Lead exposure from home and school environments: influence of diet on blood lead levels

Abstract

Introduction. Lead (Pb) is known as an important toxicant to human health since ancestral times. In 2013, a previous study showed high blood lead levels (BLL) in preschool children from some day care centers (DCC) in São Paulo, Brazil. The aim of this study was to investigate the associations between BLL and Pb exposure from diet and home/school environments. Method. A cross-sectional study was conducted with 124 children in 2 DCC (PS and PF), where was previously found a high prevalence of lead exposure. Environmental screenings were conducted to evaluate Pb concentrations in the buildings, playground and individual toys, school materials and tableware in both DCC and households. Portable XRF analyzer was used for the screenings. Pb analysis (GF AAS) were performed for venous blood (n=124), 24h-diet (n=64) and drinking water collected in the DCCs. Results. The mean for BLL was 2.1±1.5µg/dL. Five (4%) children in the sample presented BLL higher than reference value by CDC (5µg/dL). Medians for 24h-diets Pb concentration were 10.7 and 7.7µg Pb kg-1 of body weight (BW) in PS and PF, respectively. The diet Pb results varied from 0 up to 66µg Pb kg-1 BW. The environmental screenings showed Pb concentrations above 1mg cm-² (HUD guidelines) in walls, playground, toys and tableware. Lead concentrations in the water supply were found lower than detection limit of the method. Conclusions. Even though the mean BLL was below the reference value, the environmental and diet screenings showed lead concentrations above the references. WHO considers 3.6µg Pb kg-1 BW as the tolerable daily intake value. Because high diet Pb concentrations have not been reflected in the blood, the balanced diet observed in the dietary records seems to have contributed to the diet Pb not be absorbed. Pb bioavailability tests in food should be carried out to confirm this hypothesis. This study was funded by FAPESP.