Evaluation of epidemiologic approaches to the study of lung disease related to cotton dust exposures.

Epidemiologic approaches to improved understanding of the several reactions observed in cotton processors began in 1955 with Schilling's symptom classification of Monday-morning chest tightness. To date, epidemiologic studies have identified the importance of increasing years of exposure to the development of both specific and nonspecific chronic respiratory symptoms and of acute change in pulmonary function. The few longitudinal studies suggest similar associations with accelerated loss of pulmonary function. Respirable dust level has been associated, cross-sectionally, with symptoms and with acute function change, but studies have not yet been made with sufficient prospective collection of both exposure and health effects data to estimate accurately the association of continued exposure with accelerated loss of lung function or development of disability. Furthermore, there has been very limited field study comparing exposure to respirable dust distinguished from exposure to endotoxin. With careful attention to features of study design and analytic plans, investigators can take advantage of simple technology to examine the fate of the acute responder, the potential for recovery if exposure is reduced or ceased, and the long-term dose response relationship between different cumulative measures of exposure and chronic disease.