Management of work-related asthma

Cluster analysis of phenotypes, job exposure, and inflammatory patterns in elderly and nonelderly asthma patients

BACKGROUND

Asthma has been identified as different phenotypes due to various risk factors. Age differences may have potential effects on asthma phenotypes. Our study aimed to identify potential asthma phenotypes among adults divided by age as either younger or older than 65 years. We also compared differences in blood granulocyte patterns, occupational asthmagens, and asthma control-related outcomes among patient phenotype clusters.

METHODS

We recruited nonelderly (<65 years old) (n = 726) and elderly adults (≥65 years old) (n = 201) with mild-to-severe asthma. We conducted a factor analysis to select 17 variables. A two-step cluster analysis was used to classify subjects with asthma phenotypes, and a discriminant analysis was used to verify the classification of cluster results.

RESULTS

There were three clusters with different characteristics identified in both the nonelderly and elderly asthmatic adults. In the nonelderly patient group, cluster 2 (obese, neutrophilic phenotypes) had a 1.85-fold significantly increased risk of asthma exacerbations. Cluster 3 (early-onset, atopy, and smoker with an eosinophil-predominant pattern) had a 2.37-fold risk of asthma exacerbations and higher oral corticosteroid (OCS) use than cluster 1 (late-onset and LMW exposure with paucigranulocytic blood pattern). Among elderly patients, cluster 2 had poor lung function and more ex-smokers. Cluster 3 (early-onset, long asthma duration) had the lowest paucigranulocytic blood pattern percentages in the elderly group.

CONCLUSIONS

The novelty of the clusters was found in age-dependent clusters. We identified three distinct phenotypes with heterogeneous characteristics, asthma exacerbations and medicine use in nonelderly and elderly asthmatic patients, respectively. Classification of age-stratified asthma phenotypes may lead to precise identification of patients, which provides personalized disease management.

The Role of Immunotherapy and Biologic Treatments in Occupational Allergic Disease

Occupational exposures are estimated to account for 15% to 25% of all adult asthma in the general population. In some cases, workplace allergen exposures can be reduced but not entirely eliminated. Given the potentially significant impact of job change, some workers may choose to continue working in a job in which there is an ongoing occupational allergen exposure. In these cases, a combined approach including personal safety measures, pharmacotherapy, and allergen immunotherapy may result in the best clinical outcomes. This review presents existing evidence for the use of immunotherapy and biologic treatments in occupational allergic disease for various occupational allergens, including wheat flour, mammalian proteins, natural rubber latex, and Hymenoptera venom. There is increasing but modest evidence on beneficial short-term and long-term effects of allergen immunotherapy and safety in worker populations. Available data suggest that allergen immunotherapy can reduce skin and respiratory symptoms and therefore allow workers to continue their current occupation.

A field evaluation of a single sampler for respirable and inhalable indium and dust measurements at an indium-tin oxide manufacturing facility

Indium-tin oxide production has increased greatly in the last 20 years subsequent to increased global demand for touch screens and photovoltaics. Previous studies used measurements of indium in blood as an indicator of indium exposure and observed associations with adverse respiratory outcomes. However, correlations between measurements of blood indium and airborne respirable indium are inconsistent, in part because of the long half-life of indium in blood, but also because respirable indium measurements do not incorporate inhalable indium that can contribute to the observed biological burden. Information is lacking on relationships between respirable and inhalable indium exposure, which have implications for biological indicators like blood indium. The dual IOM sampler includes the foam disc insert and can simultaneously collect respirable and inhalable aerosol. Here, the field performance of the dual IOM sampler was evaluated by comparing performance with the respirable cyclone and traditional IOM for respirable and inhalable indium and dust exposure, respectively. Side-by-side area air samples were collected throughout an indium-tin oxide manufacturing facility. Cascade impactors were used to determine particle size distribution. Several statistical methods were used to evaluate the agreement between the pairs of samplers including calculating the concordance correlation coefficient and its accuracy and precision components. One-way ANOVA was used to evaluate the effect of dust concentration on sampler differences. Respirable indium measurements showed better agreement (concordance correlation coefficient: 0.932) compared to respirable dust measurements (concordance correlation coefficient: 0.777) with significant differences observed in respirable dust measurements. The dual IOM measurements had high agreement with the traditional IOM for inhalable indium (concordance correlation coefficient: 0.997) but lower agreement for inhalable dust (concordance correlation coefficient: 0.886 and accuracy: 0.896) with a significantly large mean bias (-146.9 µg/m³). Dust concentration significantly affected sampler measurements of inhalable dust and inhalable indium. Results from this study suggest that the dual IOM is a useful single sampler for simultaneous measurements of occupational exposure to respirable and inhalable indium.

