© 2007 American Thoracic Society doi: 10.1164/rccm.200707-1003ED
Chronic Obstructive Pulmonary DiseaseDoes Occupation Matter?Göteborg University Göteborg, Sweden
University of California, San Francisco In the current issue of the Journal (pp. 994–1000), Harber and colleagues present a longitudinal analysis of participants in the Lung Health Study with chronic obstructive pulmonary disease (COPD), which showed that ongoing occupational exposure to fumes was associated with an increased rate of decline of FEV1 (1). The increased decline was restricted to men. These results underscore that, in addition to causing COPD, occupational exposures to inhaled irritants can cause an accelerated rate of decline in FEV1 in patients who already have COPD. The importance of occupational exposures as a risk factor for COPD was observed in the 1950s by Fletcher and other pulmonary epidemiologists (2). Unfortunately, in the ensuing several decades, the impact of smoking as a risk factor for COPD was perceived as so overwhelming that interest in other risk factors faded away. During the 1970s and 1980s, however, several general population studies and occupational cohort studies were published in which occupational exposure to gases, dusts, and fumes was demonstrated to be a risk factor for COPD and/or accelerated decline of FEV1 (3, 4). In 2002, this work was summarized in an official American Thoracic Society (ATS) statement, which concluded that the attributable fraction of COPD due to occupational exposures was 15 to 20% (5). The data reviewed suggest that occupational exposures add an extra decline in FEV1 of 7 to 8 ml/year. Since the ATS document was published, at least four additional studies have been published that support occupational exposures as an important risk factor for COPD (6–9). In a cross-sectional study of the United States' general population (Third National Health and Nutrition Examination Survey), significantly increased risks for COPD (defined as FEV1/FVC < 70% and FEV1 < 80%) were found among workers in a number of industries, including plastic, textile, rubber and leather manufacturing; food products manufacturing; transportation and trucking; automotive repair; agriculture; construction; office services (e.g., professional cleaning); personal services (e.g., beauty care); the armed forces; and health care (6). The attributable fraction for occupation was estimated to be 19% (31% among never-smokers). In another population-based study from the United States, the attributable fraction for occupational exposure to gas, dust, and fumes was again estimated at 20% (7). In a longitudinal study from Sweden, mortality data were investigated for 300,000 construction workers, and those exposed to fumes and mineral dust had significantly higher risk of death due to COPD (8). In an Australian cross-sectional study, occupational exposure to biological dust was associated with increased risk of COPD (different definitions were used), with risks being higher in women than in men (9). In the study by Harber and colleagues, men with COPD who had continuing occupational exposure to fumes had an accelerated rate of loss of ventilatory function. After adjusting for baseline FEV1, age, bronchial hyperresponsiveness, and yearly smoking status, the annual additional decline was 0.25% of predicted, roughly corresponding to about 10 ml/year. At this rate, after 30 years of fumy work, the cumulative loss would be 300 ml or about 7.5% of predicted FEV1, a loss that could be of clinical relevance. This estimated loss is based on the mean effect observed in the Lung Health Study population. For some individuals, the amount of ventilatory function lost would be much greater. The main lesson for the clinician from the work of Harber and colleagues is that when caring for patients with COPD of working age, one must consider ongoing occupational exposures to inhaled irritants. A critical question to ask these patients is whether they are working in jobs with exposures to fumes, such as those in agriculture, metal fabrication, construction, professional cleaning, and beauty care. Should a patient with COPD remain in his/her usual job if it involves exposures to gases, dusts, or fumes? We lack adequate data to fully answer this question. The results of one study showed that subjects with COPD and ongoing occupational exposure to gases, dusts, and/or fumes have increased disability and health care utilization compared with unexposed subjects with COPD (10). To remove someone from his/her job can have devastating psychological, social, economic, and physical health consequences. Reduction of exposure to inhaled irritants through engineering controls (e.g., process enclosure or local exhaust ventilation) or respiratory protective equipment (e.g., masks or respirators) is preferable. Our judgment based on clinical experience is that workers with COPD as far as possible should remain at their workplaces. However, such a decision must be combined with efforts to reduce exposures to irritants and monitor clinical status over time to ensure that disease management is not being compromised. FOOTNOTES Conflict of Interest Statement: Neither author has a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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