreement rate was <0.8, when the CT ordinal ratings were low to moderate, or when a module with diesel questions was available. CONCLUSIONS:Our reliability assessment provided important insight into where to prioritize additional expert review; as a result, only 14% of the jobs underwent expert review, substantially reducing the exposure assessment burden. Overall, we found that we could efficiently, reproducibly, and reliably apply CT decision rules from one study to assess exposure in another study.
AIMS:The aims of this study were to examine the relationships and establish conversion factors between 'total' dust, respirable, thoracic, and inhalable aerosol fractions measured by parallel personal sampling on workers from the production departments of cement plants. 'Total' dust in this study refers to aerosol sampled by the closed face 37-mm Millipore filter cassette. METHODS:Side-by-side personal measurements of 'total' dust and respirable, thoracic, and inhalable aerosol fractions were performed on workers in 17 European and Turkish cement plants. Simple linear and mixed model regressions were used to model the associations between the samplers. RESULTS:The total number of personal samples collected on 141 workers was 512. Of these 8.4% were excluded leaving 469 for statistical analysis. The different aerosol fractions contained from 90 to 130 measurements and-side-by side measurements of all four aerosol fractions were collected on 72 workers.The median ratios between observed results of the respirable, 'total' dust, and inhalable fractions relative to the thoracic aerosol fractions were 0.51, 2.4, and 5.9 respectively. The ratios between the samplers were not constant over the measured concentration range and were best described by regression models. Job type, position of samplers on left or right shoulder and plant had no substantial effect on the ratios. CONCLUSIONS:The ratios between aerosol fractions changed with different air concentrations. Conversion models for estimation of the fractions were established. These models explained a high proportion of the variance (74-91%) indicating that they are useful for the estimation of concentrations based on measurements of a different aerosol fraction. The calculated uncertainties at most observed concentrations were below 30% which is acceptable for comparison with limit values (EN 482, 2012). The cement industry will therefore be able to predict the health related aerosol fractions from their former or future measurements of one of the fractions.
Occupational hygiene practitioners typically assess the risk posed by occupational exposure by comparing exposure measurements to regulatory occupational exposure limits (OELs). In most jurisdictions, OELs are only available for exposure by the inhalation pathway. Skin notations are used to indicate substances for which dermal exposure may lead to health effects. However, these notations are either present or absent and provide no indication of acceptable levels of exposure. Furthermore, the methodology and framework for assigning skin notation differ widely across jurisdictions resulting in inconsistencies in the substances that carry notations. The UPERCUT tool was developed in response to these limitations. It helps occupational health stakeholders to assess the hazard associated with dermal exposure to chemicals. UPERCUT integrates dermal quantitative structure-activity relationships (QSARs) and toxicological data to provide users with a skin hazard index called the dermal hazard ratio (DHR) for the substance and scenario of interest. The DHR is the ratio between the estimated 'received' dose and the 'acceptable' dose. The 'received' dose is estimated using physico-chemical data and information on the exposure scenario provided by the user (body parts exposure and exposure duration), and the 'acceptable' dose is estimated using inhalation OELs and toxicological data. The uncertainty surrounding the DHR is estimated with Monte Carlo simulation. Additional information on the selected substances includes intrinsic skin permeation potential of the substance and the existence of skin notations. UPERCUT is the only available tool that estimates the absorbed dose and compares this to an acceptable dose. In the absence of dermal OELs it provides a systematic and simple approach for screening dermal exposure scenarios for 1686 substances.
