Annals Of Work Exposures and Health最新文献

Swine workers may be occupationally exposed to Staphylococcus aureus (S. aureus) during time spent inside swine barns. Exposure may occur by inhaling S. aureus-containing particles or by touching contaminated surfaces or infected animals. Despite strong evidence that swine production work is a risk factor for increased nasal carriage of S. aureus, pathways of worker exposure within the swine barn setting have not been well characterized. We developed a Markov chain model to address this research gap by first describing the fate and transport of S. aureus-containing particles within a swine finishing barn. We defined 7 possible physical locations in and around the barn in which S. aureus-containing particles may exist and used published data to determine the probability that a particle will transition from any of these locations to the other locations during a 1-s time interval. We then used our model to estimate worker exposure to S. aureus during a period of 1 s to 30 min spent inside the swine barn. Finally, we modified inputs to simulate interventions to protect workers, such as ventilation controls, respirator use, and handwashing. Increasing the ventilation rate (ie the rate at which outdoor air replaces indoor air in the barn) in our model from the recommended rate for cold weather to the rate for mild weather resulted in a 59% decrease in the number of S. aureus-containing particles in the worker's respiratory system after 30 min. Increasing ventilation rates further to the recommended rate for hot weather resulted in an additional 58% decrease. Models simulating floor and surface cleaning prior to the worker's entry into the barn had little impact on the air concentration of S. aureus (<1% change) but reduced worker exposure to facial membranes by up to 13%. Simulations of N-95 respirator wearing had the greatest impact on worker exposure. As modeled, a well-fitting N-95 respirator may reduce worker inhalation exposure from 1,772 to 72 S. aureus-containing particles after 30 min in the barn, a 96% reduction. In our model, a poorly fitting N-95 respirator reduced exposure by about 30%, indicating that the type and fit of respirator worn has an important impact on the level worker protection.

Objectives: Studies addressing the epidemiology of silicosis in the artificial stone benchtop industry have shown that this industry includes a large number of migrant workers in Victoria, Australia. The objective of the current analyses was to compare characteristics of migrant workers in the industry with nonmigrant workers.

Methods: Data were derived from artificial stone benchtop workers who had health assessments through a regulator-funded screening program between 2019 and 2024. Migrant workers were defined as workers born outside Australia or had used an interpreter during the assessment. Participant characteristics, lung function, and silicosis prevalence were summarized by migrant status and compared between groups.

Results: There were 1,040 workers (n = 536 migrant workers). Migrant workers were older at assessment than nonmigrant workers (median age 39 versus 33 years, P < 0.001). About 1 quarter of migrant workers used an interpreter (23.8%) and 52% spoke English at home. Silicosis prevalence was higher in migrant compared with nonmigrant workers (23% versus 15%, risk-ratio 1.54, and 95% confidence interval 1.16 to 2.04) and migrant workers who used an interpreter had double the risk of silicosis than those who did not (46% versus 18%, risk-ratio 2.24, 95% confidence interval 1.61 to 3.10). Prelegislative changes, experience of carrying out dry processing was reportedly higher in nonmigrant than migrant workers. Fewer jobs among migrant workers than nonmigrant workers were reported using recommended respirators (44 versus 53%) or ventilation (24% versus 30%).

Conclusions: The risk of silicosis in the artificial stone benchtop industry differed by migration status and was higher among those with lower English language proficiency. As the use of appropriate respirators or ventilation was lower among migrant workers, this suggests the need for improved occupational health and safety practices among migrant workers, making sure the messages are communicated in a manner that is language and culturally appropriate.

Objectives: Exposure determinant modeling can help industrial hygienists understand where, when, and how to control occupational exposures for their particular work environment. Yet, in practice, the ability to evaluate exposure determinants is degraded by selection bias (where only a subset of all exposed workers is sampled) and the statistical issue of "small n, large p" (few samples but many exposure determinants). This study explored the application of the causal inference framework and machine learning algorithms in exposure determinant modeling using a "small n, large p" example of potential determinants of heavy metal concentrations among informal electronic waste recycling workers.

