Symptoms, airway responsiveness, and exposure to dust in beech and oak wood workers

Effects of mixed hardwoods dust on respiratory function and blood immunoglobulin levels in wood workers

Background

Occupational exposure to wood dust, generated by various individual wood species, both softwood and hardwood, has been extensively documented as a causative factor for reduced lung function, frequent respiratory symptoms, and increased immunological responses in wood workers. This study explores the impact of wood dust from mixed tropical hardwood species on lung function, respiratory symptoms, and Immunoglobulin (Ig) E and G levels.

Methods

A cross-sectional study was conducted among wood workers at the Accra Timber Market and a control group from the University of Ghana. Particulate matter (PM) was sampled using a Minivol Sampler set to a flow rate of 5 l/min. Respiratory symptoms were assessed using questions adapted from the British Medical Research Council (MRC) questionnaire (1960). Lung volumes and airflow rates were measured using a spirometer. Total serum IgE and IgG levels were quantified using ELISA.

Results

No significant differences were observed between the wood workers and the controls for demographic variables. Wood workers exhibited a significantly higher prevalence of respiratory symptoms, particularly rhinitis, with many reporting the absence of symptoms during holidays. Lung function parameters (VC, FEV1, FEV1%, PEFR, and FEF25-75%) were significantly reduced (p < 0.05) in wood workers. A significant negative correlation was noted between lung function parameters and years of exposure to wood dust. Wood workers showed significantly elevated levels (p < 0.05) of IgG and IgE.

Conclusion

The study findings suggest that exposure to mixed tropical hardwood dust induces elevated blood IgE and IgG levels, along with non-allergic respiratory function abnormalities.

Effect of E. cava and C. indicum Complex Extract on Phorbol 12-Myristate 13-Acetate (PMA)-Stimulated Inflammatory Response in Human Pulmonary Epithelial Cells and Particulate Matter (PM)2.5-Induced Pulmonary Inflammation in Mice

This study explores the potential of a natural composite formulation known as ED, consisting of Ecklonia cava (E. cava, family: Lessoniaceae) and Chrysanthemum indicum Linne (C. indicum, family: Asteraceae), in alleviating lung inflammation induced by fine particulate matter (PM2.5). Initial assessments confirmed that neither ED nor one of its components, dieckol, exhibited cytotoxic effects on A549 cells. Subsequently, the impact of ED and dieckol on MUC5AC gene expression in A549 cells stimulated by phorbol 12-myristate 13-acetate (PMA) was investigated, revealing promising results that demonstrated a dose-dependent inhibition of MUC5AC gene expression. The study also delves into the underlying mechanisms, demonstrating that ED and dieckol effectively suppressed the phosphorylation of mitogen-activated protein kinases (MAPKs), including JNK, ERK, and p38, which are known to be involved in the regulation of MUC5AC gene expression. In in vivo experiments using a PM2.5-induced pulmonary inflammation mouse model, the research findings showed that ED mitigated cellular accumulation in the airways, leading to a significant reduction in the total cell count in bronchoalveolar lavage fluid (BALF). Moreover, ED exhibited protective effects against PM2.5-induced pulmonary damage, characterized by reduced inflammatory cell infiltration and decreased mucus secretion in pulmonary tissues. Additionally, ED's anti-inflammatory properties were evident in its ability to decrease the levels of key inflammatory cytokines, TNF-α and IL-6, both in the serum and lung tissue of the PM2.5-induced pulmonary inflammation mouse model. These findings suggest the potential of ED as a therapeutic agent for inflammatory respiratory diseases.

Occupational Etiology of Oropharyngeal Cancer: A Literature Review

While abundant evidence exists linking alcohol, tobacco, and HPV infection to a carcinogenic impact on the oropharynx, the contribution of inhalational workplace hazards remains ill-defined. We aim to determine whether the literature reveals occupational environments at a higher-than-average risk of developing oropharyngeal cancer (OPC) and summarize the available data. To identify studies assessing the relationship between occupational exposure and risk of OPC, a search of the literature through the PubMed-NCBI database was carried out and, ultimately, 15 original articles meeting eligibility criteria were selected. Only original articles in English focusing on the association between occupational exposure and risk or death of specifically OPC were included. The available data are supportive of a potentially increased risk of OPC in waiters, cooks and stewards, artistic workers, poultry and meat workers, mechanics, and World Trade Center responders exposed to dust. However, the available literature on occupation-related OPC is limited. To identify occupational categories at risk, large cohorts with long follow-ups are needed. Identification of causal associations with occupation-related factors would require dose-response analyses adequately adjusted for confounders.

