The risk of asthma in relation to occupational exposures: a case-control study from a Swedish city

Chronic occupational exposures to irritants and asthma in the CONSTANCES cohort

OBJECTIVES

The impact of chronic occupational exposures to irritants on asthma remains discussed. We studied the associations between occupational exposures and asthma, with specific interest for chronic exposure to irritants, including disinfectants and cleaning products (DCPs) and solvents.

METHODS

Cross-sectional analyses included 115 540 adults (55% women, mean age 43 years, 10% current asthma) working at inclusion in the French population-based CONSTANCES cohort (2012-2020). Current asthma was defined by ever asthma with symptoms, medication or asthma attacks (past 12 months), and the asthma symptom score by the sum of 5 respiratory symptoms (past 12 months). Both lifetime and current occupational exposures were assessed by the Occupational Asthma-specific Job-Exposure Matrix. Associations were evaluated by gender using logistic and binomial negative regressions adjusted for age, smoking status and body mass index.

RESULTS

In women, associations were observed between current asthma and lifetime exposure to irritants (OR 1.05, 95% CI 1.00 to 1.11), DCPs (1.06, 95% CI 1.00 to 1.12) and solvents (1.06, 95% CI 0.98 to 1.14). In men, only lifetime exposure to DCPs (1.10, 95% CI 1.01 to 1.20) was associated with current asthma. Lifetime exposure to irritants was associated with higher asthma symptom score both in women (mean score ratio: 1.08, 95% CI 1.05 to 1.11) and men (1.11, 95% CI 1.07 to 1.15), especially for DCPs (women: 1.09, 95% CI 1.06 to 1.13, men: 1.21, 95% CI 1.15 to 1.27) and solvents (women 1.14, 95% CI 1.10 to 1.19, men: 1.10, 95% CI 1.05 to 1.15). For current exposures, no consistent associations were observed with current asthma and asthma symptom score.

CONCLUSIONS

Lifetime occupational exposures to irritants were associated with current asthma and higher asthma symptom score. These exposures should be carefully considered in asthma management.

Occupational Disease in New York State: An Update

An assessment of occupational disease in New York State was undertaken that partially replicated and expanded earlier work from 1987. Utilizing an expanded conception of occupational disease, the assessment used a variety of data sources and methods to provide estimates of mortality and morbidity of occupational disease; workers exposed to specific workplace hazards; disparities in occupational disease among racial/ethnic groups and gender; costs and distribution of costs of occupational disease; and accessible occupational medical resources. Examples of the pathways work may impact health in some of the major health issues of current import including stress-related health conditions; substance use; and overweight/obesity were included. The report contains recommendations for addressing the problem of occupational disease in New York State and advocates for the convening of a statewide group to develop an occupational disease prevention agenda.

Assessment of paper dust exposure and chronic respiratory symptoms among paper factory workers in, Ethiopia; a comparative cross-sectional study

BACKGROUND

Workers in pulp and paper factories are continuously exposed to paper dust. Excessive exposure to paper dust can cause respiratory disease. Information about the prevalence of chronic respiratory symptoms and dust exposure levels among workers in pulp and paper factories is not available in Ethiopia. The aim of this study was, therefore, to assess personal total dust exposure levels, the prevalence of chronic respiratory symptoms and their associated risk factors among workers in Ethiopian pulp and paper factories.

METHODS

A comparative cross-sectional study was conducted. A total of 40 dust measurements were carried out on 20 randomly selected workers. To assess chronic respiratory symptoms and associated factors, 434 workers from two paper factories and controls were interviewed using a standard questionnaire adapted from the American Thoracic Society (ATS). Gravimetric analyses of the filters were undertaken using a standard microbalance. Poisson regression was performed for comparing the prevalence of symptoms and risk factors for the two groups. Multivariable analyses were conducted to identify factors associated with chronic respiratory symptoms.

RESULT

The arithmetic mean (AM) and geometric mean (GM) of dust exposure levels among the paper factories workers were 11.3 (± 7.7) and 10.2 (± 1.4) mg/m³ respectively. This exposure level exceeded the threshold limit value recommended for total dust (10 mg/m³). The prevalence of having at least one chronic respiratory symptom was about 51% among the workers in paper factories. The prevalence ratio of having chronic respiratory symptoms among paper factory workers was 5.6 times higher (PR = 6, 95% CI 3.5-10.3) than in the controls. Chronic respiratory symptoms were significantly associated with factors such as an educational status of less than grade 9, being employed in the work sections of the factories, having work experience of 5 years and above, working more than 8 h per day and having a past history of occupation and respiratory illnesses.

CONCLUSION

The dust concentration in the paper factories exceeded the acceptable recommended limit value of 10 mg/m3. The prevalence of chronic respiratory symptoms among paper factory workers was higher than among controls. The main determining factors for chronic respiratory symptoms among the workers were the specific work section such as production section, low income, having past history of respiratory illnesses, the number of years of working and low educational status. This finding indicated the need for improving the working conditions in paper factories in Ethiopia.

Occupational Exposures to Irritants and Sensitizers, Asthma and Asthma Control in the Nutrinet-Santé Cohort

BACKGROUND

The role of chronic occupational exposures to irritants in asthma remains not well-defined. Few studies have examined their associations with asthma and its control.

OBJECTIVE

To study the associations of occupational exposures with asthma and its control, with specific interest for irritants, including disinfectants and cleaning products (DCPs) and solvents.

METHODS

Analyses included 4,469 adults (3,792 with neither asthma nor respiratory symptoms, 677 with current asthma; 75.9% women, mean age 54 years) of a case-control study (2018) from the French NutriNet-Santé cohort. Current asthma was defined by ever asthma with symptoms, medication or asthma attacks in the past 12 months, adult-onset asthma by age at first asthma attack older than 16 years, and uncontrolled asthma was defined by an Asthma Control Test score less than 20. Ever/current exposures were assessed with the Occupational Asthma-specific Job Exposure Matrix. Associations were evaluated by multinomial logistic regressions adjusted for sex, age, smoking status, and body mass index.