Exposure to stainless steel (SS) welding aerosol that contain toxic heavy metals, chromium (Cr), manganese (Mn), and nickel (Ni), has been associated with numerous adverse health effects. The gas tungsten arc welding (GTAW) is commonly applied to SS and produces high number concentration of substantially smaller particles compared with the other welding techniques, although the mass emission rate is low. Here, a field study in a workshop with the GTAW as principal welding technique was conducted to determine the physicochemical properties of the airborne particles and to improve the understanding of the hazard the SS welding aerosols pose to welders.Particle number concentration and number size distribution were measured near the breathing zone (50cm from the arc) and in the middle of the workshop with condensation particle counters and electrical mobility particle sizers, respectively. Particle morphology and chemical composition were studied using scanning and transmission electron microscopy and energy-dispersive X-ray spectroscopy.In the middle of the workshop, the number size distribution was unimodal with the geometric mean diameter (GMD) of 46nm. Near the breathing zone the number size distribution was multimodal, and the GMDs of the modes were in the range of 10-30nm. Two different agglomerate types existed near the breathing zone. The first type consisted of iron oxide primary particles with size up to 40nm and variable amounts of Cr, Mn, and Ni replacing iron in the structure. The second type consisted of very small primary particles and contained increased proportion of Ni compared to the proportion of (Cr + Mn) than the first agglomerate type.The alterations in the distribution of Ni between different welding aerosol particles have not been reported previously.
In case of incidental confinement failure, mixed oxide (MOX) fuel preparation may expose workers to plutonium aerosols. Due to its potential toxicity, occupational exposure to plutonium compounds should be kept as low as reasonably achievable. To ensure the absence of significant intake of radionuclides, workers at risk of internal contamination are monitored by periodic bioassay planned in a routine monitoring programme. From bioassay results, internal dose may be estimated. However, accurate dose calculation relies on known exposure conditions, which are rarely available when the exposure is demonstrated by routine monitoring only. Therefore, internal dose calculation is subject to uncertainty from unknown exposure conditions and from activity measurement variability. The present study calculates the minimum detectable dose (MDD) for a routine monitoring programme by considering all plausible conditions of exposure and measurement uncertainty. The MDD evaluates the monitoring quality and can be used for optimization. Here, MDDs were calculated for the monitoring of workers preparing MOX fuel. Uncertain parameters were modelled by probability distributions defined according to information provided by experts of routine monitoring, of workplace radiological protection and of bioassay analysis. Results show that the current monitoring is well adapted to potential exposure. A sensitivity study of MDD highlights high dependence on exposure condition modelling. Integrating all expert knowledge is therefore crucial to obtain reliable MDD estimates, stressing the value of a holistic approach to worker monitoring.
Introduction: The aims of this study were to produce a population-based estimate of the prevalence of work-related exposure to polycyclic aromatic hydrocarbons (PAHs), to identify the main circumstances of exposure and to describe the use of workplace control measures designed to decrease those exposures.Methods: The analysis used data from the Australian Workplace Exposures Study, a nationwide telephone survey which investigated the current prevalence and exposure circumstances of work-related exposure to 38 known or suspected carcinogens, including PAHs, among Australian workers aged 18-65 years. Using the web-based tool OccIDEAS, semi-quantitative information was collected about exposures in the current job held by the respondent. Questions were addressed primarily at tasks undertaken rather than about self-reported exposures.Results: Of the 4,993 included respondents, 297 (5.9%) were identified as probably being exposed to PAHs in their current job [extrapolated to 6.7% of the Australian working population-677 000 (95% confidence interval 605 000-757 000) workers]. Most (81%) were male; about one-third were farmers and about one-quarter worked in technical and trades occupations. In the agriculture industry about half the workers were probably exposed to PAHs. The main exposure circumstances were exposure to smoke through burning, fighting fires or through maintaining mowers or other equipment; cleaning up ash after a fire; health workers exposed to diathermy smoke; cooking; and welding surfaces with a coating. Where information on control measures was available, their use was inconsistent.Conclusion: Workers are exposed to PAHs in many different occupational circumstances. Information on the exposure circumstances can be used to support decisions on appropriate priorities for intervention and control of occupational exposure to PAHs, and estimates of burden of cancer arising from occupational exposure to PAHs.