Dynamics of pre-shift and post-shift lung function parameters among wood workers in Ghana

Background

Diseases affecting the lungs and airways contribute significantly to the global burden of disease. The problem in low- and middle-income countries appears to be exacerbated by a shift in global manufacturing base to these countries and inadequate enforcement of environmental and safety standards. In Ghana, the potential adverse effects on respiratory function associated with occupational wood dust exposure have not been thoroughly investigated.

Methods

Sixty-four male sawmill workers and 64 non-woodworkers participated in this study. The concentration of wood dust exposure, prevalence and likelihood of association of respiratory symptoms with wood dust exposure and changes in pulmonary function test (PFT) parameters in association with wood dust exposure were determined from dust concentration measurements, symptoms questionnaire and lung function test parameters.

Results

Sawmill workers were exposed to inhalable dust concentration of 3.09 ± 0.04 mg/m3 but did not use respirators and engaged in personal grooming habits that are known to increase dust inhalation. The sawmill operators also showed higher prevalence and likelihoods of association with respiratory symptoms, a significant cross-shift decline in some PFT parameters and a shift towards a restrictive pattern of lung dysfunction by end of daily shift. The before-shift PFT parameters of woodworkers were comparable to those of non-woodworkers, indicating a lack of chronic effects of wood dust exposure.

Conclusions

Wood dust exposure at the study site was associated with acute respiratory symptoms and acute changes in some PFT parameters. This calls for institution and enforcement of workplace and environmental safety policies to minimise exposure at sawmill operating sites, and ultimately, decrease the burden of respiratory diseases.

The impact of wood dust on pulmonary function and blood immunoglobulin E, erythrocyte sedimentation rate, and C‐ reactive protein: A cross‐sectional study among sawmill workers in Tangail, Bangladesh

Background and Aims

Occupational exposure to wood dust leads to lung function abnormalities that are prominent causes of morbidity and disability of sawmill workers. The adverse respiratory effects of wood dust in sawmills have not been studied thoroughly in Bangladesh. This study aimed to investigate the effect of wood dust on the respiratory health of sawmill workers compared to controls as well as to determine the association of wood dust‐exposing effects with inflammatory blood biomarkers, such as immunoglobulin E (IgE), erythrocyte sedimentation rate (ESR), and C‐reactive protein (CRP).

Methods

This cross‐sectional study included 100 sawmill workers from 25 distinct sawmills in various areas of Tangail, Bangladesh as well as 100 healthy volunteers who were adopted as a control group. Questionaries' survey and pulmonary function tests were performed face to face. Furthermore, after performing lung function tests, blood was drawn for further IgE, ESR, and CRP analyses.

Results

Respiratory symptoms including breathlessness (32%), coughing (39%), sneezing (43%), chest tightness (30%), and itching (40%) were significantly higher in sawmill workers compared with control. Besides, sawmill workers' exposure to wood dust revealed a significantly lower level of spirometry parameters (forced vital capacity ​​​​​[FVC], FVC (%), forced expiratory volume in 1 s [FEV1], FEV1 (%), peak expiratory flow [PEF], PEF (%), FEV1/FVC (%), FEF25, FEF75, and FEF2575) compared with control and these spirometry parameters decreased with the increasing length of service. Moreover, a significantly higher level of IgE was observed in sawmill workers (290.90 ± 39.49) than in the control (120.95 ± 23.00). The high level of IgE suggests that the lower pulmonary function may be linked to allergic responses to wood dust among sawmill workers.

Conclusion

This study suggested that exposure to wood dust can cause impairment of respiratory function along with high IgE levels.

