Occupational asthma
Definition
Occupational asthma is alung disorder characterized by attacks of breathing difficulty, wheezing, prolonged exhalation, and cough. It iscaused by various agents found in the work place (see also bronchial asthma). These symptoms are usually due to spasms of the muscles lining the airways, which cause them to narrow excessively.
Alternative Names
Asthma - occupational exposure; Irritant-induced reactive airways disease
Causes, incidence, and risk factors
There are many agents in the workplace that can cause occupational asthma. Most commonly, these include protein molecules (wood dust, grain dust, animal dander, fungi) or other chemicals (especially di-isocyanates).
Though the actual rate of occurrence of occupational asthma is unknown, it is suspected to cause 2-20% of all cases of asthma in industrialized nations.
The following workers are at higher risk:
- Plastics workers
- Metal workers
- Bakers
- Millers
- Farmers
- Grain elevator workers
- Laboratory workers
- Woodworkers
- Drug manufacturers
- Detergent manufacturers
Symptoms
Symptoms usually occur shortly after exposure to the offending agent (the allergen) and often improve or disappear when the affected person leaves the workplace. The symptoms often worsen as the work week progresses and resolve on weekends or vacations. Some people may experience a delayed onset of symptoms, occurring as many as 12 hours after exposure to the allergen.
Signs and tests
The medicalhistory reveals a pattern of worsening symptoms associated with exposure to a specific agent or workplace environment. Making the association with the correct allergen can be very difficult.
Wheezing may be heard when listening to the chest with a stethoscope (auscultation).
Tests used in the diagnosis of occupational asthma may include the following:
-
Pulmonary function tests
- Measurement of the peak expiratory flow rate (peak-flow) before and after work
-
Chest X-ray
-
CBC
- Bronchial provocation test (test measuring reaction to the suspected allergen)
- Blood tests to reveal specific antibodies to suspected offending substances
Treatment
The objective of treatment is to limit exposure to the allergen and improve symptoms with bronchodilator therapy. In some instances, symptoms may persist despite removal of the source of exposure. Medications include hand-held inhalers or nebulizers to deliver bronchodilators. Other therapies for
bronchial asthma may be added in more severe cases.
Support Groups
The
stress related to illness can often be helped by joining a
support group where members share common experiences and problems. See
asthma and allergy - support group.
Expectations (prognosis)
The outcome for people with
asthma in general is good, but symptoms may persist for years after workplace exposure has been eliminated.
Complications
Complications include continued asthma symptoms after removal from the source of exposure.
Calling your health care provider
Call your health care provider if signs of occupational asthma develop.
Call your health care provider if you have occupational asthma and signs of respiratory infection, or if other new symptoms, develop.
Prevention
Once the cause is determined, avoid further exposure to it.
Review Date: 2/9/2006
Reviewed By: Frederic F. Little, M.D., Department of Allergy and Pulmonary/Critical Care Medicine, Boston University School of Medicine, Boston, MA. Review provided by VeriMed Healthcare Network.
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