It is widely believed (1-5), though still not fully established (6-11), that long-term cotton workers have an increased risk of respiratory impairment. If so, the problem has the characteristics of chronic obstructive pulmonary disease (COPD). Since this also occurs frequently in non-cotton workers, there is a need for diagnostic criteria to separate those cases of COPD, which may be related to the occupational exposure from those related to non-occupational factors. The history of exposure is obviously not a sufficient criterion. While average pulmonary function data for groups of long-term cotton workers tend to be somewhat lower than in comparable non-cotton workers, the values in any individual are not diagnostic (1,12). COPD can be caused by centrilobular emphysema (CLE), small airway disease (SAD), or both (13). When both are present, severity of CLE is the more important factor (14). Several autopsy studies have shown that neither prevalence nor severity of CLE is increased in cotton workers (15,16). However, one study did show excess SAD (15). CLE is associated with an increase in total lung volume while SAD does not have this effect (14,17,18). Criteria have been reported which permit diagnosis of emphysema by recognition of this volume increase in PA and lateral chest roentgenograms (19). These criteria and the sensitivity, specificity, and predictive value of the diagnosis will be described below. Cotton workers with COPD, but not meeting these criteria for emphysema, could thus be diagnosed as having SAD as the cause. Their disability could then be considered occupational. If emphysema were present, the occupational role in the COPD and disability would be doubtful.

The following report is a review and synthesis of published evidence which led the author to the above conclusions.