Methods: As a case study, we used a multivariable logistic regression model to construct inverse probability weights to account for selection bias into a video substudy of 41 of 226 possible workers monitored for exposures to heavy metals. Forty-four determinants of biomarkers (eg tool use, job tasks, and personal protective equipment use) were quantified through video monitoring. Concentrations of heavy metals in blood (Pb and Mn) and urine (Ni and Cu) were sampled. We identified the best-performing biomarker determinant model by comparing the leave-one-out cross-validation root-mean-squared error (LOOCV-RMSE) of 5 models: 2 traditional models (multivariate linear regression and forward selection), and 3 machine learning algorithms (LASSO, boosted regression trees, and random forests). Using the best-performing model, we estimated reductions in heavy metal concentrations through hypothetical workplace controls to identify the most important determinant of biomarker concentrations.

Results: The random forest model had the lowest LOOCV-RMSE and was used as the final biomarker determinant model. Stopping workers from bending their backs while dismantling e-waste was the most important determinant of heavy metal concentrations. Using blood Pb as an example, this translated to an estimated reduction of 0.81 µg/dL (95% confidence interval: 0.66, 0.98) in comparison with maintaining the status quo. Using a traditional regression model (forward selection without inverse probability weights), back bending was not identified as an important determinant of blood Pb.

Discussion: Our causal inference approach with machine learning algorithms overcomes the common limitations of exposure determinant modeling and produces easy-to-interpret estimates of biomarker concentration reductions from hypothetical workplace controls. This can aid industrial hygienists in choosing the most effective hazard controls that can be contextualized to their particular work setting.

Occupational exposure to airborne particles and bioaerosols in dental clinics is a potential hazard to dental health workers. Current studies on airborne particles and bioaerosols in dental clinics are limited and methodologically diverse, leaving gaps in the understanding of airborne particles in real-life dental settings. The aim of the study was to investigate the size, concentration, and composition of particles produced during dental procedures, and determine the exposure levels of dental personnel to respirable particles and bioaerosols in dental clinical environments with different characteristics. The study included two conventional dentist offices and one specialty clinic. The number concentration and size distribution of particles released during different dental procedures were monitored in real-time in dental procedure rooms. Personal samplers were used in parallel to collect the respirable and inhalable particle fractions. Total bacterial and total fungal DNA concentrations were quantified in the inhalable particle fraction by droplet digital polymerase chain reaction. Particle morphology and chemical composition were analyzed using scanning electron microscopy. The highest geometric mean value of the respirable particle mass concentration (0.06 mg/m3) was below the Norwegian occupational exposure limit for respirable dust of 5 mg/m3. Real-time sampling indicated that particle number concentrations were elevated during working hours in two clinics, with peak levels observed in one clinic coinciding with air polishing activities. The results also showed significant variations in bacterial and fungal DNA concentration levels (P < 0.0001). Many collected particles originated from powders used in dental treatments. Despite low respirable particle mass concentrations, increased levels of ultrafine particles during dental procedures highlight potential health risks to dental professionals. These findings also underscore the importance of advanced ventilation and safety measures to mitigate occupational exposure in dental environments.

Background: During the Deepwater Horizon disaster in 2010, oil spill response and cleanup (OSRC) workers were exposed to crude oil, including benzene, toluene, ethylbenzene, xylene, and n-hexane (BTEX-H). Growing evidence links these exposures to cardiovascular disease (CVD). Lipid and C-reactive protein levels are used to assess CVD risk and may serve as mediators of the observed associations with CVD. However, few studies have assessed associations of oil spill cleanup-related exposures with blood levels of lipids and C-reactive protein (CRP).

Objective: This study examined associations of oil spill cleanup-related exposure to each individual BTEX-H chemical, total (aggregate sum) BTEX-H, and the BTEX-H mixture with blood lipids and CRP among OSRC workers in the Gulf Long-term Follow-up (GuLF) Study.

Methods: Subjects comprised 2,544 OSRC workers who completed a home visit (May 2011 to May 2013) and had CVD biomarker measurements. Cumulative exposures to BTEX-H (ppb-days) were estimated using a job-exposure matrix that linked air measurements with self-reported Deepwater Horizon work histories. Study biomarkers were lipids, including low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), total cholesterol, and high-sensitivity CRP (hsCRP), which were measured in blood samples collected during the home visit. Multivariable linear regression was used to estimate mean differences and 95% confidence intervals (CI) for associations of quartiles of BTEX-H with lipid and hsCRP levels. We log-transformed hsCRP due to a non-normal distribution. We used quantile g-computation to assess the joint effect of the BTEX-H mixture.

