title: Relationship between environmental phthalate exposure and the intelligence of school-age children.
abstract: BACKGROUND
  Concern over phthalates has emerged because of their potential toxicity to humans.
  
  
  OBJECTIVE
  We investigated the relationship between the urinary concentrations of phthalate metabolites and children's intellectual functioning.
  
  
  METHODS
  This study enrolled 667 children at nine elementary schools in five South Korean cities. A cross-sectional examination of urine phthalate concentrations was performed, and scores on neuropsychological tests were obtained from both the children and their mothers.
  
  
  RESULTS
  We measured mono-2-ethylhexyl phthalate (MEHP) and mono(2-ethyl-5-oxohexyl)phthalate (MEOHP), both metabolites of di(2-ethylhexyl)phthalate (DEHP), and mono-n-butyl phthalate (MBP), a metabolite of dibutyl phthalate (DBP), in urine samples. The geometric mean (ln) concentrations of MEHP, MEOHP, and MBP were 21.3 microg/L [geometric SD (GSD) = 2.2 microg/L; range, 0.5-445.4], 18.0 microg/L (GSD = 2.4; range, 0.07-291.1), and 48.9 microg/L (GSD = 2.2; range, 2.1-1645.5), respectively. After adjusting for demographic and developmental covariates, the Full Scale IQ and Verbal IQ scores were negatively associated with DEHP metabolites but not with DBP metabolites. We also found a significant negative relationship between the urine concentrations of the metabolites of DEHP and DBP and children's vocabulary subscores. After controlling for maternal IQ, a significant inverse relationship between DEHP metabolites and vocabulary subscale score remained. Among boys, we found a negative association between increasing MEHP phthalate concentrations and the sum of DEHP metabolite concentrations and Wechsler Intelligence Scale for Children vocabulary score; however, among girls, we found no significant association between these variables.
  
  
  CONCLUSIONS
  Controlling for maternal IQ and other covariates, the results show an inverse relationship between phthalate metabolites and IQ scores; however, given the limitations in cross-sectional epidemiology, prospective studies are needed to fully explore these associations.
authors.affiliation: Department of Psychiatry and Institute of Human Behavioral Medicine, Seoul National University College of Medicine, Republic of Korea.
authors.forename: Soo-Churl
authors.initials: SC
authors.lastname: Cho
authors.forename: Soo-Young
authors.initials: SY
authors.lastname: Bhang
authors.forename: Yun-Chul
authors.initials: YC
authors.lastname: Hong
authors.forename: Min-Sup
authors.initials: MS
authors.lastname: Shin
authors.forename: Boong-Nyun
authors.initials: BN
authors.lastname: Kim
authors.forename: Jae-Won
authors.initials: JW
authors.lastname: Kim
authors.forename: Hee-Jung
authors.initials: HJ
authors.lastname: Yoo
authors.forename: In Hee
authors.initials: IH
authors.lastname: Cho
authors.forename: Hyo-Won
authors.initials: HW
authors.lastname: Kim
mesh_terms: D000704:Analysis of Variance; D002648:Child; D003404:Creatinine / Q000652:urine; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000633:toxicity* / Q000652:urine; D005260:Female; D006801:Humans; D007360:Intelligence / Q000187:drug effects*; D008297:Male; D010795:Phthalic Acids / Q000633:toxicity* / Q000652:urine; D012044:Regression Analysis; D056910:Republic of Korea; D014888:Wechsler Scales
chemical_list: D004785:Environmental Pollutants; D010795:Phthalic Acids; C032279:phthalic acid; D003404:Creatinine