Work-Related Asthma

A cluster of hypersensitivity pneumonitis associated with exposure to metalworking fluids

BACKGROUND

Workers exposed to metalworking fluids (MWF) can develop respiratory illnesses including hypersensitivity pneumonitis (HP). These respiratory manifestations are likely due to microbial contamination of aerosolized MWF. This paper reports a cluster of HP and respiratory symptoms at a manufacturing plant where MWF and workplace air were contaminated with bacterial endotoxin despite frequent negative bacterial cultures of MWF.

METHODS

A pulmonologist assessed and treated three workers with respiratory symptoms. The Occupational Safety and Health Administration (OSHA) inspected the plant. OSHA's investigation included bacterial culture of MWF, measurement of endotoxin concentrations in MWF and workplace air, review of the employer's fluid management program, and distribution of a cross-sectional symptom questionnaire.

RESULTS

Three workers had biopsy-confirmed HP. In addition, 30.8% of questionnaire respondents reported work-related respiratory symptoms. OSHA detected endotoxin levels as high as 92,000 endotoxin units (EU)/ml in MWF and 3200 EU/m³ in air. Endotoxin concentrations and risk of MWF inhalation were highest near an unenclosed multistation computer numerical control machine. A contractor had tested this machine's MWF for bacterial growth weekly during the preceding three years, and most (96.0%) of those tests were negative.

CONCLUSIONS

Contaminated MWF can cause severe occupational lung disease even if microorganisms do not grow in fluid cultures. Endotoxin testing can increase the sensitivity of detection of microbial contamination. However, employers should not rely solely upon MWF testing data to protect workers. Medical surveillance and meticulous source control, such as engineering controls to suppress MWF mist and prevent its inhalation, can reduce the likelihood of respiratory disease.

Informatics Approaches for Recognition, Management, and Prevention of Occupational Respiratory Disease

Computer and information systems can improve occupational respiratory disease prevention and surveillance by providing efficient resources for patients, workers, clinicians, and public health practitioners. Advances include interlinking electronic health records, autocoding surveillance data, clinical decision support systems, and social media applications for acquiring and disseminating information. Obstacles to advances include inflexible hierarchical coding schemes, inadequate occupational health electronic health record systems, and inadequate public focus on occupational respiratory disease. Potentially transformative approaches include machine learning, natural language processing, and improved ontologies.

Progress in Occupational Asthma

Occupational asthma (OA) represents one of the major public health problems due to its high prevalence, important social and economic burden. The aim of this review is to summarize current data about clinical phenotypes, biomarkers, diagnosis and management of OA, a subtype of work-related asthma. Most studies have identified two phenotypes of OA. One is sensitizer-induced asthma, occuring after a latency period and caused by hypersensitivity to high- or low-molecular weight agents. The other is irritant-induced asthma, which can occur after one or more exposures to high concentrations of irritants without latency period. More than 400 agents causing OA have been identified and its list is growing fast. The best diagnostic approach for OA is a combination of clinical history and objective tests. An important tool is a specific inhalation challenge. Additional tests include assessments of bronchial hyperresponsiveness to methacholine/histamine in patients without airflow limitations, monitoring peak expiratory flow at- and off-work, sputum eosinophil count, exhaled nitric oxide measurement, skin prick tests with occupational allergens and serum specific IgE. Treatment of OA implies avoidance of exposure, pharmacotherapy and education. OA is a heterogeneous disease. Mechanisms of its different phenotypes, their diagnosis, role of new biomarkers and treatment require further investigation.

Use of population data for assessing trends in work-related asthma mortality

PURPOSE OF REVIEW

Work-related asthma has been associated with poorer asthma control and frequent unscheduled healthcare visits, and can be fatal. Case reports of work-related asthma deaths are rare, but can initiate efforts to prevent additional cases. We reviewed relevant literature and data sources to evaluate whether analyzing mortality data at the population level can help identify potential sources of exposures that contribute to work-related asthma.

RECENT FINDINGS

A limited number of population-based studies have addressed work-related asthma mortality. Data on asthma mortality are derived from death certificates using the International Classification of Diseases (ICD) as a standard for coding cause. However, no discrete code for work-related asthma is available. Analysis of asthma mortality relative to industries and occupations appears to identify high-risk jobs that were not identified by analyzing asthma morbidity data.

SUMMARY

Beyond recognized work-related asthma deaths, it is possible that occupational exposures have contributed to other asthma deaths that have gone unnoticed and could potentially be identified by the analysis of mortality data at the population level. Such analyses in the United States appear to assist in recognizing high-risk occupations and industries. Additional analyses would be possible if a work-related asthma ICD code were available.

Assessing the health impact of interventions for baker's allergy and asthma in supermarket bakeries: a group randomised trial

PURPOSE

To assess the impact of an intervention for baker's allergy and asthma in supermarket bakeries.

METHODS

A group randomised trial conducted in 31 bakeries (n = 337 bakers) that were randomly assigned to one of two intervention groups (n = 244 bakers) and a control group (n = 93 bakers). Health data collected prior to and 1-year after the intervention included information obtained from an ECRHS questionnaire; tests for atopy and serum-specific IgE to cereal flours; fractional exhaled nitric oxide (FeNO). Data from the two intervention groups were combined to form one intervention group for purposes of the statistical analysis.

