Heavy Metal Levels and Stunting in Healthy Ugandan Children

摘要

Introduction: The industrial transition of the past decades has increased the burden of toxic pollution in many low-income countries. Children growing up in these countries now face potentially high exposures to increasingly complex mixtures of metals. Methods: We recruited 100 healthy children between 6 and 59 months old who reside in the Katanga urban settlement in Kampala, Uganda, near Mulago Hospital. After recruitment, participants were accompanied to Mulago Hospital for a physical exam, blood sample collection, and environmental questionnaire. Results: Mean age was 27.9 mos (range 6-59 mos). 53% were male. Average height-for-age z-score (HAZ) was -0.73 (sd=1.8), and 23% were stunted (HAZ more than 2 SD below the WHO growth standard mean). We measured blood levels of 13 heavy metals (antimony, arsenic (As), barium, cadmium, cesium (Cs), chromium (Cr), cobalt, copper, lead (Pb), manganese, nickel, selenium (Se), and zinc) in all participants. A multivariable linear regression model to predict HAZ included the 13 metals and was adjusted for age, sex, hemoglobin, maternal educational level, and food security. There were significant negative associations between HAZ and chromium, arsenic, and lead, and significant positive associations between HAZ and cesium and selenium. The adjusted R2 was 0.229 (p<0.001). Individual effect estimates for the five metals that were significant in our model were as follows (beta, std. error, p-value): As (-3.71, 1.52, 0.018), Cr (-1.60, 0.45, 0.0007), Pb (-0.15, 0.086, 0.095), Cs (1.85, 0.83, 0.0304), Se (0.013, 0.0074,0.077). Conclusions: We found that stunting was prevalent in Ugandan pre-school-aged children and that higher blood levels of As, Cr, and Pb were associated with lower HAZ scores. Metal remediation and further work to identify important sources are potential intervention points to improve linear growth and developmental outcomes in this population.