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Doyen V, Gautrin D, Vandenplas O, Malo JL. Comparison of high- and low-molecular-weight sensitizing agents causing occupational asthma: an evidence-based insight. Expert Rev Clin Immunol 2024; 20:635-653. [PMID: 38235552 DOI: 10.1080/1744666x.2024.2306885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Accepted: 01/15/2024] [Indexed: 01/19/2024]
Abstract
INTRODUCTION The many substances used at the workplace that can cause sensitizer-induced occupational asthma are conventionally categorized into high-molecular-weight (HMW) agents and low-molecular-weight (LMW) agents, implying implicitly that these two categories of agents are associated with distinct phenotypic profiles and pathophysiological mechanisms. AREAS COVERED The authors conducted an evidence-based review of available data in order to identify the similarities and differences between HMW and LMW sensitizing agents. EXPERT OPINION Compared with LMW agents, HMW agents are associated with a few distinct clinical features (i.e. concomitant work-related rhinitis, incidence of immediate asthmatic reactions and increase in fractional exhaled nitric oxide upon exposure) and risk factors (i.e. atopy and smoking). However, some LMW agents may exhibit 'HMW-like' phenotypic characteristics, indicating that LMW agents are a heterogeneous group of agents and that pooling them into a single group may be misleading. Regardless of the presence of detectable specific IgE antibodies, both HMW and LMW agents are associated with a mixed Th1/Th2 immune response and a predominantly eosinophilic pattern of airway inflammation. Large-scale multicenter studies are needed that use objective diagnostic criteria and assessment of airway inflammatory biomarkers to identify the pathobiological pathways involved in OA caused by the various non-protein agents.
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Affiliation(s)
- Virginie Doyen
- Department of Chest Medicine, Centre Hospitalier Universitaire UCL Namur, Université Catholique de Louvain, Yvoir, Belgium
| | - Denyse Gautrin
- Université de Montréal and Hôpital du Sacré-Cœur de Montréal, Montréal, Canada
| | - Olivier Vandenplas
- Department of Chest Medicine, Centre Hospitalier Universitaire UCL Namur, Université Catholique de Louvain, Yvoir, Belgium
| | - Jean-Luc Malo
- Université de Montréal and Hôpital du Sacré-Cœur de Montréal, Montréal, Canada
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Kirkeleit J, Hollund BE, Riise T, Eduard W, Bråtveit M, Storaas T. Bakers' exposure to flour dust. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2017; 14:81-91. [PMID: 27540715 DOI: 10.1080/15459624.2016.1225156] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We aimed to characterize bakers' personal exposure to airborne flour dust with respect to the health-related aerosol fractions inhalable, extrathoracic, and thoracic dust, and to examine possible production-related determinants of dust exposure. Sixty-eight bakers from 7 bakeries in Bergen, Norway (2009-2012) participated in the exposure assessment, comprising full-shift personal samples of inhalable dust (n = 107) and thoracic dust (n = 61). The relation between possible determinants and exposure was estimated using mixed effects models, while associations between the various aerosol fractions across task groups and type of bakeries were described by Pearson's correlation coefficients. Bakers' overall geometric mean personal exposure to inhalable, extrathoracic, and thoracic dust were 2.6 mg/m3 (95% CI: 2.0, 3.2), 2.2 mg/m3 (95% CI: 1.9, 2.7), and 0.33 mg/m3 (95% CI 0.3, 0.4), respectively. A total of 29% of the measurements of inhalable dust were above the Norwegian Occupational Exposure Limit of 3 mg/m3. The exposure variability of inhalable dust could not be explained by any of the examined production-related determinants, while the daily production volume explained 18% of the variance in thoracic dust exposure. Overall, the thoracic dust represented 15% of the inhalable dust, being rather stable across the production-related determinants. The overall correlation between inhalable and thoracic dust was nevertheless moderate (r = 0.52, p < 0.001), with the highest correlation for craft bakers (r = 0.62) and no correlation during dough forming (r = 0.01). Bakers are exposed to flour dust at a level that most likely represents an excess risk of developing chronic diseases of the respiratory system, and a decrease of present exposure level is imperative. Extrathoracic dust-likely the most relevant sub-fraction in respect to flour-induced sensitization and occupational rhinitis-represented the main proportion of the measured inhalable dust. The variation in correlation coefficients between the dust fractions across bakery types and task groups underlines the need of more knowledge about how these aerosol fractions are distributed across the production process and bakery types.
