Colorectal cancer incidence among female textile workers in Shanghai, China: a case-cohort analysis of occupational exposures.

Previous studies have suggested increased risks of colorectal cancers among textile industry workers, potentially related to synthetic fibers. To investigate risks of colon and rectum cancers in relation to these and other textile industry exposures, we conducted a case-cohort study nested within a cohort study of female employees from the Shanghai Textile Industry Bureau (STIB). Cox proportional hazard regression modeling was used to estimate hazard ratios (HR) for colon and rectum cancers associated with duration of employment (e.g., 0, >0 to <10, 10 to <20 years, > or =20 years) in various jobs classified according to process type and exposures to specific agents. Our findings indicate that certain long term exposures may pose increased risk of colorectal cancers, especially dyes and dye intermediates with colon cancer (> or =20 years exposure versus never, HR=3.9; 95% CI: 1.4-10.6), and maintenance occupation (HR = 2.3; 95% CI: 1.0-5.7) and metals exposure (HR = 2.0; 95% CI: 1.1-3.6) with rectum cancer. A decreased risk of rectum cancer was associated with exposure to natural fibers such as cotton (HR = 0.7; 95% CI: 0.5-0.9), and a trend of decreasing rectum cancer incidence was observed by category of cumulative quantitative cotton dust or endotoxin exposures, when exposures were lagged by 20 years.