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NIOSH Respiratory Diseases Research Program

Evidence Package for the National Academies' Review 2006-2007

4.2 Obstructive Airways Disease

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Two forms of fixed obstructive airways disease are considered in this section: COPD, which is characterized by chronic airflow limitation arising from airways disease and emphysema; and bronchiolitis obliterans, a disease causing fixed obstruction involving the distal airways and alveolae.

COPD is associated with chronic airways inflammation that can be caused, at least in part, by exposure to inhaled noxious particles, vapors, and gases. COPD is the fourth leading cause of death in the U.S.125 In 2003, 10.7 million U.S. adults were estimated to have COPD, although close to 24 million adults had evidence of impaired lung function, indicating under-diagnosis of COPD in the U.S.125 The cost to the nation of COPD was approximately $37.2 billion in 2004, including healthcare expenditures of $20.9 billion in direct costs, $7.4 billion in indirect morbidity costs, and $8.9 billion in indirect mortality costs.125 Although smoking accounts for the majority of cases of COPD, occupational factors associated with many industries have been estimated to account for an estimated 19 percent of all cases (and an estimated 31 percent among never smokers).126

Over the years, reports from expert panels have invoked the need to obtain more information on the COPD relationship to occupations and industries. In 1980, a National Heart, Lung, and Blood Institute task force stated that, “Epidemiologic investigations are needed to provide the foundation for respiratory disease prevention by identifying occupational lung diseases and establishing dose-response relationships.”127 A report by the Association of Schools of Public Health in 1986 recommended, “Efforts should be continued to identify occupations in which workers are likely to have a high incidence of occupational COPD.”128 Furthermore, a 1997 AOEC report of a workshop concluded that, further research was needed to examine longitudinal measures of lung function directed at COPD prevention.129

RDRP scientists have long been aware of the link between occupation and COPD, starting with the epidemiologic work on coal miners and subsequent epidemiological work with other occupational groups and industries. Later, RDRP was responsive to the calls for further research through expanding activities to include wider surveillance across different industries. More recently, resources have been enhanced in the area of worker monitoring methodology using lung function measurements.

Relative to COPD, recognition of bronchiolitis obliterans as a significant occupational problem is a much more recent development. In 2000, the Missouri Department of Health was informed by an occupational medicine physician that eight former workers of a single small popcorn plant in Missouri had fixed obstructive lung disease consistent with bronchiolitis obliterans. Individual symptom onsets ranged from 1993 through 2000, several months to several years after starting work at the plant. Four of these individuals had been placed on lung transplant waiting lists. At the time, there was nothing in the medical or scientific literature to suggest that microwave popcorn workers were at risk for this disease. Given the severity of the disease and the need to confirm its apparent occupational cause among workers at this plant, as well as to generate recommendations to effectively prevent further cases, the Department of Health formally requested assistance from RDRP (HETA # 2000-0401-2991 Gilster-Mary Lee Corp. Jasper, Missouri, A4-49).

RDRP’s intermediate goal is to prevent and reduce work-related COPD and bronchiolitis obliterans. Four objectives that arise from this are:

  • Establish the work-relatedness of COPD
  • Develop tools and identify at-risk workers in industries and occupations in order to assess the extent, severity, and burden of work-related COPD
  • Develop, test, and disseminate recommendations for COPD prevention in the workplace
  • Prevent and reduce flavorings-related bronchiolitis obliterans

These four objectives describe an organized program intended to identify conditions that lead to obstructive airways diseases, evaluate their extent, work-relatedness, and specific etiology, where possible, and to act towards their prevention. We set these objectives with the knowledge that obstructive airways disease can arise frequently from non-occupational causes, especially smoking, and that primary disease prevention of smoking-related COPD is beyond the scope of our work.

125. American Lung Assocation [2006]. Chronic Obstructive Pulmonary Disease (COPD) Fact Sheet. 
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126. Hnizdo E, Sullivan PA, Bang KM, Wagner G [2002]. Association between chronic obstructive pulmonary disease and employment by industry and occupation in the U.S. population: a study of data from the Third National Health and Nutrition Examination Survey. Am J Epidemiol 156:738-746.

127. National Heart, Lung, and Blood Institute, Division of Lung Diseases [1986]. A report of Task force on epidemiolgy of respiratory diseases -state of knowledge - problems – needs. Washington, DC: U.S. Department of Health and Human Services 1-244.

128. NIOSH [1986]. Proposed National Strategies for the Prevention of Leading Work-Related Diseases and Injuries. Washington, DC. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) 1-12.

129. NIOSH. Airways disease and occupational exposure to particles not otherwise classified: a report of a NIOSH-sponsored workshop. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) draft report, unpublished.