Reviews and feature articleOccupational asthma: Current concepts in pathogenesis, diagnosis, and management
Section snippets
Sensitizer-induced OA
Occupational asthma from sensitizers typically presents with a latent period of exposure, followed by the onset of clinical disease. After sensitization, airway reactions develop from levels of exposure to the sensitizing agent that were tolerated before sensitization. Although the mechanism causing OA from some sensitizers has been demonstrated to have an immunologic basis (IgE antibody–mediated or otherwise), no immunologic mechanism has been demonstrated for some suspected sensitizers (eg,
OA from HMW sensitizers
High-molecular-weight agents such as proteins and glycoproteins (Table I) characteristically act as complete antigens that cause sensitizer OA through a classic IgE antibody–mediated mechanism. The allergens responsible for OA from some HMW agents have been well characterized—for example, in detergent workers who develop asthma from exposure to Bacillus subtilis enzymes, or in egg processing workers. However, identifying the actual protein sensitizers in complex plant or animal materials can be
Epidemiology and risk factors
Other than the intrinsic physicochemical and immunogenic properties of agents, the most important risk for developing OA is the level and duration of exposure to agents capable of causing OA.32 Although tobacco smoking not been found to be consistently associated with increased risk for OA,33 reports of an association between smoking and OA from certain agents suggest that the absence or presence of such an association may vary depending on the agent. Atopy is a risk factor for OA from HMW
Diagnosis
Although the diagnosis and management of OA can be complex, published guidelines provide a logical, structured approach (Fig 2). In summary, it is first necessary to establish that a patient has asthma, then that OA is present. A combined approach of using history and objective testing is important for increasing the reliability of the assessment of possible OA.
Differential diagnosis
There are a number of diagnoses that may mimic OA, including vocal cord dysfunction, upper respiratory tract irritation, hypersensitivity pneumonitis, rhinosinusitis, and psychogenic factors. Byssinosis, popcorn workers' disease, and flock workers' disease are examples of other occupational lung diseases that may also mimic OA, with the last 2 capable of causing bronchiolitis obliterans. In addition, eosinophilic bronchitis may present with a nonproductive cough, associated with increased
Management
In OA from sensitizers, complete avoidance of the sensitizer is best from a medical perspective, because better outcomes occur in patients who leave work early in the course of OA versus those who remain at work49 (Fig 2). Even when additional medications including anti-inflammatory agents are used, continued exposure after diagnosis is associated with worsening symptoms, lung function, and overall outcomes.2, 64 When patients are unable or unwilling to change jobs, an alternative approach is
Prevention and surveillance
A diagnosis of OA in an individual worker showed always be viewed as a potential sentinel health event that may merit workplace evaluation to identify and prevent OA in other workers.2
Prevention of OA is considered to have 3 components2, 3:
- 1.
Primary prevention of new OA is directed at reducing workplace exposure to potential causal agents. This may involve reduction of exposure by complete elimination of a causal agent (eg, through substitution), process modification, respirator use, or
Prognosis and outcomes
The prognosis of occupational asthma depends primarily on cessation of exposure to the offending agent, the duration of exposure to sensitizers, and the severity of asthma when diagnosed.2, 7 Timely removal of workers from exposure to a sensitizer causing OA is generally associated with favorable outcomes. Prolonged follow-up may be required to ascertain outcomes in any individual, particularly in OA from sensitizers in which there may be continued improvement of lung function for 2 years or
Clinical implications and future directions
Although great strides have been made in understanding OA, there remain many unanswered questions. There are important needs to understand better the pathogenesis of OA from LMW sensitizers, determine circumstances under which irritant asthma might occur when criteria are not met for the long-recognized condition of RADS, and develop improved diagnostic tests to assess sensitization to LMW agents. With the introduction of sputum analysis as a diagnostic tool for OA from suspected sensitizers,
References (73)
- et al.
Diagnosis and management of work-related asthma: American College of Chest Physicians consensus statement
Chest
(2008) Occupational asthma
J Allergy Clin Immunol
(2008)- et al.
Reactive airways dysfunction syndrome (RADS): persistent asthma syndrome after high level irritant exposures
Chest
(1985) - et al.
Wheat and maize thioredoxins: a novel cross-reactive cereal allergen family related to baker's asthma
J Allergy Clin Immunol
(2006) - et al.
