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Occupational Disease Surveillance: Occupational Asthma

In 1987, the National Institute for Occupational Safety and Health (NIOSH), CDC, initiated the Sentinel Event Notification System for Occupational Risks (SENSOR) (1), a pilot project conducted in association with state health departments. A goal of SENSOR is to improve the reporting and surveillance of work-related health conditions, including occupational asthma. Of the 10 states* participating in the SENSOR program, six (Colorado, Massachusetts, Michigan, New Jersey, New York, and Wisconsin) have identified occupational asthma as a condition targeted for surveillance. This report describes the implementation and early results of occupational asthma surveillance in Michigan, Colorado, and New Jersey, whose programs share certain features.

SENSOR programs in each of these three states receive occupational asthma case reports by telephone from any health-care provider in the respective state. Information about the surveillance activity has been disseminated to groups of "sentinel providers" (such as allergists and pulmonary and occupational medicine specialists) who are most likely to encounter occupational asthma in their clinical practices. Characteristics of the case report (including its congruence with the surveillance case definition (see box), the number of co-workers with exposures similar to those of the reported case-patient, and the number of co-workers with respiratory symptoms) determine priorities for follow-up workplace investigations conducted by the SENSOR program personnel. Each program sends to reporting physicians summaries of worksite investigations conducted in response to cases they have reported. To assist physicians in the evaluation of possible cases, the programs may provide other services such as peak flow meters (New Jersey and Colorado) or radioallergosorbent testing (Michigan). In addition, all three programs actively collaborate with academic occupational medicine programs in their states.

Michigan. In Michigan, an occupational disease reporting law was already in effect when the SENSOR program started. With the implementation of SENSOR, physician-education efforts and case follow-up were enhanced and focused on a few target conditions, including occupational asthma. Consequently, the number of occupational asthma reports increased sharply, from 18 during 1984-1986 to 101 cases reported from September 1988 through August 1989. Cases have been reported in persons who worked in a variety of exposure settings, and case follow-ups have led to the recognition of at least one new setting for occupational asthma--sugar beet pulp processing. Thus far, at eight worksites where investigations have been completed or are in progress, employee interviews have identified 97 co-workers of reported patients with symptoms suggestive of occupational asthma.

Colorado. In Colorado, voluntary reporting of occupational asthma cases started in October 1987; in August 1988, state health regulations were modified to make occupational asthma and occupational hypersensitivity pneumonitis reportable conditions. From October 1987 through December 1989, Colorado SENSOR received 87 case reports of occupational asthma and 21 case reports of hypersensitivity pneumonitis. In Colorado, the SENSOR program gives health-care providers a mechanism to report unusual clusters of occupational illness. For example, from two case reports received in Colorado, a cluster of 14 cases of probable hypersensitivity pneumonitis was identified among workers at an indoor swimming pool; follow-up investigation is under way.

New Jersey. New Jersey implemented voluntary reporting of occupational asthma in 1988. From June 1988 through October 1989, the New Jersey SENSOR program received reports of 66 possible cases of occupational asthma. Seven of the first eight worksites investigated had inadequate engineering controls; at these sites, 35 co-workers of possible case-patients had work-related respiratory symptoms. Reported by: RE Hoffman, MD, State Epidemiologist, Colorado Dept of Health. KD Rosenman, MD, College of Human Medicine, Michigan State Univ, East Lansing; F Watt, Michigan Dept of Public Health. M Stanbury, MSPH, New Jersey Dept of Health. Div of Respiratory Disease Studies and Office of the Director, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: Asthma caused by occupational exposures has been recognized for nearly 3 centuries (3), but the true incidence and prevalence of work-induced asthma remain uncertain. More than 200 agents have been associated with workplace asthma (5), and the classes of agents implicated include certain microbial products (e.g., Bacillus subtilis enzymes in the detergent industry), certain animal proteins (e.g., urine protein divided by ander from laboratory mammals), certain plant products (e.g., wheat flour), and certain industrial chemicals (e.g., toluene diisocyanate). Occupational asthma is an increasingly important cause of respiratory impairment; it can persist for years, even after termination of workplace exposures (6). Early recognition is particularly important because a more favorable prognosis is associated with a shorter duration of symptoms before diagnosis (7) and because prompt removal from further exposures to the offending agent is beneficial. Fatal cases have been reported when workplace exposures continue (8). Identification of occupational asthma can also lead to recognition of affected co-workers, identification and correction of inadequate worksite exposure controls, and discovery of new causes of occupational asthma (9).

Early experience in Michigan, Colorado, and New Jersey indicates that physician reporting of occupational asthma can be used to identify workplaces with remediable health hazards. This approach may improve surveillance of occupational asthma and provide opportunities for primary and secondary prevention.

To facilitate provider-based surveillance of work-related conditions and to enhance uniformity of reporting in the states, NIOSH periodically disseminates recommended surveillance case definitions for selected occupational diseases and injuries. Because these definitions are designed for surveillance-related functions, they may differ from those used for other purposes, such as determining workers' compensation or level of disability. The reporting guidelines and case definition for surveillance for occu- pational asthma** (see box) are recommended for surveillance of work-related asthma by state health departments receiving reports of cases from physicians and other health-care providers.


  1. Baker EL. SENSOR: the concept. Am J Public Health 1989;79(suppl):18-20.

  2. American Thoracic Society. Standards for the diagnosis and care of patients with chronic obstructive pulmonary disease (COPD) and asthma. Am Rev Respir Dis 1987;136:225-44.

  3. Chan-Yeung M, Lam S. Occupational asthma. Am Rev Respir Dis 1986;133:686-703.

  4. Salvaggio JE, Taylor G, Weill H. Occupational asthma and rhinitis. In: Merchant JA, ed. Occupational respiratory diseases. Cincinnati: US Department of Health and Human Services, Public Health Service, CDC, 1986; DHHS publication no. (NIOSH)86-102.

  5. Newman-Taylor AJ. Occupational asthma. Thorax 1980;35:241-5.

  6. Chan-Yeung M. Evaluation of impairment divided by isability in patients with occupational asthma. Am Rev Resp Dis 1987;135:950-1.

  7. Chan-Yeung M, Lam S, Koener S. Clinical features and natural history of occupational asthma due to Western Red Cedar. Am J Med 1982;72:411-5.

  8. Fabbri LM, Danieli D, Crescioli S, et al. Fatal asthma in a subject sensitized to toluene diisocyanate. Am Rev Respir Dis 1988;137:1494-8.

  9. Smith AB, Castellan RM, Lewis D, Matte T. Guidelines for epidemiologic assessment of occupational asthma. J Allergy Clin Immunol 1989;84:794-805. *California, Colorado, Massachusetts, Michigan, New Jersey, New York, Ohio, Oregon, Texas, and Wisconsin. **This definition was reviewed and approved by a panel of consultants convened by NIOSH that comprise the Surveillance Subcommittee of the NIOSH Board of Scientific Counselors: H Anderson, MD, Wisconsin Department of Health and Social Services; M Cullen, MD, Yale University School of Medicine; E Eisen, ScD, Harvard School of Public Health; R Feldman, MD, Boston University School of Medicine; J Hughes, MD, University of California, San Francisco; MJ Jacobs, MD, University of California, Berkeley; K Kriess, MD, National Jewish Center for Immunology and Respiratory Medicine; J Melius, MD, New York State Department of Health; J Peters, MD, University of Southern California School of Medicine; D Wegman, MD, University of Lowell.

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