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Affiliation(s)
- Jorunn Kirkeleit
- a Department of Occupational Medicine , Haukeland University Hospital , Bergen , Norway
- b Department of Clinical Science , University of Bergen , Bergen , Norway
| | - Bjørg Eli Hollund
- a Department of Occupational Medicine , Haukeland University Hospital , Bergen , Norway
- b Department of Clinical Science , University of Bergen , Bergen , Norway
| | - Trond Riise
- c Department of Global Public Health and Primary Care , University of Bergen , Bergen , Norway
| | - Wijnand Eduard
- d Department of Chemical and Biological Working Environment , National Institute of Occupational Health , Oslo , Norway
| | - Magne Bråtveit
- a Department of Occupational Medicine , Haukeland University Hospital , Bergen , Norway
- c Department of Global Public Health and Primary Care , University of Bergen , Bergen , Norway
| | - Torgeir Storaas
- a Department of Occupational Medicine , Haukeland University Hospital , Bergen , Norway
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Baatjies R, Meijster T, Heederik D, Jeebhay MF. Exposure-response relationships for inhalant wheat allergen exposure and asthma. Occup Environ Med 2014; 72:200-7. [PMID: 25535033 DOI: 10.1136/oemed-2013-101853] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND A few studies have investigated exposure-response relationships for sensitisation to wheat, work-related symptoms and wheat allergen exposure. IgG4 is suggested to protect against the development of allergic sensitisation. The main aim of this current study was to explore the nature of exposure-response relationships for a range of clinically relevant endpoints among bakery workers, and to investigate the role of IgG4 in these relationships. METHODS A cross-sectional study of 517 supermarket bakery workers in 31 bakeries used a questionnaire, serum-specific IgE and IgG4 to wheat, and methacholine challenge testing. Exposure models were developed previously using job, bakery size, tasks and specific ingredients used. These models were used to predict average personal exposure to wheat allergens. RESULTS The exposure-response relationships for average exposure followed a linear relationship for sensitisation, but a bell-shaped curve for allergic symptoms and probable occupational asthma, increasing up to 10-15 µg/m(3) wheat allergen concentration after which they plateau off and decrease at higher exposure concentrations. This relationship was modified by atopic status. IgG4 levels were strongly exposure related: a clear increase in prevalence of higher IgG4 with increase in wheat allergen exposure was observed among those sensitised and non-sensitised to wheat, with IgG4 even more strongly associated with exposure than IgE to wheat. CONCLUSIONS The bell-shaped exposure-response relationship in the current study is consistent with the findings of previous studies. IgG4 showed no protective effect for sensitisation, confirming the findings of previous studies, suggesting that the pattern is probably related to a healthy worker effect.
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Affiliation(s)
- R Baatjies
- Faculty of Applied Sciences, Department of Environmental and Occupational Studies, Cape Peninsula University of Technology, Cape Town, Western Cape, South Africa Centre for Environmental and Occupational Health Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, Western Cape, South Africa
| | - T Meijster
- Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
| | - D Heederik
- Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
| | - M F Jeebhay
- Centre for Environmental and Occupational Health Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, Western Cape, South Africa
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Coenen P, Mathiassen SE, Kingma I, Boot CRL, Bongers PM, van Dieën JH. Bias and power in group-based epidemiologic studies of low-back pain exposure and outcome--effects of study size and exposure measurement efforts. ACTA ACUST UNITED AC 2014; 59:439-54. [PMID: 25433002 DOI: 10.1093/annhyg/meu102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 10/28/2014] [Indexed: 11/12/2022]
Abstract
OBJECTIVES Exposure-outcome studies, for instance on work-related low-back pain (LBP), often classify workers into groups for which exposures are estimated from measurements on a sample of workers within or outside the specific study. The present study investigated the influence on bias and power in exposure-outcome associations of the sizes of the total study population and the sample used to estimate exposures. METHODS At baseline, lifting, trunk flexion, and trunk rotation were observed for 371 of 1131 workers allocated to 19 a-priori defined occupational groups. LBP (dichotomous) was reported by all workers during 3 years of follow-up. All three exposures were associated with LBP in this parent study (P < 0.01). All 21 combinations of n = 10, 20, 30 workers per group with an outcome, and k = 1, 2, 3, 5, 10, 15, 20 workers actually being observed were investigated using bootstrapping, repeating each combination 10000 times. Odds ratios (OR) with P values were determined for each of these virtual studies. Average OR and statistical power (P < 0.05 and P < 0.01) was determined from the bootstrap distributions at each (n, k) combination. RESULTS For lifting and flexed trunk, studies including n ≥ 20 workers, with k ≥ 5 observed, led to an almost unbiased OR and a power >0.80 (P level = 0.05). A similar performance required n ≥ 30 workers for rotated trunk. Small numbers of observed workers (k) resulted in biased OR, while power was, in general, more sensitive to the total number of workers (n). CONCLUSIONS In epidemiologic studies using a group-based exposure assessment strategy, statistical performance may be sufficient if outcome is obtained from a reasonably large number of workers, even if exposure is estimated from only few workers per group.
