1043-3155 Pediatr Neurol Briefs pedneurbriefs Pediatr Neurol Briefs Pediatric Neurology Briefs Pediatr Neurol Briefs 2166-6482 1043-3155 2166-3155 Pediatric Neurology Briefs Publishers Chicago, IL, USA PNB-6-81 10.15844/pedneurbriefs-6-11-1 Toxic Disorders Neurology Pediatrics Nervous System Diseases Child Development Brain Diseases Neurosurgery Child Infant Low Level Lead Exposures and IQ http://orcid.org/0000-0002-0173-7931 Millichap J. Gordon MD 1 2 * Division of Neurology, Children's Memorial Hospital, Chicago, IL Departments of Pediatrics and Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL Correspondence: Dr. J. Gordon Millichap, E-mail: jgmillichap@northwestern.edu 11 1992 01 07 2016 6 11 81 82 Copyright: © 1992 The Author(s) 1992 This work is licensed under the Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Environmental exposure to lead and children’s intelligence at the age of seven years

The Port Pirie cohort study which began in 1979 at the Department of Community Medicine, University of Adelaide, Australia, has been followed into the primary school age range and examines intelligence at the age of 7 years in relation to lifetime exposure to lead.

 Lead Encephalopathy Blood Lead Levels Free Erythrocyte Protoporphyrin

The Port Pirie cohort study which began in 1979 at the Department of Community Medicine, University of Adelaide, Australia, has been followed into the primary school age range and examines intelligence at the age of 7 years in relation to lifetime exposure to lead. In 494 children from a lead smelting community, the IQ was inversely related to both antenatal and postnatal blood level concentrations. An increase in blood lead concentration from 10 to 30 mcg/dL was associated with a deficit in verbal IQ that varied according to age from 5.5 to 6.4 points. In full scale IQ, the estimated deficit was 4.4 - 5.3 points. [1]

COMMENT. Mahaffey KR from the National Institute of Environmental Health Sciences, North Carolina, comments in an editorial that the results of 3 longitudinal studies (Australia, Boston and Cincinnati) demonstrate that the lead associated decrements in intelligence are persistent across cultures, racial and ethnic groups, and social and economic classes. They are not limited to socially and economically disadvantaged children [2]. Meta-analysis of 7 studies showed an average decrease of 0.25 IQ points for each 1 mcg/dL increase in blood lead levels (BPb). This inverse relationship between IQ and BPb continued well below 10 mcg/dL. [3]

Lead encephalopathy was diagnosed in 10 Saudi Arabian children, ages 8-48 months during 1984-1988. The mean BPb was 6.1 umol/L (range, 2.5-13 umol/L) [4]. In Washington, D.C. 590 (20.8%) of children aged 9 months to 3 years examined showed blood lead concentrations of 0.5 umol/L or more, which exceeded the acceptable CDC limits. At levels between 0.5 and 1.2 umol/L, the free erythrocyte protoporphyrin (FEP) screening test was a very poor predictor of toxic blood lead values. [5]

 Baghurst PA McMichael AJ Wigg NR Vimpani GV Robertson EF Roberts RJ Environmental exposure to lead and children’s intelligence at the age of seven years N Engl J Med 1992 Oct 29 327 18 1279 1284 10.1056/NEJM199210293271805 1383818 Mahaffey KR Exposure to lead in childhood. The importance of prevention N Engl J Med 1992 Oct 29 327 18 1308 1309 10.1056/NEJM199210293271811 1406822 Rosen JF Health effects of lead at low exposure levels. Expert consensus and rationale for lowering the definition of childhood lead poisoning Am J Dis Child 1992 Nov 146 11 1278 1281 10.1001/archpedi.1992.02160230036011 1415061 Yaish HM Niazi GA al Soby A Lead encephalopathy in Saudi Arabian children Am J Dis Child 1992 Nov 146 11 1257 1259 1415057 Rifai N Faser C Cohen G Wolf M DePalma L Lead poisoning in young children in Washington, DC: a crisis that remains to be addressed Am J Dis Child 1992 Nov 146 11 1259 1260 1415058