title: Occupational exposures and risks of liver cancer among Shanghai female textile workers--a case-cohort study.
abstract: BACKGROUND
  Liver cancer is the fifth most frequent malignancy worldwide. Viral hepatitis B and C, alcohol, and aflatoxin are the major established risk factors. Little is known about the aetiological contributions of occupational exposures, as previous occupational epidemiological studies of liver cancer suggest few agent-specific associations. We investigated associations of occupational exposures to dusts and chemicals in a cohort of female textile workers.
  
  
  METHODS
  Cancer incidence was determined among 267,400 female textile workers in Shanghai, China, who had been enrolled in an intervention trial of breast self-exam efficacy during 1989-98. Subjects were interviewed at baseline regarding basic demographics, smoking habits, alcohol consumption, and contraceptive practices. A case-cohort study of 360 liver cancer cases and 3,186 age-stratified randomly chosen subcohort subjects was conducted within this cohort. Exposures to workplace dusts and chemicals were reconstructed from complete work history data, historical exposure monitoring data for selected agents, and a specially designed job-exposure matrix for the textile industry. Relative risks and dose-response trends were estimated by Cox proportional hazards modelling, adapted for the case-cohort design. Latency analyses with different lag years were also applied.
  
  
  RESULTS
  2,095,904 person-years were contributed by this female cohort. The results of the case-cohort analysis revealed a protective effect of cotton fibre exposure years [adjusted hazards ratio (HR) = 0.64; 95% confidence interval (95% CI) 0.44-0.92] or endotoxin exposure (adjusted HR = 0.60; 95% CI 0.41-0.88) for the fourth quartile with significant trends for 20 year exposure lags.
  
  
  CONCLUSIONS
  This study suggests that chronic exposure to endotoxin or some other component of cotton dust exposure may have reduced liver cancer risk in this population.
authors.affiliation: Department of Epidemiology, School of Public Health and Community Medicine, University of Washington, Seattle, WA, USA. ckchang@cuhk.edu.hk
authors.forename: Chin-Kuo
authors.initials: CK
authors.lastname: Chang
authors.forename: George
authors.initials: G
authors.lastname: Astrakianakis
authors.forename: David B
authors.initials: DB
authors.lastname: Thomas
authors.forename: Noah S
authors.initials: NS
authors.lastname: Seixas
authors.forename: Roberta M
authors.initials: RM
authors.lastname: Ray
authors.forename: Dao Li
authors.initials: DL
authors.lastname: Gao
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Wernli
authors.forename: E Dawn
authors.initials: ED
authors.lastname: Fitzgibbons
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Vaughan
authors.forename: Harvey
authors.initials: H
authors.lastname: Checkoway
mesh_terms: D000328:Adult; D002681:China / Q000453:epidemiology; D004391:Dust / Q000032:analysis; D004731:Endotoxins / Q000009:adverse effects / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D004812:Epidemiologic Methods; D062665:Epidemiological Monitoring; D005260:Female; D015386:Hazardous Substances / Q000009:adverse effects / Q000032:analysis; D006801:Humans; D008113:Liver Neoplasms / Q000453:epidemiology / Q000209:etiology*; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis; D013783:Textile Industry / Q000706:statistics & numerical data*
chemical_list: D004391:Dust; D004731:Endotoxins; D015386:Hazardous Substances