Lead Poisoning
Conditions
Keywords
blood lead, iron, zinc, child, cognition, behavior, Mexico
Brief summary
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.
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.
Interventions
DIETARY_SUPPLEMENTFerrous fumarate
Tablet formulated from 30 mg ferrous fumarate.
DIETARY_SUPPLEMENTZinc oxide
Tablet formulated from 30 mg zinc oxide
DIETARY_SUPPLEMENTPlacebo
Sponsors
National Institute of Medical Sciences and Nutrition, Salvador Zubiran
National Polytechnic Institute, Mexico
Johns Hopkins Bloomberg School of Public Health
Study design
Allocation
RANDOMIZED
Intervention model
FACTORIAL
Primary purpose
TREATMENT
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
6 Years to 8 Years
Healthy volunteers
Yes
Inclusion criteria
* 1st grade child
Exclusion criteria
* Blood lead concentration =\>45 ug/dL * Hemoglobin concentration \< 9 g/dL
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Blood lead concentration | 6-12 months |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Conners Behavior Rating Scales for parents and teachers | 6-12 months | — |
| Anthropometric composite | 6-12 months | Height, weight |
| Serum ferritin concentration | 6-12 months | — |
| Hemoglobin concentration | 6-12 months | — |
| Peabody Picture Vocabulary Test, Math achievement test, tests of attention and memory | 6-12 months | — |
| Serum zinc concentration | 6-12 months | — |
Other
| Measure | Time frame | Description |
|---|---|---|
| Arsenic exposure | 6-12 months | total urinary arsenic, inorganic arsenic, monomethylarsonic acid, dimethylarsinic acid |
Countries
United States
Outcome results
None listed