title: Cumulative lead exposure and age at menopause in the Nurses' Health Study cohort.
abstract: BACKGROUND
  Early menopause has been associated with many adverse health outcomes, including increased risk of cardiovascular disease morbidity and mortality. Lead has been found to be adversely associated with female reproductive function, but whether exposures experienced by the general population are associated with altered age at menopause has not been explored.
  
  
  OBJECTIVE
  Our goal was to assess the association between cumulative lead exposure and age at natural menopause.
  
  
  METHODS
  Self-reported menopausal status and bone lead concentration measured with K-shell X-ray fluorescence-a biomarker of cumulative lead exposure-were obtained from 434 women participants in the Nurses' Health Study.
  
  
  RESULTS
  The mean (± SD) age at natural menopause was 50.8 ± 3.6 years. Higher tibia lead level was associated with younger age at menopause. In adjusted analyses, the average age of menopause for women in the highest tertile of tibia lead was 1.21 years younger (95% CI: -2.08, -0.35) than for women in the lowest tertile (p-trend = 0.006). Although the number of cases was small (n = 23), the odds ratio for early menopause (< 45 years of age) was 5.30 (95% CI: 1.42, 19.78) for women in the highest tertile of tibia lead compared with those in the lowest tertile (p-trend = 0.006). There was no association between patella or blood lead and age at menopause.
  
  
  CONCLUSIONS
  Our results support an association between low-level cumulative lead exposure and an earlier age at menopause. These data suggest that low-level lead exposure may contribute to menopause-related health outcomes in older women through effects on age at menopause.
  
  
  BACKGROUND
  Eum KD, Weisskopf MG, Nie LH, Hu H, Korrick SA. 2014. Cumulative lead exposure and age at menopause in the Nurses' Health Study Cohort. Environ Health Perspect 122:229–234; http://dx.doi.org/10.1289/ehp.1206399
authors.affiliation: Department of Environmental Health, and.
authors.forename: Ki-Do
authors.initials: KD
authors.lastname: Eum
authors.forename: Marc G
authors.initials: MG
authors.lastname: Weisskopf
authors.forename: Linda H
authors.initials: LH
authors.lastname: Nie
authors.forename: Howard
authors.initials: H
authors.lastname: Hu
authors.forename: Susan A
authors.initials: SA
authors.lastname: Korrick
mesh_terms: D000328:Adult; D017677:Age Distribution; D015415:Biomarkers / Q000378:metabolism; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000378:metabolism*; D005260:Female; D006801:Humans; D007854:Lead / Q000378:metabolism*; D008593:Menopause / Q000187:drug effects*; D008875:Middle Aged; D010329:Patella / Q000378:metabolism*; D011446:Prospective Studies; D013052:Spectrometry, X-Ray Emission; D011795:Surveys and Questionnaires; D013977:Tibia / Q000378:metabolism*; D014481:United States
chemical_list: D015415:Biomarkers; D004785:Environmental Pollutants; D007854:Lead