title: Reference levels of trace elements in hair samples from children and adolescents in Madrid, Spain.
abstract: BACKGROUND
  Hair samples are used as a tool to evaluate environmental exposure to contaminants and metabolic status in the individual. However, the use of human hair is controversial, mainly because of the lack of well-defined reference levels. In the case of Spain, very few biomonitoring studies have investigated these issues in infants, children or adolescents.
  
  
  OBJECTIVE
  To establish reference levels for trace elements in children and teenagers in Madrid, Spain.
  
  
  METHODS
  Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure Al, As, Ag, Ba, Bi, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sr, Tl and Zn levels in hair samples from 648 healthy children and adolescents (253 boys and 395 girls) between April 2008 and December 2009.
  
  
  RESULTS
  Median levels were as follows: Al 18.5μg/g, As 0.07μg/g, Ag 196ng/g, Ba 0.5μg/g, Bi 0.01μg/g, Cd 18.3ng/g, Cr 0.4μg/g, Co 14.5ng/g, Cu 25.7μg/g, Fe 15.5μg/g, Mn 328ng/g, Mo 0.04μg/g, Ni 0.5μg/g, Pb 0.70μg/g, Se 0.5μg/g, Sr 1.29μg/g, Tl 0.28ng/g and Zn 121μg/g.
  
  
  CONCLUSIONS
  The values of trace elements here described could be considered as possible reference ranges for hair samples from children and adolescents aged 0-18 years living in the Madrid region (central Spain). These values could also be selected as a preliminary screening tool to assess exposure sources and to generate information needed to develop prevention strategies and likewise could be a complement to other diagnostic procedures.
authors.affiliation: Institute of Toxicology of Defence, Gómez Ulla Central Hospital of Defence, Glorieta del Ejército s/n, 28047 Madrid, Spain. Electronic address: mllobal@oc.mde.es.
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Llorente Ballesteros
authors.affiliation: Institute of Toxicology of Defence, Gómez Ulla Central Hospital of Defence, Glorieta del Ejército s/n, 28047 Madrid, Spain. Electronic address: irene.navarroserrano@gmail.com.
authors.forename: Irene
authors.initials: I
authors.lastname: Navarro Serrano
authors.affiliation: Department of Clinical Biochemistry, Miguel Servet University Hospital, C/Padre Arrupe, s/n, 50009 Zaragoza, Spain. Electronic address: sizquierdoalvarez@gmail.com.
authors.forename: Silvia
authors.initials: S
authors.lastname: Izquierdo Álvarez
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D004781:Environmental Exposure; D004784:Environmental Monitoring; D005260:Female; D006197:Hair / Q000737:chemistry*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012737:Sex Factors; D013030:Spain; D014131:Trace Elements / Q000032:analysis*
chemical_list: D014131:Trace Elements
keywords: Children-adolescent population; Hair; Inductively coupled plasma mass spectrometry; Reference levels; Trace elements