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Affiliation(s)
| | - Svend Erik Mathiassen
- 4.Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, SE-801 76 Gävle, Sweden
| | - Idsart Kingma
- 2.MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, van der Boechorststraat 9, NL-1081 BT Amsterdam, the Netherlands 3.Body@Work, Research Center on Physical Activity, Work and Health, the Netherlands
| | - Cécile R L Boot
- 3.Body@Work, Research Center on Physical Activity, Work and Health, the Netherlands 5.Department of Public and Occupational Health, EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, van der Boechorststraat 7, NL-1081 BT Amsterdam, the Netherlands
| | - Paulien M Bongers
- 3.Body@Work, Research Center on Physical Activity, Work and Health, the Netherlands 6.TNO Healthy Living, Leiden, Schipholweg 77-89 NL-2316 ZL Leiden, the Netherlands
| | - Jaap H van Dieën
- 2.MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, van der Boechorststraat 9, NL-1081 BT Amsterdam, the Netherlands 7.King Abdulaziz University, 21589 Jeddah, Saudi Arabia
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Raulf M, Buters J, Chapman M, Cecchi L, de Blay F, Doekes G, Eduard W, Heederik D, Jeebhay MF, Kespohl S, Krop E, Moscato G, Pala G, Quirce S, Sander I, Schlünssen V, Sigsgaard T, Walusiak-Skorupa J, Wiszniewska M, Wouters IM, Annesi-Maesano I. Monitoring of occupational and environmental aeroallergens-- EAACI Position Paper. Concerted action of the EAACI IG Occupational Allergy and Aerobiology & Air Pollution. Allergy 2014; 69:1280-99. [PMID: 24894737 DOI: 10.1111/all.12456] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/30/2014] [Indexed: 11/28/2022]
Abstract
Exposure to high molecular weight sensitizers of biological origin is an important risk factor for the development of asthma and rhinitis. Most of the causal allergens have been defined based on their reactivity with IgE antibodies, and in many cases, the molecular structure and function of the allergens have been established. Significant information on allergen levels that cause sensitization and allergic symptoms for several major environmental and occupational allergens has been reported. Monitoring of high molecular weight allergens and allergen carrier particles is an important part of the management of allergic respiratory diseases and requires standardized allergen assessment methods for occupational and environmental (indoor and outdoor) allergen exposure. The aim of this EAACI task force was to review the essential points for monitoring environmental and occupational allergen exposure including sampling strategies and methods, processing of dust samples, allergen analysis, and quantification. The paper includes a summary of different methods for sampling and allergen quantification, as well as their pros and cons for various exposure settings. Recommendations are being made for different exposure scenarios.
