Occupational asthma in New Zealanders: a population based study

Respiratory symptoms and use of dust-control measures in New Zealand construction workers – A cross-sectional study

Dust-exposed construction workers have an increased risk of respiratory symptoms, but the efficacy of dust-control measures remains unclear. This study compared respiratory symptoms, using a modified European Community Respiratory Health Survey questionnaire, between construction workers (n = 208) and a reference group of bus drivers and retail workers (n = 142). Within the construction workers, we assessed the effect of collective (on-tool vacuum/’wet-cut’ systems) and personal (respirators) exposure controls on symptom prevalence. Logistic regression assessed differences between groups, adjusted for age, ethnicity, and smoking status. Construction workers were more likely to cough with phlegm at least once a week (OR 2.4, 95% CI 1.2–4.7) and cough with phlegm ≥3 months/year for ≥2 years (OR 2.8, CI 1.2–7.0), but they had similar or fewer asthma symptoms. Construction workers who had worked for 11–20 years reported more cough/phlegm symptoms (OR 5.1, 1.7–15.0 for cough with phlegm ≥3 months/year for ≥2 years) than those who had worked <10 years (OR 1.9, 0.6–5.8), when compared to the reference group. Those who used ‘wet-cut’ methods reported less cough with phlegm, although the evidence for this association was weak (OR 0.4, CI 0.2–1.1 for cough with phlegm at least once a week); use of on-tool extraction showed a similar trend. No associations between respiratory protective equipment-use and symptoms were found. In conclusion, construction workers reported more symptoms suggestive of bronchitis, particularly those employed in the industry for >10 years. Use of collective dust exposure controls might protect against these symptoms, but this requires confirmation in a larger study.

Work-related Asthma in Crop Farmers

AIM: The objective of the study was to evaluate the influence of occupational exposure on asthma development among crop farmers. METHODS: A cross-sectional study was performed, comprising 87 crop farmers, and 80 office workers, matched by gender and age. Evaluation of subjects included completion of a standard questionnaire on chronic respiratory symptoms, spirometry tests, histamine challenge, serial peak expiratory flow rates (PEFR) measurements, and skin prick tests to occupational and common inhalant allergens. RESULTS: The prevalence of chronic respiratory symptoms in the past 12 months was higher, while the mean values of spirometric parameters were lower in crop farmers. Sensitization to workplace and common inhalant allergens was similar in both groups, whereas frequencies of bronchial hyperresponsiveness (BHR) and asthma were non-significantly higher in crop farmers. The prevalence of allergic was significantly higher compared to non-allergic asthma in both groups. Asthma was registered in 8% of crop farmers and was significantly associated with atopy, and positive family history of asthma. Occupational allergic asthma (OA) was registered in 2.3% of crop farmers, while the frequency of work-aggravated asthma was 5.7%. A causal relationship between workplace and asthma, suggesting allergic OA, was documented in two crop farmers with asthma, based on serial PEFR monitoring, but specific workplace agent causing asthma in the affected subjects was not identified. CONCLUSION: The obtained results can contribute in the detection of critical points for action, and serve as a predictive factor in the development of work-related asthma, indicating the need for reduction of adverse occupational exposures through adequate preventive measures, regular health examinations, obligatory use of respiratory protective equipment, and implementation of engineering controls.

Effects of Car Painting Vapors on Spirometric Parameters in Automobile Painting Workers

BACKGROUND

Automobile spray painting is considered a high-risk occupation for respiratory diseases. The present survey aimed to assess the effects of automobile paint vapors on spirometric parameters among workers of a painting workshop in a large automobile manufacturing plant in Iran.

MATERIALS AND METHODS

This cross-sectional study was conducted on 820 workers of an automobile manufacturing plant, including 431 spray painters (case group) and 389 assembly line workers (control group). Spirometry was conducted for all participants under standard conditions, according to the American Thoracic Society (ATS) Clinical Practice Guidelines. The forced expiratory volume in one second (FEV1), forced vital capacity (FVC), FEV1/FVC, and forced expiratory flow at 25% and 75% of the pulmonary volume (FEF25-75) were reported.

RESULTS

Painters with more than ten years of work experience had significantly lower predicted values of FEV1/FVC (P= 0.005), FEV1 (P=0.008), and FEF25-75 (P=0.003), compared to the control group. Also, painters who were exposed to solvent-based paints were not significantly different from those exposed to water-based paints in terms of spirometric parameters (P>0.05).

CONCLUSION

The results indicated the impact of automobile spray painting on the spirometric parameters. A slight decrease in the mean values of these parameters calls for attention to occupational safety, regular medical examinations, and effective measures.

Occupations with an increased prevalence of self-reported asthma in Indian adults

Objectives

Occupational asthma remains relatively under-recognized in India with little or no information regarding preventable causes. We studied occupations with an increased prevalence of self-reported asthma among adult men and women in India.

Methods

Analysis is based on 64 725 men aged 15–54 years and 52 994 women aged 15–49 years who participated in India’s third National Family Health Survey, 2005–2006, and reported their current occupation. Prevalence odds ratios (ORs) for specific occupations and asthma were estimated using multivariate logistic regression, separately for men and women, adjusting for age, education, household wealth index, current tobacco smoking, cooking fuel use, rural/urban residence and access to healthcare.

Results

The prevalence of asthma among the working population was 1.9%. The highest odds ratios for asthma were found among men in the plant and machine operators and assemblers major occupation category (OR: 1.67; 95% CI: 1.14–2.45; p = 0.009). Men working in occupation subcategories of machine operators and assemblers (OR: 1.85; 95% CI: 1.24–2.76; p = 0.002) and mining, construction, manufacturing and transport (OR: 1.33; 95% CI: 1.00–1.77; p = 0.051) were at the highest risk of asthma. Reduced odds of asthma prevalence in men was observed among extraction and building trades workers (OR: 0.72; 95% CI: 0.53–0.97; p = 0.029). Among women none of the occupation categories or subcategories was found significant for asthma risk. Men and women employed in high-risk occupations were not at a higher risk of asthma when compared with those in low-risk occupations.

Conclusions

This large population-based, nationally representative cross-sectional study has confirmed findings from high income countries showing high prevalence of asthma in men in a number of occupational categories and subcategories; however, with no evidence of increased risks for women in the same occupations.