Wood Dust Exposure Levels and Respiratory Symptoms 6 Years Apart: An Observational Intervention Study Within the Danish Furniture Industry

OBJECTIVES

Occupational exposure to wood dust can cause respiratory diseases, but few studies have evaluated the impact of declining exposure on health outcome. This study aimed to investigate whether a decline in wood dust exposure between two cross sectional studies performed in 1997-1998 and 2003-2004 was related to the prevalences of respiratory symptoms among woodworkers in a well-defined geographical area.

METHODS

Two thousand and thirty-two woodworkers from 54 plants in study 1 and 1889 woodworkers from 52 plants in study 2 returned a questionnaire on respiratory diseases and symptoms, employment and smoking habits. Current individual wood dust exposure level was assessed from 2 study specific job exposure matrix's based on task, factory size and personal passive dust measurements (2217 in study 1 and 1355 in study 2).

RESULTS

The median (range) of inhalable dust was 1.0 mg/m3 (0.2-9.8), 0.6 mg/m3 (0.1-4.6) in study 1 and study 2, respectively. In study 2, the prevalence's of self-reported asthma was higher and the prevalence's of respiratory symptoms were lower compared to study 1. In adjusted logistic regression analyses using GEE methodology to account for clustering, dust exposure level could explain the differences in prevalence of coughing, chronic bronchitis and nasal symptoms between study 1 and study 2, while no effect was found for asthma.

CONCLUSIONS

A 40% decline in wood dust exposure in a 6 year period may serve as an explanation for the decline in most respiratory symptoms, but do not seems to impact the prevalence of self-reported asthma.

Workplace exposure to wood dust and the prevalence of wood-specific sensitization

Wood is processed worldwide, and occupational exposure to wood dust is affecting millions of workers. Studies have identified wood dust as a risk factor for non-malignant respiratory diseases consistent with both an allergic and a non-allergic origin. This paper summarizes our current knowledge on the importance of specific sensitization among subjects occupationally exposed to wood dust. Specific sensitization to wood dust exists, but is probably of minor importance for most wood species. In order to move the research field forward increased focus on more standardized tools for specific IgE (sIgE) diagnostics is needed and more specific tools are necessary to identify clinical relevant cases of wood dust sensitization. Moreover epidemiological studies on the occurrence of sIgE-mediated sensitization in different populations of woodworkers are needed.

Functional disorders of the lung and symptoms of respiratory disease associated with occupational inhalation exposure to wood dust in Iran

OBJECTIVES

The possible adverse respiratory effects of airborne pollutants in sawmills have not been thoroughly investigated in Iran. Additionally, the extent to which workers are exposed to this organic dust and its associated bioaerosols has not been extensively quantified. Likewise, the predominant bacterial and fungal species associated with wood dust have not been characterized. The present study was undertaken to address these issues.

METHODS

One hundred male individuals exposed to wood dust and 100 unexposed male subjects were investigated. They completed a standardized respiratory symptom questionnaire and underwent spirometry testing. Additionally, airborne concentrations of respirable and inhalable dust particles, bacteria, and fungi were measured.

RESULTS

The mean concentrations of inhalable and respirable dust particles, bacteria, and fungi were found to be 2.44, 6.76 mg/m³ , 756.38, and 299.15 colony-forming units/m³ , respectively. The predominant Gram-negative bacteria in the sawmills included the Pseudomonadaceae, Klebsiella pneumoniae, and Rhinoscleromatis spp., and the predominant fungi consisted of the zygomycetes and Aspergillus spp. Respiratory symptoms were significantly more prevalent among exposed workers. Significant cross-shift decrements were noted in some pulmonary function parameters. Similarly, pre-shift spirometry results indicated that some pulmonary function parameters were significantly lower in the exposed group.

CONCLUSIONS

Exposure to wood dust and its bioaerosols was associated with significantly higher prevalence of respiratory symptoms and both acute (i.e., partially reversible) and chronic (i.e., irreversible) decrements in the functional capacity of the lung. Additionally, the characterized bioaerosols did not differ significantly from those isolated in other parts of the world.

Asthma in furniture and wood processing workers: a systematic review

BACKGROUND

Wood dust is a common cause of occupational asthma. There is potential for high exposure to wood dust during furniture and wood manufacturing processes.