Results: Each BTEX-H chemical was associated with elevations in total cholesterol up to 3 yr after exposure, with the strongest effect estimates in the top quartile, ranging from 2.3 to 5.1 mg/dL. A one quartile simultaneous increase in the BTEX-H mixture was associated with a 1.7 mg/dL increase in total cholesterol. While trends were less consistent for hsCRP, most estimates were above the null and a one quartile increase in exposure to the BTEX-H mixture was associated with a 3% increase in hsCRP.

Conclusion: Our study suggests that oil spill cleanup-related BTEX-H exposures were associated with elevations in some CVD biomarkers.

Objectives: Many South African workers rely on respirators for protection from airborne hazards. To our knowledge, there is no public head and face anthropometric database for Black South African respirator users to inform the design of respirators for these individuals. The objective of our study was to determine the facial dimensions of Black South African respirator users using the 13 facial dimensions recommended by the United States National Institute for Occupational Safety and Health (NIOSH).

Methods: This was a descriptive and analytical cross-sectional study of Black South African respirator users working in Gauteng. Industries and companies known to use respirators in their operations were approached, and 693 participants between the ages of 18 to 65 were enrolled. Our study followed the methodology used in a NIOSH 2005 study that conducted a head and face anthropometric survey of US respirator users. Traditional measurement tools such as a tape measure, sliding caliper, spreading caliper, and pupillometer were used. Student's t-test was used to analyze data.

Results: The study found statistically significant differences between the facial dimensions of Black South African men and women respirator users and those of 3,000 Chinese respirator users studied in 2009 to develop a fit test panel. All the dimensions of males and females differed significantly, with the largest differences being in head circumference, neck circumference, and minimal frontal breadth. The majority of the facial dimensions of Black South Africans were also significantly different from the 3,997 American NIOSH 2007 fit test panel population, with only face width and nose protrusion not significantly different.

Conclusions: The mean values of Black South African facial dimensions differed significantly from those of the American and the Chinese populations. It may be that respirators designed and tested using the 2007 NIOSH and the 2009 Chinese fit test panels do not include dimensions representative of Black South Africans. Currently supplied respirators are likely to leave some Black South Africans unprotected due to poor fit.

This study investigated the compatibility of Tetrahydrofuran (THF) dissolution, following the procedures outlined in NIOSH Method 7500 and the similar OSHA ID-142 method, as a sample preparation technique for respirable crystalline silica (RCS) analysis in engineered stone materials compared to the muffle furnace (MF) ashing method. Our results revealed considerable variability in RCS content across different batches of engineered stone tested, underscoring the inherent material heterogeneity in engineered stone products. A statistically significant underestimation of RCS concentrations was observed when using THF dissolution for Stone A (polyester-based) samples collected on 47 mm polyvinyl chloride (PVC) filters, particularly at lower analyte loadings. In contrast, no statistically significant differences in RCS measurement were found between THF dissolution and MF ashing for the other 3 stone types, including one laboratory-synthetic material. The observed discrepancy in Stone A is likely attributed to the interaction of THF with its polyester resin binder, leading to swelling of the filter matrix and forming a non-volatile residue. This residue may physically entrap silica particles, hindering their complete recovery and subsequent quantification by X-ray diffraction (XRD). The suitability of THF processing as a sample preparation method is therefore highly dependent on the specific composition of the engineered stone. Based on these findings, MF ashing is recommended as the more reliable and universally applicable sample preparation method for engineered stone samples, especially those containing polyester resin binders. Caution should be exercised when considering THF dissolution for RCS analysis in engineered stones due to the potential for significant underestimation of actual RCS values, which could have implications for exposure assessments and regulatory compliance.

