title: Inverse association between intelligence quotient and urinary retinol binding protein in Chinese school-age children with low blood lead levels: results from a cross-sectional investigation.
abstract: OBJECTIVE
  Examine the relationship between blood lead concentration and children's intelligence quotient (IQ) in Chinese children 8-12 years old.
  
  
  METHODS
  This is a cross-sectional study, and participants included 446 children from three primary schools in Jiangsu, China. We collected environmental and genetic information from questionnaires. Blood lead (Pb), manganese (Mn), cadmium (Cd) and selenium (Se) concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS). IQ was assessed using the Combined Raven's Test and then converted to a standard IQ score according to Chinese children's norm. Morning urine samples were collected to measure retinol binding protein (RBP).
  
  
  RESULTS
  The average blood lead concentration was 33.13 μg L(-1) (geometric mean), and the blood lead concentration (BoxCox transform) was inversely and significantly associated with IQ (r=-0.11, p=0.02). The geometric mean of blood Mn, Cd and Se was 7.02 μg L(-1), 0.18 μg L(-1) and 94.77 μg L(-1), respectively. Blood Mn, Cd and Se showed no association with IQ, but all of them associated with urinary RBP. Urinary RBP was identified as a new factor associated with IQ (β=-6.49, p=0.011).
  
  
  CONCLUSIONS
  Urinary RBP was recognized as a new indicated factor associated with children's IQ. Mn, Cd and Se exposure might affect urinary RBP concentration and further IQ. Findings also support that blood lead concentrations in 8-12 years old children, even <44 μg L(-1), have a negative association with IQ.
authors.affiliation: Jiangsu Provincial Center for Disease Control and Prevention, Jiangsu Road 172, 210009 Nanjing, PR China. Electronic address: njmu_sunhong@hotmail.com.
authors.forename: Hong
authors.initials: H
authors.lastname: Sun
authors.affiliation: Nanjing Medical university, Hanzhong road 140, 210029 Nanjing, PR China.
authors.forename: Wen
authors.initials: W
authors.lastname: Chen
authors.affiliation: Changshu Provincial Center for Disease Control and Prevention, Fuyang Road 6, Changshu 215500, Jiansu, PR China.
authors.forename: Dongyue
authors.initials: D
authors.lastname: Wang
authors.affiliation: Chinese Center for Disease Control and Prevention, Nanwei Road 29, Beijing 100021, PR China.
authors.forename: Yinlong
authors.initials: Y
authors.lastname: Jin
authors.affiliation: Jiangsu Provincial Center for Disease Control and Prevention, Jiangsu Road 172, 210009 Nanjing, PR China; Nanjing Medical university, Hanzhong road 140, 210029 Nanjing, PR China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Chen
authors.affiliation: Jiangsu Provincial Center for Disease Control and Prevention, Jiangsu Road 172, 210009 Nanjing, PR China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Xianlin Avenue 163, Nanjing 210023, PR China. Electronic address: huanglei@nju.edu.cn.
authors.forename: Lei
authors.initials: L
authors.lastname: Huang
mesh_terms: D002104:Cadmium / Q000097:blood; D002648:Child; D002681:China; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007360:Intelligence / Q000502:physiology*; D007361:Intelligence Tests; D007854:Lead / Q000097:blood*; D008297:Male; D008345:Manganese / Q000097:blood; D013058:Mass Spectrometry; D012177:Retinol-Binding Proteins / Q000652:urine*; D012643:Selenium / Q000097:blood; D011795:Surveys and Questionnaires
chemical_list: D012177:Retinol-Binding Proteins; D002104:Cadmium; D007854:Lead; D008345:Manganese; D012643:Selenium
keywords: Children health; Manganese; Metal; Retinol binding protein; Selenium