Occupational asthma: a review

Job titles classified into socioeconomic and occupational groups identify subjects with increased risk for respiratory symptoms independent of occupational exposure to vapour, gas, dust, or fumes

Objectives: To evaluate the ability of three different job title classification systems to identify subjects at risk for respiratory symptoms and asthma by also taking the effect of exposure to vapours, gas, dust, and fumes (VGDF) into account. Background: Respiratory symptoms and asthma may be caused by occupational factors. There are different ways to classify occupational exposure. In this study, self-reported occupational exposure to vapours, gas, dust and fumes was used as well as job titles classifed into occupational and socioeconomic Groups according to three different systems. Design: This was a large population-based study of adults aged 30-69 years in Northern Sweden (n = 9,992, 50% women). Information on job titles, VGDF-exposure, smoking habits, asthma and respiratory symptoms was collected by a postal survey. Job titles were used for classification into socioeconomic and occupational groups based on three classification systems; Socioeconomic classification (SEI), the Nordic Occupations Classification 1983 (NYK), and the Swedish Standard Classification of Occupations 2012 (SSYK). Associations were analysed by multivariable logistic regression. Results: Occupational exposure to VGDF was a risk factor for all respiratory symptoms and asthma (odds ratios (ORs) 1.3-2.4). Productive cough was associated with the socioeconomic groups of manual workers (ORs 1.5-2.1) and non-manual employees (ORs 1.6-1.9). These groups include occupations such as construction and transportation workers, service workers, nurses, teachers and administration clerks which by the SSYK classification were associated with productive cough (ORs 2.4-3.7). Recurrent wheeze was significantly associated with the SEI group manual workers (ORs 1.5-1.7). After adjustment for also VGDF, productive cough remained significantly associated with the SEI groups manual workers in service and non-manual employees, and the SSYK-occupational groups administration, service, and elementary occupations. Conclusions: In this cross-sectional study, two of the three different classification systems, SSYK and SEI gave similar results and identified groups with increased risk for respiratory symptoms while NYK did not give conclusive results. Furthermore, several associations were independent of exposure to VGDF indicating that also other job-related factors than VGDF are of importance.

Evaluation of Respiratory Symptoms among Workers in an Automobile Manufacturing Factory, Iran

BACKGROUND

This study estimated the prevalence of respiratory symptoms and disorders among workers exposed to exposure to volatile organic compound (VOCs) in an automobile manufacturing factory in Tehran, Iran in 2016.

METHODS

Subjects of this case-control research were included 80 samples including 40 workers exposed to different level of BTEX as well as 40 unexposed individuals were considered as control group. Methods 1501 and 7602 presented by the National Institute of Occupational Safety and Health (NIOSH) were used for the sampling and analysis of compounds in the air. Gas Chromatography-Flame Ionization Detector (GC-FID) was used for analysis of compounds of interest. Six silica samples were collected during the campaign. Silica analyses were performed by using visible absorption spectrophotometry system. Lung functions were evaluated for 80 workers (40 exposed, 40 nonexposed) using spirometry system.

RESULTS

The average amount of total dust and free silica measured in factory were 7.3±1.04 mg.m^-3 and 0.017±0.02 mg.m^-3 respectively. Average benzene, toluene, ethyl-benzene and xylene exposure levels in exposed subject's median were 0.775±0.12, 1.2±2.08, 45.8±8.5, and 42.5±23.9 ppm respectively. Statistical tests showed significant difference between pulmonary function tests (except PEF) of exposed and non-exposed individuals before and after employment (P<0.05). Workers exposed to VOCs presented lower levels of FVC, VC, and PEF than the control group except FEV1/FVC%, FEV1, FEF2575 and FEV1/VC%.

CONCLUSION

Decline in lung volumes and respiratory symptoms, significant difference associated with the exposure to dust or gas, duration of exposure, and smoking habit. Therefore, lung function tests should be performed before and after the employment to identify sensitive workers candidates.

Welder's pulmonary hemosiderosis associated with systemic iron overload following exacerbation of acute adult T-cell leukemia/lymphoma

Herein, we describe a 61-year-old man diagnosed with pulmonary hemosiderosis following chemotherapy for acute adult T-cell leukemia/lymphoma (ATLL). Liver and heart biopsy confirmed hemosiderosis. ATLL progressed, and the patient died from multiorgan damage. Welder's lung may have been involved in hemosiderosis and systemic iron overload. Abnormal iron metabolism or immune reactions may have influenced the clinical course, but these were not validated. Detailed analyses of family medical and lifestyle histories, and genetic examination should be performed in cases of systemic iron overload.