RESULTS

At 1 year of follow-up, the incidence and level of decline of work-related ocular-nasal and chest symptoms, sensitisation status and elevated FeNO (FeNO > 25 ppb) was similar in both intervention and control groups. The mean FeNO difference was also similar across both groups (2.2 ppb vs 1.7 ppb, p = 0.86). In those with FeNO > 25 ppb at baseline, the decline was greater in the intervention compared to control group (16.9 ppb vs 7.7 ppb, p = 0.24). Multivariate logistic regression models (adjusting for smoking, baseline sensitisation to cereal flour, baseline FeNO > 25 ppb) did not demonstrate an appreciable FeNO decline (≥ 10%) in the intervention compared to control group. However, stratification by the presence of work-related ocular-nasal symptoms in bakers at baseline demonstrated a significant FeNO decline (≥ 10%) in the intervention compared to the control group (OR 3.73, CI 1.22-11.42).

CONCLUSION

This study demonstrates some evidence of an intervention effect on FeNO 1 year after an intervention, particularly in bakers with work-related ocular-nasal symptoms.

Occupational asthma associated with bleached chlorine-free cellulose dust in a sanitary pad production plant

BACKGROUND

Cellulose is an insoluble plant polysaccharide produced from soft-wood pulp. Although chronic respiratory effects associated with high cellulose-based dust levels have been previously described, occupational asthma has not. A 37 year old machine operator in a sanitary pad production factory presented with new-onset work-related asthma symptoms for two years.

METHODS

The worker underwent clinical, pulmonological and immunological (skin prick tests, serum specific IgE determinations) evaluation using standardised procedures. The cellulose product was subjected to scanning electron microscopy (SEM) examination. A specific inhalation challenge test performed with the cellulose product ensured that dust concentrations were kept below 5 mg/m³ .

RESULTS

The subject was not atopic and did not have elevated IgE to pine wood or xylanase. The cellulose product appeared to be free of protein contaminants on SEM. The Work Effect Index computed on serial PEF recordings was elevated (WEI = 3.8).Specific inhalational challenge with the cellulose product dust revealed a late bronchial response (39% drop in FEV₁ at 3 hours post challenge).

CONCLUSION

This is the first reported case of occupational asthma to a cellulose fibre product. A non-specific immune reaction or irritant response seems likely. These fibres may therefore not be biologically inert. The occupational exposure limit of 10 mg/m³ generally used for cellulose dust appears to be non-protective.

Methanosphaera stadtmanae induces a type IV hypersensitivity response in a mouse model of airway inflammation

Despite improved awareness of work‐related diseases and preventive measures, many workers are still at high risk of developing occupational hypersensitivity airway diseases. This stems from a lack of knowledge of bioaerosol composition and their potential effects on human health. Recently, archaea species were identified in bioaerosols, raising the possibility that they play a major role in exposure‐related pathology. Specifically, Methanosphaera stadtmanae (MSS) and Methanobrevibacter smithii (MBS) are found in high concentrations in agricultural environments and respiratory exposure to crude extract demonstrates immunomodulatory activity in mice. Nevertheless, our knowledge of the specific impact of methanogens exposure on airway immunity and their potential to induce airway hypersensitivity responses in workers remains scant. Analysis of the lung mucosal response to methanogen crude extracts in mice demonstrated that MSS and MBS predominantly induced T_H17 airway inflammation, typical of a type IV hypersensitivity response. Furthermore, the response to MSS was associated with antigen‐specific IgG₁ and IgG_2a production. However, despite the presence of eosinophils after MSS exposure, only a weak T_H2 response and no airway hyperresponsiveness were observed. Finally, using eosinophil and mast cell‐deficient mice, we confirmed that these cells are dispensable for the T_H17 response to MSS, although eosinophils likely contribute to the exacerbation of inflammatory processes induced by MSS crude extract exposure. We conclude that, as MSS induces a clear type IV hypersensitivity lung response, it has the potential to be harmful to workers frequently exposed to this methanogen, and that preventive measures should be taken to avoid chronic hypersensitivity disease development in workers.

Recommendations for a Clinical Decision Support System for Work-Related Asthma in Primary Care Settings

OBJECTIVE

The aim of this study was to describe a recommended clinical decision support (CDS) approach for work-related asthma for incorporation in electronic health records (EHRs) for primary care health care providers.

METHODS

Subject matter experts convened by the American Thoracic Society reviewed available guidelines and published literature to develop specific recommendations.

RESULTS

It is important to recognize possible work-related asthma among persons with new-onset or worsening asthma. The work group recommends incorporating three simple questions about temporal relations between asthma symptoms and work in EHR systems and identified specific clinical conditions to trigger this intervention. Patients with positive responses to the three questions should have the asthma diagnosis documented and have further evaluation, education, and possible referral.

CONCLUSION

An effective CDS system for improving recognition of work-related asthma may help reduce morbidity and mortality of asthma in adults.

Occupational asthma: diagnostic challenges and management dilemmas

PURPOSE OF REVIEW

Work-related asthma encompasses both sensitizer-induced and irritant-induced occupational asthma as well as work-exacerbated asthma. This review summarizes current diagnostic and management strategies for occupational asthma.

RECENT FINDINGS

Occupational asthma is the most common occupational lung disease in the industrialized world. Over 400 agents have been described to cause occupational asthma. Specific inhalation challenge is often considered the reference method for diagnosis of occupational asthma but specific inhalation challenge as well as other diagnostic tests all generate false positive or false negative results. Definitive avoidance of the inciting agent is the preferred strategy for sensitizer-induced occupational asthma and reduction of exposure is the next best step. Immunotherapy is not currently well established and can cause systemic reactions.

SUMMARY

An accurate diagnosis made in a timely fashion can positively impact the health and socioeconomic burden associated with occupational asthma. Newer diagnostic tools are promising, but much work needs to be done to standardize and validate these testing methods. Primary, secondary, and tertiary prevention strategies are crucial for effective management of sensitizer-induced occupational asthma.

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.