AIMS

To evaluate the evidence for non-neoplastic respiratory ill health associated with work in the furniture and wood manufacturing sector.

METHODS

A systematic review was performed according to PRISMA guidelines. Articles were graded using SIGN (Scottish Intercollegiate Guideline Network) and MERGE (Methods for Evaluating Research Guidelines and Evidence) criteria, with data grouped by study outcome.

RESULTS

Initial searches identified 1328 references, from which 55 articles were included in the review. Fourteen studies were graded A using MERGE or >2++ using SIGN. All but one paper describing airway symptoms reported an increased risk in higher wood dust exposed workers in comparison to lower or non-exposed groups. Five studies reporting asthma examined dose response; three found a positive effect. The relative risk for asthma in exposed workers in the single meta-analysis was 1.5 (95% CI 1.25-1.87). Two studies reported more obstructive lung function (forced expiratory volume in 1 s [FEV1]/forced vital capacity < 0.7) in exposed populations. Excess longitudinal FEV1 decline was reported in female smokers with high wood dust exposures in one study population. Where measured, work-related respiratory symptoms did not clearly relate to specific wood immunoglobulin E positivity.

CONCLUSIONS

Work in this sector was associated with a significantly increased risk of respiratory symptoms and asthma. The evidence for wood dust exposure causing impaired lung function is less clearly established. Further study is required to better understand the prevalence, and causes, of respiratory problems within this sector.

Occupational asthma caused by samba (Triplochiton scleroxylon) wood dust in a professional maker of wooden models of airplanes: a case study

OBJECTIVES

Wood dust is a known occupational allergen that may induce, in exposed workers, respiratory diseases including asthma and allergic rhinitis. Samba (obeche, Triplochiton scleroxylon) is a tropical tree, which grows in West Africa, therefore, Polish workers are rarely exposed to it. This paper describes a case of occupational asthma caused by samba wood dust.

MATERIAL AND METHODS

The patient with suspicion of occupational asthma due to wood dust was examined at the Department of Occupational Diseases and Clinical Toxicology in the Nofer Institute of Occupational Medicine. Clinical evaluation included: analysis of occupational history, skin prick tests (SPT) to common and occupational allergens, determination of serum specific IgE to occupational allergens, serial spirometry measurements, metacholine challenge test and specific inhalation challenge test with samba dust

RESULTS

SPT and specific serum IgE assessment revealed sensitization to common and occupational allergens including samba. Spirometry measurements showed mild obstruction. Metacholine challenge test revealed a high level of bronchial hyperactivity. Specific inhalation challenge test was positive and cellular changes in nasal lavage and induced sputum confirmed allergic reaction to samba.

CONCLUSIONS

IgE mediated allergy to samba wood dust was confirmed. This case report presents the first documented occupational asthma and rhinitis due to samba wood dust in wooden airplanes model maker in Poland.

Self-employment in joinery: an occupational risk facor?

OBJECTIVES

Only a few studies have analyzed the health of self-employed workers. This cross-sectional study is the first to compare health status among craftsmen joiners and paid joiners.

MATERIAL AND METHODS

Clinical and paraclinical data for self-employed craftsmen and employees were collected by occupational health doctors according to a standardized protocol and compared. Health data and professional status relationships were analyzed by logistic regression.

RESULTS

A total of 171 craftsmen and 196 paid workers were included. Craftsmen had more dermatologic pathologies (odds ratio (OR) = 2.67, p < 0.05), ear/nose/throat symptoms (OR = 3.38, p < 0.001), pulmonary symptoms (OR = 2.46, p < 0.05), musculoskeletal symptoms (OR = 3.09, p < 0.001), and abnormal audiogram (OR = 3.50, p < 0.001). The FEV1 was significantly lower among craftsmen (p < 0.01), independently of tobacco smoke exposure.

CONCLUSIONS

This survey high-lights a high morbidity rate among self-employed craftsmen, suggesting that among woodworkers, professional status can be a risk factor for health. The preventive medical system for craftsmen has to be rethought to guarantee better safety for this population.

