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dc.contributor.authorTownsend, Mary Ken_US
dc.contributor.authorFranke, Adrian Aen_US
dc.contributor.authorLi, Xingnanen_US
dc.contributor.authorHu, Frank Ben_US
dc.contributor.authorEliassen, A Heatheren_US
dc.date.accessioned2014-03-11T10:15:54Z
dc.date.issued2013en_US
dc.identifier.citationTownsend, Mary K, Adrian A Franke, Xingnan Li, Frank B Hu, and A Heather Eliassen. 2013. “Within-person reproducibility of urinary bisphenol A and phthalate metabolites over a 1 to 3 year period among women in the Nurses’ Health Studies: a prospective cohort study.” Environmental Health 12 (1): 80. doi:10.1186/1476-069X-12-80. http://dx.doi.org/10.1186/1476-069X-12-80.en
dc.identifier.issn1476-069Xen
dc.identifier.urihttp://nrs.harvard.edu/urn-3:HUL.InstRepos:11879252
dc.description.abstractBackground: Associations of bisphenol A and phthalates with chronic disease health outcomes are increasingly being investigated in epidemiologic studies. The majority of previous studies of within-person variability in urinary bisphenol A and phthalate metabolite concentrations have focused on reproducibility over short time periods. Long-term reproducibility data are needed to assess the potential usefulness of these biomarkers for prospective studies, particularly those examining risk of diseases with long latency periods. Low within-person reproducibility may attenuate relative risk estimates and reduce statistical power to detect associations with disease. Therefore, we assessed within-person reproducibility of bisphenol A, eight phthalate metabolites, and phthalic acid in spot urine samples over 1 to 3 years among women enrolled in two large cohort studies. Methods: Women in the Nurses’ Health Study and Nurses’ Health Study II provided two spot urine samples, 1 to 3 years apart (n = 80 women for analyses of bisphenol A; n = 40 women for analyses of phthalate metabolites; n = 34 women for analyses of phthalic acid). To measure within-person reproducibility, we calculated Spearman rank correlation coefficients and intraclass correlation coefficients for creatinine-adjusted concentrations of bisphenol A, phthalate metabolites, and phthalic acid. Results: Over 1 to 3 years, within-person variability of bisphenol A was high relative to total variability (intraclass correlation coefficient = 0.14) and rankings of bisphenol A levels between time-points were weakly correlated (Spearman correlation = 0.19). Seven of the eight phthalate metabolites and phthalic acid demonstrated moderate within-person stability over time (Spearman correlation or intraclass correlation coefficient = 0.39-0.55). Restricting analyses to first-morning urine samples did not alter results. Conclusions: Single measurements of bisphenol A in spot urine samples were highly variable within women over 1 to 3 years, indicating that investigation of associations between a single urinary bisphenol A measurement and disease risk may be challenging in epidemiologic studies. The majority of urinary phthalate metabolites and phthalic acid appeared moderately reproducible within women over time, suggesting single measurements may be useful in epidemiologic studies, although observed relative risks can be substantially attenuated.en
dc.language.isoen_USen
dc.publisherBioMed Centralen
dc.relation.isversionofdoi:10.1186/1476-069X-12-80en
dc.relation.hasversionhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC3847616/pdf/en
dash.licenseLAAen_US
dc.subjectAdulten
dc.subjectBiological markers/urineen
dc.subjectBisphenol aen
dc.subjectPhthalate metabolitesen
dc.subjectReproducibilityen
dc.titleWithin-person reproducibility of urinary bisphenol A and phthalate metabolites over a 1 to 3 year period among women in the Nurses’ Health Studies: a prospective cohort studyen
dc.typeJournal Articleen_US
dc.description.versionVersion of Recorden
dc.relation.journalEnvironmental Healthen
dash.depositing.authorTownsend, Mary Ken_US
dc.date.available2014-03-11T10:15:54Z
dc.identifier.doi10.1186/1476-069X-12-80*
dash.contributor.affiliatedTownsend, Mary K.
dash.contributor.affiliatedHu, Frank
dash.contributor.affiliatedEliassen, A.


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