title: Dietary Intake Estimates and Urinary Cadmium Levels in Danish Postmenopausal Women.
abstract: BACKGROUND
  Cadmium is a known carcinogen that can disrupt endocrine signalling. Cigarette smoking and food are the most common routes of non-occupational exposure to cadmium. Cadmium accumulates in the kidney and can be measured in urine, making urine cadmium (U-Cd) a biomarker of long-term exposure. However dietary-cadmium (D-Cd) intake estimates are often used as surrogate indicator of cadmium exposure in non-smoking subjects. It is therefore important to investigate the concordance between D-Cd estimates obtained with Food Frequency Questionnaires and U-Cd.
  
  
  METHODS
  U-Cd levels were compared with estimated dietary-cadmium (D-Cd) intake in 1764 post-menopausal women from the Danish Diet, Cancer and Health cohort. For each participant, a food frequency questionnaire, and measures of cadmium content in standard recipes were used to judge the daily intake of cadmium, normalized by daily caloric intake. Cadmium was measured by ICP-MS in spot urine sampled at baseline and normalized by urinary creatinine. Information on diet, socio-demographics and smoking were self-reported at baseline.
  
  
  RESULTS
  Linear regressions between U-Cd and D-Cd alone revealed minimal but significant positive correlation in never smokers (R2 = 0.0076, β = 1.5% increase per 1 ng Cd kcal(-1), p = 0.0085, n = 782), and negative correlation in current smokers (R2 = 0.0184, β = 7.1% decrease per 1 ng Cd kcal(-1) change, p = 0.0006, n = 584). In the full study population, most of the variability in U-Cd was explained by smoking status (R2 = 0.2450, n = 1764). A forward selection model revealed that the strongest predictors of U-Cd were age in never smokers (Δ R2 = 0.04), smoking duration in former smokers (Δ R2 = 0.06) and pack-years in current smokers (Δ R2 = 0.07). Food items that contributed to U-Cd were leafy vegetables and soy-based products, but explained very little of the variance in U-Cd.
  
  
  CONCLUSIONS
  Dietary-Cd intake estimated from food frequency questionnaires correlates only minimally with U-Cd biomarker, and its use as a Cd exposure indicator may be of limited utility in epidemiologic studies.
authors.affiliation: Department of Preventive Medicine and Program in Public Health, Stony Brook University, Stony Brook, New York, United States of America.
authors.forename: Caterina
authors.initials: C
authors.lastname: Vacchi-Suzzi
authors.affiliation: Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: Kirsten T
authors.initials: KT
authors.lastname: Eriksen
authors.affiliation: RTI International Trace Inorganics Department, Research Triangle Park, North Carolina, United States of America.
authors.forename: Keith
authors.initials: K
authors.lastname: Levine
authors.affiliation: Family and Community Medicine, University of Missouri, Columbia, Missouri, United States of America.
authors.forename: Jane
authors.initials: J
authors.lastname: McElroy
authors.affiliation: Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: Anne
authors.initials: A
authors.lastname: Tjønneland
authors.affiliation: Danish Cancer Society Research Center, Copenhagen, Denmark; Department of Environmental Science, Aarhus University, Aarhus, Denmark.
authors.forename: Ole
authors.initials: O
authors.lastname: Raaschou-Nielsen
authors.affiliation: RTI International Trace Inorganics Department, Research Triangle Park, North Carolina, United States of America.
authors.forename: James M
authors.initials: JM
authors.lastname: Harrington
authors.affiliation: Department of Preventive Medicine and Program in Public Health, Stony Brook University, Stony Brook, New York, United States of America.
authors.forename: Jaymie R
authors.initials: JR
authors.lastname: Meliker
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000652:urine; D002104:Cadmium / Q000652:urine*; D015331:Cohort Studies; D003718:Denmark; D004032:Diet; D015930:Diet Records; D004034:Diet Surveys; D004781:Environmental Exposure / Q000032:analysis; D005260:Female; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D017698:Postmenopause / Q000652:urine*; D012907:Smoking / Q000652:urine; D011795:Surveys and Questionnaires
chemical_list: D015415:Biomarkers; D002104:Cadmium