Epidemiology of Respiratory Allergies and Asthma

Asthma has puzzled and confused physicians from the time of Hippocrates to the present day. The word “asthma” comes from a Greek word meaning “panting” (Keeney 1964), but reference to asthma can also be found in ancient Egyptian, Hebrew, and Indian medical writings (Ellul-Micallef 1976; Unger and Harris 1974). There were clear observations of patients experiencing attacks of asthma in the second century and evidence of disordered anatomy in the lung as far back as the seventeenth century (Dring et al. 1689).

Occupational exposure to poultry dust and effects on the respiratory system in workers

Farmers are occupationally exposed to many respiratory hazards at work and display higher rates of asthma and respiratory symptoms than other workers. Dust is one of the components present in poultry production that increases risk of adverse respiratory disease occurrence. Dust originates from poultry residues, molds, and feathers and is biologically active as it contains microorganisms. Exposure to dust is known to produce a variety of clinical responses, including asthma, chronic bronchitis, chronic airways obstructive disease (COPD), allergic alveolitis, and organic dust toxic syndrome (ODTS). A study was developed to determine particle contamination in seven poultry farms and correlate this with prevalence rate of respiratory defects and record by means of a questionnaire the presence of clinical symptoms associated with asthma and other allergy diseases by European Community Respiratory Health Survey. Poultry farm dust contamination was found to contain higher concentrations of particulate matter (PM) PM5 and PM10. Prevalence rate of obstructive pulmonary disorders was higher in individuals with longer exposure regardless of smoking status. In addition, a high prevalence for asthmatic (42.5%) and nasal (51.1%) symptoms was noted in poultry workers. Data thus show that poultry farm workers are more prone to suffer from respiratory ailments and this may be attributed to higher concentrations of PM found in the dust. Intervention programs aimed at reducing exposure to dust will ameliorate occupational working conditions and enhance the health of workers.

Exercise-related respiratory symptoms and exercise-induced bronchoconstriction in industrial bakers

In order to assess prevalence and characteristics of exercise-related respiratory symptoms (ERRS) and exercise-induced bronchoconstriction (EIB) in industrial bakery, the authors performed a cross-sectional study including 57 bakers and an equal number of office workers studied as a control. Evaluation of examined subjects included completion of a questionnaire, skin prick tests to common inhalant and occupational allergens, spirometry, and exercise and histamine challenge. The authors found a similar prevalence of ERRS and EIB in both bakers and controls. EIB was significantly associated with atopy, asthma, family history of asthma, and positive histamine challenge in either group, whereas in bakers it was closely related to sensitization to occupational allergens (p = .032). Bronchial reaction to exercise was significantly higher in bakers with EIB (25.7% vs 19.2%; p = .021). These findings suggest that occupational exposure in industrial bakery may accentuate bronchoconstrictive response to exercise.

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.

Exercise-induced bronchoconstriction and exercise-induced respiratory symptoms in nurses

In order to assess prevalence and characteristics of exercise-induced respiratory symptoms (EIRSs) and exercise-induced bronchoconstriction (EIB) in health care workers, we performed a cross-sectional study including 48 female nurses from primary care settings and an equal number of female office workers studied as a control group. The evaluation of examined groups included completion of a questionnaire, skin prick tests to common inhalant allergens, spirometry, and exercise and histamine challenge. We found a similar prevalence of EIRSs and EIB in both groups. EIB was closely related to asthma, atopy, family history of asthma, and positive histamine challenge in either group, while the association between EIB and daily smoking in nurses was of borderline statistical significance. Bronchial reaction to exercise was significantly higher in nurses than in controls with EIB. With the exception of exercise induced wheezing, EIRSs were weakly associated with EIB in both groups with a large proportion of false positive results.

Asthma increase among farmers: a 12-year follow-up

Respiratory disease is a well known health hazard for farmers, but the long-term prognosis is less well known. This is a 12-year follow-up of an investigation of Swedish farmers, most of them dairy farmers. A questionnaire was mailed to all 418 farmers who were alive of the farmers originally participating in 1982. They were invited to an interview, spirometry, and blood sampling. Ninety-one per cent (380) of the farmers, 321 men and 59 women, responded to the questionnaire. The mean age was 56 years for the men and 55 years for the women. Of the group, 10% were smokers, 25% ex-smokers, and 65% had never smoked. The population estimate for asthma in the farmers was 8.9% in 1994 compared to 2% in 1982, and to 5.4%-6.6% in the general population in the region in 1982. Of the asthmatic subjects, one-third had positive RAST tests (radioallergosorbent tests). Almost 90% of the new onset asthma cases since 1982 had non-IgE-mediated asthma. Most of the IgE-mediated asthmatics had had symptoms for many years, while 70% of the non-IgE-mediated asthmatic farmers had no or only wheezing with colds 1982. Two new cases of hypersensitivity pneumonitis were identified, and 7.3% had experienced inhalation fever during the last 12 years. In general, individuals with asthma and chronic bronchitis who had left farming were in better health in 1994 as compared to 1982. In conclusion, farmers have an enhanced risk to develop asthma increasing with age. Asthma in farmers is often non-IgE-mediated.

The New Zealand workforce survey II: occupational risk factors for asthma

INTRODUCTION

We conducted a cross-sectional population-based survey in New Zealand that collected information on work history, current workplace exposures, and selected health outcomes. We report here the findings on occupational risk factors for asthma symptoms.

METHODS

A random sample of men and women aged 20-64 years were selected from the New Zealand Electoral Roll and invited to take part in a telephone survey. Current asthma was defined as: (i) woken up by shortness of breath in the past 12 months; or (ii) an attack of asthma in the past 12 months; or (iii) currently taking asthma medication. Adult-onset asthma was defined as first attack of asthma at age 18 or over. Prevalence odds ratios (ORs) for all occupations were calculated using logistic regression adjusting for sex, age, smoking, and deprivation.

RESULTS

Totally, 2903 participants were included in the analyses. The prevalence of current asthma was 17% and the prevalence of adult-onset asthma was 9%. Prevalence ORs for current asthma were elevated for ever working as a printer [OR = 2.26; 95% confidence interval (CI) = 1.09-4.66], baker (OR = 1.98; 95% CI = 1.02-3.85), sawmill labourer (OR = 3.26; 95% CI = 1.05-10.16), metal processing plant operator (OR = 2.48; 95% CI = 1.22-5.05), and cleaner (OR = 1.60; 95% CI = 1.09-2.35). Excess risks of adult-onset asthma were also found for ever working as a printer, baker, and sawmill labourer as well as ever-working as a market-oriented animal producer (OR = 1.66; 95% CI = 1.14-2.41), and other agricultural worker (OR = 2.08; 95% CI = 1.03-4.20). A number of occupations not previously considered at high risk for asthma were also identified, including teachers and certain sales professionals.

