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

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.