Work-related sensitization and respiratory symptoms in carpentry apprentices exposed to wood dust and diisocyanates

BACKGROUND

Exposure to certain substances in the workplace may lead to sensitization and increased respiratory symptoms.

OBJECTIVE

To evaluate the frequency of work-related specific sensitization and respiratory symptoms in carpentry apprentices with occupational exposure to wood dust and diisocyanates.

METHODS

Apprentices (n=101) completed an occupational and symptoms questionnaire. Spirometry and skin prick tests to aeroallergens and to a battery of 14 different woods were performed in all the participants. Blood samples were collected for total IgE measurement and detection of specific IgE to diisocyanates.

RESULTS

Half the participants (56%) had work-related respiratory symptoms: 54% due to wood dust, 15% due diisocyanates, and 9% to both. Participants with respiratory symptoms related to wood dust exposure had a significantly lower forced expiratory volume in 1 second compared with symptomatic individuals due to diisocyanates and asymptomatic individuals (P < .05). A history of rhinitis or asthma was associated with a 2.1- or 2.8-fold increase, respectively, in the likelihood of having respiratory symptoms due to wood dust exposure. Sensitization to wood was detected in 9% of participants, all of whom were atopic with a history of rhinitis and a high total IgE level (P < .05). Sensitization to diisocyanates was detected in 2% of exposed participants.

CONCLUSIONS

Work-related respiratory symptoms are common in carpentry apprentices and are more frequently related to exposure to wood dust than to diisocyanates. Symptomatic participants due to wood dust exposure had a lower forced expiratory volume in 1 second. Individuals with a history of rhinitis or asthma had an increased risk of respiratory symptoms. Sensitization to wood was more common in atopic apprentices with a history of rhinitis and a high total IgE level.

Lung function: occupational exposure to wood dust

Objectives

Occupational exposure to wood dust has been shown to cause several respiratory disorders, such as allergic rhinitis, chronic bronchitis, asthma, sino-nasal adenocarcinoma, and impairment of lung function. The aim of the study was to estimate lung function (in the woodworking industry) among workers employed by wood processing, who run the risk of being expose to wood dust.

Methods

The study concerns a group of 70 workers aged 24-55. All the workers underwent general and laryngological examination. A group of 20 workers, working at the positions where dustiness exceeded TLV (threshold limit value) took X-ray of the chest and spirometry. The following parameters were measured: VC, IC, ERV, TV, BF, FEV₁, FVC, PEF, MEF^25-75, FEV₁%FVC, FEV₁%VC. The data are presented as means ± SD and the authors applied references values according to ERS guidelines.

Results

The results show that there was no decline in FEV₁ (3.7 ± 0.7) and FVC (4.5 ± 0.8). Normal lung function was defined as FEV₁/VC ratio ≥0.7. None of the tested workers had obstructive pattern in spirometry. The mean FEV₁%VC was 77.1 ± 10.2. These results suggest that wood dust exposure might not lead to significant pulmonary damage.

Conclusions

These data do not corroborate that wood dust plays significant role in lung function impairment. Future studies of respiratory health among workers exposed to wood dust are needed.

Exposure to wood dust and its particle size distribution in a rubberwood sawmill in Thailand

A cross-sectional study on wood dust exposure and respiratory health effects was conducted at one of the largest rubberwood sawmills in Thailand. All workers (N = 340) from all jobs on a day shift were recruited for personal sampling. Overall, the personal inhalable dust (n = 742) and respirable dust (n = 241) of full-shift samples were collected from 27 job titles. These data were used to classify workers into high, moderate, and low exposure groups based on the concentrations found in each job. Static samples were also collected to determine the particle size distribution. Geometric means (GM) are used to present the concentrations of the rubber wood dust. Inhalable dust concentrations were clearly high, ranging between 0.2 to 59.4 mg/m3 and with GM of 4.7 mg/m3. The GM of inhalable dust in each job title enabled classification of the workers into three exposure groups: (1) high exposure; >5 mg/m3, (2) moderate exposure; 2.0-5.0 mg/m3, and (3) low exposure; 0.18-1.9 mg/m3. Among the high exposure group, the highest GM inhalable dust concentrations were found in sawing green lumber (12.8 mg/m3) and cutting dry lumber (7.3 mg/m3). The respirable dust concentrations were generally low, in the range of 0.1 to 6.0 mg/m3 with a GM of 0.5 mg/m3. The largest percentage of dust in major operations belonged to the thoracic fraction; 50% cutoff diameter was smaller than 9 mum. The size distribution of wood dust indicated a high proportion in the large particle sizes.

