title: Balance ability in 7- and 10-year-old children: associations with prenatal lead and cadmium exposure and with blood lead levels in childhood in a prospective birth cohort study.
abstract: OBJECTIVE
  Most studies reporting evidence of adverse effects of lead and cadmium on the ability to balance have been conducted in high-exposure groups or have included adults. The effects of prenatal exposure have not been well studied, nor have the effects in children been directly studied. The aim of the study was to identify the associations of lead (in utero and in childhood) and cadmium (in utero) exposure with the ability to balance in children aged 7 and 10 years.
  
  
  METHODS
  Prospective birth cohort study.
  
  
  METHODS
  Maternal blood lead (n=4285) and cadmium (n=4286) levels were measured by inductively coupled plasma mass spectrometry in women enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) during pregnancy. Child lead levels were measured in a subsample of 582 of ALSPAC children at age 30 months.
  
  
  METHODS
  Children completed a heel-to-toe walking test at 7 years. At 10 years, the children underwent clinical tests of static and dynamic balance. Statistical analysis using SPSS V.19 included logistic regression modelling, comparing categories of ≥ 5 vs <5 µg/dL for lead, and ≥ 1 vs <1 µg/L for cadmium.
  
  
  RESULTS
  Balance at age 7 years was not associated with elevated in utero lead or cadmium exposure (adjusted OR for balance dysfunction: Pb 1.01 (95% CI 0.95 to 1.01), n=1732; Cd 0.95 (0.77 to 1.20), n=1734), or with elevated child blood lead level at age 30 months (adjusted OR 0.98 (0.92 to 1.05), n=354). Similarly, neither measures of static nor dynamic balance at age 10 years were associated with in utero lead or cadmium exposure, or child lead level.
  
  
  CONCLUSIONS
  These findings do not provide any evidence of an association of prenatal exposure to lead or cadmium, or lead levels in childhood, on balance ability in children. Confirmation in other cohorts is needed.
authors.affiliation: Centre for Child and Adolescent Health, School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Taylor
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK Children's Hearing Centre, University Bristol NHS Foundation Trust, Bristol, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Humphriss
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK Children's Hearing Centre, University Bristol NHS Foundation Trust, Bristol, UK.
authors.forename: Amanda
authors.initials: A
authors.lastname: Hall
authors.affiliation: Centre for Child and Adolescent Health, School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Jean
authors.initials: J
authors.lastname: Golding
authors.affiliation: Centre for Child and Adolescent Health, School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Emond
mesh_terms: D000328:Adult; D002104:Cadmium / Q000097:blood*; D002648:Child; D005260:Female; D006801:Humans; D007854:Lead / Q000097:blood*; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D004856:Postural Balance / Q000502:physiology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000097:blood*; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D006113:United Kingdom
chemical_list: D002104:Cadmium; D007854:Lead
keywords: ALSPAC; Balance; Cadmium; Lead; Pregnancy; Vestibular function