CONCLUSION

This population-based study has confirmed findings of previous international studies showing elevated risks in a number of high-risk occupations. The strongest risks were consistently observed for printers, bakers, and sawmill labourers. Several occupations were also identified that have not been previously associated with asthma, suggesting that the risk of occupational asthma may be more widely spread across the workforce than previously assumed.

Effects of Passive Smoking at Work on Respiratory Symptoms, Lung Function, and Bronchial Responsiveness in Never-Smoking Office Cleaning Women

This cross-sectional study compares respiratory symptoms, lung function, and bronchial responsiveness between 27 office cleaning women exposed to environmental tobacco smoke at work and 57 unexposed controls. The age range of both groups was 24 to 56 years, and none of the women had ever smoked. Information on respiratory symptoms, cleaning work history, and passive smoking in the workplace were obtained with a questionnaire. The subjects also took a skin prick test to common inhalant allergens, a lung function test, and a histamine challenge. Despite smoking restriction in indoor environments, we found a high prevalence of passive smokers in the workplace (32.1 %). In these subjects we found a significantly higher prevalence of wheezing with breathlessness (25.9 % vs. 8.8 %; P=0.036), wheezing without cold (25.9 % vs. 7.0 %; P=0.016), and breathlessness after effort (29.6 % vs. 8.8 %; P=0.014) than in control subjects. Objective measurements showed a significantly lower MEF25 (53.6 % vs. 63.7 %; P=0.001) and a significantly higher prevalence of borderline bronchial hyperresponsiveness (22.2 % vs. 7.0 %; P=0.044) in the passive smokers in the workplace. This study provides evidence of adverse respiratory effects in office cleaning women associated with passive smoking in the workplace. Our findings support a stricter implementation of the current national law to protect respiratory health of all workers.

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.

Lung disease in flavoring and food production: learning from butter flavoring

Workers in the food industry are exposed to multiple respiratory hazards that include irritants, allergens, and substances capable of causing destruction and scarring of the lungs. Cases of constrictive bronchiolitis obliterans, a severe potentially disabling lung disease, have been identified in workers exposed to flavorings. Workplace engineering controls, work practices, and respiratory protection can minimize potential exposures. Medical surveillance of workers exposed to known respiratory hazards will help to identify disease early, facilitate the prompt removal of workers from the causative exposure(s), and prevent further worsening and/or permanence of disease. When companies or employees suspect occupational respiratory disease, they can involve public health agencies to investigate any excess risk of lung disease, risk factors among processes and exposures, and effectiveness of interventions, if needed.

Work-related asthma in automobile spray painters: two case reports

This report describes two patients who had developed asthma after working as automobile painters with isocyanate-based aerosol paint for two years or over. In both patients asthma was confirmed using the standard diagnostic procedure. One of the subjects was atopic. One was ex-smoker and the other had never smoked. Neither had a family history of asthma. The symptoms occurred after workplace exposure lasting two years in one patient and three in the other. As both reported work-relatedness of the symptoms, they underwent serial peak expiratory flow rate (PEFR) measurement and bronchoprovocation testing. Significant work-related changes in PEFR diurnal variations and in non-specific bronchial hyperresponsiveness (NSBH) were observed in one patient, suggesting allergic occupational asthma (OA), while the other patient was diagnosed work-exacerbated asthma (WEA). Our data confirm that spray painting is an occupation with increased risk of respiratory impairment and asthma.

[Epidemiology and etiologic agents of occupational asthma]

INTRODUCTION

Occupational asthma is, by definition, a disease that can be prevented through appropriate protective strategies. Epidemiological information is required to guide these interventions, and we here examine epidemiological data on the burden, causes, and risk factors for this condition.

STATE OF THE ART

Population-based surveys indicate that approximately 15% of adult asthma is attributable to the workplace environment. The most common occupational agents implicated include flour, isocyanates, latex, and persulphate salts. The occupations in which occupational asthma has been most commonly reported are bakers, spray painters, health-care workers, hairdressers, and cleaners. The level of exposure to sensitizing agents seems to be the most relevant risk factor. Atopy is a significant risk factor only for the development of sensitization to high molecular weight agents. The role of other individual determinants, such as genetic factors, has been less consistently established. Occupational asthma is associated with a substantial adverse impact on the employment and financial status of affected workers.

PERSPECTIVES

Methodological improvements are required in order to distinguish more accurately between occupational and work-exacerbated asthma. Further investigations of the effectiveness of primary and secondary preventive interventions are also needed.

Bronchial hyperresponsiveness in women cooks and cleaners

The aim of this cross-sectional study was to assess the prevalence and characteristics of bronchial hyperresponsiveness (BHR) in 43 women cleaners (aged 26 to 57) and 37 women cooks (aged 29 to 55) and compare them with 45 controls (women office workers aged 27 to 58). The evaluation of all subjects included a questionnaire, skin prick tests to common aeroallergens, spirometry, and histamine challenge (PC20 < or = 8 mg mL(-1)). We found higher BHR prevalence in cleaners and cooks than in office workers (30.2 % and 29.7 %, vs. 17.7 %, respectively), but statistical significance was not reached. The prevalence of mild and moderate to severe BHR was similar in all groups. Borderline BHR prevalence was significantly higher in cleaners than in controls (16.2 % vs. 6.6 %, P=0.032) whereas the difference was on the verge of significance in cooks (13.5 % vs. 6.6 %, P=0.081). Moderate to severe BHR was strongly associated with positive family history of asthma and atopy in all groups. Mild BHR was significantly associated with daily smoking in cleaners (P=0.031) and cooks (P=0.021), as well as with the duration of exposure in cleaners (P=0.038). Borderline BHR was closely related to daily smoking and duration of exposure in both cleaners and cooks. Our findings indicate an important role of workplace exposure in borderline BHR development, as well as the significant effect of smoking on mild BHR development in women cleaners and cooks.

Occupation and adult-onset asthma among Chinese women in a population-based cohort

BACKGROUND

Exposure to industrial irritants is believed to have contributed to the increasing prevalence of asthma worldwide. We examined the associations between occupation and asthma among women in a case-control study nested in the population-based Shanghai Women's Health Study cohort in China.

