Rationale: The degree to which chronic respiratory health effects caused by exposures to cotton dust and endotoxin is reversible after cessation of textile work is unknown.
Objectives: To investigate changes in lung function and respiratory symptoms after cessation of textile work and to determine whether past exposure to cotton dust and endotoxin or smoking history modify the associations.
Methods: We performed a prospective cohort study consisting of 447 cotton textile workers exposed to cotton dust and 472 unexposed silk textile workers, with a 25-year follow-up. Spirometry testing and respiratory questionnaires were conducted at 5-year intervals. Generalized estimated equations were used to model the average 5-year change in FEV(1) and odds ratios of respiratory symptom prevalence.
Measurements and main results: Years since cessation of textile work was positively associated with 11.3 ml/yr and 5.6 ml/yr gains in 5-year FEV(1) change for cotton and silk workers, respectively. Among male cotton workers, smokers gained more FEV(1) per year after cessation of exposure than did nonsmokers, and the risk of symptoms of chronic bronchitis and byssinosis was larger for smoking than for nonsmoking male cotton workers.
Conclusions: Cessation of textile work was significantly associated with improvement in lung function and respiratory symptoms. The positive effect of work cessation was greater for cotton workers than for silk workers. For cotton workers, the improvement in lung function loss after cessation of textile work was greater among smokers, but no differences were observed for silk workers.