Carbon nanotube (CNT) polymer composites are widely used as raw materials in multiple industries because of their excellent properties. This expansion, however, is accompanied by realistic concerns over potential release of CNTs and associated nanoparticles during the manufacturing, recycling, use, and disposal of CNT composite products. Such data continue to be limited, especially with regards to post-processing of CNT-enabled products, recycling and handling of nanowaste, and end-of-life disposal. This study investigated for the first time airborne nanoparticle and fibers exposures during injection molding and recycling of CNT polypropylene composites (CNT-PP) relative to that of PP. Exposure characterization focused on source emissions during loading, melting, molding, grinding, and recycling of scrap material over 20 cycles and included real-time characterization of total particle number concentration and size distribution, nanoparticle and fiber morphology, and fiber concentrations near the operator. Total airborne nanoparticle concentration emitted during loading, melting, molding, and grinding of CNT-PP had geometric mean ranging from 1.2 × 10(3) to 4.3 × 10(5) particles cm(-3), with the highest exposures being up to 2.9 and 300.7 times above the background for injection molding and grinding, respectively. Most of these emissions were similar to PP synthesis. Melting and molding of CNT-PP and PP produced exclusively nanoparticles. Grinding of CNT-PP but not PP generated larger particles with encapsulated CNTs, particles with CNT extrusions, and respirable fiber (up to 0.2 fibers cm(-3)). No free CNTs were found in any of the processes. The number of recycling runs had no significant impact on exposures. Further research into the chemical composition of the emitted nanoparticles is warranted. In the meanwhile, exposure controls should be instituted during processing and recycling of CNT-PP.
Outdoor workers are at high risk of exposure to solar ultraviolet radiation (UVR), a known human carcinogen. In Canada, no objective measures of UVR exposure are available for occupational settings.The Outdoor Workers Project collected UVR exposure data among outdoor workers in Vancouver, Canada during the summer of 2013. Objective measures of exposure were taken for one week using calibrated electronic UVR dosimeters. Additional data was collected from workers on skin cancer risk factors, family history of skin cancer, and job type; as well as meteorological data for sampling days. Marginal models were constructed to examine the worker, job and meteorological determinants of UVR exposure levels, as measured in standard erythemal dose (SED).Seventy-eight workers were recruited, of which 73 had at least 1 day of measured UVR exposure for this analysis. Participants were mostly male, young and Caucasian. Mean exposure (corrected for repeated measures) was 1.08 SED. Exposure measures were highly variable even in the same workplace, ranging from 0.01 SED to 19.2 SED. Younger age, working in land-based construction, and sunnier weather forecasts led to higher levels of UVR exposure.Exposure levels capable of causing sunburn were common in this study of outdoor workers, in a location not typically associated with high sun exposure.
This article describes the evaluation of an open-access web-based respiratory protective equipment selector tool (RPE-Select, accessible at http://www.healthyworkinglives.com/rpe-selector). This tool is based on the principles of the COSHH-Essentials (C-E) control banding (CB) tool, which was developed for the exposure risk management of hazardous chemicals in the workplace by small and medium sized enterprises (SMEs) and general practice H&S professionals. RPE-Select can be used for identifying adequate and suitable RPE for dusts, fibres, mist (solvent, water, and oil based), sprays, volatile solids, fumes, gases, vapours, and actual or potential oxygen deficiency. It can be applied for substances and products with safety data sheets as well as for a large number of commonly encountered process-generated substances (PGS), such as poultry house dusts or welding fume. Potential international usability has been built-in by using the Hazard Statements developed for the Globally Harmonised System (GHS) and providing recommended RPE in picture form as well as with a written specification. Illustration helps to compensate for the variabilities in assigned protection factors across the world. RPE-Select uses easily understandable descriptions/explanations and an interactive stepwise flow for providing input/answers at each step. The output of the selection process is a report summarising the user input data and a selection of RPE, including types of filters where applicable, from which the user can select the appropriate one for each wearer. In addition, each report includes 'Dos' and 'Don'ts' for the recommended RPE. RPE-Select outcomes, based on up to 20 hypothetical use scenarios, were evaluated in comparison with other available RPE selection processes and tools, and by 32 independent users with a broad range of familiarities with industrial use scenarios in general and respiratory protection in particular. For scenarios involving substances having safety data sheets, 87% of RPE-Select outcomes resulted in a 'safe' RPE selection, while 98% 'safe' outcomes were achieved for scenarios involving process-generated substances. Reasons for the outliers were examined. User comments and opinions on the mechanics and usability of RPE-Select are also presented.