METHODS

Cases were 1,050 women who reported a physician-diagnosed asthma as adults. Controls were 4,200 women matched to the cases by year of birth and age at diagnosis. Lifetime occupational histories were obtained. Logistic regression was applied to estimate odds ratios (ORs) adjusting for smoking, education, family income, and concurrent chronic bronchitis.

RESULTS

Asthma is more prevalent in production industries for metal tools (OR = 2.4; 1.3-4.7), metal products for everyday use (OR = 1.6; 1.1-2.4), ships (OR = 2.6; 1.0-6.8), and clocks (OR = 1.9; 1.0-3.4), and in occupations as farm workers (OR = 4.0; 1.2-13.0), laboratory technicians and analyzers (OR = 2.2; 1.2-3.9), and installation and maintenance workers for weaving and knitting machineries (OR = 2.4; 1.1-5.4). Other associations less commonly reported were identified for electricians (OR = 2.1; 1.1-4.1), performers (OR = 3.2; 1.4-7.4), administrative workers in organizations and enterprises (OR = 1.8; 1.1-2.8), and postal and telecommunication workers (OR = 3.5; 1.6-7.6).

CONCLUSIONS

Our findings suggest that occupational exposures contribute to the development of asthma in women.

Occupational asthma in New South Wales (NSW): a population-based study

BACKGROUND

The proportion of asthma in adults that is due to occupational exposures is not known.

AIM

To examine the contribution of workplace exposures to the development of asthma in adults in New South Wales (NSW) in a cross sectional, population-based study.

METHODS

A randomly selected population of 5,331 18- to 49-year olds completed and returned a mailed questionnaire (response rate 37%). In adult-onset asthmatics we examined the association of asthma with reported exposure, within 1 year of asthma onset, to a list of occupations and exposures known to be at risk for occupational asthma (high-risk jobs and exposures).

RESULTS

Among 910 subjects (18%) with asthma, 383 (7%) subjects reported adult-onset disease. After adjusting for sex, age and smoking, working in any high-risk job or exposure at the time of asthma onset was significantly associated with adult-onset asthma (OR 1.51, 95% CI 1.19-1.92). The population attributable risk (PAR) of adult-onset asthma for either a high-risk job or an exposure was 9.5%. Sudden onset, irritant or reactive airways dysfunction syndrome type exposures were associated with adult-onset asthma (OR 4.65, 95% CI 1.64-13.2). The PAR of adult-onset asthma for these exposures was 0.2%.

CONCLUSION

Reported adult onset of asthma is common and occupational exposures may be associated with 9.5% of prevalent cases of adult-onset asthma in NSW.

Health effects of airborne exposures from concentrated animal feeding operations

Toxic gases, vapors, and particles are emitted from concentrated animal feeding operations (CAFOs) into the general environment. These include ammonia, hydrogen sulfide, carbon dioxide, malodorous vapors, and particles contaminated with a wide range of microorganisms. Little is known about the health risks of exposure to these agents for people living in the surrounding areas. Malodor is one of the predominant concerns, and there is evidence that psychophysiologic changes may occur as a result of exposure to malodorous compounds. There is a paucity of data regarding community adverse health effects related to low-level gas and particulate emissions. Most information comes from studies among workers in CAFO installations. Research over the last decades has shown that microbial exposures, especially endotoxin exposure, are related to deleterious respiratory health effects, of which cross-shift lung function decline and accelerated decline over time are the most pronounced effects. Studies in naïve subjects and workers have shown respiratory inflammatory responses related to the microbial load. This working group, which was part of the Conference on Environmental Health Impacts of Concentrated Animal Feeding Operations: Anticipating Hazards-Searching for Solutions, concluded that there is a great need to evaluate health effects from exposures to the toxic gases, vapors, and particles emitted into the general environment by CAFOs. Research should focus not only on nuisance and odors but also on potential health effects from microbial exposures, concentrating on susceptible subgroups, especially asthmatic children and the elderly, since these exposures have been shown to be related to respiratory health effects among workers in CAFOs.

Prevalence and risk factors for work related asthma in young adults

OBJECTIVES

To investigate the prevalence and predictors of work related asthma in young adults from the general population.

METHODS

A total of 1922 subjects randomly selected from a birth cohort 1978/79 in Brazil, aged 23-25 years, completed a respiratory symptoms questionnaire based on the European Community Respiratory Health Survey, and underwent spirometry, bronchial challenge test with methacholine, and skin prick test. For subjects presenting with bronchial hyperresponsiveness, workplace exposure and its relationship with symptoms were assessed by a specific questionnaire and individualised job description to define cases of work related asthma.

RESULTS

The prevalence of work related asthma was 4.2% (81 cases): 1.5% (29 cases) were classified as aggravated asthma and 2.7% (52 cases) as occupational asthma. Work related asthma was associated with atopy and education. Lower educational level (1-8 years of schooling) was associated with work related asthma (odds ratio 7.06, 95% CI 3.25 to 15.33). There was no association between work related asthma and smoking, gender, or symptoms of rhinitis.

CONCLUSION

The prevalence of work related asthma was high (4.2%), and was associated with low schooling, probably because of low socioeconomic level. The disease may therefore be a consequence of poverty.

Atopic and non-atopic asthma in a farming and a general population

BACKGROUND

In a previous study inverse associations between asthma and exposure to fungal spores and endotoxins in atopic farmers and positive associations with the same factors in non-atopic farmers were documented. No external reference population had been included. We, therefore, compared this farming population with the general population from an adjacent region.

METHODS

Random samples of a farming (n=2,106) and a rural (n=351) and urban (n=727) general population were selected. Atopy was assessed by serum IgE and asthma by questionnaires.

RESULTS

The asthma prevalence was 4.0% among farmers, 5.7% in the rural, and 7.6% in the urban population. Atopy was similar (9-10%). Most asthmatics were not atopic, 67-75%. Farmers had asthma less often than the general population OR 0.52 (95% CI 0.36-0.75); both atopic (OR 0.33 (95% CI 0.15-0.69)) and non-atopic asthma (OR 0.60 (95% CI 0.39-0.93)).

CONCLUSION

This may indicate a protective effect of the farm environment on asthma but a healthy worker effect may also play a role.

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.

