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Patients & Consumers Online Tools Find an Allergist / Immunologist Pollen Counts Diseases 101 Drug Guide Featured Resources » AAAAI Tips Brochures Topic of the Month New Research Information Request Form Donate Now En Español Just for Kids Seniors Contact Us Search by Condition (A-Z) Request a Speaker Smoke Free Homes Referral Guidelines Other Resources En Español Just for Kids Seniors		Topic of the Month: January 2006: Show occupational asthma who's boss In this Topic of the Month, you will learn: Symptoms of occupational asthma Who is at risk Causes of occupational asthma How to prevent occupational asthma Links to other resources Occupational-induced asthma is the most prevalent work-related disease in developed countries. It is estimated that up to 15% of asthma cases in adults may have job-related factors, and it accounts for approximately 24.5 million missed work days for adults annually in the United States. Occupational asthma is defined as a lung disorder caused by inhaling fumes, gases, dust or other potentially harmful substances while "on the job." What are the signs of occupational asthma? Symptoms of occupational asthma include: Wheezing Shortness of breath Chest tightness Difficulty exercising Cough Runny nose Nasal congestion Eye irritation These symptoms of occupational asthma may develop for the first time in a previously healthy worker, childhood asthma that had previously cleared may recur, or pre-existing asthma may be aggravated by exposures within the work place. The cause of symptoms may be allergic or non-allergic in nature, and the disease may last for a lengthy period in workers, even if they are no longer exposed to the agents that caused their symptoms. Commonly, symptoms worsen through the work week, improve on the weekend and recur when the worker returns to the job. Early recognition and control of triggers are important in occupational-induced asthma because the longer people are exposed to the triggers, the less likely it is that they will be able to completely overcome their asthma symptoms. If you experience any of these symptoms, see an allergist/immunologist for an evaluation. Who is at risk? Workers who smoke are at a greater risk for developing asthma following occupational exposures. The length of occupational exposure that triggers asthma varies, and can range from months to years before symptoms occur. Occasionally, an accident at work involving high exposure to irritating fumes or dusts may cause asthma within 24 hours. The incidence of occupational asthma varies within individual industries. For example, in the detergent industry, inhalation of a particular enzyme used to produce washing powders has led to the development of respiratory symptoms in approximately 25% of exposed employees. Approximately 5% of people working with laboratory animals or with powdered natural rubber latex gloves have developed occupational asthma. Chemicals widely used in many industries, including spray painting, insulation installation, and in manufacturing plastics, rubber and foam, can cause asthma in up to 10% of exposed workers. What causes occupational asthma? Occupational asthma may be caused by one of three mechanisms. These include: Direct irritant effects - Irritants that provoke occupational asthma include hydrochloric acid, sulfur dioxide or ammonia, which is found in the petroleum or chemical industries. Workers exposed to these substances will frequently begin wheezing and experiencing other asthma symptoms immediately after exposure to the irritant substance. This is an irritant reaction rather than an allergic reaction, since it does not involve the immune system. Workers who already have asthma or some other respiratory disorder are particularly affected by this type of exposure. Allergy (long-term exposure) - Allergies play a role in many cases of occupational asthma. This type of asthma generally develops only after long-term exposure (e.g., months or years) to a work-related substance. This is because the body's immune system needs time to develop allergic antibodies or other immune responses to a particular substance. For example, workers in the washing powder industry may develop an allergy to the enzymes of the bacteria Bacillus Subtilis, and food processing workers may develop an allergy and occupational asthma symptoms from exposure to castor beans, green coffee beans and papain. Allergic occupational asthma can occur in workers in the plastic, rubber or resin industries following repeated exposure to small chemical molecules in the air. Veterinarians, fishermen and animal handlers in laboratories can develop allergic reactions to animal proteins, and health care workers can develop asthma from breathing in powdered proteins from latex gloves or from mixing powdered medications. Pharmacologic mechanisms - Inhalation of some substances in aerosol form can directly lead to the accumulation of naturally occurring chemicals in the body, such as histamine or acetylcholine within the lung, which in turn lead to asthma. For example, insecticides, used in agricultural work, can cause a buildup of acetylcholine, which causes airway muscles to contract, thereby constricting airways. Prevention Once the cause of the occupational asthma is identified, exposure to these triggers should be reduced. For instance, a worker should be moved to another job within the plant. Employers should consider pre-screening potential employees with lung function tests, and then continue to test for symptoms once the worker has been hired, to ensure that he or she has not developed asthma. Work areas should be closely monitored so exposure to asthma-causing substances is kept at the lowest possible levels. Workers who are currently experiencing symptoms or who anticipate being exposed to an agent or agents that increases their risk of developing asthma should see an allergist/immunologist for an evaluation and proper diagnosis. In some cases, pre-treatment with specific medications to counteract the effects of workplace substances can be helpful. In other situations, complete avoidance may be necessary. Occasionally, workers with persistent asthma symptoms caused by substances in the workplace are incorrectly diagnosed as having bronchitis. If occupational asthma is not correctly diagnosed early, and the worker is not protected or removed from the exposure, permanent lung changes may occur and asthma symptoms may persist even without exposure. Reducing exposure to occupational asthma triggers, receiving appropriate treatment and practicing careful avoidance measures will improve your quality of life and help you feel symptom relief. In some cases, pre-treatment with specific medications to counteract the effects of workplace substances may be helpful. If you have questions about these treatments, be sure to ask your allergist/immunologist. Additional Resources Attaining Optimal Asthma Control: A Practice Parameter Allergic Conditions: Occupational Asthma How the Allergist/Immunologist Can Help: Consultation and Referral Guidelines Citing the Evidence Disease Group: Occupational Asthma Patient Update: Occupational Asthma Tips to Remember: Occupational Asthma Tips to Remember: Asthma Triggers and Management This topic was reviewed on 1/1/2006 by Stuart Friedman, MD, FAAAAI, Patients & Consumers Web Editor <back>
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