title: Association between long working hours and serum gamma-glutamyltransferase levels in female workers: data from the fifth Korean National Health and Nutrition Examination Survey (2010-2011).
abstract: OBJECTIVE
  The present study investigated the association between long working hours and serum gamma-glutamyltransferase (GGT) levels, a factor influencing the incidence of cardiovascular disease.
  
  
  METHODS
  Data from the fifth Korean National Health and Nutrition Examination Survey (2010-2011) were used to analyze 1,809 women. Subjects were divided into three groups based on the number of weekly working hours: ≤29, 30-51, and ≥52 hours per week. Complex samples logistic regression was performed after adjusting for general and occupational factors to determine the association between long working hours and high serum GGT levels.
  
  
  RESULTS
  The prevalence of high serum GGT levels in groups with ≤29, 30-51, and ≥52 working hours per week was 22.0%, 16.9%, and 26.6%, respectively. Even after adjusting for general and occupational factors, those working 30-51 hours per week had the lowest prevalence of high serum GGT levels. Compared to those working 30-51 hours per week, the odds ratios (OR) of having high serum GGT levels in the groups with ≥52 and ≤29 working hours per week were 1.56 (95% confidence interval [CI], 1.10-2.23) and 1.53 (95% CI, 1.05-2.24), respectively.
  
  
  CONCLUSIONS
  Long working hours were significantly associated with high serum GGT levels in Korean women.
authors.affiliation: Department of Occupational & Environmental Medicine, Soonchunhyang University Cheonan Hospital, 31, Soonchunhyang 6-gil, Dongnam-gu, Cheonan-si, Chungcheongnam-do, 330-930 Republic of Korea.
authors.forename: Seung-Gwon
authors.initials: SG
authors.lastname: Park
authors.affiliation: Department of Occupational & Environmental Medicine, Soonchunhyang University Cheonan Hospital, 31, Soonchunhyang 6-gil, Dongnam-gu, Cheonan-si, Chungcheongnam-do, 330-930 Republic of Korea.
authors.forename: Yong-Jin
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: Department of Occupational & Environmental Medicine, Soonchunhyang University Cheonan Hospital, 31, Soonchunhyang 6-gil, Dongnam-gu, Cheonan-si, Chungcheongnam-do, 330-930 Republic of Korea.
authors.forename: Jung-Oh
authors.initials: JO
authors.lastname: Ham
authors.affiliation: Department of Occupational & Environmental Medicine, Soonchunhyang University Cheonan Hospital, 31, Soonchunhyang 6-gil, Dongnam-gu, Cheonan-si, Chungcheongnam-do, 330-930 Republic of Korea.
authors.forename: Eun-Chul
authors.initials: EC
authors.lastname: Jang
authors.affiliation: Department of Occupational & Environmental Medicine, Soonchunhyang University Cheonan Hospital, 31, Soonchunhyang 6-gil, Dongnam-gu, Cheonan-si, Chungcheongnam-do, 330-930 Republic of Korea.
authors.forename: Seong-Woo
authors.initials: SW
authors.lastname: Kim
authors.affiliation: Department of Occupational & Environmental Medicine, Soonchunhyang University Cheonan Hospital, 31, Soonchunhyang 6-gil, Dongnam-gu, Cheonan-si, Chungcheongnam-do, 330-930 Republic of Korea.
authors.forename: Hyun
authors.initials: H
authors.lastname: Park
keywords: Cardiovascular disease; Gamma-glutamyltransferase; Long working hours