Low-level lead exposure and autistic behaviors in school-age children

Introduction: 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 7-8 years who had no prior history of developmental disorders were analyzed. Two follow-up surveys were conducted biennially until the children reached 11-12 years of age. Blood lead concentrations were measured at every survey, and autistic behaviors were evaluated at 11-12 years 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 7-8 years of age (geometric mean: 1.64 mu g/dL), but not at 9-10 and 11-12 years of age, were associated with more autistic behaviors at 11-12 years of age, according to the ASSQ(beta = 0.151; 95% confidence interval [CI]: 0.061, 0.242) and SRS (beta = 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. Conclusion: Even low blood lead concentrations at 7-8 years of age are associated with more autistic behaviors at 11-12 years of age, underscoring the need for continued efforts to reduce lead exposure. (C) 2016 Elsevier Inc. All rights reserved.