SWORD '98: surveillance of work-related and occupational respiratory disease in the UK

Incidence of Occupational Asthma and Exposure to Toluene Diisocyanate in the United States Toluene Diisocyanate Production Industry

Objective

This study examines asthma risk in facilities producing toluene diisocyanate (TDI).

Methods

A total of 197 workers were monitored from 2007 to 2012. TDI air concentrations were used to estimate exposures.

Results

The incidence of cases consistent with TDI-induced asthma was 0.009 per person-years (seven cases) or consistent with TDI-induced asthma or asthma indeterminate regarding work-relatedness was 0.012 (nine cases). Increased risk of cases consistent with TDI asthma was observed for cumulative (odds ratio [OR] = 2.08, 95% confidence interval [CI] 1.07 to 4.05) per logarithm parts per billion-years and peak TDI exposures (OR = 1.18, 95% CI 1.06 to 1.32) (logarithm parts per billion). There was a weak association with cumulative and peak exposures for decline of short-term forced expiratory volume in one second (FEV₁). Asthma symptoms were associated with workers noticing an odor of TDI (OR 6.02; 95% CI 1.36 to 26.68).

Conclusions

There is evidence that cumulative and peak exposures are associated with TDI-induced asthma.

DNA damage assessment in the lymphocytes of construction painters by comet assay

BACKGROUND

Exposure to chemicals is inevitable for certain occupational groups, particularly in industrial countries. Some cytogenetic tests such as comet assay are effectively utilized to screen genotoxic effects of these chemicals in humans. The purpose of this study has been to assess the DNA damage in construction painters' lymphocytes using the comet assay.

METHODS

Fourteen male construction painters with 1 year of required work experience were randomly selected from the list of Painter Union in Gonabad city, Iran. In addition, 14 healthy male non-painters were randomly selected as controls. The DNA damage degree was determined using a fluorescence microscope and CometScore software. The obtained data were analyzed employing independent t-test using SPSS software v. 14 at the significant level of p < 0.05.

RESULTS

All participants were non-smokers and non-alcoholics. No significant differences were found between the two groups in terms of age, weight, height, body mass index, and systolic and diastolic blood pressure. The DNA damage in the painter group was significantly greater than that of the control group. Tail length (µm) was 12.63 ± 6.54 versus 2.90 ± 0.84, tail DNA (%) was 4.33 ± 1.84 versus 1.29 ± 0.43, and tail moment (µm) was 1.85 ± 0.98 versus 0.14 ± 0.20 in painter and control groups ( p < 0.001), respectively.

CONCLUSION

The chemicals used in oil paint may increase the DNA damage in painter blood lymphocytes.

A compendium of causative agents of occupational asthma

Objective

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

Methods

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

Results

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

Conclusion

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

The role of inhalant food allergens in occupational asthma

Workers handling food products and derivatives are at increased risk of developing occupational asthma. Exposure to food allergens occurs primarily through inhalation of dust, steam, vapors, and aerosolized proteins generated during cutting, scrubbing or cleaning, cooking or boiling, and drying activities. Suspicion of the diagnosis of occupational asthma should lead to proper investigation to confirm the diagnosis objectively. Most inhaled food allergy is IgE mediated, and skin prick tests or specific IgE tests are useful tools to support the diagnosis, but objective evidence of asthma by monitoring of peak expiratory flows at and off work or specific inhalation challenges offers a better diagnostic value. This article provides a list of the various foods, food additives, and contaminants that have been associated with occupational asthma.

Occupational asthma in Korea

Occupational asthma (OA) is the leading occupational respiratory disease. Cases compensated as OA by the Korea Workers' Compensation and Welfare Service (COMWEL) (218 cases), cases reported by a surveillance system (286 cases), case reports by related scientific journals and cases confirmed by the Occupational Safety and Health Research Institute (OSHRI) over 15 yr from 1992 to 2006 were analyzed. Annual mean incidence rate was 1.6 by compensation and 3.5 by surveillance system, respectively. The trend appeared to increase according to the surveillance system. Incidence was very low compared with other countries. The most frequently reported causative agent was isocyanate followed by reactive dye in dyeing factories. Other chemicals, metals and dust were also found as causative agents. OA was underreported according to compensation and surveillance system data. In conclusion, a more effective surveillance system is needed to evaluate OA causes and distribution, and to effectively prevent newly developing OA.