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Affiliation(s)
- M. Raulf
- Institute for Prevention and Occupational Medicine of the German Social Accident Insurance; Ruhr-Universität Bochum (IPA); Bochum Germany
| | - J. Buters
- ZAUM- Center of Allergy & Environment; Helmholtz Zentrum München/Technical Universität München; Christine Kühne Center for Allergy Research and Education (CK-CARE); Member of the German Center of Lung Research (DZL); Munich Germany
| | | | - L. Cecchi
- Interdepartmental Centre of Bioclimatology; University of Florence; Allergy and Clinical Immunology Section; Azienda Sanitaria di Prato; Prato Italy
| | - F. de Blay
- Department of Chest Diseases; University Hospital Strasbourg; Strasbourg France
| | - G. Doekes
- Division of Environmental Epidemiology; Institute for Risk Assessment Sciences (IRAS); Utrecht University; Utrecht the Netherlands
| | - W. Eduard
- Department of Chemical and Biological Work Environment/National Institute of Occupational Health; Institute of Medical Biology; University in Tromsø; Tromsø Norway
| | - D. Heederik
- Division of Environmental Epidemiology; Institute for Risk Assessment Sciences (IRAS); Utrecht University; Utrecht the Netherlands
| | - M. F. Jeebhay
- Centre for Occupational and Environmental Health Research; School of Public Health and Family Medicine, University of Cape Town; Cape Town South Africa
| | - S. Kespohl
- Institute for Prevention and Occupational Medicine of the German Social Accident Insurance; Ruhr-Universität Bochum (IPA); Bochum Germany
| | - E. Krop
- Division of Environmental Epidemiology; Institute for Risk Assessment Sciences (IRAS); Utrecht University; Utrecht the Netherlands
| | - G. Moscato
- Department of Public Health; Experimental and Forensic Medicine of the University of Pavia; Pavia Italy
| | - G. Pala
- Occupational Physician's Division; Local Health Authority of Sassari; Sassari Italy
| | - S. Quirce
- Department of Allergy; Hospital La Paz Institute for Health Research (IdiPAZ) and CIBER of Respiratory Diseases CIBERES; Madrid Spain
| | - I. Sander
- Institute for Prevention and Occupational Medicine of the German Social Accident Insurance; Ruhr-Universität Bochum (IPA); Bochum Germany
| | - V. Schlünssen
- Department of Public Health; Section for Environment; Occupation and Health; Aarhus University; Aarhus Denmark
| | - T. Sigsgaard
- Department of Public Health; Section for Environment; Occupation and Health; Aarhus University; Aarhus Denmark
| | | | | | - I. M. Wouters
- Division of Environmental Epidemiology; Institute for Risk Assessment Sciences (IRAS); Utrecht University; Utrecht the Netherlands
| | - I. Annesi-Maesano
- INSERM; Equipe Epidémiologie des allergies et des maladies respiratorires UMR-S 707; Paris France
- EPAR; Faculté de Médecine Saint-Antoine; UPMC; Paris France
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Baatjies R, Meijster T, Lopata A, Sander I, Raulf-Heimsoth M, Heederik D, Jeebhay M. Exposure to flour dust in South African supermarket bakeries: modeling of baseline measurements of an intervention study. ACTA ACUST UNITED AC 2010; 54:309-18. [PMID: 20200089 DOI: 10.1093/annhyg/meq005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
INTRODUCTION Exposure to flour dust has been reported as an important risk factor for allergic respiratory disease among bakery workers. A high prevalence of allergic sensitization and asthma was recently reported in South African supermarket bakeries. The aim of this study was to conduct a detailed exposure assessment of these bakeries so as to provide the baseline for a broader intervention study. METHODS A total of 211 full-shift personal samples were collected on randomly selected individuals within five different job categories in 18 bakeries. The samples were analyzed for particulate mass and specific flour dust allergens (wheat, rye, and fungal alpha-amylase). Exposure models were developed using job, bakery size, tasks, and specific ingredients used. Bakery and worker were regarded as random effect components. RESULTS Bread bakers had the highest average (geometric mean) exposures (1.33 mg m(-3) flour dust particulate, 13.66 microg m(-3) wheat allergens, and 5.14 microg m(-3) rye allergens). For alpha-amylase allergens, most samples were below the limit of detection for several occupational titles. In the mixed effect models, the significant predictors of elevated exposure to inhalable dust particulate as well as wheat and rye allergen concentrations were large bakery size, bread baking, and use of cereal flours, while tasks such as confectionery work were negatively correlated with these exposure metrics. Weighing tasks and use of premix products were associated with increased exposure to fungal alpha-amylase. A high correlation between particulate dust and wheat (r = 0.84) as well as rye (r = 0.86) was observed, with a much lower correlation between particulate dust and fungal alpha-amylase (r = 0.33). Overall, a low proportion (39%) of bakery stores implemented various control measures to reduce dust exposures in the bakeries. CONCLUSIONS This study confirms that current exposure control strategies in supermarket bakery stores are inadequate in reducing dust exposures to protect the health of bakery workers.
