Health surveillance for occupational asthma

Identification of true chemical respiratory allergens: Current status, limitations and recommendations

Asthma in the workplace is an important occupational health issue. It comprises various subtypes: occupational asthma (OA; both allergic asthma and irritant-induced asthma) and work-exacerbated asthma (WEA). Current regulatory paradigms for the management of OA are not fit for purpose. There is therefore an important unmet need, for the purposes of both effective human health protection and appropriate and proportionate regulation, that sub-types of work-related asthma can be accurately identified and classified, and that chemical respiratory allergens that drive allergic asthma can be differentiated according to potency. In this article presently available strategies for the diagnosis and characterisation of asthma in the workplace are described and critically evaluated. These include human health studies, clinical investigations and experimental approaches (structure-activity relationships, assessments of chemical reactivity, experimental animal studies and in vitro methods). Each of these approaches has limitations with respect to providing a clear discrimination between OA and WEA, and between allergen-induced and irritant-induced asthma. Against this background the needs for improved characterisation of work-related asthma, in the context of more appropriate regulation is discussed.

[Occupational obstructive airway diseases: How can early diagnosis be made to avoid chronic courses?]

Since abolishing the obligation to terminate the harmful professional activity from January 1st, 2021 onwards for some occupational diseases including obstructive respiratory diseases in Germany, the recognition of occupational diseases coded under 4301, 4302 and 1315 according the Occupational Diseases Ordinance has increased significantly. By the time these diseasese are recognized, they are usually already at an advanced stage. Therefore, early detection will play a greater role in the future, as the statutory accident insurance can offer individual preventive measures in order to minimize the consequences of illness and thus also the socio-economic burden. However, precursors of such obstructive airway diseases are often overlooked. For optimizing early detection, the statutory accident insurance worked out an early notification procedure for the respiratory tract - comparable to the already well-established dermatological procedure. "Early cases" from the pilot regions can be reported there; to qualify for being reported as early cases, patients must persue insured professional activity with potential effects on the respiratory tract and suffer from a disease of the upper or lower respiratory tract according to the ICD-10 code (e.g. J31.0 chronic rhinitis).

Impact of occupational asthma on health and employment status: a long-term follow-up study

OBJECTIVES

The aim of this study was to assess the predictors of a favourable prognosis of occupational asthma (OA) and the employment status of patients with OA at least 2 years after diagnosis.

METHODS

We collected data from 204 patients who had a diagnosis of OA confirmed by a positive specific inhalation challenge. We defined OA remission as meeting the following three criteria: no asthma symptoms, no antiasthma therapy for the last year and having normal lung function at the end of follow-up. A logistic regression analysis was performed to estimate the effects of the covariates.

RESULTS

At 10.6±7.8-year follow-up, 60 of 204 possible patients participated in the study, and among them 17 showed OA remission. When compared with the 43 patients with persistent OA, these patients exhibited at diagnosis younger age (p=0.0039), shorter duration of symptomatic exposure (p=0.0512), better lung function expressed by higher forced vital capacity (FVC%) predicted (p=0.0164), forced expiratory volume in 1 s (FEV₁) % predicted (p=0.0066) and FEV₁/FVC% (p=0.0132), and less bronchial hyper-responsiveness (p=0.0118). Nevertheless, in the multivariable model, no variables were significantly associated with OA remission. At follow-up, three individuals have retired; among the remaining 57 workers, 91.2% were still employed and 43.8% of them had continued working in the same factory after ceasing exposure to the causative agent.

CONCLUSIONS

This monocentric study did not identify a strong predictor of OA remission, but documented a high employment rate and a good job preservation over a long timeframe after diagnosis of OA mainly induced by low molecular weight agents.

Prevention of baker's asthma

PURPOSE OF REVIEW

Baker's allergy and asthma continue to represent an important contributor of occupational asthma globally. This review identified recent studies related to the prevention of baker's allergy and asthma.

RECENT FINDINGS

Studies with respect to regulatory exposure standards, workplace control measures aimed at reduction of flour dust exposures, surveillance programmes (exposure monitoring, medical surveillance) and workplace information, education and training programmes were identified.

SUMMARY

Detailed knowledge on risk factors and detection methods to assess exposure and early identification of high-risk workers exist, but workplace control measures remain sub-optimal because they are rarely multifaceted. This is compounded by the lack of health-based exposure standards globally. Exposure level monitoring and medical surveillance are integral to assessing effectiveness of preventive strategies. Triage systems for optimizing the efficiency of medical surveillance programmes show promise, but need replication in different contexts. Future studies need to focus on evaluating the relevance and quantification of peak exposures in increasing risk; developing standardized respiratory questionnaires for medical surveillance; and further exploration of serial fractional exhaled nitric oxide (FeNO) measurements as an adjunct to allergic sensitization for the early identification of baker's asthma and assessing the long-term impact of interventions.

Update on exhaled breath condensate analyses in occupational disease

PURPOSE OF REVIEW

The present work represents an update of the review published in this journal by Corradi et al., regarding the use of exhaled breath condensate (EBC) to investigate occupational lung diseases.

RECENT FINDINGS

The relevant literature was searched in the Medline database, assessed through PubMed using key terms such as 'breath AND condensate AND occupational'. Eleven pertinent publications were retrieved between January 2018 and October 2019. One article only was related to occupational allergy, and the conclusion is that EBC hydrogen peroxide is not an useful marker in laboratory animal allergy. The biomarkers of exposure most often assessed with EBC are metals. However, it is controversial whether this approach has any advantage over the conventional environmental monitoring. The biomarkers of effect studied by the majority of investigations were those related to oxidative stress. They appear consistently elevated upon occupational exposures to various agents, including welding fumes, crystalline silica, nanomaterials and chemicals.

SUMMARY

Although EBC represent a suitable tool to sample airway lining fluid in a noninvasive manner, it remains a niche approach to the investigation of occupational diseases. The confounding influence of EBC dilution should be better addressed in the expression of the results.

Update on the Management of Occupational Asthma and Work-Exacerbated Asthma

Work-related asthma is the most common occupational lung disease encountered in clinical practice. In adult asthmatics, work-relatedness can account for 15%-33% of cases, but delays in diagnosis remain common and lead to worse outcomes. Accurate diagnosis of asthma is the first step to managing occupational asthma, which can be sensitizer-induced or irritant-induced asthma. While latency has traditionally been recognized as a hallmark of sensitizer-induced asthma and rapid-onset a defining feature of irritant-induced asthma (as in Reactive Airway Dysfunction Syndrome), there is epidemiological evidence for irritant-induced asthma with latency from chronic moderate exposure. Diagnostic testing while the patient is still in the workplace significantly improves sensitivity. While specific inhalational challenges remain the gold-standard for the diagnosis of occupational asthma, they are not available outside of specialized centers. Commonly available tests including bronchoprovocation challenges and peak flow monitoring are important tools for practicing clinicians. Management of sensitizer-induced occupational asthma is notable for the central importance of removal from the causative agent: ideally, removal of the culprit agent; but if not feasible, this may require changes in the work process or ultimately, removal of the worker from the workplace. While workers' compensation programs may reduce income loss, these are not universal and there can be significant socio-economic impact from work-related asthma. Primary prevention remains the preferred method of reducing the burden of occupational asthma, which may include modification to work processes, better worker education and substitution of sensitizing agents from the workplace with safer compounds.