Early incidence of occupational asthma among young bakers, pastry-makers and hairdressers: design of a retrospective cohort study

Background

Occupational exposures are thought to be responsible for 10-15% of new-onset asthma cases in adults, with disparities across sectors. Because most of the data are derived from registries and cross-sectional studies, little is known about incidence of occupational asthma (OA) during the first years after inception of exposure. This paper describes the design of a study that focuses on this early asthma onset period among young workers in the bakery, pastry making and hairdressing sectors in order to assess early incidence of OA in these "at risk" occupations according to exposure duration, and to identify risk factors of OA incidence.

Methods/Design

The study population is composed of subjects who graduated between 2001 and 2006 in these sectors where they experience exposure to organic or inorganic allergenic or irritant compounds (with an objective of 150 subjects by year) and 250 young workers with no specific occupational exposure. A phone interview focusing on respiratory and 'Ear-Nose-Throat' (ENT) work-related symptoms screen subjects considered as "possibly OA cases". Subjects are invited to participate in a medical visit to complete clinical and lung function investigations, including fractional exhaled nitric oxide (FE_NO) and carbon monoxide (CO) measurements, and to collect blood samples for IgE (Immunoglobulin E) measurements (total IgE and IgE for work-related and common allergens). Markers of oxidative stress and genetic polymorphisms exploration are also assessed. A random sample of 200 "non-cases" (controls) is also visited, following a nested case-control design.

Discussion

This study may allow to describ a latent period between inception of exposure and the rise of the prevalence of asthma symptoms, an information that would be useful for the prevention of OA. Such a time frame would be suited for conducting screening campaigns of this emergent asthma at a stage when occupational hygiene measures and adapted therapeutic interventions might be effective.

Trial registration

Clinical trial registration number is NCT01096537.

Review series: Occupational and environmental lung disease: Chronic obstructive pulmonary disease and the workplace

Chronic Obstructive Pulmonary Disease (COPD) is a progressive respiratory disease associated with increasing morbidity and mortality worldwide. Whilst tobacco smoking is the important cause, other cuases are regognised. This article discusses the contribution that harmful inhaled occupational exposures make to the overall burden of COPD, and goes on to discuss other aspects of the COPD workplace interface. Prevention is key. All healthcare professionals have a resposibility to consider workplace issues when dealing with their COPD patients.

Work-related asthma in Montreal, Quebec: population attributable risk in a community-based study

BACKGROUND

Occupational exposures are an important cause of adult-onset asthma but the population attributable risk percentage (PAR%) has been less frequently studied.

OBJECTIVES

To examine the distribution and determinants of adult asthma in six centres across Canada using data gathered in a community-based study.

METHODS

Data were gathered in a community survey of 2959 adults using the European Community Respiratory Health Survey Protocol. A subsample of 498 subjects completed detailed health and occupational questionnaires, methacholine challenge tests and allergy skin tests. Asthma was defined in three ways: current wheeze, asthma symptoms and/or medication, and airway hyperresponsiveness. Occupational exposures were classified as sensitizers or irritants. Associations between asthma and occupational exposures were examined using logistic regression analysis. Model selection was based on the findings for current wheeze, and the same model was applied to the other definitions of asthma.

RESULTS

Fifty-six per cent of subjects reported ever having had occupational exposure to sensitizers, and 9.8% to irritants. Current wheeze was associated with exposure to irritants (PAR% 4.54%), and airway hyperresponsiveness was associated with exposure to sensitizers (PAR% 30.7%). Neither a history of childhood asthma, atopy, nor confining the analysis to adult-onset asthma affected these associations. Analysis of effect modification suggested two types of work-related asthma: one due to exposure to occupational sensitizers, and the other due to exposure to irritants.

