There is this doctor...rats, I misplaced the quote....who remarked that blood is "dirty as stool." That's differs from its normal description: "life-giving."
Of course, it is both. The red and white cells, especially the red that carry oxygen, account for the "life-giving" part. But blood also carries away cellular wastes. Thus, the bloodstream doubles as a sewer. That's okay if you're speaking of your own blood, but it gives you pause for thought if you're thinking someone else's blood, as in transfusion!
Blood banks get better and better at screening. Still, every so often we hear of some new disease or contamination passed on through blood transfusion. In the late 1980s and 1990s, it came out that the Japanese "Green Cross," a pharmaceutical company [Japanese name: Midori Juchi] with $1 billion in assets, ignored government standards for AIDS screening and sold infected blood to medical facilities in the U.S, Japan, and South Korea. 2000 people ended up with transfusion-induced AIDS. Of course, they sued, and in the consequent publicity, the Green Cross' surprising and unsavory past came to light.
The company was the brainchild of Hideo Futaki, Masaji Kitano, and Ryoichi Naito, three principle architects of Japan's WWII medical experiments program. Dubbed Unit 731, hundreds of prisoners perished in sadistic experiments (without anesthesia) that rivaled any deeds from Nazi Joseph Mendele, the Doctor of Death. Unit 731, located way out there in middle-of-nowhere Mongolia, also brewed plague, cholera, and so forth, released it into the surrounding population to see what would happen...to give Japan a "leg up" in germ warfare. Daniel Barenblatt, author of A plague Upon Humanity: The Hidden History of Japan's Biological Warfare Program, reports hundreds of thousands died. The exact number, he remarks, may never be known, since the victims were peasants who had no idea they were being deliberately exterminated, and thus kept no records. They just thought they were getting sick. Why would they suspect it was deliberate?
Among the experiments performed in the Unit 731 Mongolian prison itself were animal to human blood transfusions. Naturally, all the expendable victims died. After the war, however, Futaki, Kitano, and Naito cut an immunity deal with the United States victors to avoid war crimes prosecution. later, they put their expertise to good use when they founded the Japan Blood Plasma Company, which later changed its name to Green Cross. The Japan Blood Plasma company made major money supplying blood to the U. S. Army for use during the Korean War. Thus, the founders of one of the world's principle blood banks are among the world's great mass murderers!
The Green Cross still thrives, having outlived it's long-dead founders (who were never brought to justice). It changed its name twice and, in 2001, was merged into the huge Mitsubishi conglomerate. Extensive research has, thus far, uncovered no evidence that Joseph Mengele, the Nazi doctor of death, ever started a blood bank like his Japanese counterparts.