BSA the blocking agent - How did BSA become the common blocking agent? (Apr/04/2002 )

Does anyone know why BSA is so commonly used as a blocking agent in protocols such as the western blot? And are there alternatives??

BSA is readily available, inexpensive and most importantly has a large hydrophobic pocket by which it can bind fairly strongly to non-specific sites. We have used ovalbumin, gelatin and even non-fat dry milk suspensions as proteins to reduce non-specific interactions