RESULTS

Ever exposures to sensitizers (high molecular weight [HMW]: OR 1.53, 95% CI 1.18-2.00; and low molecular weight [LMW]: OR 1.42; 95% CI 1.09-1.87), irritants (OR 1.32; 95% CI 1.03-1.68), and DCPs (OR 1.43; 95% CI 1.10-1.85) were associated with current adult-onset asthma. Significant associations between ever exposures and uncontrolled adult-onset asthma were observed for high molecular weight (OR 2.69; 95% CI 1.52-4.78) and low molecular weight (OR 2.27; 95% CI 1.24-4.37) sensitizers, irritants (OR 2.32; 95% CI 1.36-3.95), and DCPs (OR 2.59; 95% CI 1.48-4.54). Results were similar for current exposures, with higher ORs. No association was observed with solvents.

CONCLUSIONS

Occupational exposures to both sensitizers and irritants were associated with current adult-onset asthma and uncontrolled asthma. Irritant and sensitizing agents should be carefully considered in asthma management.

Occupational Exposures to Organic Solvents and Asthma Symptoms in the CONSTANCES Cohort

Solvents are used in many workplaces and may be airway irritants but few studies have examined their association with asthma. We studied this question in CONSTANCES (cohort of ‘CONSulTANts des Centres d’Examens de Santé’), a large French cohort. Current asthma and asthma symptom scores were defined by participant-reported respiratory symptoms, asthma medication or attacks, and the sum of 5 symptoms, in the past 12 months, respectively. Lifetime exposures to 5 organic solvents, paints and inks were assessed by questionnaire and a population-based Job-Exposure Matrix (JEM). Cross-sectional associations between exposures and outcomes were evaluated by gender using logistic and negative binomial regressions adjusted for age, smoking habits and body mass index. Analyses included 115,757 adults (54% women, mean age 47 years, 9% current asthma). Self-reported exposure to ≥1 solvent was significantly associated with current asthma in men and women, whereas using the JEM, a significant association was observed only in women. Significant associations between exposures to ≥1 solvent and asthma symptom score were observed for both self-report (mean score ratio, 95%CI, women: 1.36, 1.31–1.42; men: 1.34, 1.30–1.40) and JEM (women: 1.10, 1.07–1.15; men: 1.14, 1.09–1.18). Exposure to specific solvents was significantly associated with higher asthma symptom score. Occupational exposure to solvents should be systematically sought when caring for asthma.

Exposure to heavy metals alters the surface topology of alveolar macrophages and induces respiratory dysfunction among Indian metal arc-welders

BACKGROUND

Despite the available clinico-epidemiological evidence of heavy metal-associated respiratory health hazards among metal arc-welders, experimental confirmation of such an association is lacking.

METHODS

In this study, we recruited 15 metal arc-welders and 10 referent workers without direct exposure. We assessed respiratory health through a questionnaire and spirometry; estimated manganese, nickel and cadmium levels in blood, urine and induced sputum; performed differential counts of sputum leucocytes and measured plasma malondialdehyde (MDA). We used atomic force and scanning electron microscopy to assess the physical property of the alveolar macrophages (AMs) obtained from induced sputum and analysed cell surface deposition of heavy metals using energy dispersion X-ray analysis (EDX). Sputum cellular DNA damage was assessed by DNA-laddering assay.

RESULTS

There was a higher body burden of manganese and nickel in the metal arc-welders than the referents. Among major spirometric indices, only the forced mid-expiratory flow rates (FEF_25-75) were reduced in the welders compared with the referents (63.4 ± 14.7 vs. 89.2 ± 26.7, p < 0.01); this reduction was associated with both heavy metal levels (β: -41.8, 95% CI: -78.5% to -5.1%) and plasma MDA (-0.37; -0.68 to -0.06). In metal arc-welders, significant physical and morphological changes were observed in AMs through microscopic evaluation while EDX analyses demonstrated higher deposition of heavy metals on the AM cell surface than the referents. We also observed a higher degree of DNA damage in the sputum cells of the exposed workers than the referents.

CONCLUSION

Heavy metal exposure-induced adverse respiratory effects among metal arc-welders are mediated through haematological and cytological interactions.

Impact of occupational exposures on exacerbation of asthma: a population-based asthma cohort study

Background

Asthma is a prevalent chronic disease and occupation contributes to approximately 15 % of cases among adults. However, there are still few studies on risk factors for work-exacerbated asthma. The current study investigated the association between asthma exacerbations and occupational exposures.

Methods

The study comprised all currently working adults (n = 1356) who reported ever asthma in prior population-based cohorts. All subjects completed a questionnaire about exposures, occupations and exacerbations of asthma. Exposure to high and low molecular weight agents, irritating agents and asthmagens were classified using the asthma-specific job exposure matrix for northern Europe (N-JEM). Severe exacerbation of asthma was defined as sought emergency care at a hospital, admitted to a hospital overnight, or made an urgent visit to a primary care physician or district medical office due to breathing problems during the last 12 months. Moderate exacerbation was defined as both being not severe exacerbation and an additional visit to a primary care physician or district medical office, or had extra treatments with corticosteroid tablets. Mild exacerbation was defined as being neither severe nor moderate exacerbation, and increasing usage of inhaled corticosteroids.

Multiple logistic regression was applied to investigate the association between exacerbation of asthma and occupational exposures while adjusting for potential confounders.

Results

Approximately 26 % of the working asthmatics reported exacerbation, and more than two-thirds of them had moderate or severe exacerbation. From 23 to 49 % of the asthmatics reported occupational exposure to a variety of different types of agents. Exposure to any gas, smoke or dust (OR 1.7[95 % CI 1.2–2.6]) was associated with severe exacerbation of asthma, as were organic dust (OR 1.7[1.2–2.5]), dampness and mold (OR 1.8[1.2–2.7]), cold conditions (OR 1.7[1.1–2.7]), and a physically strenuous job (OR 1.6[1.03–2.3]). Asthmagens and low molecular weight agents classified by the N-JEM were associated with mild exacerbation, with OR 1.6[1.1–2.5] and OR 2.2[1.1–4.4], respectively.

Conclusions

Self-reported exposure to any gas, smoke or dust, organic dust, dampness and mold, cold conditions and physically strenuous work, and jobs handling low molecular weight agents were associated with exacerbation of asthma. Reduction of these occupational exposures may help to reduce exacerbation of asthma.

Redemption of asthma pharmaceuticals among stainless steel and mild steel welders: a nationwide follow-up study

PURPOSE

The purpose was to examine bronchial asthma according to cumulative exposure to fume particulates conferred by stainless steel and mild steel welding through a proxy of redeemed prescribed asthma pharmaceuticals.