INTRODUCTIONFirefighters have high rate of injuries and illnesses, as well as exposures to high levels of noise. This study explored the relationship between noise exposure and injury among firefighters.METHODSWe recruited firefighters undergoing vehicle extrication and structural collapse emergency response training at a highly realistic training facility. Demographics, health status, body mass index (BMI), and history of serious injuries (i.e. injuries requiring first aid treatment, treatment in a medical clinic or office, or treatment at a hospital) were assessed at baseline, and daily activities, injury events, and near misses were assessed daily via surveys. Participants' noise exposures were monitored for one 24-h period using noise dosimeters. We used a mixed-effects logistic regression model to estimate the odds of injury events and near misses associated with noise exposure as an independent variable.RESULTSOf 56 subjects, 20 (36%) reported that they had ever suffered a serious injury during firefighting activities, and 9 (16%) reported a serious injury within the past year. We estimated rates of 6.6 lifetime serious injuries per 100 FTE 16.1 serious injuries per 100 FTE within the past year. Our models indicated a significant increase in injury events and near misses among those with higher BMI, and as well as a dose-response relationship between near misses/injuries and increasing noise levels. Noise levels >90 dBA in the 30 min prior to time of injury or near miss were associated with substantially increased odds ratios for injury or near miss. Our models further indicated that perceived job demands were significantly associated with increased risk of injury or near miss.CONCLUSIONOur results suggest that noise exposures may need to be incorporated into injury prevention programs for firefighters to reduce injuries among this high-risk occupational group.
High and low flow rate respirable size selective samplers including the CIP10-R (10 l min(-1)), FSP10 (11.2 l min(-1)), GK2.69 (4.4 l min(-1)), 10-mm nylon (1.7 l min(-1)), and Higgins-Dewell type (2.2 l min(-1)) were compared via side-by-side sampling in workplaces for respirable crystalline silica measurement. Sampling was conducted at eight different occupational sites in the USA and five different stonemasonry sites in Ireland. A total of 536 (268 pairs) personal samples and 55 area samples were collected. Gravimetric analysis was used to determine respirable dust mass and X-ray diffraction analysis was used to determine quartz mass. Ratios of respirable dust mass concentration, quartz mass concentration, respirable dust mass, and quartz mass from high and low flow rate samplers were compared. In general, samplers did not show significant differences greater than 30% in respirable dust mass concentration and quartz mass concentration when outliers (ratio <0.3 or >3.0) were removed from the analysis. The frequency of samples above the limit of detection and limit of quantification of quartz was significantly higher for the CIP10-R and FSP10 samplers compared to low flow rate samplers, while the GK2.69 cyclone did not show significant difference from low flow rate samplers. High flow rate samplers collected significantly more respirable dust and quartz than low flow rate samplers as expected indicating that utilizing high flow rate samplers might improve precision in quartz measurement. Although the samplers did not show significant differences in respirable dust and quartz concentrations, other practical attributes might make them more or less suitable for personal sampling.
