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Holly A. Ruff,¹ Morri E. Markowitz,^1,2 Polly E. Bijur,¹ and John F. Rosen^1,2

¹Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY 10461 USA; ²Montefiore Medical Center, Bronx, NY 10467 USA

Abstract
The goals of this study were to explore the relationship of declining blood lead levels and cognitive development in 42 moderately lead-poisoned children around 2 years of age and to investigate the potential interaction between iron and lead levels in the course of development. The cognitive functioning of children was assessed upon enrollment into a comprehensive intervention and 6 months later. The intervention consisted of chelation treatment, if appropriate, iron supplementation, if needed, and steps to eliminate the source of lead in the home environment. The children were referred because of blood lead levels between 25 and 55 g/dl ; they were also selected on the basis of age between 18 and 30 months. The outcome measures were the global score on a standardized test of cognitive development and subscale scores for perceptual-motor and language functioning. Cognitive change over 6 months was related to an interaction between change in blood lead and initial iron status. Specifically, the change in standardized score (particularly change in perceptual-motor performance) was strongly related to change in blood lead in children who were iron sufficient at the outset: there was an increase of 1.2 points for every 1 g/dl decrease in blood lead. There was no such relationship in iron-deficient children. Secondary analyses suggested that 1) the change in cognitive functioning of iron-deficient children was related to change in hemoglobin, and 2) the decline in blood lead was less in iron-deficient than in iron-sufficient children. Thus, when iron is sufficient, changes in blood lead and changes in cognition are inversely related. When iron is deficient, other processes affect the outcome. Key words: blood lead, cognitive development, intervention, iron deficiency, lead poisoning, perceptual-motor functioning. Environ Health Perspect 104:180-185 (1996)

Address correspondence to H. A. Ruff, Room 222, Kennedy Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461 USA.

This research was supported by grants ES04039 from the National Institute of Environmental Health Sciences ; 86109286 from the W. T. Grant Foundation ; and a Research Scientist Development Award, MH00652, from the National Institute of Mental Health. The research was also facilitated by grant HD07199 from the National Institute of Child Health and Human Development to the Rose F. Kennedy Center for Research in Mental Retardation and Human Development at Albert Einstein College of Medicine.

Received 17 July 1995 ; accepted 27 October 1995.