METHODS

A Danish national company-based historical cohort of 5,303 male ever-welders was followed from 1995 to 2011 in the Danish Medicinal Product Registry to identify the first-time redemption of asthma pharmaceuticals including beta-2-adrenoreceptor agonists, adrenergic drugs for obstructive airway diseases and inhalable glucocorticoids. Lifetime exposure to welding fume particulates was estimated by combining questionnaire data on welding work with a welding exposure matrix. The estimated exposure accounted for calendar time, welding intermittence, type of steel, welding methods, local exhaustion and welding in confined spaces. Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated using a Cox proportional hazards model adjusting for potential confounders and taking modifying effects of smoking into account.

RESULTS

The average incidence of redemption of asthma pharmaceuticals in the cohort was 16 per 1,000 person year (95% CI 10-23 per 1,000 person year). A moderate nonsignificant increased rate of redemption of asthma medicine was observed among high-level exposed stainless steel welders in comparison with low-level exposed welders (HR 1.54, 95% CI 0.76-3.13). This risk increase was driven by an increase risk among non-smoking stainless steel welders (HR 1.46, 95% CI 1.06-2.02). Mild steel welding was not associated with increased risk of use asthma pharmaceuticals.

CONCLUSION

The present study indicates that long-term exposure to stainless steel welding is related to increased risk of asthma in non-smokers.

Gender differences in work-related asthma: surveillance data from California, Massachusetts, Michigan, and New Jersey, 1993-2008

OBJECTIVE

To characterize work-related asthma by gender.

METHODS

We analyzed state-based sentinel surveillance data on confirmed work-related asthma cases collected from California, Massachusetts, Michigan, and New Jersey during 1993-2008. We used Chi-square and Fisher's Exact Test statistics to compare select characteristics between females and males.

RESULTS

Of the 8239 confirmed work-related asthma cases, 60% were female. When compared to males with work-related asthma, females with work-related asthma were more likely to be identified through workers' compensation (14.8% versus 10.6%) and less likely to be identified through hospital data (14.2% versus 16.9%). Moreover, when compared to males, females were more likely to have work-aggravated asthma (24.4% versus 13.5%) and less likely to have new-onset asthma (48.0% versus 56.5%). Females were also more likely than males with work-related asthma to work in healthcare and social assistance (28.7% versus 5.2%), educational services (11.8% versus 4.2%), and retail trade (5.0% versus 3.9%) industries and in office and administrative support (20.0% versus 4.0%), healthcare practitioners and technical (13.4% versus 1.6%), and education training and library (6.2% versus 1.3%) occupations. Agent groups most frequently associated with work-related asthma were miscellaneous chemicals (20.3%), cleaning materials (15.3%), and indoor air pollutants (14.9%) in females and miscellaneous chemicals (15.7%), mineral and inorganic dusts (13.2%), and pyrolysis products (12.7%) in males.

CONCLUSIONS

Among adults with work-related asthma, males and females differ in terms of workplace exposures, occupations, and industries. Physicians should consider these gender differences when diagnosing and treating asthma in working adults.

Rhinitis phenotypes correlate with different symptom presentation and risk factor patterns of asthma

BACKGROUND

Asthma and rhinitis frequently coexist, but no population study has previously determined the relationship between nasal comorbidities and symptom expression and risk factors of asthma.

METHODS

In 2008, a postal questionnaire on respiratory health was sent to 30,000 randomly selected subjects aged 16-75 years in West Sweden; 29218 could be traced and 18,087 (62%) responded. The questionnaire included questions on asthma, rhinitis, chronic rhinosinusitis, respiratory symptoms and possible determinants.

RESULTS

Prevalence of allergic rhinitis in asthma was 63.9% and of asthma in allergic rhinitis 19.8%. Prevalence of chronic rhinosinusitis in asthma was 8.4% and of asthma in chronic rhinosinusitis 24.4%. Asthma subjects with chronic rhinitis, or chronic rhinosinusitis, had more symptoms of asthma and bronchitis than those without rhinitis (p < 0.001). There was an obvious trend of higher ORs for various environmental exposures including occupational exposure to dust, gases and fumes (OR 2.32 vs. OR 1.44), visible mould at home (OR 1.72 vs. OR 1.27) and water damage at home (OR 1.82 vs. OR 1.06) for asthma with chronic rhinosinusitis than for asthma with allergic rhinitis. Family history of allergy yielded a higher OR for asthma with allergic rhinitis than with asthma with chronic rhinosinusitis (OR 7.15 vs. OR 4.48).

CONCLUSION

Considerable overlap between asthma and nasal comorbidities was documented, confirming a close relationship between nasal disease and asthma. Allergic rhinitis, chronic rhinitis and chronic rhinosinusitis were associated with different risk factor patterns and symptom expression of asthma. Thus, different nasal comorbidities may reflect different phenotypes of asthma.

Reported occupational respiratory diseases in three Spanish regions

BACKGROUND

In 2002, a voluntary registry of occupational respiratory diseases was initiated in the test phase in Asturias, Catalonia, and Navarre (Spain). Based on data from the fully implemented voluntary registry, we assessed the differences in the incidence and characteristics of the diseases reported in the three regions studied and compared them with those notified to the compulsory official system.

METHODS

Physicians whose daily practice includes patients with occupational respiratory diseases were invited to participate. Newly diagnosed cases occurring during 2003 in the work force of the three regions studied were reported on a notification form every 2 months. Data from the compulsory official notification system were obtained from statistics on work-related diseases for possible disability benefits.

RESULTS

Five hundred thirty-three new cases, representing a cumulative incidence of 183.52 (168.27-199.78) per million workers per year, were reported. The number of cases and the incidence, overall and for each disease, causes of the diseases, and the occupations varied considerably between regions. The number of cases reported to the voluntary system was more than threefold greater than the number reported to the compulsory official system.

CONCLUSIONS

The compulsory scheme for reporting occupational respiratory diseases is seriously under-reporting in the three Spanish regions studied. Our voluntary surveillance program, which showed considerable differences in the characteristics and incidence of these diseases among the regions, appears to be more effective.