Hazard banding in compliance with the new Globally Harmonised System (GHS) for use in control banding tools

Many control banding tools use hazard banding in risk assessments for the occupational handling of hazardous substances. The outcome of these assessments can be combined with advice for the required risk management measures (RMMs). The Globally Harmonised System of Classification and Labelling of Chemicals (GHS) has resulted in a change in the hazard communication elements, i.e. Hazard (H) statements instead of Risk-phrases. Hazard banding schemes that depend on the old form of safety information have to be adapted to the new rules. The purpose of this publication is to outline the rationales for the assignment of hazard bands to H statements under the GHS. Based on this, this publication proposes a hazard banding scheme that uses the information from the safety data sheets as the basis for assignment. The assignment of hazard bands tiered according to the severity of the underlying hazards supports the important principle of substitution. Additionally, the set of assignment rules permits an exposure-route-specific assignment of hazard bands, which is necessary for the proposed route-specific RMMs. Ideally, all control banding tools should apply the same assignment rules. This GHS-compliant hazard banding scheme can hopefully help to establish a unified hazard banding strategy in the various control banding tools.

Occupational diseases in Poland--an overview of current trends

INTRODUCTION

The number of occupational diseases (OD) recorded in Poland in the 1990's rapidly increased, and the number of recognized cases has steadily decreased until now. Hence, it was decided to demonstrate the trends of selected pathologies which in Poland are "underestimated" in comparison to other countries. The presented data may constitute a basis for further research into the dependence of OD on socio-economic factors.

MATERIALS AND METHODS

Occupational Disease Reporting Forms, completed and sent obligatorily by the state health inspectors to the Central Register of Occupational Diseases were used as source documents for analysis. This work analyzes changes in the incidence of chronic poisonings, asbestosis, voice organ diseases, cancers, viral hepatitis, asthma and the musculoskeletal disorders over the years 1998-2011.

RESULTS

In 1998, the total number of registered diseases reached the maximum - 12,017 cases, which fell in the subsequent years to 2,562 cases in 2011. During that period, the incidence rate decreased by 6 cases per year per 100,000 employees. A considerable decrease, exceeding 90% of cases, was observed in voice organ disorders, hearing loss, chronic poisonings and viral hepatitis. The abovementioned changes, as well as improved detection of asbestos-related diseases through implementing a medical examination program of former asbestos processing plant workers, are advantages of the current situation in the epidemiology of OD. However, the disadvantages include underestimation, in comparison to other countries, of asthma, cancer and pathologies of the musculoskeletal system.

CONCLUSION

The reported data indicates the need to assess the occupational fraction of the underestimated pathologies present in the work environment in Poland, as well as the need for studies aimed at clarifying the effect of systemic factors on identifying their occupational background.

A compendium of causative agents of occupational asthma

Objective

The objective is to provide an evidence-based compendium of allergenic and irritant agents that are known to cause occupational asthma in order to improve diagnostics and disease management.

Methods

Two previously published reviews from our group utilized database searches to identify studies which were then rated according to the Scottish Intercollegiate Guideline Network (SIGN) grading system. The evidence level for each causative agent or worksite was graded using the Royal College of General Practitioners (RCGP) three-star system.

Results

Approximately 3,000 relevant papers were identified, which covered 372 different causes of allergic and 184 different causes of irritant occupational asthma. The highest level achieved using the SIGN grading system was 2++, indicating a high quality study with a very low risk of confounding or bias and a high probability of a causal relationship. Using the modified RCGP three-star grading system, the strongest evidence of association with an individual agent or worksite ('***') was found for exposure to laboratory animals. Associations with moderate evidence level (‘**’) were obtained for a) the allergenic agents or worksites: alpha-amylase from Aspergillus oryzae, various enzymes from Bacillus subtilis, papain, bakeries, western red cedar, latex, psyllium, storage mites, rat, carmine, egg proteins, Atlantic salmon, fishmeal, Norway lobster, prawn, snow crab, seafood, trout and turbot, reactive dyes, b) the irritant agents or worksites: benzene-1,2,4-tricarboxylic acid, 1,2- anhydride [trimellitic anhydride], chlorine, cobalt, cement, environmental tobacco smoke, grain, welding fumes, construction work, swine confinement, World Trade Center disaster 2001, and c) agents or worksites causing allergic as well as irritant occupational asthma, included farming, poultry confinement, various isocyanates and platinum salts. A low evidence level (RCGP) was obtained for 84 agents or worksites (42 from each group), providing a total of 141 conditions with a low, moderate or strong evidence level.

Conclusion

This work comprises the largest compendium and evaluation of agents and worksites causing allergic or irritant occupational asthma from the literature assessed in an evidence-based manner.

Allergens causing occupational asthma: an evidence-based evaluation of the literature

PURPOSE

The aim of this work is to provide an evidence-based evaluation and overview of causative substances in order to improve disease management.

METHODS

We conducted a database search with MEDLINE via PubMed, screened reference lists of relevant reviews and matched our findings with a list of agents denoted as "may cause sensitisation by inhalation" by the phrase H334 (till 2011 R42). After exclusion of inappropriate publications, quality of the selected studies was rated with the Scottish Intercollegiate Guideline Network (SIGN) grading system. The evidence level for each causative agent was graded using the modified Royal College of General Practitioners (RCGP) three-star system.