Determinants of wood dust exposure in the Danish furniture industry--results from two cross-sectional studies 6 years apart

Objectives: This paper investigates determinants of wood dust exposure and trends in dust level in the furniture industry of Viborg County, Denmark, using data from two cross-sectional studies 6 years apart.

Methods: During the winter 1997/1998, 54 factories were visited (hereafter study 1). In the winter 2003/2004, 27 factories were revisited, and personal dust measurements were repeated. In addition, 14 new factories were included (hereafter study 2). A total of 2303 woodworkers participated in study 1, and 2358 measurements from 1702 workers were available. From study 2, 1581 woodworkers participated and 1355 measurements from 1044 workers were available. Information on occupational variables describing potential determinants of exposures like work task, exhaust ventilation, enclosure and cleaning procedures were collected. A total of 2627 measurements and 1907 persons were included in the final mixed model in order to explore determinants of exposure and trends in dust level.

Results: The overall inhalable wood dust concentration (geometric means (geometric standard deviation)) has decreased from 0.95 mg/m³ (2.05) in study 1 to 0.60 mg/m³ (1.63) in study 2, representing a 7% annual decrease in dust concentration, which was confirmed in the mixed model. From study 1 to study 2 there has been a change towards less manual work and more efficient cleaning methods, but on the contrary also more inadequate exhaust ventilation systems. The following determinants were found to ‘increase’ dust concentration: sanding; use of compressed air; use of full-automatic machines; manual work; cleaning of work pieces with compressed air; kitchen producing factories and small factories (<20 employees). The following determinants of exposure were found to ‘decrease’ dust concentration: manual assembling/packing; sanding with adequate exhaust ventilation; adequate exhaust ventilation; vacuum cleaning of machines and special cleaning staff.

Conclusions: Despite a substantial drop in the dust concentration during the last 6 years in the furniture industry in Viborg County, further improvements are possible. There should be more focus on improved exhaust ventilation, professional cleaning methods and avoiding use of compressed air.

Does the inclusion of wheeze detection as an outcome measure affect the interpretation of methacholine challenge tests? A study in workers at risk of occupational asthma

Methacholine challenge testing (MCT) is widely used to assess airway hyperresponsiveness (AHR). Traditionally, a 20% or greater decline in forced expiratory volume in 1 (FEV(1)) is the primary outcome measure. We examined whether the inclusion of wheeze detection as outcome measure influenced the categorical interpretation of MCT in workers at risk of occupational asthma (OA). We examined 28 occupationally exposed smokers with asthma-like symptoms (SympAsth), 22 asymptomatic, occupationally exposed smokers (Symp0), and 30 nonexposed, asymptomatic controls (Ctrl). MCT was done using an abbreviated technique. Spirometry and tracheal wheezes were recorded using a computerized system. MCT was considered either positive or negative using three outcome measures separately: (1) > or = 20% fall in FEV(1) (MCT("FEV1")); (2) wheeze appearance (MCT("Wheeze")); and (3) whichever among the two was present (MCT("FEV1Wheeze")). The proportion of reactors in each group were, by outcome measure, as follows: MCT("FEV1"): Ctrl = 2 (6.7%), Symp0 = 6 (27.3%), SympAsth = l2 (42.8%) (chi(2) = 10.2; p = 0.006); MCT("Wheeze"): Ctrl = 1 (3.3%), Symp0 = 4 (18.2%), SympAsth = 13 (46.4%) (chi(2) = l5.7; p = 0.001); MCT("FEV1Wheeze") Ctrl = 2 (6.7%), Symp0 = 7 (31.8%), SympAsth = 18 (64.3%) (chi(2) = 21.5; p = 0.001). Overall, including wheeze detection increased the proportion of "reactors" detected by spirometry by 30% (27 reactors vs. 20). This increase reached 50% (18 vs. 12) among workers with asthma like symptoms. In summary, the inclusion of wheeze detection as outcome measure for MCT allowed the recognition as reactors of subjects that otherwise would be "missed" by spirometry. The resulting increase in the number of true positives improved the sensitivity of MCT to detect AHR in occupationally exposed workers at risk of occupational asthma.