OBJECTIVE:The purpose of this study was to compare thermal desorption tubes and stainless steel canisters for measuring volatile organic compounds (VOCs) emitted from petrochemical factories.METHODS:Twelve petrochemical factories in the Mailiao Industrial Complex were recruited for conducting the measurements of VOCs. Thermal desorption tubes and 6-l specially prepared stainless steel canisters were used to simultaneously perform active sampling of environmental air samples. The sampling time of the environmental air samples was set up on 6 h close to a full work shift of the workers. A total of 94 pairwise air samples were collected by using the thermal adsorption tubes and stainless steel canisters in these 12 factories in the petrochemical industrial complex. To maximize the number of comparative data points, all the measurements from all the factories in different sampling times were lumped together to perform a linear regression analysis for each selected VOC. Pearson product-moment correlation coefficient was used to examine the correlation between the pairwise measurements of these two sampling methods. A paired t-test was also performed to examine whether the difference in the concentrations of each selected VOC measured by the two methods was statistically significant.RESULTS:The correlation coefficients of seven compounds, including acetone, n-hexane, benzene, toluene, 1,2-dichloroethane, 1,3-butadiene, and styrene were >0.80 indicating the two sampling methods for these VOCs' measurements had high consistency. The paired t-tests for the measurements of n-hexane, benzene, m/p-xylene, o-xylene, 1,2-dichloroethane, and 1,3-butadiene showed statistically significant difference (P-value < 0.05). This indicated that the two sampling methods had various degrees of systematic errors. Looking at the results of six chemicals and these systematic errors probably resulted from the differences of the detection limits in the two sampling methods for these VOCs.CONCLUSIONS:The comparison between the concentrations of each of the 10 selected VOCs measured by the two sampling methods indicted that the thermal desorption tubes provided high accuracy and precision measurements for acetone, benzene, and 1,3-butadiene. The accuracy and precision of using the thermal desorption tubes for measuring the VOCs can be improved due to new developments in sorbent materials, multi-sorbent designs, and thermal desorption instrumentation. More applications of thermal desorption tubes for measuring occupational and environmental hazardous agents can be anticipated.
Asbestos and non-asbestos containing brake products are currently used in low- and middle-income countries like Colombia. Because brake products are distributed detached from their supports, they require manipulation before installation, which release fibers and expose workers. Previous studies of our research group have documented exposures in excess of the widely accepted 0.1 f/cm(3) exposure guideline. The aim of this study is to identify factors associated with non-compliance of the 8-h time weighted average (TWA) 0.1 f/cm(3) asbestos occupational limit among brake mechanics (i.e. riveters). Eighteen brake repair shops (BRS) located in Bogotá (Colombia) were sampled during 3 to 6 consecutive days for the entire work-shift. Personal and short-term personal samples were collected following NIOSH methods 7400 and 7402. Longitudinal based logistic regression models were used to determine the association between the odds of exceeding the 8-h TWA 0.1 f/cm(3) asbestos occupational limit and variables such as type of tasks performed by workers, workload (number of products manipulated daily), years of experience as riveters, and shop characteristics. These models can be used to estimate the odds of being currently or historically overexposed when sampling data do not exist. Since the information required to run the models can vary for both retrospective and current asbestos occupational exposure studies, three models were constructed with different information requirements. The first model evaluated the association between the odds of non-compliance with variables related to the workload, the second model evaluated the association between the odds of non-compliance with variables related to the manipulation tasks, and the third model evaluated the association between the odds of non-compliance with variables related with both the type of tasks performed by workers and the workload. Variables associated with the odds of non-compliance included conducting at least one manipulation activity with beveling and grinding of asbestos and non-asbestos containing brake products during the work shift, the location of the worker in the shop during non-manipulation activities, cleaning activities of the manipulation area, the years of experience working as riveters, and the number of asbestos and non-asbestos containing brake products manipulated daily. These models could be useful for current and retrospective occupational studies, in determining the odds of non-compliance of the asbestos occupational limit among brake mechanics.
