Chronic Lung Function Decline in Cotton Textile Workers: Roles of Historical and Recent Exposures to Endotoxin

• Published in: Environmental health perspectives 2010-11, Vol.118 (11), p.1620-1624
• Main Authors: Shi, Jing, Mehta, Amar J., Hang, Jing-qing, Zhang, Hongxi, Dai, Helian, Su, Li, Eisen, Ellen A., Christiani, David C.
• Format: Article
• Language: English
• Subjects: Adult; Air Pollutants, Occupational - analysis; Bacteriology; Biological and medical sciences; Bronchitis, Chronic - epidemiology; Byssinosis; Byssinosis - epidemiology; Care and treatment; Chemical and industrial products toxicology. Toxic occupational diseases; Cotton; Cotton dust; Cotton Fiber; Cotton textiles; Cough; Cough - epidemiology; Development and progression; Dose response relationship; Endotoxins; Endotoxins - analysis; Environment. Living conditions; Environmental health; Exposure; Female; Forced Expiratory Volume; Fundamental and applied biological sciences. Psychology; Health aspects; Humans; Inhalation Exposure - analysis; Inhalation Exposure - statistics & numerical data; Inorganic dusts (pneumoconiosises) and organic dusts (byssinosis etc.); Intervals; Lung Diseases - epidemiology; Lung diseases, Obstructive; Lungs; Male; Mathematical analysis; Mathematical models; Medical sciences; Microbiology; Middle Aged; Musical intervals; Occupational Exposure - analysis; Occupational Exposure - statistics & numerical data; Occupational health and safety; Odds Ratio; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Physiological aspects; Prospective Studies; Public health. Hygiene; Public health. Hygiene-occupational medicine; Respiratory Function Tests; Respiratory symptoms; Risk factors; Textiles; Toxicology; Toxins
• ISSN: 0091-6765; 1552-9924
• DOI: 10.1289/ehp.0901178

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 > 5 years). Results and 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 > 5 years after baseline. Recent endotoxin exposure was significantly associated with byssinosis, chronic bronchitis, and chronic cough.