Reproductive history, occupational exposures, and thyroid cancer risk among women textile workers in Shanghai, China.
OBJECTIVE
Thyroid cancer risk has been previously associated with increased age at first pregnancy and history of miscarriage. Occupational risk factors for thyroid cancer, with the exception of radioactive iodine, have not been well investigated. We conducted a case-cohort study nested in a cohort of 267,400 female textile workers in Shanghai, China, who had been followed for cancer incidence during 1989-1998.


METHODS
The analysis included 130 incident thyroid cases and 3,187 subcohort non-cases. Reproductive history was determined by questionnaire at baseline. Historical exposures were reconstructed from work history and information on factory processes and exposures. Cox proportional hazards analysis was performed to estimate hazard ratios (HR) for reproductive factors and occupational exposures.


RESULTS
Associations were observed between thyroid cancer and employment in jobs with 10 or more years of benzene exposure (HR 6.43, 95% CI: 1.08, 38) and formaldehyde exposure (HR 8.33, 95% CI: 1.16, 60). Administration workers also had an increased risk (HR 1.56, 95% CI: 1.08, 2.25). No associations between examined reproductive factors and thyroid cancer were observed in this study.


CONCLUSIONS
Despite statistically imprecise risk estimates, the findings suggest potential associations with some occupational chemical exposures in this cohort of textile workers.
Wong
E Y
EY
Department of Epidemiology, School of Public Health and Community Medicine, University of Washington, Seattle, WA, USA.
Ray
R
R
Gao
D L
DL
Wernli
K J
KJ
Li
W
W
Fitzgibbons
E D
ED
Feng
Z
Z
Thomas
D B
DB
Checkoway
H
H
D000328:Adult; D000368:Aged; D000395:Air Pollutants, Occupational / Q000009:adverse effects*; D000428:Alcohol Drinking; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D017533:Marital Status; D008875:Middle Aged; D009784:Occupational Diseases / Q000139:chemically induced* / Q000453:epidemiology; D016273:Occupational Exposure / Q000009:adverse effects*; D017584:Reproductive History; D018570:Risk Assessment; D012907:Smoking; D013783:Textile Industry; D013964:Thyroid Neoplasms / Q000139:chemically induced* / Q000453:epidemiology
D000395:Air Pollutants, Occupational