Asma Ocupacional

Occupational Asthma

REVIEW ARTICLE

Occupational Asthma

S.M. Tarlo and C. Lemiere

Asthma is common in the general population, including among those in the workforce. Work exposures can cause or exacerbate asthma and can also be associated with asthma variants (e.g., eosinophilic bronchitis and aluminum potroom asthma) as well as symptoms that mimic asthma (e.g., the irritable larynx syndrome). In addition, even non–work-related asthma can affect the ability to work.

Clinical Pearls

What is sensitizer-induced asthma?

Occupational asthma can be caused by a specific workplace sensitizer, defined as an agent that induces asthma through a mechanism that is associated with a specific immunologic response. Occupational sensitizers are commonly high-molecular-weight agents (>10 kD, usually a protein or glycopeptide) that can cause production of specific IgE antibodies and typical allergic responses. Once a person is sensitized, very low exposures can induce asthma, which is often associated with rhinoconjunctivitis. It would appear that almost any protein that becomes airborne and inhaled might be a potential cause of occupational asthma. Low-molecular-weight occupational chemicals can also cause sensitization and, subsequently, asthma. A few have been associated with the production of specific IgE antibodies, such as complex platinum salts used in platinum refineries or the manufacture of catalysts. However, most low-molecular-weight chemical sensitizers induce asthma through mechanisms that are poorly understood, despite a phenotype suggesting sensitization. Diisocyanates are important sensitizers that are used in the production of rigid or flexible polyurethane foam; they are also used as hardeners in urethane spray paints and adhesives. Diisocyanates have been the most common cause of occupational asthma in many industrialized areas. Most chemical sensitizers have highly reactive side chains.

Table 1. Common Causative Agents in Sensitizer-Induced Occupational Asthma.

What is irritant-induced occupational asthma?

Irritant-induced occupational asthma is a term used to describe occupational asthma that occurs from exposure to agents considered to be airway irritants, in the absence of sensitization. In 1985, diagnostic criteria for the reactive airways dysfunction syndrome, a severe form of irritant-induced asthma, were introduced. Subsequent reports have modified the initial, stringent diagnostic criteria for this syndrome and use the term “irritant-induced asthma” to include cases with induced airway symptoms and an onset after one or more high-level exposures. This category also includes cases with less immediate responses

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