- • Typical symptoms of asthma, bronchodilator
reversible expiratory airflow limitation, and airway hyperresponsiveness.
- • Symptoms due to asthma rather than an alternative
- • Onset after entering the workplace.
- • Directly attributable to exposures in the workplace.
- • Specific immunoglobulin E (IgE) formation or positive
skin testing may only represent allergic sensitization.
- • Specific inhalational challenge may confirm the
Occupational asthma can be defined as new-onset asthma that is
directly attributable to one or more exposures in the workplace
and not to exposures encountered outside the workplace. A diagnosis
of occupational asthma can be made only after a diagnosis of asthma
has been established and after the onset of asthma has been clearly
related to the workplace. In addition to providing an environment
in which asthma may be induced, the workplace can provide a number
of exposures that exacerbate preexisting asthma and it is important
to distinguish between preexisting asthma that is exacerbated by
work and true occupational asthma.
Occupational asthma is the most prevalent occupational lung disease
in the industrialized world. Studies in Canada and the United Kingdom
indicate that occupational asthma accounts for up to approximately
50% of all cases of work-related lung disease, and a significant
proportion of patients who are disabled due to asthma relate their
disability to occupational asthma. United States Social Security
Administration disability data indicate that approximately 15–20% of
those individuals who are disabled due to asthma have occupational
Over 200 agents have been identified as causes of occupational
asthma. Isocyanates are commonly implicated, as are wood dusts,
anhydrides, dyes, metals, cereals, and latex. Common causes of occupational
asthma in at-risk workers are listed in Table 34–1.
Risk for occupational asthma appears to be directly related to the
type of workplace exposures that an individual sustains, although
traditional risk factors for asthma such as atopy are also considered
to be risk factors for the development of occupational asthma.
Selected Causes of Occupational Asthma in at-Risk Workers. |Favorite Table|Download (.pdf)
Selected Causes of Occupational Asthma in at-Risk Workers.
|Agent||Workers at Risk|
|Acid anhydrides||Epoxy resin, plastic workers|
|Complex amines||Painters, photographers|
|Diisocyanates||Plastic and varnish workers|
|Methacrylates||Health care workers, histologists|
|Proteases||Detergent industry workers|
|Chromium, nickel||Metal platers|
|Platinum salts||Platinum refiners|
|Latex||Health care workers|
|Western Red Cedar||Carpenters, sawmill operators|
The pathogenesis of occupational asthma is complex and multifactorial,
involving both environmental and host factors. The majority of patients
with occupational asthma develop the disease within the first 1–2
years of exposure, although there are differences in the time to
development of occupational asthma based on the molecular weight
of the inciting antigen.
Occupational asthma can be classified as one of two types: immunological
or nonimmunological (Table ...