RESULTS

A total of 865 relevant papers were identified, which covered 372 different causes of allergic work-related asthma. The highest level achieved using the SIGN grading system was 2++ indicating a high-quality study with a very low risk of confounding or bias and a high probability of a causal relationship. According to the modified RCGP three-star grading system, the strongest evidence of association with an individual agent, profession or worksite ("***") was found to be the co-exposure to various laboratory animals. An association with moderate evidence level ("**") was obtained for α-amylase from Aspergillus oryzae, various enzymes from Bacillus subtilis, papain, bakery (flour, amylase, storage mites), western red cedar, latex, psyllium, farming (animals, cereal, hay, straw and storage mites), storage mites, rat, carmine, egg proteins, atlantic salmon, fishmeal, norway lobster, prawn, snow crab, seafood, trout and turbot, reactive dyes, toluene diisocyanates and platinum salts.

CONCLUSION

This work comprises the largest list of occupational agents and worksites causing allergic asthma. For the first time, these agents are assessed in an evidence-based manner. The identified respiratory allergic agents or worksites with at least moderate evidence for causing work-related asthma may help primary care physicians and occupational physicians in diagnostics and management of cases suffering from work-related asthma. Furthermore, this work may possibly provide a major contribution to prevention and may also initiate more detailed investigations for broadening and updating these evidence-based evaluations.

Conceptual heuristic models of the interrelationships between obesity and the occupational environment

OBJECTIVE

Research and interventions targeting the relationship between work, its attendant occupational hazards, and obesity are evolving but merit further consideration in the public health arena. In this discussion paper, conceptual heuristic models are described examining the role of obesity as both a risk factor and health outcome in the occupational setting.

METHODS

PubMed was searched using specific criteria from 2000 and onwards for evidence to support conceptual models in which obesity serves as a risk factor for occupational disease or an outcome of occupational exposures. Nine models are presented: four where obesity is a risk factor and five where it is an adverse effect.

RESULTS

A broad range of work-related health effects are associated with obesity including musculoskeletal disorders, asthma, liver disease, and cardiovascular disease, among others. Obesity can be associated with occupational hazards such as shift work, sedentary work, job stress, and exposure to some chemicals.

CONCLUSION

Identification of combinations of risk factors pertinent to obesity in the occupational environment will provide important guidance for research and prevention.

Asthma symptoms among adults with work-related asthma

Objective. To examine the number of days with asthma symptoms among individuals with work-related asthma (WRA) and non-WRA. Methods. We calculated adjusted prevalence ratios and compared mean number of days with asthma symptoms using 2006-2009 Behavioral Risk Factor Surveillance System Asthma Call-back Survey data for ever-employed adults with current asthma from 38 states and District of Columbia. Results. Compared with persons with non-WRA, those with WRA had higher mean number of days with asthma symptoms. Regardless of WRA status, individuals with higher number of days with asthma symptoms were more likely to be unable to work or carry out their usual activities due to asthma. Associations between frequency of asthma symptoms and activity limitation due to asthma were weaker among currently employed adults and stronger among adults not currently employed than the observed associations for all ever-employed adults. Conclusions. These results suggest higher frequency of asthma symptoms among adults with WRA and underscore the need for optimal asthma management in individuals with WRA.

Occupation and the prevalence of respiratory health symptoms and conditions: the Atherosclerosis Risk in Communities Study

OBJECTIVES

To examine associations between occupation and respiratory health in a large, population-based cohort of adults in the United States.

METHODS

Data from 15,273 participants, aged 45 to 64 years, in the Atherosclerosis Risk in Communities study were used to examine associations of current or most recent job held with the prevalence of self-reported chronic cough, chronic bronchitis, wheezing, asthma, and measures of lung function collected by spirometry.

RESULTS

Eleven percent of participants reported wheezing and 9% were classified as having airway obstruction. Compared with individuals in managerial and administrative jobs, increased prevalences of respiratory outcomes were observed among participants in selected occupations, including construction and extractive trades (wheezing, prevalence ratio = 1.92, 95% confidence interval = 1.35, 2.73; airway obstruction, prevalence ratio = 1.31, 95% confidence interval = 1.05, 1.65).

CONCLUSIONS

Specific occupations are associated with adverse respiratory health.

Occupation and three-year incidence of respiratory symptoms and lung function decline: the ARIC Study

Background

Specific occupations are associated with adverse respiratory health. Inhalation exposures encountered in these jobs may place workers at risk of new-onset respiratory disease.

Methods

We analyzed data from 8,967 participants from the Atherosclerosis Risk in Communities (ARIC) study, a longitudinal cohort study. Participants included in this analysis were free of chronic cough and phlegm, wheezing, asthma, chronic bronchitis, emphysema, and other chronic lung conditions at the baseline examination, when they were aged 45-64 years. Using data collected in the baseline and first follow-up examination, we evaluated associations between occupation and the three-year incidence of cough, phlegm, wheezing, and airway obstruction and changes in forced expiratory volume in one second (FEV₁) and forced vital capacity (FVC) measured by spirometry. All associations were adjusted for age, cigarettes per day, race, smoking status, and study center.