Respiratory Symptoms in Hospital Cleaning Staff Exposed to a Product Containing Hydrogen Peroxide, Peracetic Acid, and Acetic Acid

Cleaning and disinfecting products consisting of a mixture of hydrogen peroxide (HP), peracetic acid (PAA), and acetic acid (AA) are widely used as sporicidal agents in health care, childcare, agricultural, food service, and food production industries. HP and PAA are strong oxidants and their mixture is a recognized asthmagen. However, few exposure assessment studies to date have measured HP, PAA, and AA in a health care setting. In 2015, we performed a health and exposure assessment at a hospital where a new sporicidal product, consisting of HP, PAA, and AA was introduced 16 months prior. We collected 49 full-shift time-weighted average (TWA) air samples and analyzed samples for HP, AA, and PAA content. Study participants were observed while they performed cleaning duties, and duration and frequency of cleaning product use was recorded. Acute upper airway, eye, and lower airway symptoms were recorded in a post-shift survey (n = 50). A subset of 35 cleaning staff also completed an extended questionnaire that assessed symptoms reported by workers as regularly occurring or as having occurred in the previous 12 months. Air samples for HP (range: 5.5 to 511.4 ppb) and AA (range: 6.7 to 530.3 ppb) were all below established US occupational exposure limits (OEL). To date, no full-shift TWA OEL for PAA has been established in the United States, however an OEL of 0.2 ppm has been suggested by several research groups. Air samples for PAA ranged from 1.1 to 48.0 ppb and were well below the suggested OEL of 0.2 ppm. Hospital cleaning staff using a sporicidal product containing HP, PAA, and AA reported work-shift eye (44%), upper airway (58%), and lower airway (34%) symptoms. Acute nasal and eye irritation were significantly positively associated with increased exposure to the mixture of the two oxidants: HP and PAA, as well as the total mixture (TM)of HP, PAA, and AA. Shortness of breath when hurrying on level ground or walking up a slight hill was significantly associated with increased exposure to the oxidant mixture (P = 0.017), as well as the TM (P = 0.026). Our results suggest that exposure to a product containing HP, PAA, and AA contributed to eye and respiratory symptoms reported by hospital cleaning staff at low levels of measured exposure.

Occupational Allergies: A Brief Review

Occupational allergies are groups of work-related disorders that are accompanied by immunologic reaction to workplace allergens and include occupational asthma, rhinitis, hypersensitivity pneumonitis, dermatitis, and anaphylaxis. This mini review presents a brief analysis of the more important aspects of occupational allergic disorders.

Occupational asthma in a cable manufacturing company

Background:

During the past decade, incidence of asthma has increased, which might have been due to environmental exposures.

Objectives:

Considering the expansion of cable manufacturing industry in Iran, the present study was conducted to evaluate the prevalence of occupational asthma in a cable manufacturing company in Iran as well as its related factors.

Patients and Methods:

This study was conducted on employees of a cable manufacturing company in Yazd, Iran, in 2012. The workers were divided into two groups of exposure (to toluene diisocyanate, polyvinyl chloride, polyethylene or polypropylene) and without exposure. Diagnosis of occupational asthma was made based on the subjects’ medical history, spirometry and peak flowmetry, and its frequency was compared between the two groups.

Results:

The overall prevalence of occupational asthma was 9.7%. This rate was 13.8% in the exposed group. Logistic regression analysis showed that even after adjustment for confounding factors, a significant correlation existed between the frequency of occupational asthma and exposure to the produced dust particles (P < 0.05). In addition, age, work experience, body mass index, cigarette smoking and shift work had significant correlations with the prevalence of occupational asthma (P < 0.05).

Conclusions:

Considering the high prevalence of occupational asthma among cable manufacturing company workers in Iran, this issue needs to be addressed immediately in addition to reduction of exposure among subjects. Reduction in work shift duration, implementation of tobacco control and cessation programs for the personnel, and performing spirometry tests and respiratory examinations in shorter periods may be among effective measures for reducing the incidence of occupational asthma in this industry.

