RE: Testing 123
From what I understand, when they used prisoners it was also voluntary and they had time taken off their sentences for the risk.
During some tests of extreme danger, such as the polio testing and other deadly diseases, entire sentences could be commuted. Lord only knows some of the after effects.
I always figured it was like that John Wayne thing from Blazing saddles, John Wayne was the only one that ever survived and even he walked funny.