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dc.contributor.authorGutiérrez-González, Enrique 
dc.contributor.authorGarcía-Esquinas, Esther
dc.contributor.authorFernandez de Larrea, Nerea 
dc.contributor.authorSalcedo-Bellido, Inmaculada
dc.contributor.authorNavas-Acien, A
dc.contributor.authorLope, Virginia 
dc.contributor.authorGómez-Ariza, José Luis
dc.contributor.authorPastor-Barriuso, Roberto 
dc.contributor.authorPollan-Santamaria, Marina 
dc.contributor.authorPerez-Gomez, Beatriz
dc.identifier.citationEnviron Res. 2019 Dec;179(Pt A):108787es_ES
dc.description.abstractHealth problems associated with essential trace metals can result from both inadequate (i.e., low intake) and excessive exposures (i.e., from environmental and/or occupational source). Thus, measuring the exposure level is a real challenge for epidemiologists. Among non-invasive biomarkers that intend to measure long-term exposure to essential trace metals, the toenail is probably the biological matrix with the greatest potential. This systematic review collects the current evidence regarding the validity of toenail clippings as exposure biomarker for trace metals such as boron, cobalt, copper, iron, manganese, molybdenum, selenium, silicon, vanadium and zinc. Special attention was paid to the time-window of exposure reflected by the toenail, the intraindividual variability in exposure levels over time in this matrix, and the relationship of toenail with other biomarkers, personal characteristics and environmental sources. Our search identified 139 papers, with selenium and zinc being the most studied elements. The variability among studies suggests that toenail levels may reflect different degrees of exposure and probably correspond to exposures occurred 3-12 months before sampling (i.e., for manganese/selenium). Few studies assessed the reproducibility of results over time and, for samples obtained 1-6 years apart, the correlation coefficient were between 0.26 and 0.66. Trace metal levels in toenails did not correlate well with those in the blood and urine and showed low-moderate correlation with those in the hair and fingernails. Available data suggests that for some elements (Se, Mn, Zn) toenail concentrations reflect long-term external exposures in fairly reproducible levels, while for other metals, this association has not yet been assessed. Among dietary factors, only toenail selenium showed clear associations with the intake of supplements or specific foods. The toenail levels could also represent occupational exposure, for instance, Mn exposure in welders. The scarcity of information on other essential trace elements, together with the great heterogeneity among studies makes the validation of the usage of toenails as biomarkers of exposure to these elements difficult. Standardization of sample collection, quality control, analytical techniques and reporting procedures might facilitate further research focused on the clear understanding of the significance of essential levels in this promising matrix and would enhance its utility in epidemiological research.es_ES
dc.description.sponsorshipThis work was supported by FIS grants PI12/00150, PI17CIII/00034 & PI18/00287 (Instituto de Salud Carlos III, State Secretary of R + D + I and European Union (ERDF/ESF, "Investing in your future")).es_ES
dc.relation.isversionofPublisher's versiones_ES
dc.subjectEssential trace essential metalses_ES
dc.subjectSystematic reviewes_ES
dc.subject.meshMetals es_ES
dc.subject.meshBiomarkers es_ES
dc.subject.meshEnvironmental Exposure es_ES
dc.subject.meshHumans es_ES
dc.subject.meshNails es_ES
dc.subject.meshReproducibility of Results es_ES
dc.subject.meshSelenium es_ES
dc.subject.meshTrace Elements es_ES
dc.titleToenails as biomarker of exposure to essential trace metals: A review.es_ES
dc.rights.licenseAttribution-NonCommercial-NoDerivatives 4.0 Internacional*
dc.format.numberPt Aes_ES
dc.contributor.funderInstituto de Salud Carlos III - ISCIII
dc.identifier.journalEnvironmental Researches_ES
dc.repisalud.centroISCIII::Centro Nacional de Epidemologíaes_ES
dc.repisalud.centroISCIII::Escuela Nacional de Sanidades_ES
dc.relation.projectFISinfo:fis/Instituto de Salud Carlos III/Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia/Subprograma Estatal de Generación de Conocimiento/PI17-ISCIII Modalidad Proyectos de Investigacion en Salud Intramurales./PI17CIII/00034es_ES
dc.relation.projectFISinfo:fis/Instituto de Salud Carlos III/Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia/Subprograma Estatal de Generación de Conocimiento/PI18 - Proyectos de investigacion en salud (AES 2018). Modalidad proyectos en salud./PI18/00287es_ES

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Attribution-NonCommercial-NoDerivatives 4.0 Internacional
This item is licensed under a: Attribution-NonCommercial-NoDerivatives 4.0 Internacional