Mechanisms of particle-induced pulmonary inflammation in a mouse model: exposure to wood dust

Repeated airway exposure to wood dust has long been known to cause adverse respiratory effects such as asthma and chronic bronchitis and impairment of lung function. However, the mechanisms underlying the inflammatory responses of the airways after wood dust exposure are poorly known. We used a mouse model to elucidate the mechanisms of particle-induced inflammatory responses to fine wood dust particles. BALB/c mice were exposed to intranasally administered fine (more than 99% of the particles had a particle size of < or = 5 microm, with virtually identical size distribution) birch or oak dusts twice a week for 3 weeks. PBS, LPS, and titanium dioxide were used as controls. Intranasal instillation of birch or oak dusts elicited influx of inflammatory cells to the lungs in mice. Enhancement of lymphocytes and neutrophils was seen after oak dust exposure, whereas eosinophil infiltration was higher after birch dust exposure. Infiltration of inflammatory cells was associated with an increase in the mRNA levels of several cytokines, chemokines, and chemokine receptors in lung tissue. Oak dust appeared to be a more potent inducer of these inflammatory mediators than birch dust. The results from our in vivo mouse model show that repeated airway exposure to wood dust can elicit lung inflammation, which is accompanied by induction of several proinflammatory cytokines and chemokines. Oak and birch dusts exhibited quantitative and qualitative differences in the elicitation of pulmonary inflammation, suggesting that the inflammatory responses induced by the wood species may rise via different cellular mechanisms.

Identification of an obeche (Triplochiton scleroxylon) wood allergen as a class I chitinase

BACKGROUND

Wood dust is known to cause allergic occupational asthma and obeche (Triplochiton scleroxylon) is a prominent exponent in this field. However, the knowledge about wood allergens is still limited. The aim of this study was to identify and characterize obeche wood allergens.

METHODS

Obeche extracts were prepared from freshly ground in comparison to 7 years stored wood dust and investigated by Sodium dodecyl sulfate-polyacrylamid gel electrophoresis, enzyme-linked allergosorbent test and immunoglobulin (Ig)E-immunoblot. Allergens were detected by specific IgE of seven obeche allergic patients' sera and protein analysis was performed by mass spectrometry. Cross-reactivity was demonstrated by ImmunoCAP-inhibition with sera of seven obeche and four latex-allergic patients.

RESULTS

Obeche extracts showed different protein pattern and IgE-binding capacities depend on the age of the wood dust. A 38 kDa protein was identified as major obeche wood allergen, detected by six of seven (85%) obeche allergic patients' sera and was entitled as Trip s 1. Trip s 1 is homologous to plant class I chitinases and exhibited enzyme activity demonstrated by chitinolysis. Co-recognition or cross-reactivity of Trip s 1 according to structural similarity was seen in sera of latex allergic patients. IgE inhibition studies with obeche as solid phase and Trip s 1 and latex hevein as inhibitor demonstrated that Trip s 1 was a more effective inhibitor in obeche as well as in latex allergic patients' sera.

CONCLUSIONS

Trip s 1 is a new obeche wood allergen of the plant class I chitinase family. This finding may explain the dominant role of obeche in sensitization against wood dust.

Indices of asthma among atopic and non-atopic woodworkers

AIMS

To investigate the relation between wood dust exposure and different indices of asthma among woodworkers and non-exposed subjects.

METHODS

A total of 302 woodworkers and 71 non-exposed subjects answered a respiratory health questionnaire, underwent a non-specific bronchial provocation test using the Yan method, and received a skin prick test with 12 common inhalant allergens. Subgroups performed repeated peak flow monitoring and underwent a reversibility test. A total of 347 dust measurements among 234 woodworkers were performed with passive dust monitors.

