Lead exposure in infancy and subsequent growth in childhood

Abstract

BACKGROUND AND AIM: Studies suggest that elevated postnatal blood lead levels (BLL) are negatively associated with child growth. None has examined this association in African populations where the prevalence of malnutrition is high. This study aimed to investigate associations of childhood BLL at age 1 and growth outcomes at age 6 in a cohort of children in Allada, Benin. METHODS: We assessed children for lead in whole blood in 661 children at 12 months and followed them until 6 years (+/- 0.17). Weight, height and head circumference were assessed at a maternity clinic by trained staff at different age points between birth and 6 years. Weight-for-age Z-score (WAZ), height-for-age Z-score (HAZ) and BMI for-age Z-score (BMIZ) were then calculated from modeled individual postnatal growth trajectories from repeated measures of weight and height. Univariate and multivariable regression models examined associations between blood lead levels and growth outcomes with adjustment for potential confounders. RESULTS:The geometric mean of BLL was 59.3 (95% CI: 56.6 - 62.0) and 58.1% of children presented with BLL 50 μg/L. Mean WAZ, HAZ, BMIZ and head circumference (HC) in children at age 6 years were -1.24 (+/- 0.78), -0.31 (+/- 0.83), -1.65 (+/-0.87) and 49.9 cm (+/- 1.8), respectively. Overall, there were few associations between BLL and child growth. In boys only, BLL was associated with HC at age 6 in the crude model, but this association was weaker after adjustment for confounding factors (β = -0.38 cm [95% CI: -0.83, 0.08]). A negative association was observed between BLL at age 1 and HAZ at age 6 in girls, but this association was weaker after adjustment (β = - 0.11[-0.27, 0.03)]). CONCLUSIONS:We found no evidence of a relationship between BLL and physical growth in children living in a resource-poor setting with a high prevalence of undernutrition. KEYWORDS: Heavy metals Outcomes