Do farming exposures cause or prevent asthma? Results from a study of adult Norwegian farmers

BACKGROUND

A protective effect of endotoxin exposure on atopy and asthma in farmers' children has been postulated. Studies of adult farmers have shown conflicting results but often lack exposure data. The prevalence of asthma in farmers with different exposure levels to microbial agents and irritant gases was compared.

METHODS

Atopy was defined as a positive response to multiple radioallergosorbent tests (RAST) with a panel of 10 common respiratory allergens, and asthma was ascertained by a questionnaire using a stratified sample (n = 2169) of a farming population from south-eastern Norway. Exposure of farmers to total dust, fungal spores, bacteria, endotoxins, and ammonia was assessed by exposure measurements.

RESULTS

The prevalence of asthma was 3.7% for physician diagnosed asthma and 2.7% for current asthma. The prevalence of atopy was 14%, but most asthmatic subjects were non-atopic (80%). Compared with farmers without livestock, (1) asthma was significantly higher in cattle farmers (OR(adj) 1.8, 95% CI 1.1 to 2.8) and pig farmers (OR(adj) 1.6, 95% CI 1.0 to 2.5), (2) non-atopic asthma was significantly higher in pig farmers (OR(adj) 2.0, 95% CI 1.2 to 3.3) and in farmers with two or more types of livestock (OR(adj) 1.9, 95% CI 1.1 to 3.3), and (3) atopic asthma was less common in farmers with two or more types of livestock (OR(adj) 0.32, 95% CI 0.11 to 0.97). Exposure to endotoxins, fungal spores, and ammonia was positively associated with non-atopic asthma and negatively associated with atopic asthma. No associations were found with atopy.

CONCLUSIONS

Exposure to endotoxins and fungal spores appears to have a protective effect on atopic asthma but may induce non-atopic asthma in farmers.

Diesel exhaust, solvents, and other occupational exposures as risk factors for wheeze among farmers

Farmers engage in activities that result in exposure to diesel exhaust, solvents, welding fumes, and other respiratory irritants. Using the Agricultural Health Study, a cohort of pesticide applicators in Iowa and North Carolina, we evaluated the odds of wheeze associated with nonpesticide occupational exposures. We used logistic regression models controlling for age, state, smoking, and history of asthma or atopy to evaluate odds of wheeze in the past year among the 20898 farmers who provided complete information on all covariates. Driving diesel tractors was associated with elevated odds of wheeze (odds ratio = 1.31; 95% confidence interval = 1.13, 1.52); the odds ratio for driving gasoline tractors was 1.11 (95% confidence interval = 1.02, 1.21). A duration-response relationship was observed for driving diesel tractors but not for driving gasoline tractors. Activities involving solvent exposure, including painting and use of solvents for cleaning, were associated with an increased odds of wheeze in a duration-dependent fashion. The highest odds of wheeze for farm activities were for daily painting (odds ratio = 1.82; 95% confidence interval = 0.89, 3.73), an indication of daily solvent exposure. These results add to the growing body of evidence of adverse respiratory effects of diesel exposure on the lung and suggest exposure to solvents may contribute as well.

Occupational exposures associated with work-related asthma and work-related wheezing among U.S. workers

BACKGROUND

National estimates of occupational asthma (OA) in the United States are sparse.

METHODS

Using data from the Third National Health and Nutrition Examination Survey (NHANES III) 1988-1994, we analyzed associations between occupation and work-related asthma and work-related wheezing among U.S. workers.

RESULTS

This study identified several occupations that were at risk of developing work-related asthma and/or wheezing, with cleaners and equipment cleaners showing the highest risks. Other major occupations identified were farm and agriculture; entertainment; protective services; construction; mechanics and repairers; textile; fabricators and assemblers; other transportation and material moving occupations; freight, stock, and material movers; and motor vehicle operators. The population attributable risks for work-related asthma and work-related wheezing were 26% and 27%, respectively.

CONCLUSIONS

This study adds evidence to the literature that identifies work-related asthma as an important public health problem. Several occupations are targeted for additional evaluation and study. Of particular interest are cleaners, which are being increasingly reported as a risk group for asthma. Future intervention strategies need to be developed for effective control and prevention of asthma in the workplace.

Animal production and wheeze in the Agricultural Health Study: interactions with atopy, asthma, and smoking

BACKGROUND

Exposure to animals, their feeds, and by-products contribute to respiratory symptoms among farmers.

AIMS

To investigate the role of animal exposures and wheeze, and to assess whether their impact differs among susceptible subgroups, including atopics, asthmatics, and smokers.

METHODS

Using the Agricultural Health Study, a cohort of pesticide applicators in Iowa and North Carolina enrolled in 1994-97, wheeze associated with animal production was evaluated and interactions among susceptible subgroups assessed. Logistic regression models were used to examine risk factors for wheeze in the past year among 20 468 farmers.

RESULTS

Individuals raising animals requiring direct contact had the highest odds ratios (OR) for wheeze (OR(dairy) = 1.26; OR(eggs) = 1.70). A significant dose response was observed for both the number of poultry and the number of livestock on the farm. Farmers who performed veterinary procedures on a daily basis had an OR of 1.51. The odds of wheeze associated with poultry production was greater among atopic than non-atopic individuals. Milking cows daily increased the odds of wheeze in all individuals, with the largest association observed among atopic asthmatic individuals. The impact of dairy, poultry, and egg production varied among smoking groups. Past smokers had the highest odds ratios, followed by never smokers, and then current smokers. The OR(eggs) was 2.88 among past smokers but only 1.46 for never smokers. The OR(eggs) for current smokers of 0.80 might reflect self selection of exposure among smokers.

CONCLUSIONS

Results are consistent with animal production and respiratory symptoms, and suggest that subgroups may respond differently to exposure.

Epidemiology of occupational asthma

Information gathered through epidemiologic studies of occupational asthma is useful for the establishment of prevalence or incidence data for public health purposes, which can be used to determine which industry or workplace requires assistance from preventive services. These studies address etiologic questions regarding exposure and host risk factors. They can establish an exposure-response relationship that provides scientific basis for setting environmental control measures. They also examine the effectiveness of preventive 5 control measures. In the conduct of epidemiologic studies of occupational asthma, choosing the type of study to answer the study question is important. Observational studies have predominated in studies of occupational asthma. Although these types of studies have provided much useful data, they are associated with the problem of the healthy-worker effect. In the future, use of more robust epidemiologic study designs should foster a greater understanding of occupational asthma.