CONCLUSIONS

Detailed assessment of past and current exposures is essential in the investigation of work-related asthma. Childhood asthma reactivated or aggravated by work exposures is not easy to distinguish from asthma induced by work, a misclassification that could lead to an underestimation of work-induced asthma. This should be taken into account in jurisdictions in which persons with work-aggravated asthma are not eligible for workers' compensation.

Effective health surveillance for occupational asthma in motor vehicle repair

BACKGROUND

Diisocyanates are the commonest reported cause of occupational asthma (OA) in the UK. Health surveillance should play an important part in the early detection of disease and the prevention of long-term morbidity.

AIM

To assess the efficacy of a UK-wide health surveillance programme provided to the motor vehicle repair industry.

METHODS

Analysis of respiratory questionnaire and spirometry results during the period 1995-2000 and more detailed assessment of the outcome of cases suggestive of OA between 1998 and 2000.

RESULTS

Approximately 3700 employees underwent health surveillance each year. As a result, a number (27%) required further assessment; information on 92 employees who were referred to their general practitioner (GP) for further assessment was examined. Half of these employees subsequently failed to see their GP and of those referred to a specialist only 63% attended that appointment. Of the 20 employees who did see a specialist, nine (45%) were subsequently diagnosed as having OA due to isocyanates, indicating a mean annual incidence rate of 0.79 per 1000 workers identified by surveillance. A year after identification, five of the diagnosed employees were still working in the same job.

CONCLUSIONS

Health surveillance is only one part of a process for identifying OA. In this programme, the high drop out rate of employees in the medical investigation process initiated by surveillance was a significant problem. Recommendations are suggested for the future operation of respiratory health surveillance programmes.

Fifteen-year trends in occupational asthma: data from the Shield surveillance scheme

BACKGROUND

Trends of occupational asthma (OA) differ between regions depending on local industries, provisions for health and safety at the workplace and the availability of a reporting scheme to help in data collection and interpretation.

AIM

To assess trends in OA in an industrialized part of the UK over a 15-year period.

METHODS

Occupational and chest physicians in the West Midlands were invited to submit details of newly diagnosed cases with OA. Data were then transferred to the regional centre for occupational lung diseases for analysis.

RESULTS

A total of 1461 cases were reported to the scheme. Sixty-eight per cent were males with mean (standard deviation) age of 44 (12) years. The annual incidence of OA was 42 per million of working population (95% CI = 37-45). OA was most frequently reported in welders (9%) and health care-related professions (9%) while < 1% of cases were reported in farmers. Isocyanates were the commonest offending agents responsible for 21% of reports followed by metal working fluids (MWFs) (11%), adhesives (7%), chrome (7%), latex (6%) and glutaraldehyde (6%). Flour was suspected in 5% of cases while laboratory animals only in 1%.

CONCLUSIONS

Our data confirm a high annual incidence of OA in this part of the UK. MWFs are an emerging problem, while isocyanates remain the commonest cause. Incidence remained at a fairly stable background level with many small and a few large epidemics superimposed. Schemes like Midland Thoracic Society's Rare Respiratory Disease Registry Surveillance Scheme of Occupational Asthma could help in identifying outbreaks by linking cases at the workplace.

Diisocyanate asthma and gene-environment interactions with IL4RA, CD-14, and IL-13 genes

BACKGROUND

Diisocyanate asthma (DA) affects 2% to 10% of exposed workers, yet the pathogenetic mechanisms underlying this disorder remain ill defined.

OBJECTIVE

To determine if specific single nucleotide polymorphisms (SNPs) of interleukin 4 receptor alpha (IL4RA), IL-13, and CD14 promoter genes are associated with DA.

METHODS

Sixty-two workers with DA confirmed by specific inhalation challenge (SIC) and 75 diisocyanate-exposed, SIC-negative workers were analyzed for SNPs associated with IL4RA, IL-13, and CD14 promoter genes.

