Declining blood lead and zinc protoporphyrin levels in Ecuadorian Andean children

Objectives: To investigate current lead (Pb) exposure in children living in Andean Ecuadorian communities. Blood Pb (PbB) and zinc protoporphyrin (ZPP) levels were used respectively as biomarkers of acute and chronic Pb poisoning. The current PbB-ZPP levels were compared with previous pediatric PbB-ZPP levels recorded over years in the study area. Design and methods: Samples of whole blood were collected from 22 Andean children of Quechua and Mestizo backgrounds and measured for PbB concentrations by graphite furnace atomic absorption spectroscopy. ZPP/heme ratio and ZPP whole blood (ZPP WB) levels were measured with a hematofluorometer. Results: The mean PbB level for children in the current study group was 14.5. μg/dL, which was significantly lower than the mean PbB level of 41.1. μg/dL found in the same study area in the 1996-2000 test period, and lower than the 22.2. μg/dL mean level found in the 2003-2007 period. The current mean ZPP/heme ratio was 102.1. μmol/mol, and the mean ZPP WB level was 46.3. μg/dL, both lower than values previously found in children in the study area. Conclusion: While the current pediatric PbB-ZPP levels in the study area remain elevated in some children, the overall levels indicate a decline relative to levels observed in the same Pb-contaminated area in the period between 1996 and 2007. The elevated ZPP levels suggest a history of chronic Pb exposure, and potential iron deficiency in some children. The overall reduction in PbB-ZPP levels suggests a positive outcome of a Pb-exposure education and prevention program, and the therapeutic intervention of succimer chelation therapy.