Background: We published a meta-analysis of the association between work as a motor vehicle mechanic and mesothelioma in 2004. Since then, several relevant studies on this topic have been published. Thus, to update the state-of-the-science on this issue, we conducted a new systematic review and meta-analysis.Methods: A comprehensive PubMed literature search through May 2014 was conducted to identify studies that reported relative risk estimates for mesothelioma among motor vehicle mechanics (in general), and those who were engaged in brake repair (specifically). Studies were scored and classified based on study characteristics. Random-effects meta-analyses generated summary relative risk estimates (SRREs) and corresponding 95% confidence intervals (CI). Heterogeneity of results was examined by calculating Q-test P-values (P-H) and I-2 estimates. Sub-group and sensitivity analyses were conducted for relevant study characteristics and quality measures.Results: Ten case-control studies, one cohort study, and five proportionate mortality ratio (PMR)/standardized mortality odds ratio (SMOR) studies were identified and included in the quantitative assessment. Most meta-analysis models produced SRREs below 1.0, and no statistically significant increases in mesothelioma were observed. The SRRE for all studies was 0.80 (95% CI: 0.61-1.05) with significant heterogeneity (P-H < 0.001, I-2 = 62.90). A similar SRRE was observed among the five Tier 1 studies with the highest quality ratings (SRRE = 0.76, 95% CI: 0.46-1.25), with no heterogeneity among studies (P-H = 0.912, I-2 = 0.00). Meta-analysis of the Tier 2 (n = 5) and Tier 3 (n = 6) studies resulted in SRREs of 1.09 (95% CI: 0.76-1.58) and 0.73 (95% CI: 0.49-1.08), respectively. Restricting the analysis to Tiers 1 and 2 combined resulted in an SRRE of 0.92 (95% CI: 0.72-1.29). The SRRE specific to brake work (n = 4) was 0.64 (95% CI: 0.38-1.09).Conclusions: This meta-analysis of the epidemiologic studies provides evidence that motor vehicle mechanics, including workers who were engaged in brake repair, are not at an increased risk of mesothelioma.
To assess exposure to benzene (BEN) and other aromatic compounds (toluene, ethylbenzene, m+p-xylene, o-xylene) (BTEX), methyl tert-butyl ether (MTBE), and ethyl tert-butyl ether (ETBE) in petrol station workers using air sampling and biological monitoring and to propose biological equivalents to occupational limit values.Eighty-nine petrol station workers and 90 control subjects were investigated. Personal exposure to airborne BTEX and ethers was assessed during a mid-week shift; urine samples were collected at the beginning of the work week, prior to and at the end of air sampling.Petrol station workers had median airborne exposures to benzene and MTBE of 59 and 408 A mu g m(-3), respectively, with urinary benzene (BEN-U) and MTBE (MTBE-U) of 339 and 780ng l(-1), respectively. Concentrations in petrol station workers were higher than in control subjects. There were significant positive correlations between airborne exposure and the corresponding biological marker, with Pearson's correlation coefficient (r) values of 0.437 and 0.865 for benzene and MTBE, respectively. There was also a strong correlation between airborne benzene and urinary MTBE (r = 0.835). Multiple linear regression analysis showed that the urinary levels of benzene were influenced by personal airborne exposure, urinary creatinine, and tobacco smoking [determination coefficient (R (2)) 0.572], while MTBE-U was influenced only by personal exposure (R (2) = 0.741).BEN-U and MTBE-U are sensitive and specific biomarkers of low occupational exposures. We propose using BEN-U as biomarker of exposure to benzene in nonsmokers and suggest 1457ng l(-1) in end shift urine samples as biological exposure equivalent to the EU occupational limit value of 1 p.p.m.; for both smokers and nonsmokers, MTBE-U may be proposed as a surrogate biomarker of benzene exposure, with a biological exposure equivalent of 22 A mu g l(-1) in end shift samples. For MTBE exposure, we suggest the use of MTBE-U with a biological exposure equivalent of 22 A mu g l(-1) corresponding to the occupational limit value of 50 p.p.m.