Chemical and biological work-related risks across occupations in Europe: a review

BACKGROUND

Work-related health inequalities are determined to some extent by an unequal exposure to chemical and biological risk factors of disease. Although their potential economic burden in the European Union (EU-25) might be substantial, comprehensive reviews focusing on the distribution of these risks across occupational groups are limited. Thus, the main objective of this review is to provide a synopsis of the exposure to chemical and biological hazards across occupational groups. In addition, main industrial applications of hazardous substances are identified and some epidemiological evidence is discussed regarding societal costs and incidence rates of work-related diseases.

METHODS

Available lists of carcinogens, sensitisers, mutagens, reprotoxic substances and biological hazards were consulted. For each work-related hazard the main industrial application was identified in order to assess which ISCO occupational groups may be associated with direct exposure. Where available, information on annual tonnage production, risk assessment of the substances and pathogens, and other relevant data were collected and reported.

RESULTS

Altogether 308 chemical and biological hazards were identified which may account to at least 693 direct exposures. These hazards concentrate on the following major occupational groups: technicians (ISCO 3), operators (ISCO 8), agricultural workers (ISCO 6) and workers in elementary occupations (ISCO 9). Common industrial applications associated with increased exposure rates relate among others to: (1) production or application of pigments, resins, cutting fluids, adhesives, pesticides and cleaning products, (2) production of rubber, plastics, textiles, pharmaceuticals and cosmetics, and (3) in agriculture, metallurgy and food processing industry, Societal costs of the unequal distribution of chemical and biological hazards across occupations depend on the corresponding work-related diseases and may range from 2900 EUR to 126000 EUR per case/year.

CONCLUSIONS

Risk of exposure to chemical and biological risks and work-related disease incidence are highly concentrated on four occupational groups. The unequal burden of exposure across occupations is an important contributing factor leading to health inequalities in society. The bulk of societal costs, however, are actually being borne by the workers themselves. There is an urgent need of taking into account the health impact of production processes and services on workers' health.

Work aggravated asthma; a review of the recent evidence

BACKGROUND

The link between asthma and inhaled workplace exposures has been long appreciated, and yet aggravation of asthma symptoms by work conditions, known as work-aggravated asthma (WAA), remains relatively common.

SOURCES OF DATA

A review of the literature published over the last 3 years was carried out, and additional key articles were included from outside this timeframe.

AGREEMENT

WAA is commonly reported by workers with asthma. One published assessment of 12 studies identified a median prevalence of 21.5% among workers with asthma. Commonly reported causes included a variety of inhaled dusts, smoke, vapours, fumes, gases and mists, common and workplace-specific aeroallergens, physical environmental factors including temperature and humidity and physical activity at work.

CONTROVERSY

Remains in relation to definition, and how to distinguish WAA from occupational asthma in which there is sensitization to an agent in the workplace. Both these areas, and the development of workplace interventions to reduce WAA, are timely topics for future research.

Diagnosis and frequency of work-exacerbated asthma among bakers

BACKGROUND

Work-exacerbated asthma (WEA) is asthma worsened by workplace exposures, although the asthma is not caused by sensitizers in the work environment.

OBJECTIVES

To evaluate the frequency of WEA in bakers reporting work-related respiratory symptoms and the usefulness of diagnostic tests in differentiating WEA from occupational asthma (OA).

METHODS

The study group included 393 bakers reporting respiratory symptoms at the workplace. In all patients, questionnaire, spirometry, skin prick tests (SPTs), and evaluation of serum total and specific IgE levels were performed. Recognition of OA was based on a specific inhalation challenge test.

RESULTS

Occupational asthma was found in 44.5% of patients, whereas WEA was recognized in 16%. The latency period was 11.2 ± 8.2 years in patients with OA vs 13.3 ± 9.7 years in those with WEA. Sixty percent of patients with OA and 50.8% of those with WEA had positive SPT reactions to common allergens; occupational SPT results were positive in 74.9% and 34.9%, respectively. Specific IgE to flours were found in 61.7% of patients with OA and 28.6% of those with WEA. In addition, OA frequently coexisted with occupational rhinitis (53.7% of patients), whereas WEA and rhinitis were found in 31.7% of patients.

