title: Low-level lead exposure and autistic behaviors in school-age children.
abstract: BACKGROUND
  The association between lead exposure and autism spectrum disorder is inconclusive. We hypothesized an association between higher blood lead concentrations and more autistic behaviors, including impaired social interactions and communication, stereotypical behaviors, and restricted interests, among school-age children.
  
  
  METHODS
  Data from 2473 Korean children aged 7-8years who had no prior history of developmental disorders were analyzed. Two follow-up surveys were conducted biennially until the children reached 11-12years of age. Blood lead concentrations were measured at every survey, and autistic behaviors were evaluated at 11-12years of age using the Autism Spectrum Screening Questionnaire (ASSQ) and Social Responsiveness Scale (SRS). The associations of blood lead concentration with ASSQ and SRS scores were analyzed using negative binomial, logistic, and linear regression models.
  
  
  RESULTS
  Blood lead concentrations at 7-8years of age (geometric mean: 1.64μg/dL), but not at 9-10 and 11-12years of age, were associated with more autistic behaviors at 11-12years of age, according to the ASSQ (β=0.151; 95% confidence interval [CI]: 0.061, 0.242) and SRS (β=2.489; 95% CI: 1.378, 3.600). SRS subscale analysis also revealed associations between blood lead concentrations and social awareness, cognition, communication, motivation, and mannerisms.
  
  
  CONCLUSIONS
  Even low blood lead concentrations at 7-8years of age are associated with more autistic behaviors at 11-12years of age, underscoring the need for continued efforts to reduce lead exposure.
authors.affiliation: Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Kyoung-Nam
authors.initials: KN
authors.lastname: Kim
authors.affiliation: Department of Preventive Medicine and Public Health, Dankook University College of Medicine, Cheonan, Republic of Korea.
authors.forename: Ho-Jang
authors.initials: HJ
authors.lastname: Kwon
authors.affiliation: Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Institute of Environmental Medicine, Medical Research Center, Seoul, Republic of Korea; Environmental Health Center, Seoul National University College of Medicine, Seoul, Republic of Korea. Electronic address: ychong1@snu.ac.kr.
authors.forename: Yun-Chul
authors.initials: YC
authors.lastname: Hong
mesh_terms: D000367:Age Factors; D001321:Autistic Disorder / Q000453:epidemiology*; D002648:Child; D002658:Developmental Disabilities / Q000097:blood / Q000453:epidemiology* / Q000209:etiology*; D005260:Female; D006801:Humans; D007854:Lead / Q000097:blood; D007855:Lead Poisoning / Q000097:blood / Q000453:epidemiology*; D008297:Male; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D011795:Surveys and Questionnaires
chemical_list: D007854:Lead
keywords: Autism Spectrum Screening Questionnaire; Autism spectrum disorder; Lead; School age population; Social Responsiveness Scale