Respiratory disease in cotton textile workers: epidemiologic assessment of small airway function

We performed a cross-sectional study of 705 textile workers in two cotton mills and one silk mill in Shanghai, People's Republic of China, to assess small airway function among cotton textile workers and to compare the FEV1 to the FEF25-75 in detecting airflow obstruction in these workers. All workers had at least 2 years of work experience. Environmental sampling was performed with vertical elutriators and revealed that in the cotton mills mean elutriated dust levels were 1.07 +/- 0.23 mg/m3 in mill 1 and 1.01 mg/m3 +/- 0.24 mg/m3 in mill 2. Mean endotoxin levels were 332 +/- 83 ng/m3 in mill 1 and 101 +/- 46 ng/m3 in mill 2. No differences were found in preshift FEV1 or FEF25-75 between cotton and silk workers. Cotton workers had significantly greater declines than silk workers in FEV1 across a workshift, but not in FEF25-75. These acute changes in FEV1 were noted in both byssinotic and nonbyssinotic workers. Although cotton dust may affect both large and small airways, spirometric measures of small airway function (e.g., FEF25-75) add little to the FEV1 and FVC in detecting airflow limitation in cotton dust-exposed workers.