Scott SoCal said:A distinction without a difference.
EPO is a naturally occurring protein hormone, so it could be argued it's not a PED as well.
Sure, blood doping isn't a PED -- it is a "prohibited method".
Synthetic EPO is a "prohibited substance",
"Prohibited substance" is WADA-speak for "PED" or "masking agent" or "thing we just don't like because"
Some prohibited substances can be allowed with a TUE. Some you will not get a TUE for if you should apply.
Some prohibited substances have thresholds, commonly those found naturally, or frequently in the environment.
Others have no thresholds, and just aren't supposed to be present at all. Their level isn't considered by the process. You might argue some inadvertant contamination, but it doesn't completely remove the liability.
Some substances have both natural and synthetic origins, and the presence of natural is OK, but the presence of synthetic is not -- this is the situation with testosterone. (Determining the presence of synthetic is tricky, and involves things that look like "thresholds" that aren't Thresholds as for Threshold Substances)
Some prohibited methods are allowed for some medical reasons -- for example, saline IV; others are plain not-allowed (blood infusion).
-dB