RESULTS

No associations were found with individual SNPs and DA. When stratified according to specific diisocyanate exposure, a significant association was found between IL4RA (I50V) II and DA among individuals exposed to hexamethylene diisocyanate (HDI) (odds ratio [OR], 3.29; 95% confidence interval [CI], 1.33-8.14; P = .01) only. Similarly, the IL4RA (I50V) II and IL-13 (R110Q) RR combination was significantly associated with DA in HDI-exposed workers (OR, 4.13; 95% CI, 1.35-12.68; P = .01), as was the IL4RA (I50V) II and CD14 (C159T) CT genotype combination (OR, 5.2; 95% CI, 1.82-14.88; P = .002) and the triple genotype combination IL4RA (I50V) II, IL-13 (R110Q) RR, and CD14 (C159T) CT (OR, 6.4; 95% CI, 1.57-26.12; P = .01).

CONCLUSIONS

Gene-environmental interactions may contribute to the pathogenesis of DA, and gene-gene interactions may modulate this relationship.

Airway disease in highway and tunnel construction workers exposed to silica

BACKGROUND

Construction workers employed in a unique type of tunnel construction known as tunnel jacking were exposed over an 18-month period to respirable crystalline silica at concentrations that exceeded the OSHA permissible exposure limit. The present study examines workplace exposures and occurrence of airway disease in these workers.

METHODS

Medical and occupational histories and chest radiographs were obtained on 343 active construction workers who had worked on the site during the period in question. Chest radiographs were interpreted according to the ILO-1980 system of classification. Standardized questions were used to develop an algorithm to define symptoms consistent with asthma (SCA) and to determine these respiratory outcomes: chronic bronchitis, shortness of breath (SOB), and physician-diagnosed asthma (current vs. not current). Relationships with each of three work activities were examined: slurry wall breakthrough (SWB), chipping caisson overpour, and tunneling/mining.

RESULTS

Participants included laborers, carpenters, tunnel workers, ironworkers, operating engineers, and electricians. No cases of silicosis were found on chest X-ray. Overall prevalence of chronic bronchitis, SCA, SOB, and physician-diagnosed asthma was 10.7%, 25%, 29%, and 6.6%, respectively. Odds ratios (OR) for carpenters compared to laborers were significantly elevated for chronic bronchitis, SCA, and SOB. SWB was associated with chronic bronchitis and SCA (OR 4.93, 95% CI = 1.01, 24.17; OR 3.32, 95% CI = 1.25, 8.84, respectively). The interaction between SWB, SCA, and trade was significant for carpenters (OR 6.87, 95% CI = 1.66, 28.39). Inverse trends were observed for months on the site and chronic bronchitis, SCA, and SOB (P = 0.0374, 0.0006, and 0.0307, respectively).

CONCLUSIONS

Tunnel construction workers exposed to respirable crystalline silica and cement dust are at increased risk for airway disease. Extent of risk varies by trade and work activity. Our data indicate the importance of bystander exposures and suggest that tunnel jacking may be associated with greater risk compared to more traditional methods of tunnel construction. A healthy worker effect is suggested.

Allergy in bakers’ apprentices and factors associated to non-participation in a cohort study of allergic sensitization

OBJECTIVE

To describe the prevalence of atopy and respiratory symptoms among baker apprentices at the start of the education and factors associated with non-participation in the study.

METHODS

A total of 346 students, 22.1(0.6) years of age, mean (SD), from the food production programme of technical colleges in Denmark were invited to participate in a 3 year study. Of the students, 187 agreed to participate and filled in a physician-administered questionnaire. The presence of atopy was determined by skin prick test (SPT) and serum allergen specific IgE (SpIgE). Bronchial hyper responsiveness to methacholine (PD(20) <or= 1,440 microg) was determined.

RESULTS

Prevalence of atopy was 32%. The prevalence of symptoms from the lungs and nose was 19.8 and 25.5%, respectively. Significantly, more SPT reactions were seen in males compared to females (39 vs. 22%, P < 0.05). Sensitization towards flour was significantly more frequent if determined as SpIgE (7.3%) compared to SPT (0.5%). We found a positive association between atopy and lung symptoms OR 6.1 (2.8-13.2 SD) and nasal symptoms OR 3.7 (1.8-7.5 SD). The major reason for non-participation was fear of blood sampling (25.5%).