Wheat lipid transfer protein is a major allergen associated with baker's asthma
J Allergy Clin Immunol
(2007) - et al.
Changes in sputum cell counts after exposure to occupational agents: what do they mean?
J Allergy Clin Immunol
(2001) - et al.
Immunology and immunopathology of trimellitic anhydride pulmonary reactions
J Allergy Clin Immunol
(1982) - et al.
Changes in specific IgE and IgG and monocyte chemoattractant protein-1 in workers with occupational asthma caused by diisocyanates and removed from exposure
J Allergy Clin Immunol
(2006) - et al.
Biophysical determinants of toluene diisocyanate antigenicity associated with exposure and asthma
J Allergy Clin Immunol
(2006) - et al.
Is occupational asthma to diisocyanates a non-IgE-mediated disease?
J Allergy Clin Immunol
(2006)
A novel mouse model of diisocyanate induced asthma showing allergic-type inflammation in the lung after inhaled antigen challenge
J Allergy Clin Immunol
Airway inflammation and functional changes after exposure to different concentrations of isocyanates
J Allergy Clin Immunol
Characterization of the severe asthma phenotype by the National Heart, Lung, and Blood Institute's Severe Asthma Research Program
J Allergy Clin Immunol
Risk of asthma among Finnish patients with occupational rhinitis
Chest
HLA associations with occupational sensitization to rat lipocalin allergens: a model for other animal allergies?
J Allergy Clin Immunol
T-cell receptor V beta gene segment expression in diisocyanate-induced occupational asthma
J Allergy Clin Immunol
From asthma in the workplace to occupational asthma
Lancet
Exposure to substances in the workplace and new-onset asthma: an international prospective population-based study (ECRHS-II)
Lancet
Natural history of occupational asthma: relevance of type of agent and other factors in the rate of development of symptoms in affected subjects
J Allergy Clin Immunol
Material safety data sheets: are they reliable in identifying human. hazards?
J Allergy Clin Immunol
Absence of hyperresponsiveness to methacholine in a worker with methylene diphenyl diisocyanate (MDI)-induced asthma
Chest
Occupational asthma in symptomatic workers exposed to natural rubber latex: evaluation of diagnostic procedures
J Allergy Clin Immunol
Clinical and socioeconomic features of subjects with red cedar asthma: a follow-up study
Chest
Effect of respiratory protective devices on development of antibody and occupational asthma to an acid anhydride
Chest
Persistence of toluene diisocyanate-induced asthma despite negligible workplace exposures
Chest
Primary prevention of natural rubber latex allergy in the German health care system through education and intervention
J Allergy Clin Immunol
Environmental and Occupational Health Assembly, American Thoracic Society. American Thoracic Society Statement: occupational contribution to the burden of airway disease
Am J Respir Crit Care Med
Occupational asthma
Curr Opin Pulm Med
New insights into occupational asthma
Curr Opin Allergy Clin Immunol
Occupational asthma
Am J Respir Crit Care Med
Evidence based guidelines for the prevention, identification, and management of occupational asthma
Occup Environ Med
Pulmonary disease in rescue workers at the World Trade Center site
Curr Opin Pulm Med
Adult-onset asthma and wheeze among irritant-exposed bleachery workers
Am J Ind Med
Irritant-induced asthma: clinical and functional aspects
J Asthma
Molecular and immunological characterization of a wheat serine proteinase inhibitor as a novel allergen in baker's asthma
J Immunol
Occupational hypersensitivity to metal salts, including platinum, in the secondary industry
Allergy
Cited by (119)
Questionnaire for diagnosing asthma-COPD overlap in COPD: Development of ACO screening questionnaire (ACO-Q)
2023, Allergology InternationalChemical- and Drug-Induced Asthma
2018, Comprehensive Toxicology: Third EditionAn Investigation of Latex Sensitivity and Respiratory Complaints in Workers in a Rubber-Based Material Manufacturing Industry
2023, Journal of Occupational and Environmental MedicineEvaluation of Oxidative Stress Parameters and Genotoxic Effects in Patients With Work-Related Asthma and Silicosis
2023, Journal of Occupational and Environmental Medicine
Series editors: Donald Y. M. Leung, MD, PhD, and Dennis K. Ledford, MD