title: Urinary bisphenol A and age at menarche among adolescent girls: evidence from NHANES 2003-2010.
abstract: BACKGROUND
  Bisphenol A (BPA) is an environmental estrogen used in the manufacture of polycarbonate plastics and epoxy resins used to make food and beverage packaging. Increasing evidence suggests that BPA mimics estrogens in the body and may be associated with putative markers of breast cancer risk.
  
  
  OBJECTIVE
  We analyzed the National Health and Nutrition Examination Survey (NHANES) 2003-2010 data to investigate the association of BPA with age at menarche in adolescent girls. We hypothesized that urinary BPA, as a surrogate biomarker for BPA exposure, is associated with earlier age at menarche, and that body mass index (BMI) may modulate this association.
  
  
  METHODS
  We conducted cross-sectional analyses of urinary BPA, BMI and age of menarche in a subsample of 987 adolescent girls aged 12-19, using pooled data from the 2003-2010 NHANES. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI) for the association between urinary BPA and early onset of menarche, with adjustment for sampling design. We additionally assessed interaction of BPA with BMI.
  
  
  RESULTS
  Adolescent girls with moderate BPA levels appeared to be less likely to have early onset of menarche than those with the lowest levels (OR=0.57; 95% CI=0.30, 1.08) after adjusting for age, race/ethnicity, parental education, country of birth, NHANES cycle, BMI and creatinine. BMI appeared to modify the BPA-menarche association.
  
  
  CONCLUSIONS
  Although a non-significant trend suggests increasing urinary BPA may be associated with delayed menarche in adolescent girls, these results are based on cross-sectional data. Results should be clarified in carefully designed longitudinal cohort studies.
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Electronic address: lmcguinn@live.unc.edu.
authors.forename: Laura A
authors.initials: LA
authors.lastname: McGuinn
authors.affiliation: National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Armen A
authors.initials: AA
authors.lastname: Ghazarian
authors.affiliation: National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: L
authors.initials: L
authors.lastname: Joseph Su
authors.affiliation: National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Gary L
authors.initials: GL
authors.lastname: Ellison
mesh_terms: D000293:Adolescent; D001559:Benzhydryl Compounds / Q000652:urine*; D015992:Body Mass Index; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008572:Menarche; D009749:Nutrition Surveys; D010636:Phenols / Q000652:urine*; D055815:Young Adult; D000098826:Bisphenol A Compounds
chemical_list: D001559:Benzhydryl Compounds; D010636:Phenols; C006780:bisphenol A; D000098826:Bisphenol A Compounds
keywords: Bisphenol A; Breast cancer; Endocrine disruptors; Menarche; Puberty