CONCLUSION

The prevalence of atopy in bakers' apprentices was of the same magnitude in the general Danish population. Significantly, more male bakers' apprentices had atopy. This finding has major impact on the diagnostic procedures of occupational allergy in bakery workers emphasizing the need for standardization of the clinical tests. The main reasons for non-participation were, fear of blood-sampling (57%) and the 3 years commitment to the follow-up study (39%).

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.

Clinical practice guidelines: medical follow-up of patients with asthma--adults and adolescents

The follow-up of patients with asthma should focus on asthma control (disease course over a number of weeks).

Non-malignant occupational respiratory diseases in Germany in comparison with those of other countries

OBJECTIVE

To present recent data on the occurrence of non-malignant occupational airway diseases in Germany and to compare mainly affected occupations of obstructive airway diseases caused by allergens and irritants with available surveillance data from other countries.

METHODS

Sources of German data were statistics for the year 2003 of the Ministry of Labour and Social Affairs and of the federation of statutory accident insurance institutions for the industrial sector.

RESULTS

Confirmed cases of non-malignant occupational respiratory diseases in Germany are mainly benign asbestos-associated diseases (occupational disease no. 4103: 1,975 cases), silicosis/coal worker's pneumoconiosis (occupational disease no. 4101: 1,158 cases), obstructive airway diseases due to allergens (occupational disease no. 4301: 935 cases), chronic obstructive bronchitis and/or emphysema in hard coal miners (occupational disease no. 4111: 414 cases), obstructive airway diseases due to irritants and toxic agents (occupational disease no. 4302: 181 cases), diseases caused by ionising radiation (171 cases), diseases due to isocyanates (occupational disease no. 1315: 55 cases), and 22 cases of other rare occupational lung and airway diseases. Miners, bakers, chemical workers, hairdressers and health care workers are mostly affected. Bakers were also frequently affected by occupational asthma in Finland, France, Sweden, the United Kingdom, the Piedmont region in Italy, South Africa, and New Zealand. Further, high frequencies of occupational asthma were reported for health care workers in France, Italy, New Jersey, Michigan, and South Africa.

CONCLUSION

Despite completely different legal definitions and regulations, comparably high numbers of occupational obstructive diseases in western countries require better primary and secondary prevention in industries with high incidence, especially in bakeries, the health care sector, farming, and mining. Furthermore, there is a urgent need for harmonization of recognition and compensation systems for occupational diseases as well as of respective preventive strategies within the European Union.

Evidence based guidelines for the prevention, identification, and management of occupational asthma

BACKGROUND

Occupational asthma is the most frequently reported work related respiratory disease in many countries. This work was commissioned by the British Occupational Health Research Foundation to assist the Health and Safety Executive in achieving its target of reducing the incidence of occupational asthma in Great Britain by 30% by 2010.

AIM

The guidelines aim to improve the prevention, identification, and management of occupational asthma by providing evidence based recommendations on which future practice can be based.

METHODS

The literature was searched systematically using Medline and Embase for articles published in all languages up to the end of June 2004. Evidence based statements and recommendations were graded according to the Royal College of General Practitioner's star system and the revised Scottish Intercollegiate Guidelines Network grading system.

RESULTS

A total of 474 original studies were selected for appraisal from over 2500 abstracts. The systematic review produced 52 graded evidence statements and 22 recommendations based on 223 studies.

DISCUSSION

Evidence based guidelines have become benchmarks for practice in healthcare and the process used to prepare them is well established. This evidence review and its recommendations focus on interventions and outcomes to provide a robust approach to the prevention, identification, and management of occupational asthma, based on and using the best available medical evidence. The most important action to prevent cases of occupational asthma is to reduce exposure at source. Thereafter surveillance should be performed for the early identification of symptoms, including occupational rhinitis, with additional functional and immunological tests where appropriate. Effective management of workers suspected to have occupational asthma involves the identification and investigation of symptoms suggestive of asthma immediately they occur. Those workers who are confirmed to have occupational asthma should be advised to avoid further exposure completely and early in the course of their disease to offer the best chance of recovery.