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Affiliation(s)
- Roslynn Baatjies
- Department of Environmental and Occupational Studies, Faculty of Applied Sciences, Cape Peninsula University of Technology, Cape Town 8001, South Africa
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Jacobs JH, Meijster T, Meijer E, Suarthana E, Heederik D. Wheat allergen exposure and the prevalence of work-related sensitization and allergy in bakery workers. Allergy 2008; 63:1597-604. [PMID: 18513267 DOI: 10.1111/j.1398-9995.2008.01698.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Occupational airway diseases are common among bakers. The present study describes the association between exposure to wheat allergen levels and sensitization to wheat allergens, work-related upper and lower respiratory symptoms and asthma in bakery workers. METHODS As part of a Health Surveillance System for early detection of (allergic) occupational airway diseases a so-called 'validation study' was performed among Dutch bakers for validation of a diagnostic model that predict the likelihood of sensitization to specific workplace allergens. The present study used serology and questionnaire results of a subgroup of 860 bakers participating in the validation study. An earlier developed job-exposure matrix was used to predict average and cumulative personal exposure to wheat allergens. RESULTS The prevalence of wheat sensitization, work-related respiratory symptoms and asthma increased till average wheat exposure levels of approximately 25-30 microg/m3, leveled off and decreased at higher exposure concentrations. Exposure-response curves showed a stronger pronounced bell-shape with cumulative exposure. Associations were strongest for asthma and work-related lower respiratory symptoms (PR approximately 2 and PR approximately 3.5-4.5 for average and cumulative exposure, respectively). Associations were only found in atopics. Wheat sensitization was an important factor in the prevalence of respiratory symptoms. CONCLUSION In accordance with earlier studies, the present study showed a bell-shaped exposure-response relationship especially for cumulative wheat allergen exposure with sensitization, allergic respiratory symptoms and asthma. The healthy worker effect may be the possible explanation for the bell-shaped relationship.
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Affiliation(s)
- J H Jacobs
- Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
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Woodward K. Assessment of user safety, exposure and risk to veterinary medicinal products in the European Union. Regul Toxicol Pharmacol 2008; 50:114-28. [DOI: 10.1016/j.yrtph.2007.10.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Revised: 10/10/2007] [Accepted: 10/10/2007] [Indexed: 10/22/2022]
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Bogdanovic J, Wouters IM, Sander I, Raulf-Heimsoth M, Elms J, Rodrigo MJ, Heederik DJJ, Doekes G. Airborne exposure to wheat allergens: measurement by human immunoglobulin G4 and rabbit immunoglobulin G immunoassays. Clin Exp Allergy 2007; 36:1168-75. [PMID: 16961717 DOI: 10.1111/j.1365-2222.2006.02543.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Exposure to airborne wheat allergens in the bakery trade is associated with a high risk of occupational allergy and asthma. Control and reduction of allergen exposure require relatively simple but reliable monitoring techniques. We developed new rabbit IgG-based enzyme immunoassays (EIA) for wheat allergens, which might be a convenient alternative for the thus far used human IgG4 inhibition assay. METHODS The reactivity and specificity of rabbit antibodies were assessed by EIA and immunoblotting, and compared with those of IgE from wheat-sensitized bakers, and with the antibodies used in the IgG4 inhibition EIA. An IgG inhibition and a sandwich EIA were developed for analysis of airborne dust samples. RESULTS Human IgG4 and rabbit IgG inhibition EIAs had comparable sensitivities, with limits of detection (LOD) between 18 and 88 ng/mL, while the sandwich EIA was much more sensitive (LOD<0.2 ng/mL). Human IgG4 and rabbit IgG reacted in immunoblotting with most of the IgE-binding wheat proteins, although with quantitative differences. All three assays showed a strong reaction with wheat proteins, and some cross-reactivity with rye and barley, but were further highly specific for cereal flour proteins. Concentrations measured with the three EIAs in 432 airborne dust samples were highly correlated (r>0.95) and their absolute values showed less than 10-20% differences. CONCLUSION The rabbit IgG EIAs are valid substitutes for the human IgG4 inhibition EIA, with important practical advantages. The inhibition EIA is recommended for routine wheat allergen measurements. The sandwich EIA may be used to measure low allergen levels, as in short task-related exposure measurements or in subfractions of airborne dust samples.