Relationship between total and allergen-specific IgE serum levels and presence of symptoms in farm workers sensitized to Tetranychus urticae

BACKGROUND

Clinical complaints in atopic subjects with asthma and rhinitis occur more frequently in the presence of high total and allergen-specific IgE serum levels. Here we report on the relationship between total and allergen-specific IgE serum levels and presence of symptoms in an unselected farmer population sensitized to Tetranychus urticae (TU).

METHODS

Farmers were recruited as previously described. Total IgE and allergen-specific IgE were measured by immunoassay in TU-positive skin prick test (SPT) farmers (n = 58) and two control groups including Dermatophagoides pteronyssinus (Dp)-positive SPT subjects (n = 40) and non-atopic, TU-negative SPT healthy farmers (n = 25).

RESULTS

Both TU+ and Dp+ subjects had significantly higher total IgE values (P < 0.001) than healthy non-atopic subjects. TU-specific IgE levels were significantly more elevated in symptomatic than non-symptomatic TU+ subjects (P = 0.028). Dp-specific IgE levels were higher in symptomatic than non-symptomatic Dp+ subjects (P = 0.003). Finally, total IgE levels were significantly higher in the symptomatic than non-symptomatic subgroups in both TU+ and Dp+ subjects (P < 0.0001 and P = 0.007, respectively). Logistic regression analysis showed that only total IgE concentrations were significant predictors of current symptoms in TU+ subjects.

CONCLUSIONS

High total IgE and allergen-specific IgE levels are associated with symptoms in TU+ subjects. Definition of their predictive value requires further studies.

Occupational airborne exposure and the incidence of respiratory symptoms and asthma

Several prevalence studies have suggested an association between occupational exposure and respiratory symptoms and asthma, but there has been a lack of incidence studies to verify this. This study examined the incidence of respiratory symptoms and asthma in an 11-year Norwegian community cohort study with 2,819 subjects. Predictors examined were sex, age, educational level, lifetime exposure to quartz, asbestos, and dust or fumes, as well as smoking habits and pack-years. The prevalence of exposure to quartz, asbestos, and dust or fumes was, respectively, 3.7%, 5.0%, and 28.3% at baseline. In those exposed to dust or fumes, the odds ratios (95% confidence intervals) varied between 1.4 (1.1, 1.7) and 2.1 (1.3, 3.2) for developing respiratory symptoms or asthma after adjusting for sex, age, educational level, and smoking. Between 5.7% and 19.3% of the incidence of respiratory symptoms and 14.4% of the incidence of asthma were attributable to dust or fumes exposure after adjustment for sex, age, educational level, and smoking. In conclusion, airborne occupational exposure increases the incidence of respiratory symptoms and asthma, independent of sex, age, educational level, smoking habits, and pack-years.

Epidemiology of latex sensitization and allergies in health care workers

Although it is often claimed that health care workers are at increased risk of latex sensitization and type I allergies, there has been no systematic analysis of the epidemiologic studies that are relevant to this conclusion. A systematic analysis of the epidemiologic literature found that, in the past 14 years, there have been 48 epidemiologic studies of type I latex allergy among health care workers. Of these, 2 cohort studies estimated the incidence of latex sensitization by skin prick testing at between 1% and 2.5% per year. Neither compared the risk to that in the general population. The prevalence of sensitization in health care workers varied between 0% and 30%, yet this large variation was unexplained. Increased risk of sensitization was not clearly associated with the duration of work in health care, the time spent wearing latex gloves, the frequency of exposure, the specific job categories, the use of powdered versus nonpowdered latex gloves, the use of latex versus nonlatex gloves, or any measurements of ambient exposure to latex proteins. The epidemiologic studies do not support a conclusion that health care workers are at clearly increased risk of latex sensitization or type I allergies compared to other occupations in the United States. The role of latex gloves in causing latex sensitization and type I allergic symptoms remains poorly defined because of the inconsistent results across studies. Future epidemiologic studies are needed that include measured exposures to latex antigens, that compare health care workers to appropriate referent groups, and that address confounding by atopy, age, sex, and race.

Prevalence and risk factors of work related asthma by industry among United States workers: data from the third national health and nutrition examination survey (1988-94)

OBJECTIVES

To estimate the prevalence of work related asthma and work related wheezing in United States workers. To identify high risk industries that could be targeted for future intervention. To determine the population attributable risk of work related asthma and work related wheezing.

METHODS

The third national health and nutrition examination survey, 1988-1994 (NHANES III) was analyzed to determine the prevalence of work related asthma and wheezing and to identify initially defined industries at risk among United States workers aged 20 and older. Separate logistic models were developed with work related asthma and work related wheezing as outcomes. Work related asthma was defined as affirmative response to questions on self reported physician diagnosed asthma and work related symptoms of rhinitis, conjunctivitis, and asthma. Work related wheezing was defined as affirmative response to questions on self reported wheezing or whistling in the chest in the previous 12 months and work related symptoms of rhinitis, conjunctivitis, and asthma. All analyses were adjusted for age, sex, smoking, and atopy.

RESULTS

The prevalence of work related asthma was 3.70% (95% confidence interval (95% CI) 2.88 to 4.52) and the prevalence of work related wheezing was 11.46% (95% CI 9.87 to 13.05). The main industries identified at risk of work related asthma and wheeze included the entertainment industry; agriculture, forestry, and fishing; construction; electrical machinery; repair services; and lodging places. The population attributable risk for work related asthma was 36.5% and work related wheezing was 28.5%.

CONCLUSIONS

The findings provide impetus for further research and actions by public health professionals which prioritise occupational asthma on the public health agenda. Future intervention strategies need to be developed for effective control and prevention of asthma in the workplace.

