Aims: To determine chronic effects of long term exposure to cotton dust and endotoxin on incidence of
respiratory symptoms and the effect of cessation of exposure.
Methods: Respiratory health in 429 Chinese cotton textile workers (study group) and 449 silk textile
workers (control group) was followed prospectively from 1981 to 1996. Byssinosis, chest tightness, and
non-specific respiratory symptoms were assessed by means of identical standardised questionnaires at
four time points. Exposures to cotton dust and endotoxin were estimated using area samples collected at
each survey. Incidence and persistence of symptoms were examined in relation to cumulative exposure
and exposure cessation using generalised estimating equations (GEE).
Results: Among cotton workers, the cumulative incidence of byssinosis and