Simultaneous sampling of diisocyanates and diamines is of great importance since occupational exposure to both diamines and diisocyanates may occur during production of the diisocyanates and polyurethane (PU) products or during thermal degradation of PU material. A methodology for the simultaneous collection and determination of diisocyanates and diamines using ASSET EZ4-ICA dry sampler (Supelco, PA, United States) was presented. The sampler was previously validated and is sold commercially for isocyanate detection. This work investigated to also include diamine determinations (specifically MDA and TDA) to enable a user-friendly approach, without the use of fragile glassware and solvents during sampling. In addition, a sampler based on the same design as the ASSET-sampler but with a modified impregnation with dibutyl amine (DBA) and sulfuric acid was also demonstrated. During sampling, isocyanates were collected and derivatized with DBA and the diamines were derivatized in a subsequent work-up procedure with ethyl chloroformate to form carbamate esters. For the ASSET-ICA sampler, no breakthrough was observed for 2,4'-MDA or 4,4'-MDA for sampling at 200 mL/min for up to 4 h (240 min). For 2,4-TDA and 2,6-TDA, no breakthrough was observed for up to 60 min of sampling. For the sampler with modified impregnation, no breakthrough of TDA was observed for up to 240 min of sampling. No losses were observed for the MDA isomers when storing the samplers in a refrigerator (8 °C) for up to 21 d after sampling. However, for the TDA isomers, minor losses could be observed after storage for 8 d. Storing the samplers in a freezer (-18 °C) or performing the addition of 500 µL of 3M sulphuric acid to the sampler filter media after sampling improved the stability of the TDA isomers during storage and no losses were observed for 21 d of storage. Also, for the sampler with modified impregnation, storage for up to 21 d could be made without any significant losses of TDA. Comparable concentrations were measured in ASSET-ICA samplers and in impinger-filter samples when sampling of a controlled test atmosphere was performed at different relative humidity (30% to 70% RH) and also during sampling of thermal degradation products from PU foam.

Crystalline silica was categorized by the International Agency for Research on Cancer as a known human carcinogen. Activities related to the processing of ceramic tiles, releasing crystalline silica, may vary considerably in terms of hours worked per day and days worked per week. This variability could be particularly high for craftsmen who process ceramic materials directly on-site during installation. The aim of this study is to measure the likely exposure to respirable crystalline silica (RCS) during ceramic tiles installation, evaluating the exposure to RCS of workers processing these tiles. Exposure assessments to RCS were conducted via both fixed-site and personal sampling for 2 working hours. The measured concentrations were calculated as 8-h time-weighted average (TWA) exposures, assuming no further RCS exposure in the time period. The permitted exposure time, not to exceed the occupational exposure limit (OEL) value, was then calculated also considering the assigned protection factor of selected respiratory protective equipment. The results of this study, considered as a worst-case simulation, show that, during the processing of ceramic tiles releasing RCS, the worker exposure can be very high (up to 240.9 µg/m3), exceedance of several OELs, including the European OEL of 100 µg/m³. Even working for a few hours a day, the RCS 8-h TWA OEL is likely to be exceeded. Inhaled exposure concentrations can be reduced by using appropriate respiratory protection, by a factor equal to 10 or 20. The assumption of this work was that (i) the cutting/grinding times are not always necessarily equal to 2 h and that (ii) these processes are not characterized by pre-established and continuous processing times. For these reasons, it is important to carefully evaluate the duration of exposure to RCS during the various tasks/activities performed, as these may vary depending on different factors.

Objectives: To understand the total exposure of a human population to a chemical, it is necessary to aggregate exposures from different exposure routes (ingestion, inhalation, dermal uptake) and exposure sources (eg food, air, consumer products) from different environments (ie general, occupational, consumer use). Preventive actions or regulatory decisions require decisions to be taken on priority exposure routes and sources. This study explores the development of a quantitative decision tree to identify relevant exposure sources in the context of aggregate exposure. As a case study for spray applications, it focuses on joint exposure to a specific chemical in a consumer product through domestic use of hairspray, and exposure at the workplace involving surface spraying, such as spray application of paints.

Methods: Determinant of the exposure models ART (for workers) and ConsExpo (for the general population) were used to generate a wide range of realistic exposure scenarios. The dominance of one source over another was analyzed through pairwise random comparisons. Exposure estimates from one source containing a specific determinant are compared with those from the other source, scaled by a dominance ratio that defines how much higher one source's exposure must be to be considered dominant. For each comparison, the number of times one source exceeds the other by at least a dominance ratio is counted, resulting in the occurrence. The occurrence is compared with a predefined threshold (eg 80%). If the threshold is met or exceeded, the higher-contributing source is considered dominant and no exposure aggregation is needed; otherwise, aggregation of both sources is recommended.

Results: The findings indicated that the use of high- or medium-specification glove boxes, as forms of permanent encapsulation or encasing of the emission source, results in occupational exposure that is negligible compared with the exposure from consumer product use. When these glove boxes were used, hair spray exposure was the dominant source in 89% and 82% of cases, for high and medium specifications, respectively. A spraying activity with surface liquids performed outdoors (close to buildings) showed a significant trend toward occupational exposure dominance in 81% of cases. Using these three determinants, a three-layer quantitative decision tree was built to help users quickly decide whether aggregation was relevant before performing calculations. Aggregation was suggested in 91% of cases and avoided it in 9%.