Elsevier

The Journal of Pediatrics

Volume 147, Issue 5, November 2005, Pages 632-639
The Journal of Pediatrics

Original Article
Iron and Zinc Supplementation does not Improve Parent or Teacher Ratings of Behavior in First Grade Mexican Children Exposed to Lead

https://doi.org/10.1016/j.jpeds.2005.06.037Get rights and content

Objective

To determine the efficacy of iron and zinc supplementation on behavior ratings of lead-exposed children.

Study design

In this double-blind, randomized trial, 602 first-grade children received 30 mg ferrous fumarate, 30 mg zinc oxide, both, or placebo daily for 6 months. Lead, iron, and zinc status were determined at baseline and follow-up. Parents and teachers provided ratings of child behavior using the Conners Rating Scales.

Results

The baseline mean (SD) blood lead concentration was 11.5 (6.1) μg/dL, with 51% of children ≥ 10 μg/dL. The prevalence of attention deficit hyperactivity disorder, estimated by combined parent and teacher ratings, was 6%. At follow-up, parent ratings of oppositional, hyperactive, cognitive problems, and attention deficit hyperactivity disorder decreased by 1.5, 1.2, 2.5, and 3.4 points, respectively (P < .05). Teacher ratings of hyperactivity increased by 1.1 points (P = .008), and the mean cognitive problem score declined by 0.7 points (P = .038). There were no treatment effects on mean change in scores, but children receiving any zinc had a higher likelihood of no longer receiving clinically-significant teacher ratings of oppositional behaviors.

Conclusions

This regimen of supplementation did not result in consistent improvements in ratings of behavior in lead-exposed children over 6 months.

Section snippets

Participants

This randomized, double-blind trial was conducted in the city of Torreón, in the northern Mexican state of Coahuila. The main source of lead exposure was a metal foundry located close to the city center. Nine public elementary schools located within a 3.5-km radius of the foundry comprised the study site, and 724 children regularly attending first grade at the schools were eligible for enrollment (Figure). Signed parental consent was returned for 602 children. The exclusion criteria were a PbB

Sample Characteristics at Baseline

The mean (SD) blood lead concentration for the whole sample was 11.5 (6.1) μg/dL, and 51% of children had PbBs ≥ 10μg/dL.16 The overall prevalence of iron (ID; SF < 15 μg/L) and zinc deficiency (ZnD; serum zinc < 65 μg/dL) was 21.7% and 28.9%, respectively. In all other respects, the randomized groups were similar (Table I).

The mean scores at baseline for both parent and teacher ratings were well within the clinically normal range; Table II). According to parents, 17% of the children exhibited

Discussion

This study was conducted to determine whether supplementation with iron or zinc would benefit behavior ratings by parents or teachers in lead-exposed children. In this sample of children aged 6 to 8 years, 51% had PbB ≥ 10 μg/dL, and 6% were rated by both parents and teachers as exhibiting ADHD-like behaviors. Alternative treatment of ADHD and other behavior problems in children is not new, either because parents prefer not to use stimulant medication with young children or because children do

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