Occupational asthma reviewed in JACI

The workplace is a significant contributor to the burden of asthma. Although the majority of cases probably represent what is labeled work-exacerbated asthma, in a significant number of subjects, asthma is actually caused by 1 or more agents present in the workplace; this is occupational asthma.

Occupational asthma (OA) may account for 25% or more of de novo adult asthma.

Two types of occupational asthma are distinguished:

1. asthma with a latency period and acting through an apparently immunologic mechanism (high-molecular-weight agents and low-molecular-weight agents)

2. asthma without a latency period.

OA is caused by:

1. sensitizing agents
1-1. high-molecular-weight agent such as a protein from biological sources
1-2. low-molecular-weight reactive chemical such as an isocyanate

2. irritants, for example, the reactive airways dysfunction syndrome

Timely removal from exposure leads to the best prognosis in OA.

Work-related asthma (WRA) has 3 phenotypes:

1. sensitizer-induced occupational asthma (OA) caused by high-molecular-weight (HMW) proteins or low-molecular-weight (LMW) chemicals

2. irritant-induced asthma

3. work-exacerbated asthma

When evaluating patients for occupational asthma, sputum eosinophil counts at 7 and 24 hours after specific inhalation challenge have a greater sensitivity and positive predictive value than exhaled nitric oxide (eNO).

Work-related Asthma - AAAAI COLA video lecture by David Bernstein, MD, 07/2012:



References:
Occupational asthma: Current concepts in pathogenesis, diagnosis, and management. Mark S. Dykewicz. JACI, Volume 123, Issue 3, Pages 519-528 (March 2009)
Agents causing occupational asthma. Jean-Luc Malo et al. JACI, Volume 123, Issue 3, Pages 545-550 (March 2009)
Hairdressers Working in Hair Salons for Women are at increased risk for occupational asthma - prevalence is 9.5% http://goo.gl/fKPDq
Occupational sensitization to soy allergens in workers at a processing facility, high molecular weight allergens Gly m 5 and Gly m 6 may be the respiratory sensitizers http://goo.gl/6oXYd
Workforce occupational asthma in New Zealand. The highest risks: printer/baker/sawmill labourer/metal processing. Ann Occup Hyg. 2010.
The new guidelines for management of work-related asthma - ERJ 2012.
Image source: A factory worker in 1940s Fort Worth, Texas. Wikipedia, public domain.

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