Renal effects in children living in the vicinity of a lead smelter

A cross-sectional study was carried out to determine whether environmental exposure of children to lead may cause renal effects. The study involved a total of 195 children aged 12 to 15 years. One hundred forty-four children (63 boys and 81 girls) were recruited from two schools in the vicinity of a lead smelter and 51 (25 boys and 26 girls) from a school in a rural area. Compared to their referents, boys and girls from the two schools in the polluted area had significantly higher levels of lead in blood (PbB) but similar levels of cadmium (CdB) and zinc protoporphyrins (ZPP). The functional integrity of the kidney was assessed by measuring the urinary excretion of beta 2-microglobulin, Clara cell protein, retinol-binding protein (RBP), albumin and beta-N-acetyl-D-glucosaminidase. The most significant and consistent finding of the study was that children from the two schools in the polluted area showed a significant elevation of the urinary excretion of RBP that paralleled the level of lead in blood or in the dust collected on the school playgrounds. A similar pattern was observed for the prevalence of elevated values of urinary RBP which increased from 3.9% in the control area up to 17% in the most polluted school. Urinary RBP was found to be associated with PbB (partial r2 = 0.046, P = 0.005) in a stepwise regression analysis testing also the influence of age, sex, CdB, and ZPP. In conclusion, the present study suggests that lead contaminating the environment may cause slight effects on the proximal tubule function in children at exposure levels close to those associated with CNS deficit.