A meta-analysis on wood dust exposure and risk of asthma

Work-related asthma is the most common occupational respiratory disorder in the industrialized countries. It has been postulated that wood dust exposure may increase the risk of work-related asthma. The objective of this study was to assess, through a meta-analysis, the risk of developing work-related asthma associated with wood dust exposure. A systematic search of the literature was performed. Inclusion and exclusion criteria were applied and a quality scale used to measure the quality of the included studies was developed. Using standard meta-analysis techniques, studies were pooled using both random and fixed effects models. Nineteen studies were included which consisted of three cohort studies, twelve case-control studies and four mortality studies. The pooled relative risk (RR) of asthma among workers exposed to wood dust was 1.53 (95% CI 1.25-1.87). When the analysis was restricted to studies carried out on Caucasian populations, the pooled RR was 1.59 (95% CI 1.26-2.00) while the pooled RR of studies on Asian populations was 1.15 (95% CI 0.92-1.44). Wood workers present a higher risk of asthma. Future research should include careful evaluation of ethnicity and nativity as risk modifiers.

Effect of occupation and smoking on respiratory symptoms in working children

OBJECTIVES

To compare the respiratory symptoms and the lung function of children who work in different occupational groups.

METHODS

The study was performed among children attending vocational training centers. The participants were evaluated in six different occupation groups. Chronic cough, wheezing and shortness of breath were evaluated by questionnaire. The association of independent variables with the respiratory symptoms was investigated through both univariate and multivariate methods.

RESULTS

Among 642 children, 534 were males; the mean age was 17.7 +/- 1.0 years. Using an internal reference group, the odds ratios of chronic cough were significantly higher in the lathe (OR: 2.0, 95%CI: 1.07-3.74), coiffure (OR: 1.94. 95%CI: 1.01-3.70), and electricity-construction (OR: 2.63, 95%CI: 1.06-6.54) groups after adjustment for smoking, age, gender, and work characteristics. There were no significant differences in spirometric values between occupational groups in either smoking or non-smoking males. In non-smoking females, median values of FEV(1) (P: 0.046), PEF (P: 0.005) and FEF(25-75%) (P: 0.019) were lower in the textile compared to the coiffure group. There was no significant association between the total working time and spirometric values. There was no statistically significant relationship between the work-related factors and the smoking status.

CONCLUSIONS

The prevalence of chronic cough was higher in the lathe, coiffure, and electricity-construction groups and pulmonary function tests were lower in the non-smoking textile female group. Working children should be screened for respiratory symptoms and disease.

Asthma caused by occupational exposures is common - a systematic analysis of estimates of the population-attributable fraction

Background

The aim of this paper is to highlight emerging data on occupational attributable risk in asthma. Despite well documented outbreaks of disease and the recognition of numerous specific causal agents, occupational exposures previously had been relegated a fairly minor role relative to other causes of adult onset asthma. In recent years there has been a growing recognition of the potential importance of asthma induced by work-related exposures

Methods

We searched Pub Med from June 1999 through December 2007. We identified six longitudinal general population-based studies; three case-control studies and eight cross-sectional analyses from seven general population-based samples. For an integrated analysis we added ten estimates prior to 1999 included in a previous review.

Results

The longitudinal studies indicate that 16.3% of all adult-onset asthma is caused by occupational exposures. In an overall synthesis of all included studies the overall median PAR value was 17.6%.

Conclusion

Clinicians should consider the occupational history when evaluating patients in working age who have asthma. At a societal level, these findings underscore the need for further preventive action to reduce the occupational exposures to asthma-causing agents.

The healthy worker effect in asthma: work may cause asthma, but asthma may also influence work

Despite the increasing attention to the relationship between asthma and work exposures, occupational asthma remains underrecognized and its population burden underestimated. This may be due, in part, to the fact that traditional approaches to studying asthma in populations cannot adequately take into account the healthy worker effect (HWE). The HWE is the potential bias caused by the phenomenon that sicker individuals may choose work environments in which exposures are low; they may be excluded from being hired; or once hired, they may seek transfer to less exposed jobs or leave work. This article demonstrates that population- and workplace-based asthma studies are particularly subject to HWE bias, which leads to underestimates of relative risks. Our objective is to describe the HWE as it relates to asthma research, and to discuss the significance of taking HWE bias into account in designing and interpreting asthma studies. We also discuss the importance of understanding HWE bias for public health practitioners and for clinicians. Finally, we emphasize the timeliness of this review in light of the many longitudinal "child to young adult" asthma cohort studies currently underway. These prospective studies will soon provide an ideal opportunity to examine the impact of early workplace environments on asthma in young adults. We urge occupational and childhood asthma epidemiologists collaborate to ensure that this opportunity is not lost.

Work tasks, chemical exposure and respiratory health in construction painting

BACKGROUND

There is insufficient knowledge about the role of house painting tasks and chemical exposure in the respiratory health of construction workers.

METHODS

A cross-sectional questionnaire survey was conducted of 1,000 Finnish male construction painters and 1,000 carpenters (response rates 60.6% and 60.4%, respectively). Multivariate logistic regression models were adjusted for age, smoking, and atopy.

RESULTS

Outdoor painting, more than indoor painting, was associated with asthma-like respiratory symptoms [odds ratios (OR) 2.7-6.5], rhinitis symptoms [OR 2.4, 95% confidence interval (CI) 1.1-5.2], asthma (OR 4.7, 95% CI: 1.4-16.1), and chronic bronchitis (OR 2.9, 95% CI: 1.0-8.4) when compared to carpentry work. Risk factors for respiratory symptoms and chronic bronchitis were the use of epoxy/urethane paints, putties, and plasters and the use of glues or traditional paints. Water-based paints were not a common cause of symptoms.

CONCLUSIONS

Special attention should be paid to work methods and personal protection, not only in outdoor painting, but also in all filling, plastering, and sanding tasks. The shift from epoxy/urethane and other solvent-based paints to water-based products should be further encouraged.

Office work exposures and adult-onset asthma

BACKGROUND

Office exposures have been linked to symptoms of sick building syndrome, but their relation to the development of asthma has not been studied previously. These exposures have increasing importance because an increasing proportion of the workforce is working in office environments.

OBJECTIVES

The aim of this study was to assess the relations of exposure to carbonless copy paper (CCP), paper dust, and fumes from photocopiers and printers to adult-onset asthma.

