Epidemiologic studies suggest that older stored blood is associated with worse outcomes in certain hospitalized patients. Storage of red cells is associated with a storage lesion and the survival of transfused red cells decreases with increasing storage time, thus older blood is associated with an increased acute delivery of hemoglobin-iron to the reticuloendothelial system. The investigators have preliminary data in healthy human volunteers suggesting that delivery of a significant iron load to the reticuloendothelial system from aged red cells leads to the elaboration of a potentially toxic form of iron known as non-transferrin-bound iron.