Results

During the approximately three-year follow-up, the percentage of participants developing chronic cough was 3%; chronic phlegm, 3%; wheezing, 3%; and airway obstruction, defined as FEV₁ < lower limit of normal (LLN) and FEV₁/FVC < LLN, 2%. The average annual declines in FEV₁ and FVC were 56 mL and 66 mL, respectively, among men and 40 mL and 52 mL, respectively, among women. Relative to a referent category of managerial and administrative support occupations, elevated risks of new-onset chronic cough and chronic phlegm were observed for mechanics and repairers (chronic cough: RR: 1.81, 95% CI: 1.02, 3.21; chronic phlegm: RR: 2.10, 95% CI: 1.23, 3.57) and cleaning and building service workers (chronic cough: RR: 1.85, 95% CI: 1.01, 3.37; chronic phlegm: RR: 2.28, 95% CI: 1.27, 4.08). Despite the elevated risk of new-onset symptoms, employment in cleaning and building services was associated with attenuated lung function decline, particularly among men, who averaged annual declines in FEV₁ and FVC of 14 mL and 23 mL, respectively, less than the declines observed in the referent population.

Conclusions

Employment in mechanic and repair jobs and cleaning and building service occupations are associated with increased incidence of respiratory symptoms. Specific occupations affect the respiratory health of adults without pre-existing respiratory health symptoms and conditions, though long-term health consequences of inhalation exposures in these jobs remain largely unexplored.

Pathogenesis and disease mechanisms of occupational asthma

Occupational asthma (OA) is one of the most common forms of work-related lung disease in all industrialized nations. The clinical management of patients with OA depends on an understanding of the multifactorial pathogenetic mechanisms that can contribute to this disease. This article discusses the various immunologic and nonimmunologic mechanisms and genetic susceptibility factors that drive the inflammatory processes of OA.

Work-related asthma, financial barriers to asthma care, and adverse asthma outcomes: asthma call-back survey, 37 states and District of Columbia, 2006 to 2008

BACKGROUND

Proper asthma management and control depend on patients having affordable access to healthcare yet financial barriers to asthma care are common.

OBJECTIVE

To examine associations of work-related asthma (WRA) with financial barriers to asthma care and adverse asthma outcomes.

RESEARCH DESIGN

Cross-sectional, random-digit-dial survey conducted in 37 states and District of Columbia.

SUBJECTS

A total of 27,927 ever-employed adults aged ≥18 years with current asthma.

MEASURES

Prevalence ratios (PR) for the associations of WRA with financial barriers to asthma care and of WRA with adverse asthma outcomes stratified by financial barriers.

RESULTS

Persons with WRA were significantly more likely than those with non-WRA to have at least 1 financial barrier to asthma care [PR, 1.66; 95% confidence interval (CI), 1.43-1.92]. Individuals with WRA were more likely to experience adverse asthma outcomes such as asthma attack (PR, 1.31; 95% CI, 1.22-1.40), urgent treatment for worsening asthma (PR, 1.57; 95% CI, 1.39-1.78), asthma-related emergency room visit (PR, 1.69; 95% CI, 1.41-2.03), and very poorly controlled asthma (PR, 1.54; 95% CI: 1.36-1.75). After stratifying for financial barriers to asthma care, the associations did not change.

CONCLUSIONS

Financial barriers to asthma care should be considered in asthma management, and individuals with WRA are more likely to experience financial barriers. However, individuals with WRA are more likely to experience adverse asthma outcomes than individuals with non-WRA, regardless of financial barriers. Additional studies are needed to identify medical, behavioral, occupational, or environmental factors associated with adverse asthma outcomes among individuals with WRA.

Increased rates of asthma among World Trade Center disaster responders

BACKGROUND

Studies have documented high rates of asthma symptoms among responders to the World Trade Center (WTC) disaster. However, whether there are increased rates of asthma among responders compared to the general population is unknown.

METHODS

The study population consisted of a prospective cohort of 20,834 responders participating in the WTC Medical Monitoring and Treatment Program between July 2002 and December 2007. We calculated prevalence and standardized morbidity ratios (SMRs) of lifetime asthma and 12-month asthma (defined as ≥1 attacks in the prior 12 months) among WTC responders. The comparison population consisted of >200,000 adults who completed the National Health Interview Survey in 2000 (for pre-9/11 comparisons) and between 2002 and 2007 (for post-9/11 comparisons).