METHODS

We conducted a population-based incident case-control study of adults 21-63 years of age living in the Pirkanmaa District in South Finland. All new clinically diagnosed cases (n = 521) of asthma were recruited during a 3-year study period. A random sample of the source population formed the controls (n = 1,016). This part focused on 133 cases and 316 controls who were office workers according to their current occupation classified by the 1988 International Standard Classification of Occupations. All participants answered a questionnaire on health, smoking, occupation, and exposures at work and home. Subjects with previous asthma were excluded.

RESULTS

Exposures to paper dust [adjusted odds ratio (OR) = 1.97; 95% confidence interval (CI), 1.25-3.10] and CCP (OR = 1.66; 95% CI, 1.03-2.66) were related to significantly increased risk of adult-onset asthma. An exposure-response relation was observed between exposure to paper dust and risk of asthma.

CONCLUSIONS

This study provides new evidence that exposures to paper dust and CCP in office work are related to increased risk of adult-onset asthma. Reduction of these exposures could prevent asthma in office workers. Clinicians seeing asthma patients should be aware of this link to office exposures.

Reported occupational respiratory diseases in Catalonia

OBJECTIVES

A voluntary surveillance system was implemented in Catalonia (Spain) to ascertain the feasibility, incidence, and characteristics of occupational respiratory diseases and compare them with those of the compulsory official system.

METHODS

In 2002, in collaboration with the Occupational and Thoracic Societies of Catalonia, occupational and chest physicians and other specialists were invited to report, on a bimonthly basis, newly diagnosed cases of occupational respiratory diseases. Information requested on each case included diagnosis, age, sex, place of residence, occupation, suspected agent, and physician's opinion on the likelihood that the condition was work related. Compulsory official system data derived from statistics on work related diseases for possible disability benefits declared by insurance companies, which are responsible for declaring these diseases to the Autonomous Government of Catalonia.

RESULTS

Of 142 physicians seeing patients with occupational respiratory diseases approached, 102 (74%) participated. Three hundred and fifty nine cases were reported, of which asthma (48.5%), asbestos related diseases (14.5%), and acute inhalations (12.8%) were the most common. Physicians rated 63% of suspected cases as highly likely, 28% as likely, and 8% as low likelihood. The most frequent suspected agents reported for asthma were isocyanates (15.5%), persulphates (12.1%), and cleaning products (8.6%). Mesothelioma (5.9%) was the most frequent diagnosis among asbestos related diseases. The number of acute inhalations reported was high, with metal industries (26%), cleaning services (22%), and chemical industries (13%) being the most frequently involved. The frequency of occupational respiratory diseases recorded by this voluntary surveillance system was four times higher than that reported by the compulsory official system.

CONCLUSIONS

The compulsory scheme for reporting occupational lung diseases is seriously underreporting in Catalonia. A surveillance programme based on voluntary reporting by physicians may provide better understanding of the incidence and characteristics of these diseases. Persulphates and cleaning products, besides isocyanates, were the most reported causes of occupational asthma. Metal industries and cleaning services were the occupations most frequently involved in acute inhalations with a remarkably high incidence in our register.

Self-reported asthma was biased in relation to disease severity while reported year of asthma onset was accurate

BACKGROUND AND OBJECTIVES

The aims of the study were to assess the accuracy of self-reported asthma and notified year of asthma onset.

METHODS

The study was performed on a sample of 365 subjects, 18-60 years old, with clinically diagnosed onset of asthma between 1983 and 1986. All subjects were investigated 10 years later, in 1996, with a respiratory questionnaire about the items of asthma and year of onset. The material was analyzed with logistic regression models.

RESULTS

Of the 289 subjects who returned the questionnaire, asthma was reconfirmed in 251 subjects. In a logistic regression model, asthma severity was significantly associated with confirmation of asthma. The median difference between the "true" year of onset and the reported year 10 years later, the recall period was zero, with a 10th to 90th interpercentile range of -2 to 6 years. The recall period was not associated with asthma severity, bronchial hyperresponsiveness, smoking, atopy, or sex.

CONCLUSION

Self-reported asthma is biased in relation to disease severity, meaning that subjects with mild disease were less prone to report their asthma. Reported year of asthma onset among adults seems to be rather accurate, with no obvious dependent misclassifications.

Obstructive airway diseases in women exposed to biomass smoke

The majority of women living in rural areas in Turkey use biomass fuels for domestic energy and are exposed to high levels of indoor air pollution every day. The objective of this study was to compare the presence of chronic airway diseases (CAD) in two groups of nonsmoking women older than 40 years with (exposed group, n=397) and without a history of exposure to biomass cooking (liquid petroleum gas (LPG); control group, n=199), in 2002 in Kirikkale, Turkey. Detailed respiratory symptoms were collected with a standard questionnaire adapted from that of the British Medical Research Council. Exposure was calculated as the average hours spent daily for cooking multiplied by the number of years. CAD were defined as either chronic airway obstruction (CAO; (forced expiratory volume in 1s/forced vital capacity)<0.70), chronic bronchitis, or chronic bronchitis with CAO. The prevalence of CAD in the exposed group was found to be higher than that in the LPG group (28.5% vs. 13.6%, crude odds ratios (ORs) 2.5 (1.5--4.0), P=0.0001). The fraction of CAD attributed to exposure to biomass smoke after adjusting for possible confounding factors was 23.1% (95% confidence interval (CI) 13.4--33.2). Acute symptoms during exposure to biomass smoke were important predictors for the presence of CAD. Biomass smoke pollution is an important contributing factor in the development of CAD in nonsmoking women living in a rural area. The presence of acute symptoms during cooking in women in rural areas should signal to general practitioners the possibility of CAD.

Occupational asthma

Substantial epidemiologic and clinical evidence indicates that agents inhaled at work can induce asthma. In industrialized countries, occupational factors have been implicated in 9 to 15% of all cases of adult asthma. Work-related asthma includes (1) immunologic occupational asthma (OA), characterized by a latency period before the onset of symptoms; (2) nonimmunologic OA, which occurs after single or multiple exposures to high concentrations of irritant materials; (3) work-aggravated asthma, which is preexisting or concurrent asthma exacerbated by workplace exposures; and (4) variant syndromes. Assessment of the work environment has improved, making it possible to measure concentrations of several high- and low-molecular-weight agents in the workplace. The identification of host factors, polymorphisms, and candidate genes associated with OA is in progress and may improve our understanding of mechanisms involved in OA. A reliable diagnosis of OA should be confirmed by objective testing early after its onset. Removal of the worker from exposure to the causal agent and treatment with inhaled glucocorticoids lead to a better outcome. Finally, strategies for preventing OA should be implemented and their cost-effectiveness examined.

