['To facilitate further assessment of transfusion-associated lead exposure by designing a procedure to test packed red blood cells (pRBCs) prepared for transfusion.', 'The relationship between pRBCs and whole blood lead concentration was investigated in 27 samples using a modified clinical assay. Lead concentrations were measured in 100 pRBC units.', 'Our sample preparation method demonstrated a correlation between whole blood lead and pRBC lead concentrations (R(2) = 0.82). In addition, all 100 pRBC units tested had detectable lead levels. The median pRBC lead concentration was 0.8 μg/dL, with an SD of 0.8 μg/dL and a range of 0.2-4.1 μg/dL. In addition, after only a few days of storage, approximately 25% of whole blood lead was found in the supernatant plasma.'] Does primary prevention of pediatric lead exposure require new approaches to transfusion screening?