RESULTS

WTC responders were on average 43 ± 9 years old, 86% male, 59% white, and 42% had an occupation in protective services. The lifetime prevalence of asthma in the general population was relatively constant at about 10% from 2000 to 2007. However, among WTC responders, lifetime prevalence increased from 3% in 2000, to 13% in 2002, and 19% in 2007. The age-adjusted overall SMR for lifetime asthma among WTC responders was 1.8 (95% CI: 1.8-1.9) for men and 2.0 (95% CI: 1.9-2.1) for women. Twelve-month asthma was also more frequent among WTC responders compared to the general population (SMR 2.4, 95% CI: 2.2-2.5) for men and 2.2 (95% CI: 2.0-2.5) for women.

CONCLUSIONS

WTC responders are at an increased risk of asthma as measured by lifetime prevalence or active disease.

Interaction of occupational and personal risk factors in workforce health and safety

Most diseases, injuries, and other health conditions experienced by working people are multifactorial, especially as the workforce ages. Evidence supporting the role of work and personal risk factors in the health of working people is frequently underused in developing interventions. Achieving a longer, healthy working life requires a comprehensive preventive approach. To help develop such an approach, we evaluated the influence of both occupational and personal risk factors on workforce health. We present 32 examples illustrating 4 combinatorial models of occupational hazards and personal risk factors (genetics, age, gender, chronic disease, obesity, smoking, alcohol use, prescription drug use). Models that address occupational and personal risk factors and their interactions can improve our understanding of health hazards and guide research and interventions.

Persistence of multiple illnesses in World Trade Center rescue and recovery workers: a cohort study

BACKGROUND

More than 50,000 people participated in the rescue and recovery work that followed the Sept 11, 2001 (9/11) attacks on the World Trade Center (WTC). Multiple health problems in these workers were reported in the early years after the disaster. We report incidence and prevalence rates of physical and mental health disorders during the 9 years since the attacks, examine their associations with occupational exposures, and quantify physical and mental health comorbidities.

METHODS

In this longitudinal study of a large cohort of WTC rescue and recovery workers, we gathered data from 27,449 participants in the WTC Screening, Monitoring, and Treatment Program. The study population included police officers, firefighters, construction workers, and municipal workers. We used the Kaplan-Meier procedure to estimate cumulative and annual incidence of physical disorders (asthma, sinusitis, and gastro-oesophageal reflux disease), mental health disorders (depression, post-traumatic stress disorder [PTSD], and panic disorder), and spirometric abnormalities. Incidence rates were assessed also by level of exposure (days worked at the WTC site and exposure to the dust cloud).

FINDINGS

9-year cumulative incidence of asthma was 27·6% (number at risk: 7027), sinusitis 42·3% (5870), and gastro-oesophageal reflux disease 39·3% (5650). In police officers, cumulative incidence of depression was 7·0% (number at risk: 3648), PTSD 9·3% (3761), and panic disorder 8·4% (3780). In other rescue and recovery workers, cumulative incidence of depression was 27·5% (number at risk: 4200), PTSD 31·9% (4342), and panic disorder 21·2% (4953). 9-year cumulative incidence for spirometric abnormalities was 41·8% (number at risk: 5769); three-quarters of these abnormalities were low forced vital capacity. Incidence of most disorders was highest in workers with greatest WTC exposure. Extensive comorbidity was reported within and between physical and mental health disorders.

INTERPRETATION

9 years after the 9/11 WTC attacks, rescue and recovery workers continue to have a substantial burden of physical and mental health problems. These findings emphasise the need for continued monitoring and treatment of the WTC rescue and recovery population.

FUNDING

Centers for Disease Control and Prevention and National Institute for Occupational Safety and Health.

Chemical pneumonitis and acute lung injury caused by inhalation of nickel fumes

A 50-year-old man with a 30-year occupational history of welding presented with low-grade fever, fatigue and persistent dry cough. Computed tomography (CT) of the chest revealed interlobular septal thickening and bilateral non-segmental patchy ground-glass opacities except in the sub-pleural zone. He revealed that he had inhaled nickel fumes 3 days previously at work. These findings suggested a diagnosis of pneumonitis induced by inhalation of nickel fumes. Fewer reports describe pneumonitis associated with the inhalation of nickel compared with zinc fumes. Although nickel compounds are particularly pernicious among the transition metals and more toxic than zinc compounds, nickel fume inhalation rarely induces lethal acute respiratory distress syndrome. Our patient was successfully treated with corticosteroid.