Women and occupational lung disease: sex differences and gender influences on research and disease outcomes

We have attempted to describe the current state of knowledge regarding occupational lung disease in women. A large section of this article was devoted to describing the methodologic challenges that face researchers when evaluating gender differences in occupational lung disease. The findings of the presented studies are likely limited by many of the methodologic problems that were identified earlier. To accurately identify the true risk of occupational lung disease in women workers, these findings must be replicated in future studies with special attention paid to the various aspects of occupational lung disease research that are susceptible to gender-related bias.

Interaction of atopy and smoking on respiratory effects of occupational dust exposure: a general population-based study

BACKGROUND

For individual exposures, effect modification by atopy or smoking has been reported on the occurrence of occupational airway disease. It is unclear if effect modification can be studied in a general population by an aggregated exposure measure. Assess relationship between airway obstruction and occupational exposure using a job-exposure-matrix (JEM) classifying jobs into 3 broad types of exposure, and test for effect modification by atopy, and smoking.

METHODS

Data from 1,906 subjects were analyzed, all participants of the European Community Respiratory Health Survey. Job titles were categorized by an a priori constructed job exposure matrix into three classes of exposure to respectively organic dust, mineral dust, and gases/ fumes. Relationships were assessed for 'current wheeze', bronchial hyperresponsiveness (BHR), 'current asthma' (wheeze+BHR), and 'chronic bronchitis' (morning phlegm or morning cough), and lung function.

RESULTS

Subjects with organic dust exposure in their work environment more frequently had 'current asthma' (OR 1.48, 95% C.I. 0.95;2.30), and a lower FEV1 (-59 mL, 95% C.I. -114;-4). The relationship was only present in asthmatic workers, and their risk was four-fold greater than in subjects with either atopy or exposure alone. Mineral dust exposure was associated with 'chronic bronchitis' (OR 2.22, 95% C.I. 1.16;4.23) and a lower FEV1/FVC ratio (-1.1%, 95% C.I. -1.8;-0.3). We observed an excess risk in smokers, greater than the separate effects of smoking or mineral dust exposure together.

CONCLUSION

Occupational exposure to organic dust is associated with an increased risk of asthma, particularly in atopics. Chronic bronchitis occurs more frequently among individuals exposed to mineral dust, and smoking doubles this risk.

Respiratory findings in gun factory workers exposed to solvents

OBJECTIVE

Gun factory workers are exposed to many solvents (toluene, acetone, butanol, xylene, benzene, trichloroethylene). We investigated whether chronic exposure to solvents had adverse effect on respiratory system.

MATERIAL AND METHODS

The workers were questionnaired by modified Medical Research Council's respiratory questionnaire before morning start shift. Then physical examination and measurement of pulmonary functions by portable dry rolling spirometer were performed. The study group consisted of 1091 gun factory workers. The workers were grouped according to their smoking habits (smokers, [exposed n: 353 vs. unexposed n: 339] and non-smokers [exposed n: 58 vs. unexposed n: 341]). Asthma-related symptoms were defined as either definite asthma, probable asthma, and possible asthma.

RESULTS

In non-smokers, the report of asthma-related symptoms was more prevalent in exposed workers than unexposed (39.7% vs. 21.7% OR 2.4[1.3-4.3], respectively P = 0.003). In smokers, the report of asthma-related symptoms was more common in exposed group than unexposed (50.7% vs. 42.5% OR 1.4[1.0-1.9], respectively P = 0.03). Logistic regression analysis showed that smoking (OR 2.8[2.0-3.8] P = 0.00001) and exposure to solvents (OR 1.4[1.1-1.9] P = 0.01) were independent risk factors for asthma-related symptoms, after adjusting for age. Logistic regression analysis identified that smoking (OR 3.3[2.3-4.6] P = 0.00001) was independent risk factors for chronic bronchitis. Multiple linear regression analysis of lung-function parameters (% forced expiratory volume (FEV1), FEV1/forced vital capacity, FEF(25-75)) indicated significant effects of smoking.

CONCLUSION

Present study indicated significant effects of smoking and exposure to solvents, with the smoking effect being the most important on asthma-related symptoms of gun factory workers.

Non-sensitising air pollution at workplaces and adult onset asthma

OBJECTIVE

The aim of this study was to elucidate further whether occupational exposure to non-sensitising air pollution at workplaces increases the risk of adult onset asthma.

METHODS

One hundred and twenty persons with asthma diagnosed by general practitioners, aged 20-65 years, were compared with 446 referents matched for age and gender and living in the same community as the cases. Information about occupation, exposure to specific allergens, smoking habits, dwellings and atopy was obtained from a postal questionnaire. The subjects' occupations were categorised as clean or polluted, based on the judgement of the referents on their respective occupations.

RESULTS

Three years or more of work in air-polluted workplaces resulted in an odds ratio of 1.7 (95% confidence interval 1.0-2.7). Stratification of the material on smoking habits, gender or atopy did not alter the results, nor did exclusion of subjects exposed to specific allergens of statistical significance in this material, e.g. flour dust. Smoking per se did not bring any risk of asthma. Working in buildings affected by dampness and mould brought a fourfold significant risk.

CONCLUSION

In this study occupational exposure to unspecific air pollution at workplaces was associated with an increased risk of adult-onset asthma.

Prevalence and association of welding related systemic and respiratory symptoms in welders

BACKGROUND

The prevalence of welding related respiratory symptoms coexisting with welding related systemic symptoms in welders is unknown.

AIMS

To determine in a sample of welders the prevalence of coexisting welding related systemic symptoms indicative of metal fume fever (MFF) and welding related respiratory symptoms suggestive of occupational asthma (OA), and the strength and significance of any association between these two groups of symptoms.

METHODS

A respiratory symptoms questionnaire, a systemic symptoms questionnaire, and a questionnaire on occupational history were administered by telephone to 351 of a sample of 441 welders (79.6%) from two cities in Québec, Canada.

