title: Sulfur dioxide exposure and other factors affecting age at natural menopause in the Jinchuan cohort.
abstract: OBJECTIVE
  To describe the associations between occupational exposures and age at natural menopause in the Jinchuan cohort.
  
  
  METHODS
  The Jinchuan cohort consists of all current or retired workers of the Jinchuan Nonferrous Metals Corporation (JNMC) in Jinchang, Gansu, China. Our final study population consisted of 3167 postmenopausal women. The data used for this study were derived from the epidemiological survey and were self-reported. Age at natural menopause (ANM) was defined as the age at the last period prior to 12 months of amenorrhea in women who experienced natural menopause. ANM was related to five commonly reported occupational exposures using bivariate and multivariate Cox proportional hazards regressions.
  
  
  RESULTS
  Blue-collar workers have significantly earlier mean ANM (49.0 years) than white-collar workers (49.5 years). Sulfur dioxide exposure was found to be associated with earlier mean ANM in blue-collar workers. After stratifying both blue-collar workers and white-collar workers further by exposure time for each of the exposures, blue-collar workers exposed to sulfur dioxide for 21-25 years had the earliest mean ANM (47.8 years) of any level of any exposure in this study.
  
  
  CONCLUSIONS
  This paper is significant because it is the first report of an association between sulfur dioxide and menopause, and one of few papers to look at the determinants of ANM in an occupational cohort. Blue-collar workers had earlier mean ANM than white-collar workers. Blue-collar workers are more exposed to sulfur dioxide and other occupational exposures than white-collar workers, and blue-collar workers who are more exposed to sulfur dioxide have earlier menopause. Sulfur dioxide may be part of the reason that blue-collar workers experience earlier menopause than white-collar workers.
authors: a * Center for Cancer Prevention and Treatment, School of Public Health, Lanzhou University , Lanzhou , Gansu, China.|b Department of Epidemiology , School of Public Health, Brown University , Providence , RI , USA.
authors: D
authors: D
authors: Wang
authors: a * Center for Cancer Prevention and Treatment, School of Public Health, Lanzhou University , Lanzhou , Gansu, China.
authors: M
authors: M
authors: Wang
authors: c College of Basic Medicine, Lanzhou University , Lanzhou, Gansu , China.
authors: N
authors: N
authors: Cheng
authors: b Department of Epidemiology , School of Public Health, Brown University , Providence , RI , USA.
authors: T
authors: T
authors: Zheng
authors: a * Center for Cancer Prevention and Treatment, School of Public Health, Lanzhou University , Lanzhou , Gansu, China.
authors: X
authors: X
authors: Hu
authors: d Jinchuan Worker's Hospital , Jinchang , Gansu, China.
authors: H
authors: H
authors: Li
authors: b Department of Epidemiology , School of Public Health, Brown University , Providence , RI , USA.
authors: C
authors: C
authors: Chan
authors: b Department of Epidemiology , School of Public Health, Brown University , Providence , RI , USA.
authors: Y
authors: Y
authors: Zhang
authors: a * Center for Cancer Prevention and Treatment, School of Public Health, Lanzhou University , Lanzhou , Gansu, China.
authors: X
authors: X
authors: Ren
authors: a * Center for Cancer Prevention and Treatment, School of Public Health, Lanzhou University , Lanzhou , Gansu, China.
authors: Y
authors: Y
authors: Bai
mesh_terms: D000328:Adult; D000375:Aging / Q000187:drug effects*; D002681:China; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008593:Menopause / Q000187:drug effects*; D008669:Metallurgy; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects*; D013458:Sulfur Dioxide / Q000633:toxicity*
chemical_list: D013458:Sulfur Dioxide
keywords: AGE AT NATURAL MENOPAUSE; CHINESE WOMEN; SULFUR DIOXIDE