Exposure-response relationship between endotoxin exposure and lung function impairment in cotton textile workers

Objectives Preventive workplace regulations are so far not based on an ubiquitously accepted threshold for airborne endotoxin in the bioaerosol. Methods In a cross-sectional study, 150 employees of a cotton spinning mill underwent lung function testing. Furthermore, in a random subset of 75 textile workers cross-shift lung function test and methacholine challenges were performed. Airborne current endotoxin exposure was classified as low, medium, and high (<= 100, > 100-<= 450, and > 450 Endotoxin Units (EU)/m(3), respectively) based on endotoxin activity. Results The exposure-response relationship between current endotoxin exposure and prevalence of an obstructive ventilation pattern was significant (test for linear trend: P = 0.019); the adjusted odds ratio for high endotoxin exposure was 11.22 (95% confidence interval 1.03-121.17). Within individuals, FEV1/FVC% was significantly reduced after the shift (paired t test: P = 0.009) but not related to current endotoxin exposure. Twelve workers showed bronchial hyperresponsiveness (8.1% before and 12.2% after the work shift; Fisher's exact test: P = 0.021). Conclusion The study among German cotton textile workers suggests an exposure-dependent effect of current endotoxin exposure on lung function impairment with significant effects above 450 EU/m(3).