RESULTS

The co-occurrence of possible MFF (defined as having at least two symptoms of fever, feelings of flu, general malaise, chills, dry cough, metallic taste, and shortness of breath, occurring at the beginning of the working week, 3-10 hours after exposure to welding fumes) together with welding related respiratory symptoms suggestive of OA (defined as having at least two welding related symptoms of cough, wheezing, and chest tightness) was 5.8%. These two groups of symptoms were significantly associated (chi(2) = 18.9, p < 0.001).

CONCLUSION

There is a strong association between welding related MFF and welding related respiratory symptoms suggestive of OA. As such, MFF could be viewed as a pre-marker of welding related OA, a hypothesis that requires further investigation.

Workplace irritant exposures: do they produce true occupational asthma?

OBJECTIVE

To describe the features of irritant-induced asthma and discuss the diagnosis in relation to differing workplace irritant exposures and symptomatic responses.

DATA SOURCES

A review of MEDLINE articles on this topic from January 1, 1985, through December 31, 2001 was performed.

STUDY SELECTION

The author selected relevant articles for inclusion in the review.

RESULTS

Many reports indicate that unintentional high-level respiratory irritant exposures can induce the new onset of asthma. Cases that meet strict criteria for a syndrome of irritant-induced asthma, termed reactive airways dysfunction syndrome, can be diagnosed with relative certainty. Several reports of irritant-induced asthma, especially prevalence studies, have relied on historical data or have otherwise modified the reactive airways dysfunction syndrome criteria for diagnosis (eg, expanding the definition to include the symptom onset several days after exposure). Such modifications, or inclusion of cases with incomplete documentation, likely increase diagnostic sensitivity but may reduce the certainty of diagnosis for individual cases. Expanding exposure criteria to moderate or long-term low-level irritant exposures causes difficulty in excluding transient irritant exacerbation of underlying asthma or coincidental onset of asthma during working life. Although recent population studies suggest a greater relative risk of asthma in occupations with expected low-to-moderate respiratory irritant exposures, currently no objective laboratory tests exist to exclude coincidental asthma in such patients.

CONCLUSIONS

Irritant-induced asthma can be produced by high-level unintentional respiratory irritant exposures at work or outside the workplace. Lower levels of exposure to respiratory irritants at work are more common, and additional studies are needed to determine the airway effects of such exposures.

Reported incidence of occupational asthma in France, 1996-99: the ONAP programme

AIMS

To estimate the general and specific incidence of occupational asthma in France in 1996-99; and to describe the distribution of cases by age, sex, suspected causal agents, and occupation.

METHODS

New cases of occupational asthma were collected by a national surveillance programme, based on voluntary reporting, named Observatoire National des Asthmes Professionnels (ONAP), involving a network of occupational and chest physicians. For each case, the reporting form included information on age, sex, location of workplace, occupation, suspected causal agent, and methods of diagnosis. Estimates of the working population, used to calculate incidence rates by age, sex, region, and occupation, were obtained from the Institut National de la Statistique et des Etudes Economiques (INSEE) and from the French Securite Sociale statistics.

RESULTS

In 1996-99, 2178 cases of occupational asthma were reported to the ONAP, giving a mean annual rate of 24/million. Rates in men were higher than rates in women (27/million versus 19/million). The highest rate was observed in the 15-29 years age group (30/million). The most frequently incriminated agents were flour (20.3%), isocyanates (14.1%), latex (7.2%), aldehyde (5.9%), persulphate salts (5.8%), and wood dusts (3.7%). The highest risks of occupational asthma were found in bakers and pastry makers (683/million), car painters (326/million), hairdressers (308/million), and wood workers (218/million).

CONCLUSION

Despite likely underreporting, the number of cases of occupational asthma reported to the ONAP was approximately twice the number of compensated cases over the same period. The relevance of the programme is confirmed by the reproducibility of the results year after year, and its consistency with other surveillance programmes. The ONAP programme is useful for the identification of targets for primary prevention.

Incidence of asthma among Finnish construction workers

We wanted to explore the risk of asthma among male workers of the construction industry. All Finnish male construction industry workers and all those employed in administrative work were followed for asthma incidence through a register linkage in 1986 through 1998. Age-adjusted relative risks (RR) were estimated for 24 construction occupations. The risk was increased in nearly all construction occupations studied, but it was highest among welders and flame cutters (RR 2.34), asphalt roofing workers (RR 2.04), plumbers (RR 1.90), and brick layers and tile setters (RR 1.83). Only 45 (2%) of the cases of asthma among construction workers had been recognized as occupational asthma. Construction industry workers have an increased risk of adult-onset persistent asthma and cases of occupational asthma caused by well-established causative agents have only a minor contribution to this overall asthma excess.

Prevalence of obstructive lung diseases and respiratory symptoms in relation to living environment and socio-economic group

We wanted to test whether living environment, occupation and social position are risk factors for asthma and chronic bronchitis/emphysema (CBE). The prevalence of bronchial asthma, CBE, respiratory symptoms and smoking habits in a random sample of 12,071 adults aged 20-59 years was assessed in a postal survey with a slightly modified questionnaire previously used in central and northern Sweden (The OLIN studies). Occupation was coded according to a socio-economic classification system. Six different living environment areas were defined; city-countryside, seaside-not seaside and living close to heavy traffic-not living close to heavy traffic. Multiple logistic regression analysis (forward conditional) was applied to estimate the association between the proposed set of risk factors and self-reported obstructive lung diseases and lower respiratory symptoms controlling for age, gender and smoking. After two reminders, the response rate was 70.1% (n=8469); 33.8% of the responders were smokers. In all, 469 subjects (5.5%) stated that they had asthma and 4.6% reported CBE. Besides smoking, which was a risk for both asthma and CBE, there were different risk patterns for self-reported asthma and CBE. In the economically active population there was a tendency that CBE was more common among 'unskilled and semi-skilled workers'. This fact was further emphasized when the population was merged into the two groups 'low social position' and 'middle/high social position', with 'low social position' as a risk for CBE (OR=1.35, 95% CI=1.06-1.72). No social risk factors were identified for asthma. Living close to heavy traffic was a risk factor for asthma (OR=1.29, 95% CI=1.02-1.62) but not for CBE. Apart from this no living environmental risk factors for obstructive pulmonary diseases were identified. Asthma symptoms and long-standing cough were more common among those subjects living close to heavy traffic compared to those not living close to heavy traffic. To conclude, low social position was a risk factor for CBE and living close to heavy traffic was a risk factor for asthma.

