"After September 11, the Red Cross started thinking about developing multiple storage depots across the U.S. for frozen red blood cells," says Colonel Thomas Reid, chief of the department of Blood Research at the Walter Reed Army Institute of Research (Silver Springs, MD). "The problem we have is that when the blood ships during times when the temperature dips, the bags containing the blood become brittle," he says. Once the bags break, sterility is compromised and the blood becomes a loss. "In some conditions, our loss rate is 50 to 80% of the entire shipment." Reid and his colleagues investigated the physical and thermal properties of several commercially available blood storage bags. The bags were made from polyvinyl chloride (PVC) with diethylhexylphthalate (DEHP) or trimellitate (TEHTM) plasticizer; polyolefin (PO); polyethylene-co-vinyl acetate (EVA); or fluorinated ethylene propylene (FEP). Bags containing EVA were more shock resistant, giving the lowest rate of breakage (10%) compared to PO or PVC, according to Reid's research. Blood product storage bags made of EVA appear better suited for shipping frozen blood products on dry ice and are cost effective replacements for PVC and other bags, reports Reid. For more information on the research, call (202) 782-3501 or go to www.wramc.amedd.army.mil.