Rationale: The study was conducted to determine early pulmonary responses to cotton dust exposure, including respiratory symptoms and pulmonary function, in previously-unexposed workers. Methods: The cohort was comprised of 225 newly hired workers at three cotton textile mills in Shanghai, China. Workers were young (average age 18 years), non-smoking, previously unexposed to industrial dust, and healthy. Their respiratory health status was followed up at three months and at one year after working, in addition to the pre-employment examination. Results: After working for three months, the incidence was 3.6% for usual cough with phlegm, 6.7% for usual dry cough. At one year, however, no workers reported these symptoms except two (1.5%) who reported cough with phlegm. In contrast, detectable changes in spirometry were observed at one year, with an increase of 43ml for FEV1 at three months versus a decline of 70ml at one year. Workers reporting respiratory symptoms at three months had a greater cross-shift change in FEV1 (delta-FEV1) at one year (-2.3%) than those without symptoms (-0.7%). In addition, workers exposed to high levels of endotoxin and cotton dust experienced a greater change either in delta-FEV, or in FEV, at one year, relative to those exposed to low levels. Conclusion: Respiratory symptoms are the earliest pulmonary response to cotton dust exposure, followed by observable changes in pulmonary function. In spite of reversibility, the ehrly respiratory symptoms, as well as exposure level of endotoxin or cotton dust, may be associated with excess loss of pulmonary function.
American Journal of Respiratory and Critical Care Medicine. Abstracts of the American Thoracic Society 2001 International Conference, May 18-23, 2001, San Francisco, California