Multiple Low‐Level Metal Exposure and Indicators of Weight and Height in Uruguayan Urban School Children

Abstract

The contribution of chronic environmental lead and other toxic metal exposure to anthropometric status of children is unclear. Effects of multiple metal interactions at low levels of exposure are unknown. In this study, associations between concentrations of lead in blood, and of arsenic, cadmium, and manganese in hair, and indicators of weight and height status were examined in Uruguayan urban school children (n=290). Study recruitment, procedures and informed consent were approved by Institutional Ethical Committees. Fasting blood samples were collected, and lead in blood (BLL) was analyzed by GFAAS. Hair was cut close to the scalp with stainless steel scissors, from back of the head. Metals in hair were analyzed by ICPMS. Associations were examined by multifactor ANOVA and multiple regression analyses, with gender and tertiles of metal concentrations entered as factors into a single model, adjusted for serum ferritin corrected for C‐reactive protein. HAZ (height for age Z score), WAZ (weight for age Z score) and BAZ (body mass index for age Z score), were modeled separately. Children were 6–9 years old, 45% girls, non‐anemic, and with low iron reserves (median serum ferritin: 17.9 μg/L). Median Z scores of anthropometric measures were adequate (0.41, 0.70, 0.60, for HAZ, WAZ, BAZ, respectively), but with wide ranges between extreme values. Median (range) for BLL was 4.0 (0.8–13.2) μg/dL, and for hair metals: Mn 0.81 (0.06–25.7), As 0.052 (0.002–1.332), Cd 0.095 (0.005–0.8), μg/g. BLL was negatively associated with all 3 anthropometric Z scores (P≤0.003). Children at the lowest BLL tertile had higher mean Z scores than in each of the other tertiles (0.48 and 0.59 higher for HAZ; 0.77 and 0.60 for WAZ; 0.78 and 0.40 for BAZ). Hair Mn was positively associated with BAZ (P=0.017). Hair As tended to have a positive association with WAZ (P=0.0502). Exposure to low levels of lead may impair measures of anthropometric growth in children of school age. Interactions between low levels of combined metals exposure and anthropometric indices in children appear to be complex, and possibly related to nutritional status and other unknown factors.Support or Funding InformationNIEHS R21ES16523, R21ES019949