Bitter taste receptors on airway smooth muscle bronchodilate by localized calcium signaling and reverse obstruction

Bitter taste receptors (TAS2Rs) on the tongue probably evolved to evoke signals for avoiding ingestion of plant toxins. We found expression of TAS2Rs on human airway smooth muscle (ASM) and considered these to be avoidance receptors for inhalants that, when activated, lead to ASM contraction and bronchospasm. TAS2R agonists such as saccharin, chloroquine and denatonium evoked increased intracellular calcium ([Ca²(+)](i)) in ASM in a Gβγ-, phospholipase Cβ (PLCβ)- and inositol trisphosphate (IP₃) receptor-dependent manner, which would be expected to evoke contraction. Paradoxically, bitter tastants caused relaxation of isolated ASM and dilation of airways that was threefold greater than that elicited by β-adrenergic receptor agonists. The relaxation induced by TAS2Rs is associated with a localized [Ca²(+)](i) response at the cell membrane, which opens large-conductance Ca²(+)-activated K(+) (BK(Ca)) channels, leading to ASM membrane hyperpolarization. Inhaled bitter tastants decreased airway obstruction in a mouse model of asthma. Given the need for efficacious bronchodilators for treating obstructive lung diseases, this pathway can be exploited for therapy with the thousands of known synthetic and naturally occurring bitter tastants.

Exposure to SO2 does not have a chronic effect on pulmonary functions of apricot workers

The authors have previously demonstrated that apricot sulfurization workers develop asthma-like syndrome during apricot sulfurization due to exposure to sulfur dioxide (SO(2)) gas. The aim of the current study was to demonstrate if exposure to SO(2) gas had any chronic effects on pulmonary functions and bronchial reactivity of the workers. Twenty-five apricot sulfurization workers and a control group were included in the study. Physical examination, skin prick tests, pulmonary function tests (PFTs), and bronchoprovocation tests (BPTs) were performed before and after the season of sulfurization in the worker group. Skin prick tests, PFTs, and BPTs were performed also in the control group without a history of exposure to SO(2) gas. There was no statistically significant difference between PFT and BPT results of the workers and the control group. Comparison of the PFT results of the workers before and after the season of apricot sulfurization neither reveal a significant difference. Four (16%) out of 25 workers were positive for BPTs before the period. Only one worker who had a negative BPT result before the sulfurization season was positive afterwards. The lack of a chronic effect on pulmonary functions is consistent with the diagnosis of asthma-like syndrome in apricot sulfurization workers.

Frequency of work-related respiratory symptoms in workers without asthma

BACKGROUND

Clinicians are faced with subjects complaining of work-related respiratory symptoms (WRS) without any evidence of asthma. We sought to assess the prevalence of subjects with WRS without asthma in a cohort of workers referred for possible work-related asthma (WRA) as well as compare the characteristics and the work environment of subjects with WRS to subjects with WRA.

METHODS

A prospective observational study of workers referred for possible WRA over a 1-year period. Detailed medical and occupational questionnaires were administered. Pulmonary function tests as well as specific-inhalation challenges were performed.

RESULTS

One hundred twenty workers were investigated. Fifty-one had WRA while 69 had WRS. The type and the severity of the respiratory symptoms were similar in both groups, except for wheezing which was more frequently reported in subjects with WRA (32 (62.7%)) than in subjects with WRS (16 (23.2%)) (P < 0.01). Both the workers with WRS and WRA were mainly employed in the manufacturing sector (64.7% (WRA) and 71% (WRS)). At the time of the first assessment 64.7% of subjects with WRA and 56.5% with WRS had left their workplace because of their bothersome respiratory symptoms.

CONCLUSIONS

Subjects with WRS without asthma represent a large proportion of the subjects assessed in clinics specialized in the field of WRA. Like subjects with WRA, the population with WRS is likely to represent a significant medical burden. The similarity of the symptoms between the WRA and the WRS groups emphasizes the need to perform a thorough and objective investigation to diagnose WRA.

The burden of exposure-related diffuse lung disease

Estimating the burden of exposure-related diffuse lung disease in terms of health effects and economic burden remains challenging. Labor statistics are inadequate to define the scope of the problem, and few studies have analyzed the prevalence of exposure-related illnesses and the subsequent health care cost. Well-defined exposures, such as those associated with coal mines, asbestos mines, and stonecutting, have led to more accurate assessment of prevalence and cost. As governmental regulation of workplace exposure has increased, the prevalence of diseases such as silicosis and coal workers' pneumoconiosis has diminished. However, the health and economic effects of diseases with long latency periods, such as asbestosis and mesothelioma, continue to increase in the short term. Newer exposures, such as those related to air pollution, nylon flock, and the World Trade Center collapse, have added to these costs. As a result, estimates of cost for occupational diseases, including respiratory illnesses, exceed $26 billion annually, and the true economic burden is likely much higher.

Quality of life and employment status of workers with Western red cedar asthma

OBJECTIVE

The impact of current employment status and other factors on quality of life was evaluated for workers diagnosed with western red cedar asthma in British Columbia, Canada.

METHODS

Telephone interviews by questionnaire included the Short Form 36 (SF-36) and Marks Asthma quality-of-life instruments.

RESULTS

Of the 302 subjects contacted, 70.5% (n = 213) participated. Employment status was the most consistent predictor of quality-of-life domains, with highest scores for employed subjects, particularly those who were no longer exposed to red cedar. Subjects who had quit work because of their asthma had worse scores, particularly for vitality and general health perceptions. Other factors independently associated with specific aspects of poor quality of life were having asthma-like symptoms, taking medication, and not being married.

