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Ananya Roy,¹ David Bellinger,^2,3 Howard Hu,^1,2,4 Joel Schwartz,^2,4 Adrienne S. Ettinger,^1,2,4 Robert O. Wright,^2,4,5 Maryse Bouchard,² Kavitha Palaniappan,⁶ and Kalpana Balakrishnan⁶

¹Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA; ²Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA; ³Department of Neurology, Children’s Hospital Boston, Boston, Massachusetts, USA; ⁴Channing Laboratory, Brigham and Women’s Hospital, Boston, Massachusetts, USA; ⁵Department of Medicine, Children’s Hospital Boston, Boston, Massachusetts, USA; ⁶Department of Environmental Health Engineering, Sri Ramachandra Medical College and Research Institute, Chennai, Tamil Nadu, India

Abstract
Background: Lead exposure has long been associated with deficits in IQ among children. However, few studies have assessed the impact of lead on specific domains of behavior and cognition.

Objective: We evaluated the associations between lead and different domains of neurobehavior and their relative sensitivity to lead.

Methods: We determined blood lead levels using a LeadCare instrument in 756 children 3–7 years of age attending pre- and elementary schools in Chennai, India. Anxiety, social problems, inattention, hyperactivity, and attention deficit hyperactivity disorder (ADHD) , as well as executive function were assessed in children by their schoolteachers using Conners’ Teacher Rating Scales-39, Conners’ ADHD/Diagnostic and Statistical Manual for Mental Disorders, 4th Edition Scales (CADS) , and the Behavior Rating Inventory of Executive Function questionnaires, with higher scores denoting worse behavior. Analyses were carried out using multivariate generalized estimating equations with comparisons of outcome Z-scores to assess the relative strengths of the associations between log-blood lead and the different domains of behavior.

Results: Mean blood lead level was 11.4 ± 5.3 µg/dL. Blood lead was associated with higher anxiety (β = 0.27, p = 0.01) , social problems (β = 0.20, p = 0.02) , and higher scores in the ADHD index (β = 0.17 ; p = 0.05) . The effect estimate was highest for global executive function (β = 0.42 ; p < 0.001) .

Conclusions: Higher blood lead levels in this population of young children is associated with increased risk of neurobehavioral deficits and ADHD, with executive function and attention being particularly vulnerable domains to the effects of lead.

Key words: ADHD, anxiety, blood lead, children, executive function, India, sociability. Environ Health Perspect 117:1607–1611 (2009) . doi:10.1289/ehp.0900625 available via http://dx.doi.org/ [Online 26 June 2009]

Address correspondence to A. Roy, University of Michigan School of Public Health, Department of Environmental Health Sciences, 109 South Observatory St., Building 1, Ann Arbor, MI 48109 USA. Telephone: (617) 642-1376. Fax: (734) 936-7283. E-mail: aroyk@umich.edu

This study was supported by U.S. National Institutes of Health (NIH) grants 1R03TW005914 and R01ES007821. This work was carried out as a part of the Sc.D. thesis of A.R. at the Harvard School of Public Health, where she was supported by the training core of NIH P42-ES05947.

The contents of this study are solely the responsibility of the authors and do not necessarily represent the official views of the NIH.

The authors declare they have no competing financial interests.

Received 28 January 2009 ; accepted 26 June 2009.