Small problem: Humans only have 5 liters of blood to start with, removing more than 1 liter will put the human on death's edge, and more than 2 liters past that.
Not so.
An adult human will have 5.6 to 7 liters of blood on average, and can lose up to an average of 40% of their total blood content without dying. Granted, there may be other adverse health effects caused by the upper end of that, loss of consciousness being the most obvious, but it won't kill you.
To copy paste from the internet:
40% or greater is usually considered the maximum amount of blood that an adult can loose before the body can no longer compensate. In an 80 kg adult this would be about 2.24 liters.
A Class I Hemorrhage is usually considered 15%, or less, of an adult’s blood volume. In an 80 kg person this would be about 0.84 liters. At this level there are almost no signs or symptoms.
A Class II Hemorrhage is 15 to 30% loss of an adult’s blood volume. In an 80 kg person this would be about 1.68 liters. At this level the heart will start to beat faster, and the person will start to look pale, and feel cool. This is the beginning stages of shock.
A Class III Hemorrhage is 30 to 40% loss of blood. In an 80 kg person this would be about 2.24 liters. At this level the heart will be beating very fast, trying to keep up with the bodies needs. The person will look very pale, and start to be confused. This person is in shock, and in trouble. Fluids are needed very quickly.
A Class IV Hemorrhage is as described above. This is usually greater than 40% and in an 80 kg adult this would be more than 2.24 liters. The body can no longer keep up with the blood loss and the person is in serious trouble. Without very fast help the person will die.
I've actually donated a liter of blood in a session in the past. I am, obviously, still among the living.
EDIT: All that aside, I assume the author meant to use a smaller unit of measurement.