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Affiliation(s)
- J Bogdanovic
- Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, The Netherlands.
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Symanski E, Maberti S, Chan W. A Meta-Analytic Approach for Characterizing the Within-Worker and Between-Worker Sources of Variation in Occupational Exposure. ACTA ACUST UNITED AC 2006; 50:343-57. [PMID: 16513810 DOI: 10.1093/annhyg/mel006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
While many studies have quantified the sources of variation in exposure to workplace contaminants for individual groups of workers, patterns of exposure variability have not been investigated since a comprehensive evaluation was carried out over 10 years ago. Therefore, a systematic review of the literature was conducted to identify studies that applied the one-way random-effects model to describe exposure profiles of groups of workers classified on the basis of the kind of work performed and where it was performed. Quantitative estimates of the sources of variation in exposure along with information related to the workplace, contaminant and sampling strategy were compiled. For subsets of the data, based upon the classification scheme used to group workers, weighted empirical cumulative distribution functions were constructed and compared using the non-parametric Kolomogorov-Smirnov two-sample test. Further stratifications evaluated differences by industry, agent and characteristics of the sampling strategy. The review identified nearly 60 studies that examined the within-worker and between-worker sources of variation in exposure to workplace contaminants. In pooling results across studies, the between-worker variability increased as workers were aggregated across jobs and locations. The within-worker variability for an occupational group of workers was generally larger than the between-worker variability, although the differences in the variation in exposures across work shifts relative to the variation among workers' mean exposure levels diminished as groups were combined across jobs and locations. On average, gaseous exposures were more homogeneous than exposures to aerosols or dermal agents as were exposures in the chemical industry compared with the non-chemical industry. The design of sampling strategies also plays an important role with greater variability among groups of workers who were sampled randomly rather than systematically; in addition, differences were detected on the basis of the study period and sample size. In evaluating key features of the design and methods of the studies identified in the review, several methodological issues emerged given the heterogeneity in terms of how censored data were handled, which estimation method was applied and whether underlying assumptions of the models were met. Notwithstanding the utility of quantifying sources of variation in exposure, several challenges lie ahead with regard to ensuring quality in the collection, analysis and reporting of exposure monitoring data that would enhance efforts to accurately assess exposure.
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Affiliation(s)
- Elaine Symanski
- The University of Texas School of Public Health at Houston, 1200 Herman Pressler Drive, Houston, TX 77030, USA.
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Bogdanovic J, Wouters IM, Sander I, Zahradnik E, Joanne HR, Rodrigo MJ, Gómez-Ollés S, Heederik DJJ, Doekes G. Airborne exposure to wheat allergens: optimised elution for airborne dust samples. ACTA ACUST UNITED AC 2006; 8:1043-8. [PMID: 17240910 DOI: 10.1039/b608770a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Well-validated methods for measuring airborne occupational allergens are essential for effective control and reduction of allergen exposures. For wheat flour allergens, specific immunoassays are available, but there is a need for optimisation and standardization of sample processing procedures. Wheat flour allergen elution and storage were studied using airborne dust samples collected in bakeries with a new parallel sampler. Forty-eight series of 9 parallel filters were subjected to extraction procedures varying in elution medium, shaking method, extraction vial, and centrifugation speed. Wheat allergens were measured with enzyme immunoassays, and the effect of various procedures evaluated by mixed regression analyses. The stability of the eluted allergens was assessed after storage for 20 days and 4 months at -20 degrees C, in the presence or absence of casein in the medium. Only the type of elution medium had significant effects on allergen recovery: addition of Tween-20 resulted in 3- to 100-fold increased levels, an effect that was most pronounced at low concentrations. Allergen levels in extracts were stable for at least 4 months at -20 degrees C, irrespective of the presence of casein in the medium. Addition of Tween-20 to the elution medium is essential for optimal extraction of wheat allergen. The recommended procedure further includes the use of conventional polystyrene tubes, simple shaking methods, and centrifugation after extraction. Wheat dust extracts in PBS-Tween can be stored frozen for at least 4 months, and addition of a stabilising protein is not required.
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Affiliation(s)
- Jelena Bogdanovic
- Institute for Risk Assessment Sciences, Division Environmental Epidemiology, Utrecht University, P.O. Box 80178, 3508 TD, The Netherlands.
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