Work is related to a substantial portion of adult-onset asthma incidence in the Finnish population

There are no population-based follow-up studies to estimate the fraction of asthma incidence that is attributable to work. In Finland, individuals with clinically well-established persistent asthma are registered for reimbursement of medication from the national health insurance scheme. We combined, at an individual level, these data with the population census data of 1985, 1990, and 1995 to estimate the attributable fraction of work in adult-onset persistent asthma. Our follow-up study covered the entire 25- to 59-yr-old employed population of Finland in 1986-1998. Relative risks (RR) for occupational categories were estimated in comparison to those employed in administrative work. There were 49,575 incident cases of asthma. The attributable fraction of occupation was 29% (95% CI 25-33%) for men and 17% (95% CI 15-19%) for women. The risk was increased especially in agricultural work, manufacturing work, and service work. In addition to already established risk occupations of occupational asthma, such as food and beverage work, the analysis identified a large number of occupations with significant excess of asthma incidence. The results indicate that the impact of occupational factors in the inception of adult-onset persistent asthma, and consequently the potential for prevention, is much larger and more widely spread than generally assumed.

A guide to the diagnosis and treatment of occupational asthma

Occupational asthma is the most prevalent form of occupational lung disease in industrialized nations. As increasing numbers of new chemicals are produced and new manufacturing processes are introduced, the variety of environments in which individuals may become exposed to respiratory sensitizers and irritants makes diagnosing and treating this illness even more challenging. In addition to adverse pulmonary effects, the diagnosis of occupational asthma may bring with it negative social and financial implications that may ultimately affect the patient's quality of life. For this reason, it is important for clinicians to recognize work-related respiratory symptoms early on in their course, maintain a high clinical suspicion for an occupational cause in the diagnostic work-up of asthma, and have a high degree of certainty in the diagnosis. While a number of classification schemes have been proposed to simplify the diagnostic approach to occupational asthma, the inciting factors typically involve sensitization (often by an IgE mechanism), direct airway inflammation, various pharmacologic responses, or irritant reflex pathways. Clinicians must first document the presence of asthma, then establish a relationship between asthma and the work-place. The occupational history is the key diagnostic tool, and clinical suspicions may be evaluated further by serial peak expiratory flow measurements, nonspecific hypersensitivity challenges with histamine or methacholine, collaboration with industrial/occupational hygienists to obtain workplace exposure measurements, and specific challenge testing at tertiary referral centers providing specialized laboratories. Removal from the inciting exposure is the mainstay of therapy, and pharmacologic treatment of patients with occupational asthma is similar to the treatment of patients with other forms of asthma.

Recent advances in occupational asthma

In the past year, many advances were made in occupational asthma (OA). As in previous years, several new causes of OA were described and the prevalences of some causes of OA were studied. Animal studies suggested possible mechanisms for the induction of sensitization to low-molecular-weight chemicals, and a study in humans indicated the ability of diisocyanates to bind with lung epithelial cells and stimulate mononuclear cells in sensitized patients with OA. New diagnostic and research methods, such as induced-sputum assessment and measurement of exhaled nitric oxide, were evaluated. The effectiveness of protective respiratory devices in patients with OA was shown to be suboptimal (although these devices are necessary in some cases), and the need to prevent OA by reducing or eliminating exposures remains paramount.

How much adult asthma can be attributed to occupational factors?

PURPOSE

Many occupational factors can cause asthma or reactivate preexisting disease. We carried out a critical review and synthesis of the available literature to estimate the proportion of adult asthma that is attributable to workplace factors.

METHODS

We reviewed published citations from 1966 through May 1999 as well as recent abstracts of studies providing risk estimates for asthma among various occupations. We extracted published attributable risk estimates, derived others from published data, and extrapolated estimates from the incidence rates of occupational asthma. We used a semiquantitative score to rank studies based on their characteristics.

RESULTS

We obtained 43 attributable risk estimates from 19 different countries: 23 were published estimates, 8 were derived from published data, and 12 were extrapolated from incidence data. The median value for the attributable risk of occupationally associated asthma was 9%(25th to 75th interquartile range: 5% to 19%). The derived estimates (median attributable risk = 25%) were significantly greater than published values (median = 9%, P = 0.002), whereas the extrapolated estimates were significantly lower (median = 5%, P = 0.04). The 12 highest scored studies based on their characteristics yielded a median risk estimate of 15%.

CONCLUSION

Occupational factors are associated with about 1 in 10 cases of adult asthma, including new onset disease and reactivation of preexisting asthma.

Asthma-related work disability in Sweden. The impact of workplace exposures

Work disability due to respiratory disease, especially asthma, is common and costly among working age adults. The goal of this analysis was to characterize the risk factors for such disability. We analyzed data from the Swedish part of the European Community Respiratory Health Survey (ECRHS), a random population-based sample of adults age 20 to 44, enriched with symptomatic subjects at increased likelihood of having asthma. We analyzed structured interview data available for 2,065 subjects and further analyzed methacholine challenge and skin prick test data for 1,562 of these. We defined respiratory work disability as reported job change or work loss due to breathing affected by a job. We used binary generalized linear modeling with a log link to estimate disability risk. Eighty-four subjects (4%) reported such work disability. This increased to 13% among those with asthma (45 of 350 subjects). Adjusting for covariates, occupations at high risk for asthma were associated with disability (prevalence ratio [PR] 1.8; 95% confidence interval [CI] 1.1 to 3.0), as was self-reported regular exposure to environmental tobacco smoke (ETS) at work (PR 1.8; 95% CI 1.1 to 3.1) and self- reported job exposure to vapors, gases, dust, or fumes (VGDF) (PR 4.3; 95% CI 2.2 to 8.6). Workplace ETS exposure was also associated with methacholine challenge-positive asthma reported to be symptomatic at work among male subjects (PR 4. 2; 95% CI 1.8 to 9.8), whereas high asthma-risk occupations were associated with this outcome among female subjects (PR 2.7; 95% CI 1. 05 to 7.1). Respiratory work disability, defined as breathing-related job change due to work loss, was associated with workplace exposures themselves, even after taking into account other covariates. Better control of workplace exposures, including workplace ETS, may reduce work disability caused by respiratory conditions, especially adult asthma.