Relationship between chemical structure and the occupational asthma hazard of low molecular weight organic compounds

AIMS

To investigate quantitatively, relationships between chemical structure and reported occupational asthma hazard for low molecular weight (LMW) organic compounds; to develop and validate a model linking asthma hazard with chemical substructure; and to generate mechanistic hypotheses that might explain the relationships.

METHODS

A learning dataset used 78 LMW chemical asthmagens reported in the literature before 1995, and 301 control compounds with recognised occupational exposures and hazards other than respiratory sensitisation. The chemical structures of the asthmagens and control compounds were characterised by the presence of chemical substructure fragments. Odds ratios were calculated for these fragments to determine which were associated with a likelihood of being reported as an occupational asthmagen. Logistic regression modelling was used to identify the independent contribution of these substructures. A post-1995 set of 21 asthmagens and 77 controls were selected to externally validate the model.

RESULTS

Nitrogen or oxygen containing functional groups such as isocyanate, amine, acid anhydride, and carbonyl were associated with an occupational asthma hazard, particularly when the functional group was present twice or more in the same molecule. A logistic regression model using only statistically significant independent variables for occupational asthma hazard correctly assigned 90% of the model development set. The external validation showed a sensitivity of 86% and specificity of 99%.

CONCLUSIONS

Although a wide variety of chemical structures are associated with occupational asthma, bifunctional reactivity is strongly associated with occupational asthma hazard across a range of chemical substructures. This suggests that chemical cross-linking is an important molecular mechanism leading to the development of occupational asthma. The logistic regression model is freely available on the internet and may offer a useful but inexpensive adjunct to the prediction of occupational asthma hazard.

Relevance of inhalational exposure to food allergens

PURPOSE OF REVIEW

This review discusses the inhalational route as a clinically important route of exposure to food allergens.

RECENT FINDINGS

In childhood, we have recently demonstrated that food allergens can induce both early and late phase bronchial reactions within blinded, placebo-controlled challenges. Additionally, clinically important levels of food allergens have been measured in environmental air samples.

SUMMARY

It is well known that the ingestion of food allergens frequently causes respiratory symptoms and that the mechanism of death in fatal anaphylaxis is usually profound bronchospasm. The mechanism by which ingested food allergens induce bronchial reactions is unclear. There are many case reports of bronchial reactions to aerosolized food allergens. Within the food industry the problems have been examined more systematically. From such work it is possible to gain an impression of the potential prevalence of the problem. With 10% of adult asthma being occupational and 10% of occupational asthma being induced by aerosolized food, inhalational exposure to food allergens plays a major role in at least 1% of adult asthma. For a patient with co-existent food allergy and asthma it is important that both dietary and environmental avoidance be practised. The similar pathophysiology of allergic and occupational asthma and the ability of inhaled food allergens to cause the latter raises the question as to whether aerosolized food could play a role in the pathogenesis of childhood asthma.

Assessing the burden of respiratory disease in the UK

This review explores the health and social burden of some of the main respiratory diseases (asthma, chronic obstructive pulmonary disease, cryptogenic fibrosing alveolitis, cystic fibrosis, lung cancer, mesothelioma, obstructive sleep apnoea and tuberculosis) in order to increase awareness of these diseases and highlight areas where improvements in care are required. The overall impact of respiratory diseases in the U.K. in terms of prevalence, mortality, morbidity and economic costs, with particular reference to secondary care has been considered and comparisons made with the rest of Europe where data are available. Respiratory diseases are responsible for a significant proportion of serious morbidity and premature death among the population of the U.K. and they will continue to present a growing challenge; special support is needed to tackle this burden.

Glucoamylase: another fungal enzyme associated with baker's asthma

BACKGROUND

Aspergillus-derived enzymes are widely used as dough additives in the baking industry. These enzymes may give rise to immunoglobulin (Ig)E-mediated sensitization and occupational asthma. Glucoamylase (or amyloglucosidase) is an important industrial enzyme obtained from Aspergillus niger and used to provide fermentable sugars for yeast to improve loaf volume and texture.

