Chronic lung function decline in cotton textile workers: roles of historical and recent exposures to endotoxin.
BACKGROUND
Long-term occupational exposure to cotton dust that contains endotoxin is associated with chronic respiratory symptoms and excessive decline in forced expiratory volume in 1 sec (FEV1), but the mechanisms of endotoxin-related chronic airflow obstruction remain unclear.


OBJECTIVE
In the current study, we examined temporal aspects of the exposure-response relationship between airborne endotoxin exposure, longitudinal change in FEV1, and respiratory symptoms in a cohort of Chinese cotton textile workers.


METHODS
This prospective cohort study followed 447 cotton textile workers from 1981 to 2006. at approximately 5-year intervals. We used a generalized estimating equations approach to model FEV1 level and respiratory symptoms as a function of past exposure (cumulative exposure up to the start of the most recent 5-year survey interval) and cumulative exposure (within the most recent interval) to endotoxins, after adjusting for other covariates. Models were stratified by active versus retired work status and by years employed before the baseline survey (< 5 and > or = 5 years).


CONCLUSIONS
Past exposure to endotoxin was associated with reduced FEV1 level among retired cotton workers. Among all cotton workers, past exposure was more strongly associated with reduced FEV1 for those hired < 5 years before baseline than for those who were hired > or = 5 years after baseline. Recent endotoxin exposure was significantly associated with byssinosis, chronic bronchitis, and chronic cough.
Shi
Jing
J
Department of Safety Engineering, China Institute of Industrial Relations, Beijing, China.
Mehta
Amar J
AJ
Hang
Jing-Qing
JQ
Zhang
Hongxi
H
Dai
Helian
H
Su
Li
L
Eisen
Ellen A
EA
Christiani
David C
DC
D000328:Adult; D000395:Air Pollutants, Occupational / Q000032:analysis*; D029481:Bronchitis, Chronic / Q000453:epidemiology; D002095:Byssinosis / Q000453:epidemiology; D032561:Cotton Fiber; D003371:Cough / Q000453:epidemiology; D004731:Endotoxins / Q000032:analysis*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D019570:Inhalation Exposure / Q000032:analysis / Q000706:statistics & numerical data*; D008171:Lung Diseases / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000032:analysis / Q000706:statistics & numerical data*; D016017:Odds Ratio; D011446:Prospective Studies; D012129:Respiratory Function Tests
D000395:Air Pollutants, Occupational; D004731:Endotoxins
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