Effects of Iron and/or Zinc Supplementation in Mexican School Children Exposed to Lead

January 23, 2015 updated by: Johns Hopkins Bloomberg School of Public Health

Effects of Iron and Zinc Supplementation on Neuropsychological and Educational Achievement in Lead-exposed School Children

Lead is negatively linked to nutritional status, behavior and cognition in children. Despite extensive knowledge of its toxicity and efforts to reduce exposure, lead continues to be a problem in developed and developing countries. When lead exposure is unavoidable due to its pervasive nature, effective means of protecting or disrupting that exposure need to be developed. Nutritional interventions are one such option. We conducted a 2x2 factorial, placebo-controlled trial of 6-month iron and zinc supplementation among lead-exposed children in Torreón, Mexico (altitude 1060 m). Nine schools were selected based on proximity to a lead smelter and first-graders were individually randomized to daily treatment with 30 mg iron, 30 mg zinc, both, or placebo. In addition to biochemical indicators, cognitive functions and behavior were evaluated at baseline, after the 6-month supplementation period, and again after another 6 months (without supplementation).

At baseline, 602 children ages 6.2-8.5 years were enrolled.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

We conducted a 2x2 factorial, placebo-controlled trial of 6-month iron and zinc supplementation among lead-exposed children in Torreón, Mexico (altitude 1060 m) to test the hypothesis that supplementation with iron, zinc or both will reduce blood lead concentrations of the children and improve their cognition and behavior. Nine schools were selected based on proximity to a lead smelter and first-graders were individually randomized to daily treatment with 30 mg iron, 30 mg zinc, both, or placebo. In addition to biochemical indicators (blood lead, serum ferritin, CRP, serum zinc, urinary arsenic concentrations), cognitive functions and behavior were measured. Assessments were conducted at three time points: at baseline, after the 6 month treatment, and again after another 6 months without treatment. At baseline, 602 children ages 6.2-8.5 years were enrolled.

Study Type

Interventional

Enrollment (Actual)

602

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Maryland
      • Baltimore, Maryland, United States, 21205
        • Johns Hopkins Bloomberg School of Public Health

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

4 years to 6 years (Child)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • 1st grade child

Exclusion Criteria:

  • Blood lead concentration =>45 ug/dL
  • Hemoglobin concentration < 9 g/dL

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Factorial Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Ferrous fumarate
Tablet formulated as ferrous fumarate, 30 mg. Given once daily for 6 months.
Dietary supplement: Ferrous fumarate
Tablet formulated from 30 mg ferrous fumarate.
Experimental: Zinc oxide
Tablet formulated as zinc oxide, 30 mg. Given once daily by mouth for 6 months.
Dietary supplement: Zinc oxide
Tablet formulated from 30 mg zinc oxide
Experimental: Ferrous fumarate and zinc oxide
Tablet, formulated as ferrous fumarate 30 mg plus zinc oxide 30 mg. Given once daily by mouth for 6 months.
Dietary supplement: Ferrous fumarate
Tablet formulated from 30 mg ferrous fumarate.
Dietary supplement: Zinc oxide
Tablet formulated from 30 mg zinc oxide
Placebo Comparator: Placebo
Sugar tablet formulated to look like the experimental arms of the study. Given daily by mouth for 6 months.
Dietary supplement: Placebo

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Blood lead concentration
Time Frame: 6-12 months
6-12 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Anthropometric composite
Time Frame: 6-12 months
Height, weight
6-12 months
Serum ferritin concentration
Time Frame: 6-12 months
6-12 months
Serum zinc concentration
Time Frame: 6-12 months
6-12 months
Hemoglobin concentration
Time Frame: 6-12 months
6-12 months
Conners Behavior Rating Scales for parents and teachers
Time Frame: 6-12 months
6-12 months
Peabody Picture Vocabulary Test, Math achievement test, tests of attention and memory
Time Frame: 6-12 months
6-12 months

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Arsenic exposure
Time Frame: 6-12 months
total urinary arsenic, inorganic arsenic, monomethylarsonic acid, dimethylarsinic acid
6-12 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Johns Hopkins Bloomberg School of Public Health

Collaborators

National Polytechnic Institute, Mexico
National Institute of Medical Sciences and Nutrition, Salvador Zubiran

Investigators

  • Principal Investigator: Rebecca J Stoltzfus, PhD, Johns Hopkins Bloomberg School of Public Health

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

January 1, 2000

Primary Completion (Actual)

December 1, 2001

Study Completion (Actual)

December 1, 2001

Study Registration Dates

First Submitted

January 20, 2015

First Submitted That Met QC Criteria

January 23, 2015

First Posted (Estimate)

January 26, 2015

Study Record Updates

Last Update Posted (Estimate)

January 26, 2015

Last Update Submitted That Met QC Criteria

January 23, 2015

Last Verified

January 1, 2015

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • H.22.00.07.06B

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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