OBJECTIVE

The aim of our study was to investigate the potential allergenic role of glucoamylase in baker's asthma.

METHODS

We report four subjects with work-related allergic respiratory symptoms who were exposed to glucoamylase and other starch-cleaving enzymes used as baking additives. The causative role of glucoamylase in work-related asthma was investigated by immunologic tests and specific inhalation challenges (SIC). Glucoamylase allergenic components were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting.

RESULTS

Skin prick tests to glucoamylase (10 mg/mL) gave a positive response in all patients. Further, a positive skin prick test to alpha-amylase was obtained in the four patients and to hemicellulase in two of them. SIC to glucoamylase elicited isolated early asthmatic responses in the three patients tested, and SIC to alpha-amylase elicited early asthmatic responses in two patients and a dual asthmatic response in another patient. Immunoblotting with glucoamylase showed several IgE-binding bands with molecular masses between 33 and 96 kD. IgE-inhibition assays showed scarce to moderate allergenic cross-reactivity between glucoamylase and alpha-amylase.

CONCLUSIONS

These bakers had developed IgE-mediated occupational asthma to glucoamylase and alpha-amylase. Fungal glucoamylase is widely used as a baking additive and this enzyme may give rise to allergic respiratory reactions among exposed workers.

Dust-induced interstitial lung disease in the tropics

Inhalation of dusts is an important cause of interstitial lung disease in the tropical countries such as India. While dusts of organic origin, such as the cotton dust causing byssinosis, generally cause bronchial or bronchiolar involvement and hypersensitivity pneumonitis, inorganic metallic dusts cause progressive pulmonary fibrosis. Silicosis, coal workers' pneumoconiosis, and asbestosis are the three most commonly recognized forms of pneumoconiotic pulmonary fibrosis. Pulmonary tuberculosis is an important complication seen in up to 50% of patients of silicosis in some reports from India. The presentation is generally chronic, although acute and accelerated forms of silicosis are known when the exposures are heavy. Breathlessness, dry cough, and general constitutional symptoms are commonly seen. Patients with silicotuberculosis or other forms of infection may also have significant expectoration, hemoptysis, fever, and rapid progression. Respiratory failure and chronic cor pulmonale occur in the later stages. The diagnosis is easily established if the occupational history is available. Dense nodular opacities on chest roentgenograms, which may be large in patients with massive pulmonary fibrosis, are characteristic. Emphysematous changes generally appear in advanced stages or in patients who smoke. Bronchoalveolar lavage and/or lung biopsy may occasionally be required to establish or exclude other causes of interstitial lung disease. Treatment is largely palliative, although a variety of drugs including corticosteroids and procedures such as whole lung lavage have been tried. None of these methods has yet been found successful in the treatment. Preventive safety steps, including removal of the patient from the site of exposure, are the only effective strategies to control disease progression.

Laboratory animal allergy: a British perspective on a global problem

In the United Kingdom, laboratory animal allergy (LAA) has been recognized as an important occupational disease for nearly 25 years. However, introduction of health and safety legislation (e.g., the Control of Substances Hazardous to Health Regulations of 1988) and an increasing knowledge of the factors that contribute to the etiology of this disease have had surprisingly little impact on the prevalence and incidence of LAA over the last 10 to 20 yr. Studies of the relation between exposure to animal allergens and the development of LAA reveal that the risk of disease increases with increasing intensity of exposure. Current evidence suggests that animal allergens are very potent, and substantial decreases in allergen exposure are therefore necessary before a reduction in symptoms will be observed. In the United Kingdom, it is unlikely that an Occupational Exposure Limit will be set for animal allergens in the near future, partly because an adequately standardized assay for quantifying exposure is not yet available. Prevention of LAA in the future will probably be driven by the needs of the industry and will most likely rely on the adoption of guidelines describing " best practise" which incorporate sophisticated engineering methods of controlling exposure to animal allergens.