RESULTS

The overall geometric mean (geometric standard deviation) exposure to inhalable dust was 0.96 (2.02) mg/m3. There was a tendency to increased risk of asthma among atopic woodworkers compared to atopic non-exposed subjects, with ORs between 3.0 (0.8-11.9) (symptomatic BHR) and 1.3 (0.5-4.2) (work related symptoms). In woodworkers, asthma was associated with atopy, with ORs between 7.4 (2.8-19.7) (symptomatic BHR) and 4.2 (2.4-7.7) (asthma symptoms). Asthma was related to dust level, most pronounced for symptomatic BHR among atopics, with OR 22.9 (1.0-523.6) for the highest compared to the lowest dust level. For work related asthma symptoms the association with dust level was seen only for non-atopics.

CONCLUSIONS

Wood dust exposure was associated with asthma, despite a low dust level compared to other studies. Atopy was an important effect modifier in the association between asthma and wood dust exposure.

Bronchial challenge testing in occupational epidemiology: is the diluent step really necessary?

BACKGROUND

There is no unanimous agreement on the use of a diluent step to preface methacholine challenge testing. The "pros" for this step are that it allows a better training of the patient; the "cons" are that it requires additional time and effort.

OBJECTIVE

We examined if there were any systematic effects when either the baseline or postdiluent (saline) forced expiratory volume in 1 second (FEV1) was used to define the reactivity status.

METHODS

All methacholine challenge tests performed during a 1-year period by a group of occupationally exposed workers (n = 183) were examined.

RESULTS

The mean percentage change in FEV1 from baseline to postsaline was -1.44 (+/- 3.47)% and the mean absolute change was -0.043 (+/- 0.11) L (P < 0.0001 for both comparisons). The maximum decrease and increase in FEV1 from baseline were -12.7% and +10.9%, respectively. Three subjects had a fall in FEV1 after saline of 10% or more and were not given methacholine. From the remaining 180 subjects, 172 were equally classified as reactors (n = 67) or nonreactors (n = 105), both by baseline FEV1 and postsaline FEV1. Eight subjects were classified as reactors by baseline FEV1 but as nonreactors by saline FEV1. In these subjects, the average FEV1 dropped 4.9% from baseline to saline and 17.3% from saline to end-test; thus, the total FEV1 drop (22.5%) exceeded the 20% required for the test to be positive. Among reactors, no relationship was found between the response to saline and the subsequent response to methacholine (r = 0.13).

CONCLUSIONS

Our data did not provide evidence to support the compulsory use of a diluent step when measuring bronchial responsiveness in populations. In general, the diluent step added time and expense to the test and, on occasion, forced a greater absolute drop in FEV1 than is needed to demonstrate bronchial hyperresponsiveness.

Respiratory symptoms, lung function, and nasal cellularity in Indonesian wood workers: a dose-response analysis

OBJECTIVES

It was hypothesised that inflammation plays a dominant part in the respiratory effects of exposure to wood dust. The purpose of this study was to relate the nasal inflammatory responses of workers exposed to meranti wood dust to (a) levels of exposure, (b) respiratory symptoms and (c) respiratory function.

METHODS

A cross sectional study was carried out in 1997 in a woodworking plant that used mainly meranti, among 982 workers exposed to different concentrations of wood dust. Personal sampling (n=243) of inhalable dust measurements indicated mean exposure in specific jobs, and enabled classification of 930 workers in three exposure classes (<2, 2-5, and >5 mg/m(3)) based on job title. Questionnaires were used to screen respiratory symptoms in the entire population. Lung function was measured with two different techniques, conventional flow-volume curves and the forced oscillation technique. Nasal lavage was done to assess inflammation in the upper respiratory tract.

RESULTS

A negative trend between years of employment and most flow-volume variables was found in men, but not in women workers. Current exposure, however, was not related to spirometric outcomes, respiratory symptoms, or nasal cellularity. Some impedance variables were related to current exposure but also with better function at higher exposure.

CONCLUSIONS

Exposure to meranti wood dust did not cause an inflammation in the upper respiratory tract nor an increase of respiratory symptoms or decrease of lung function. These data do not corroborate the hypothesis that inflammation plays a part in airway obstruction induced by wood dust.