Iron and zinc supplementation does not improve parent or teacher ratings of behavior in first grade Mexican children exposed to lead

Abstract

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) mug/dL, with 51% of children > or = 10 microg/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.