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Asa Bradman,^1,2 Brenda Eskenazi,³ Patrice Sutton,¹ Marcos Athanasoulis,¹ and Lynn R. Goldman⁴

¹Division of Environmental and Occupational Disease Control, California Department of Health Services, Berkeley, California, USA; ²Center for Children's Environmental Health Research, School of Public Health, University of California, Berkeley, CA, USA; ³Departments of Epidemiology and Maternal and Child Health, Center for Children's Environmental Health Research, School of Public Health, University of California, Berkeley, California, USA; ⁴Department of Environmental Health Sciences, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, Maryland, USA

Abstract

The evidence that iron deficiency increases lead child exposure is based primarily on animal data and limited human studies, and some of this evidence is contradictory. No studies of iron status and blood lead levels in children have accounted for environmental lead contamination and, therefore, the source of their exposure. Thus, no studies have directly determined whether iron deficiency modifies the relationship of environmental lead and blood lead. In this study, we compared blood lead levels of iron-deficient and iron-replete children living in low, medium, or highly contaminated environments. Measurements of lead in paint, soil, dust, and blood, age of housing, and iron status were collected from 319 children ages 1-5. We developed two lead exposure factors to summarize the correlated exposure variables: Factor 1 summarized all environmental measures, and Factor 2 was weighted for lead loading of house dust. The geometric mean blood lead level was 4.9 µg/dL ; 14% exceeded 10 µg/dL. Many of the children were iron deficient (24% with ferritin < 12 ng/dL) . Seventeen percent of soil leads exceeded 500 µg/g, and 23% and 63% of interior and exterior paint samples exceeded 5,000 µg/g. The unadjusted geometric mean blood lead level for iron-deficient children was higher by 1 µg/dL ; this difference was greater (1.8 µg/dL) after excluding Asians. Blood lead levels were higher for iron-deficient children for each tertile of exposure as estimated by Factors 1 and 2 for non-Asian children. Elevated blood lead among iron-deficient children persisted after adjusting for potential confounders by multivariate regression ; the largest difference in blood lead levels between iron-deficient and -replete children, approximately 3 µg/dL, was among those living in the most contaminated environments. Asian children had a paradoxical association of sufficient iron status and higher blood lead level, which warrants further investigation. Improving iron status, along with reducing exposures, may help reduce blood lead levels among most children, especially those living in the most contaminated environments. Key words: children, environmental exposure, epidemiology, iron deficiency, lead poisoning. Environ Health Perspect 109:1079-1084 (2001) . [Online 3 October 2001]

http://ehpnet1.niehs.nih.gov/docs/2001/109p1079-1084bradman/ abstract.html

Address correspondence to A. Bradman, Associate Director, Center for Children's Environmental Health Research, School of Public Health, UC Berkeley, 2150 Shattuck Ave., Suite 600, Berkeley, CA 94720-7380 USA. Telephone: (510) 643- 3023. Fax: (510) 642-9083. E-mail: abradman@socrates.berkeley.edu

We thank M. Haan for collaboration in conduct of the survey, L. Zahler for superb coordination of fieldwork, R. McLaughlin for data management, J. Irias for blood lead and iron parameter measurements, P. Flessel and G. Guirguis for environmental laboratory measurements and quality control, and S. Samuels for statistical consultation. We appreciate the advice of R.D. Schlag, D.F. Smith, and R.R. Neutra, who reviewed the questionnaire and study design ; S. Cummins and B. Abrams for reviewing drafts of this manuscript ; and B. Lubin for assistance on iron deficiency parameters.

This research was supported in part by the California Department of Health Services Childhood Lead Poisoning Prevention Program ; NIEHS award P01 ES09605 and EPA award R826709.

Received 3 July 2000 ; accepted 4 April 2001.