Chemical predictors of wheeze among farmer pesticide applicators in the Agricultural Health Study

Pesticides may contribute to respiratory symptoms among farmers. Using the Agricultural Health Study, a large cohort of certified pesticide applicators in Iowa and North Carolina, we explored the association between wheeze and pesticide use in the past year. Self-administered questionnaires contained items on 40 currently used pesticides and pesticide application practices. A total of 20,468 applicators, ranging in age from 16 to 88 years, provided complete information; 19% reported wheezing in the past year. Logistic regression models controlling for age, state, smoking, and history of asthma or atopy were used to evaluate associations between individual pesticides and wheeze. Among pesticides suspected to contribute to wheeze, paraquat, three organophosphates (parathion, malathion, and chlorpyrifos), and one thiocarbamate (S-ethyl-dipropylthiocarbamate [EPTC] ) had elevated odds ratios (OR). Parathion had the highest OR (1.5, 95% confidence interval [CI] 1.0, 2.2). Chlorpyrifos, EPTC, paraquat, and parathion demonstrated significant dose-response trends. The herbicides, atrazine and alachlor, but not 2,4-D, were associated with wheeze. Atrazine had a significant dose-response trend with participants applying atrazine more than 20 days/year having an OR of 1.5 (95% CI 1.2,1.9). Inclusion of crops and animals into these models did not significantly alter the observed OR. These associations, though small, suggest an independent role for specific pesticides in respiratory symptoms of farmers.

Does environmental endotoxin exposure prevent asthma?

The evidence as to whether exposure to environmental airborne endotoxin plays a protective or an inducing role in the development of asthma is reviewed. Studies of endotoxin and atopy, endotoxin and asthma, and farming and asthma are considered and, in each instance, a distinction is made between evidence of primary causation and evidence of secondary causation. It is concluded that, although it is plausible that bacterial endotoxin may protect against the development of asthma, there is considerable reason for caution regarding this hypothesis.

Epidemiology of allergic occupational diseases induced by Tetranychus urticae in greenhouse and open-field farmers living in a temperate climate area

BACKGROUND

The role of Tetranychus urticae (TU) as an occupational allergen has thus far been investigated only in selected farmer samples.

METHODS

The prevalence of TU-induced sensitization and occupational diseases in a randomized sample of farmers living in a temperate climate area was investigated. Occupational/nonoccupational symptoms, skin prick test (SPT) results with common allergens and TU, specific occupational test results, and greenhouse or open-field sources of TU exposure were assessed. The study design was cross-sectional.

RESULTS

The prevalence of positive SPT to TU was 6%. TU-induced allergic/nonallergic complaints accounted for 65% of farmers with challenge-confirmed occupational disease. In all farmers, sensitization to common allergens was a risk factor for both current occupational and nonoccupational complaints, while TU sensitization was a prominent risk factor for occupational complaints. Furthermore, in SPT-positive farmers, only the presence of seasonal occupational complaints was significantly associated with TU sensitization. Common allergen sensitization was a risk factor for development of TU sensitization, which was more frequent in greenhouse than in open-field workers.

CONCLUSIONS

TU was a common nontraumatic, allergic occupational hazard for farmers. Since occupational seasonal symptoms could be directly related to the presence of TU sensitization, allergy to this mite should be routinely investigated in farmers.

The European Community Respiratory Health Survey: what are the main results so far? European Community Respiratory Health Survey II

The European Community Respiratory Health Survey (ECRHS) was the first study to assess the geographical variation in asthma and allergy in adults using the same instruments and definitions. The database of the ECRHS includes information from approximately 140,000 individuals from 22 countries. The aim of this review is to summarize the results of the ECRHS to date. The ECRHS has shown that there are large geographical differences in the prevalence of asthma, atopy and bronchial responsiveness, with high prevalence rates in English speaking countries and low prevalence rates in the Mediterranean region and Eastern Europe. Analyses of risk factors have highlighted the importance of occupational exposure for asthma in adulthood. The association between sensitization to individual allergens and bronchial responsiveness was strongest for indoor allergens (mite and cat). Analysis of treatment practices has confirmed that the treatment of asthma varies widely between countries and that asthma is often undertreated. In conclusion, the European Community Respiratory Health Survey has shown that the prevalence of asthma varies widely. The fact that the geographical pattern is consistent with the distribution of atopy and bronchial responsiveness supports the conclusion that the geographical variations in the prevalence of asthma are true and most likely due to environmental factors.

Occupational asthma

The workplace can be responsible for approximately one in 10 cases of adult-onset asthma. Two types of occupational asthma (OA) are distinguished by whether they arise after a latency period that is necessary for acquiring sensitization or as a result of acute exposure to irritant materials (irritant-induced asthma). The pathophysiology of OA with a latency period is similar to that of nonoccupational asthma, whereas the mechanism of irritant-induced asthma is still uncertain. HLA haplotypes and other genetic polymorphisms have been found to be associated with OA. According to various sources of data, the overall frequency of OA has remained stable in the last 10 years, although the frequency of causal agents vary. Registers of causal occupations and agents have been issued on Web sites (eg, www.asmanet.com ). Improved sampling methods have shown that the degree of exposure plays a key role in the onset of the disease, whereas prospective data collected in high-risk workplaces have also identified personal risk factors (eg, atopy, smoking, and rhinoconjunctivitis). A diagnosis of OA should no longer be based on a compatible history only but should be confirmed by means of objective testing. Once the diagnosis is confirmed, the worker should be removed from exposure, and satisfactory compensation programs should be offered, the most important being retraining programs with financial compensations because affected workers are generally young. The cost-effectiveness of prevention programs in high-risk workforces should be assessed.

Occupational inhalant exposure and respiratory disorders among never-smokers referred to a hospital pulmonary function laboratory

BACKGROUND

Multiple reports have described associations between occupational inhalant exposure and lung disease. Previous occupational lung disease investigations have studied populations consisting of both smokers and nonsmokers. Smoking complicates interpretation of toxicant exposure-response relationships. The objective of this study was to determine whether, among never-smokers, occupational exposure to gases, dusts, or fumes is associated with a history of respiratory disorders and pulmonary function test defined obstructive lung disease.

METHODS

We performed a retrospective analysis of 517 never-smoker patients who underwent pulmonary function testing in our clinical laboratory between 1986 and 1999. We calculated the relative risks of developing adverse respiratory health outcomes given a history of exposure to occupational inhalants.

RESULTS

Compared with persons with a negative occupational exposure history, exposed persons had an increased risk of reporting a history of bronchitis [relative risk (RR), 1.59; 95% confidence interval (CI), 1.20-2.12], recurrent lung infections (RR, 2.09; 95% CI, 1.14-3.82), and bronchodilator use (RR, 1.61; 95% CI, 1.26-2.06). There was also a statistically significant association between a history of inhalant exposure and the finding of an obstructive ventilatory defect on pulmonary function testing (RR, 1.79; 95% CI, 1.12-2.85). A history of inhalant exposure was not associated with self-reported asthma (RR, 1.08; 95% CI, 0.83-1.41). The population attributable risk estimates for respiratory disorders due to inhalant exposure were: bronchitis, 23.6%; recurrent lung infection, 36.3%; bronchodilator use, 24.3%; and obstructive lung disease, 29.6%.