CONCLUSIONS

Continued employment was associated with better quality of life for workers with western red cedar asthma.

Management of asthma with anti-immunoglobulin E: a review of clinical trials of omalizumab

Immunoglobulin E (IgE) is a key mediator of the inflammatory reactions that are central to the pathogenesis of allergic diseases such as asthma and rhinitis. The recognition of the importance of IgE in allergic disease led to the development of omalizumab, a humanized monoclonal anti-IgE antibody that binds free circulating IgE and prevents the interaction between IgE and high-affinity (FcepsilonRI) and low-affinity (FcepsilonRII) IgE receptors on inflammatory cells. By removing free IgE, omalizumab also markedly downregulates the expression of high-affinity receptors on basophils, mast cells and dendritic cells. Several studies have shown that omalizumab effectively reduces the risk of exacerbations and hospitalization and improves symptom control, lung function and quality of life in patients with severe persistent allergic asthma. Importantly, omalizumab has been shown to be effective in patients with poorly controlled severe persistent allergic asthma, a group of patients with few effective additional treatment options. In addition, omalizumab has been shown to provide effective relief from the symptoms of allergic rhinitis (including patients with concomitant asthma). Patients with uncontrolled severe persistent allergic asthma are a challenging and difficult-to-treat population for whom omalizumab might represent an important new treatment option. In addition, omalizumab may provide a means to address comorbid allergic disease in patients with asthma. Further investigation is also warranted to explore potential applications of omalizumab in occupational asthma.

Trimellitic anhydride-conjugated serum albumin activates rat alveolar macrophages in vitro

BACKGROUND

Occupational exposure to airborne low molecular weight chemicals, like trimellitic anhydride (TMA), can result in occupational asthma. Alveolar macrophages (AMs) are among the first cells to encounter these inhaled compounds and were previously shown to influence TMA-induced asthma-like symptoms in the Brown Norway rat. TMA is a hapten that will bind to endogenous proteins upon entrance of the body. Therefore, in the present study we determined if TMA and TMA conjugated to serum albumin induced the production of the macrophage mediators nitric oxide (NO), tumour necrosis factor (TNF), and interleukin 6 (IL-6) in vitro using the rat AM cell line NR8383 and primary AMs derived from TMA-sensitized and naïve Brown Norway rats.

METHODS

Cells were incubated with different concentrations of TMA, TMA conjugated to bovine serum albumin (BSA), and BSA as a control for 24 h and the culture supernatant was analyzed for mediator content.

RESULTS

TMA alone was not able to induce the production of mediators by NR8383 cells and primary AMs from sensitized and sham-treated rats. TMA-BSA, on the contrary, dose-dependently stimulated the production of NO, TNF, and IL-6 by NR8383 cells and of NO and TNF, but not IL-6, by primary AMs independent of sensitization.

CONCLUSION

Results suggest that although TMA is a highly reactive compound, conjugation to a suitable protein is necessary to induce mediator production by AMs. Furthermore, the observation that effects of TMA-BSA were independent of sensitization suggests involvement of an immunologically non-specific receptor. In the discussion it is argued that a macrophage scavenger receptor is a likely candidate.

Alveolar macrophages suppress non-specific inflammation caused by inhalation challenge with trimellitic anhydride conjugated to albumin

Occupational exposure to low molecular weight chemicals, like trimellitic anhydride (TMA), can result in occupational asthma. Alveolar macrophages (AMs) are among the first cells to encounter these inhaled compounds and were previously shown to affect TMA-induced asthma-like symptoms in the Brown Norway rat (Valstar et al., Toxicol. Appl. Pharmacology 211:20-29, 2006). TMA is a hapten that will bind to endogenous proteins upon entrance of the body. Therefore, in the present study we determined if TMA conjugated to albumin is able to induce asthma-like symptoms and if these are affected by AM depletion. Female Brown Norway rats were sensitized by dermal application of TMA or received vehicle alone on days 0 and 7. One day prior to the inhalation challenge the rats were treated intratracheally with either empty liposomes or liposomes containing clodronate (dichloromethylene diphosphonate) to specifically deplete the lungs of AMs. On day 21, all groups of rats were challenged by inhalation of TMA-BSA. Breathing frequency, tidal volume, and minute ventilation were measured before, during, within 1 h, and 24 h after challenge and the gross respiratory rate score was determined during challenge. Total and TMA-specific IgE levels were determined in serum and lung lavage fluid and parameters of inflammation and tissue damage were assessed in lung lavage fluid and/or lung tissue 24 h after challenge. Sensitization with TMA had no effect on the lung function before challenge, but TMA-BSA challenge resulted in an early asthmatic response as compared to the non-sensitized rats, irrespective of AM depletion. AM depletion had no effect on the sensitization-induced serum and lung lavage fluid IgE levels. TMA-BSA inhalation did not induce airway inflammation and tissue damage irrespective of sensitization, unless AM were depleted. Data indicate that AMs inhibit immunologically non-specific damage and inflammatory cell influx into the lungs as caused by TMA-BSA inhalation. Since effects of inhalation challenge with TMA-BSA are partly different from those of TMA, challenge with the latter is to be preferred for hazard identification.