CONCLUSION

Work-exacerbated asthma was diagnosed in 16% of bakers who reported allergic respiratory symptoms. The specific challenge test for occupational allergens should be performed in bakers with suspected work-related asthma, because an assessment of sensitization (SPT to occupational allergens, evaluation of specific IgE) is not specific enough to differentiate OA from WEA.

Asthma phenotypes in adults and clinical implications

It is becoming increasingly recognized that asthma is a heterogeneous disease, whether based on clinical factors, including the patient's age at diagnosis, symptom spectrum and treatment response, triggering factors, or the level and type of inflammation. Attempts to analyze the importance of these characteristics to the clinical presentation of asthma have led to the appreciation of numerous separate and overlapping asthma phenotypes. However, these approaches are 'biased' and based on the clinician/scientist's own experience. Recently, unbiased approaches have also been attempted using both molecular and statistical tools. Early results from these approaches have supported and expanded on the clinician's concepts. However, until specific biologic markers are identified for any of these proposed phenotypes, the definitive nature of any phenotype will remain speculative.

Genetics of occupational asthma

PURPOSE OF REVIEW

To discuss gene association studies conducted in workers diagnosed with occupational asthma.

RECENT FINDINGS

Human leukocyte antigen studies conducted in European workers have defined major histocompatibility complex class II alleles and haplotypes associated with diisocyanate asthma. Recently, certain glutathione S-transferase genotypes (e.g. the GSTM1 null genotype) and N-acetyltransferase genotypes associated with slow acetylation phenotypes have been reported to be associated with diisocyanate asthma. Genotype combinations of IL-4 receptor-α and CD14 single nucleotide polymorphisms (SNPs) were significantly associated with diisocyanate asthma, but only in workers exposed to hexamethylene diisocyanate. A recent genome-wide association study (GWAS) conducted in Korea identified several SNPs of the α-T-catenin gene that were significantly associated with diisocyanate asthma.

SUMMARY

Although candidate gene association studies have yet to identify reliable predictors of occupational asthma, future investigations including GWAS studies may identify high-risk genotypes allowing identification of workers at risk.

Risks of exposure to occupational asthmogens in atopic and nonatopic asthma: a case-control study in Taiwan

RATIONALE

Asthma is often work-related and can be classified as atopic or nonatopic on the basis of its pathogenesis. Few studies have reported an association between exposure to occupational asthmogens and asthma with and without atopy.

OBJECTIVES

We investigated, in adults with asthma, whether occupational exposure to asthmogens influenced the risk of having atopic or nonatopic asthma, and their level of lung function.

METHODS

We recruited 504 hospital-based adults with current asthma, 504 community-based control subjects, and 504 hospital-based control subjects in southern Taiwan. Asthma with atopy was defined as having asthma in combination with an increase in total IgE (≥100 U/ml) or a positive Phadiatop test (≥0.35 Pharmacia arbitrary unit/L) (Pharmacia ImmunoCAP; Pharmacia, Uppsala, Sweden). Occupational exposure to asthmogens was assessed with an asthma-specific job exposure matrix.

MEASUREMENTS AND MAIN RESULTS

We found a significant association between atopic asthma and exposure to high molecular weight asthmogens (adjusted odds ratio [AOR], 4.0; 95% confidence interval [CI], 1.8-8.9). Nonatopic asthma was significantly associated with exposure to low molecular weight asthmogens (AOR, 2.6; 95% CI, 1.6-4.3), including industrial cleaning agents and metal sensitizers. Agriculture was associated with both atopic and nonatopic asthma (AOR, 7.8; 95% CI, 2.8-21.8; and AOR, 4.1; 95% CI, 1.3-13.0, respectively). The ratio of FEV₁ to FVC in the high-risk group was significantly lower than in the no-risk group (P = 0.026) in currently employed patients with asthma.

CONCLUSIONS

In adults with asthma, occupational exposure to high and low molecular weight asthmogens appears to produce differential risks for atopic and nonatopic asthma.

Advances in environmental and occupational respiratory diseases in 2009

The year 2009 led to a number of significant advances in environmental and occupational allergic diseases. The role of exposure to environmental pollutants, respiratory viruses, and allergen exposure showed significant advances. New allergens were identified. Occupational asthma and the relationship of complementary and alternative medicine to allergic diseases were extensively reviewed. New approaches to immunotherapy, novel vaccine techniques, and methods to reduce risks for severe allergic disease were addressed.