Effects of ALAD genotype on the relationship between lead exposure and anthropometry in a Cohort of Mexican children

Brendan T Kerr; Heather M Ochs-Balcom; Patricia López; Gonzalo G García-Vargas; Jorge L Rosado; Mariano E Cebrián; Katarzyna Kordas

doi:10.1016/j.envres.2018.12.003

Effects of ALAD genotype on the relationship between lead exposure and anthropometry in a Cohort of Mexican children

Environ Res. 2019 Mar:170:65-72. doi: 10.1016/j.envres.2018.12.003. Epub 2018 Dec 5.

Authors

Brendan T Kerr¹, Heather M Ochs-Balcom¹, Patricia López², Gonzalo G García-Vargas³, Jorge L Rosado⁴, Mariano E Cebrián⁵, Katarzyna Kordas⁶

Affiliations

¹ Department of Epidemiology and Environmental Health, School of Public Health and Health Professions, State University of New York at Buffalo, Buffalo, NY, USA.
² Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.
³ Universidad Juárez del Estado de Durango, Gómez Palacio Durango, Mexico.
⁴ Escuela de Nutrición, Universidad de Querétaro, Querétaro, Mexico.
⁵ Departamento de Toxicología, CINVESTAV, Mexico City, Mexico.
⁶ Department of Epidemiology and Environmental Health, School of Public Health and Health Professions, State University of New York at Buffalo, Buffalo, NY, USA. Electronic address: kkordas@buffalo.edu.

PMID: 30557693
DOI: 10.1016/j.envres.2018.12.003

Abstract

Objectives: Lead exposure is associated with children's growth, but this relationship may depend on the presence of susceptibility factors, including genetic variation. Blood lead levels (BLL) differ by ALAD (aminolevulinic acid dehydratase) genotype. We investigated the association between BLL and growth in Mexican first-graders with different ALAD genotypes.

Methods: Children between the ages of 6-8 years (n = 602) attending first grade in schools within the vicinity of a metal foundry in Torreón, Mexico were enrolled into a randomized controlled trial (RCT) testing the efficacy of iron and/or zinc supplementation on blood lead levels (BLL) and cognition. BLL and anthropometry were assessed at baseline (height, height-for-age z-score (HAZ), knee height, head circumference), after 6 (head circumference) and 12 months (height, HAZ, knee height). Children with ALAD_1-1 and ALAD_1-2/2-2 were compared. The study sample included 538 and 470 participants who had complete data at baseline and follow-up, respectively. Separate multivariable linear regression models adjusted for covariates were used to test the association between BLL at baseline and each anthropometric measure. Covariates included age, sex, hemoglobin, crowding, and maternal education. BLL x ALAD genotype interaction term was tested.

Results: Median BLL (10.1 μg/dL) did not differ by ALAD genotype. After covariate adjustment, baseline BLL was inversely associated with baseline height, HAZ, and knee height. The association (β [95% CI]) between BLL and baseline height (-0.38[-0.68, -0.09]), HAZ (-0.07[-0.12, -0.02]) and knee height (-0.14[-0.25, -0.02]), was somewhat stronger in children with ALAD_1-2/2-2 than ALAD_1-1 (-0.09[-0.16, -0.02], -0.02[-0.03, -0.004] and -0.04[-0.06, -0.01], respectively). No associations between BLL and growth at 6 or 12 months were detected irrespective of ALAD genotype.

Conclusions: BLL was adversely associated with anthropometric measures among Mexican children. ALAD genotype may be a susceptibility factor for the effects of lead on child growth.

Keywords: ALAD; Children; Growth; Lead; Mexico.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Anthropometry*
Child
Environmental Exposure / statistics & numerical data*
Genotype
Humans
Lead*
Mexico
Porphobilinogen Synthase / genetics*

Substances

Lead
Porphobilinogen Synthase