Asthma severity and exposure to occupational asthmogens

RATIONALE

Severe asthma is a public health problem with limited information regarding preventable causes. Although occupational exposures have been implicated as important risk factors for asthma and asthma exacerbations, associations between occupational exposures and asthma severity have not been reported.

OBJECTIVE

To examine associations between occupational exposures and asthma severity.

METHODS

The Epidemiological Study on the Genetics and Environment of Asthma combines a case-control study with a family study of relatives of patients with asthma. Adult patients (n = 148) were recruited in chest clinics and control subjects without asthma (n = 228) were population-based. Occupational exposures to nonasthmogenic irritants and asthmogens (classified as "any asthmogen" including three broad groups: high-molecular-weight agents, low-molecular-weight agents, and mixed environments) were assessed by an asthma-specific job exposure matrix. Asthma severity was defined from an 8-grade clinical score (frequency of attacks, persistent symptoms, and hospitalization). Patients with severe (score >or= 2) and mild asthma were compared with control subjects using nominal logistic regression.

MAIN RESULTS

Significant associations were observed between severe adult-onset asthma and exposure to any occupational asthmogen (odds ratio [OR], 4.0; 95% confidence interval [CI], 2.0-8.1), high-molecular-weight agents (OR, 3.7; CI, 1.3-11.1), low-molecular-weight agents (OR, 4.4; CI, 1.9-10.1), including industrial cleaning agents (OR, 7.2; CI, 1.3-39.9), and mixed environments (OR, 7.5; CI, 2.4-23.5). No significant associations were found between nonasthmogenic irritants and asthma severity, nor between asthmogens and childhood-onset asthma or mild adult-onset asthma.

CONCLUSIONS

Our results suggested a strong deleterious role of occupational asthmogens in severe asthma. Clinicians should consider occupational exposures in patients with moderate to severe asthma.

Genetic factors and asthma in aluminum smelter workers

An asthma-like condition has been reported among aluminum smelter potroom workers. The pathophysiologic mechanisms and the causative agent involved are unknown. Inasmuch as gene polymorphisms are associated with asthma in the general population, the authors of this case-control study examined whether polymorphisms were associated with the development of potroom asthma. Genotyping was performed for the beta2-adrenoreceptor, high-affinity Ig (immunoglobulin) E receptor, and Tumor Necrosis Factor on potroom workers who developed a new asthma-like condition and on individuals who did not develop respiratory problems. No associations were found between potroom asthma case status and genotype. The asthma-like condition associated with potroom work remains poorly understood. Future investigations of genetic susceptibility and occupational asthma may provide pathophysiologic insights into these work-related conditions, but larger numbers of subjects will be required.

Hapten-induced hypersensitivity reactions in the airways: atopic versus non-atopic

Hypersensitivity reactions induced by low molecular weight compounds are investigated extensively in the skin. However, these reactions can also occur in the lungs of previously sensitized individuals after local airway challenge. This hapten-induced pulmonary hypersensitivity reaction resembles features observed in asthmatic patients, such as bronchial hyperreactivity, accumulation of inflammatory cells, and airway edema. We review data that hapten-induced hypersensitivity reactions in mouse airways can be models for both atopic and non-atopic asthma associated with low molecular weight compounds.

Persistence of airway responsiveness to occupational agents: what does it matter?

In the majority of workers with occupational asthma, the disease remains active even several years after removal from exposure or diminution of the levels of exposure to the causal agent. Only 25% or so normalize their lung function and their bronchial responsiveness to nonspecific agents. The aim of this review is to present recent findings illustrating the persistence of specific bronchial responsiveness and the associated factors in workers who apparently have recovered from occupational asthma. This subject is also examined from a socioeconomic perspective.

Occupational asthma with paroxysmal atrial fibrillation in a diamond polisher

We present a case of a diamond polisher who developed occupational asthma as a result of prolonged exposure to various potent and well-recognized asthma-inducing agents, including cobalt dust. Although the patient was seen by various medical professionals during the initial course of his illness and given an early diagnosis of a respiratory condition, there were no attempts to evaluate the nature of his work, and therefore to establish a possible causal relationship with his exposures. This case clearly illustrates the importance of such an assessment. The ultimate fate of this patient (he had to retire from his job with a chronic and permanent illness) could have been avoided by early environmental intervention. In addition, this case illustrates a possible complication of asthma, that is, a severe cardiac arrhythmia. In this case, both the patient's symptoms and the prescribed medications contributed to worsening of the patient's underlying condition. Early diagnosis and intervention of this patient's work practices could have avoided this complication.