Reported incidence of occupational asthma in the United Kingdom, 1989-97

OBJECTIVES

To examine trends in estimated population based incidence of occupational asthma by age, sex, occupation, geographical region, and causal agents based on 9 years of the Surveillance of Work Related and Occupational Respiratory Disease (SWORD) data.

METHODS

In January 1989 the SWORD scheme for the surveillance of occupational respiratory disease was established in the United Kingdom to make good the lack of epidemiological information on the incidence of these diseases in the United Kingdom. Between 80% and 90% of chest and occupational physicians report voluntarily all new cases they see, on a monthly or random sampling basis. During the 9 years 1989-97, an estimated 25 674 new cases of occupational respiratory disease, including 7387 of occupational asthma, were reported. Suspected causal agents were classified into 44 categories and estimated annual incidences of asthma were calculated with denominators from the labour force survey.

RESULTS

Overall, a third of the suspected causes of asthma were organic, a third chemical, 6% metallic, and the rest miscellaneous, or in 8%, unknown. There was evidence of an increase since 1989 in cases due to latex, and possibly glutaraldehyde, and an apparent drop since 1991 in the proportion of cases attributed to isocyanates. Incidences were higher in men than women and the disparity was especially marked in the population aged 45 years or more in which rates for men were at least twice those for women. Average annual rates per million workers for 1992-7 ranged from 7 (95% confidence interval (95% CI) 5 to 9) for the lowest risk group of professional, clerical, and service workers to 1464 (95% CI 968 to 2173) for coach and other spray painters. Except for laboratory technicians, all other occupations with rates over 100 were concerned with manufacturing and processing that used chemicals, metals, and organic materials. Incidences were two to three times higher in the north and midlands than in East Anglia and the south. The introduction of a sampling scheme in 1992 doubled estimates of reported incidence of occupational asthma, but there was little evidence of other temporal changes.

CONCLUSIONS

The SWORD scheme has produced consistent estimates of the causes and incidence of occupational asthma as seen by chest and occupational physicians. It has allowed the epidemiology of occupational asthma in the population to be studied and high risk occupations to be identified. There is certainly more occupational asthma in the population than that which reaches specialists in occupational and chest medicine; therefore the incidence rates presented here are underestimates, but by how much remains unknown.

Surveillance of occupational skin disease: EPIDERM and OPRA

Consultant dermatologists in the U.K. have been reporting to EPIDERM, a voluntary surveillance scheme for occupational skin disease, since February 1993; reporting by occupational physicians to the scheme began in May 1994 and was superseded in January 1996 by OPRA (Occupational Physicians Reporting Activity). Currently 244 dermatologists and 790 occupational physicians report incident cases to these schemes. During the 6 years to January 1999 a total of 12, 574 new cases of occupational skin disease was estimated from reports by consultant dermatologists and 10,136 cases estimated from occupational physicians (since May 1994). The annual incidence of occupational contact dermatitis using data from both schemes was 12. 9 per 100,000 workers. The incidence of contact dermatitis per 100, 000 workers increased with age in men from 4.9 (age 16-29 years) to 6.6 (age 45-60 years); in women a higher rate (9.5) was apparent in the younger age group, with lower rates in older female workers. High rates in young workers were associated with wet work and in older workers with exposure to oils. For men, high rates of contact dermatitis were seen in reports from both schemes for chemical operatives, machine tool setters and operatives, coach and spray painters and metal workers. For women, high rates were found for hairdressers, biological scientists and laboratory workers, nurses and those working in catering. The most frequent agents for contact dermatitis were rubber chemicals and materials (14.1% of cases reported by dermatologists), soaps and cleaners (12.7%), nickel (11. 9%), wet work (11.1%), personal protective equipment (6.2%), petroleum products (6.3%), cutting oils and coolants (5.6%), and epoxy and other resins (6.1%). In the 1608 estimated cases of skin cancer all but 4% were attributed to ultraviolet radiation. Cases of contact urticaria attributed to latex peaked in 1996, with a decline in cases since that time.