CONCLUSIONS

Occupational inhalant exposure is a strong risk factor for lung disease in this population of never smokers. A significant burden of respiratory disease in this population may be attributable to occupational inhalant exposure.

Occupational asthma in adults in six Canadian communities

We examined the prevalence, population attributable risk (PAR), and clinical characteristics of occupational asthma (OA) in a randomly selected population in six communities in Canada. Our study followed the European Community Respiratory Health Survey protocol. A randomly selected population of 18,701 (87% response rate) persons from the study communities, ranging in age from 20 to 44 yr, completed an initial questionnaire, of whom 2,974 (39% response rate) attended the laboratory and completed supplementary questionnaires. Of these latter individuals, 383 had asthma. Asthma was defined as physician-diagnosed asthma, and adult-onset asthma was defined as a first attack at age 15 yr or older. We used several methods for estimating OA as follows: (1) reporting of a high-risk job (occupation and industry) for OA at the time of asthma onset (Probable OA); (2) reporting of exposure to a substance that may cause OA (Possible OA) while not in a high-risk job at the time of asthma onset; and (3) combination of the PAR for high-risk jobs and exposures. The prevalence (95% confidence interval [CI]) of Probable OA and Possible OA combined was 36.1% (31.3 to 41.0%) among subjects with adult-onset asthma. The occupations most commonly reported in association with OA were nursing in the Probable OA group and clerical and food preparation in the Possible OA group. The clinical characteristics and exposures reported by both groups were similar. The PAR for adult-onset asthma in high-risk jobs and exposures was 18.2%. The assessment of occupation and industry alone, rather than of exposures, may underestimate the contribution of occupational exposures to asthma prevalence.

Development of an asthma specific job exposure matrix and its application in the epidemiological study of genetics and environment in asthma (EGEA)

OBJECTIVES

To develop a method suitable for estimating exposure risks in population studies of asthma from job titles and international codes, by combining a new job exposure matrix (JEM) with the expert judgement approach. The method was applied in the French epidemiological study of the genetics and environment in asthma (EGEA).

METHODS

The JEM contains 22 exposure groups including 18 high risk groups based on known risk factors for occupational asthma, divided into high molecular weight agents, low molecular weight agents, and mixed environments. After applying the JEM to job codes, exposure estimates for each subject were re-evaluated by examining job title texts. Three high risk exposure estimates for asthma were compared: firstly, applying the JEM to original codes (from different coders in each study centre); secondly, applying the JEM to revised codes (from one experienced coder); and thirdly, after reviewing JEM exposure estimates in the light of job title texts.

RESULTS

The study comprised 173 cases with asthma and 285 controls (age 18-65). Odds ratios (ORs) for asthma for high risk jobs were 1.0 (95% confidence interval (95% CI) 0.6 to 1.7), applying the JEM to original codes; 1.4 (95% CI 0.8 to 2.3), applying the JEM to revised codes; and 1.7 (95% CI 1.1 to 2.7), applying the JEM and subsequently re-evaluating exposure estimates from job title texts. Asthma ORs were 1.4 (95% CI 0.6 to 2.9) for high molecular weight agents, 2.3 (95% CI 1.2 to 4.4) for low molecular weight agents, and 2.1 (95% CI 0.9 to 5.2) for mixed environments.

CONCLUSIONS

This asthma JEM, when enhanced by expert re-evaluation of exposure estimates from job title texts, may be a useful tool in general population studies of asthma. In this study, a 1.7-fold increase in prevalence odds of high risk exposures was found among asthmatic workers compared with controls, with risk magnitude varying for different classes of exposure.

Asthma is more prevalent in rural New South Wales than metropolitan Victoria, Australia

OBJECTIVE

The aim of this study was to compare the prevalence of adult respiratory symptoms and conditions in a rural setting with a metropolitan setting.

METHODOLOGY

We used cross-sectional population surveys of respiratory health using the European Respiratory Health Survey screening questionnaire. A random sample of 4455 eligible young adults aged 20-44 years, from electoral rolls in south-eastern metropolitan Melbourne, Victoria, and 4521 from rural south-western New South Wales were surveyed.

RESULTS

Response rates of 72% (n=3194) and 69% (n=3121) were achieved in Melbourne and the Riverina, respectively. Respondents from the Riverina reported significantly higher prevalences of nocturnal dyspnoea (P<0.01), chronic bronchitis (P=0.03), an asthma attack in the previous 12 months (P<0.001), ever having had asthma (P<0.001) and doctor-diagnosed asthma (P<0.001) compared to those from Melbourne. However, among those with 'asthma attacks in the last 12 months', Melbourne respondents experienced a higher frequency of attacks (P<0.05). Riverina respondents reported a higher prevalence of smoking (P<0.05) and smoked more cigarettes on average (P<0.001) than Melbourne respondents. However, annoyance from air pollution was higher in Melbourne than in the Riverina.

CONCLUSIONS

These results suggest that asthma is more prevalent in rural southern New South Wales than in Melbourne but follows a different pattern of exacerbations.

Incidence of occupational asthma by occupation and industry in Finland

BACKGROUND

Systematic research on occupation or industry-specific incidence of occupational asthma (OA) is sparse. We calculated the incidence of notified OA by occupation, industry and causative agent in Finland for the years 1989-95.

METHODS

The numbers of cases of reported OA were retrieved from the Finnish Registry of Occupational Diseases for the population between 20 and 64 years of age. The numbers of employed workers were retrieved from Statistics Finland. Incidence rates were calculated for each occupation, industry and the total workforce.

RESULTS

Altogether 2602 cases of OA were notified and the mean annual incidence rate was 17.4 cases/100,000 employed workers. The incidence rate was the highest in bakers, other painters and lacquerers, veterinary surgeons, chemical workers, farmers, animal husbandry workers, other food manufacturing workers, welders, plastic product workers, butchers and sausage makers, and floor layers. Cases caused by animal epithelia, hairs and secretions or flours, grains, and fodders accounted for 60% of the total.

CONCLUSIONS

Estimation of occupation and industry-specific incidence rates forms the basis for successful prevention of OA, but necessitates collection of data over several years from well-established surveillance systems.

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.