To make dropping from the air possible, a robust blood container is needed. Fortunately, the sturdy PVC plastic is the material of choice for blood containers and has been so since the 1950s. The plastic first proved its worth during the Korean War where its sturdiness helped save thousands of lives. Since then PVC blood bags have enabled billions of safe blood transfusions.
PVC’s sturdiness is paired with other advantages. Blood stored in a PVC container can last up to 42 days, which is crucial for rare blood types. On top of that, the material is very affordable, thereby making quality healthcare more accessible.
Currently most blood bags are made flexible with the substance DEHP, which has come under scrutiny by authorities. Yet due to innovation in the medical device value chain, alternative plasticisers have been developed for all medical devices, including blood bags. You can learn more about the recent developments here and here. The alternative plasticisers are also listed in the European Pharmacopeia for blood containers, which means a new breakthrough for blood bags is imminent.