the Doctor in Let's Kill Hitler
, that River/Mels poisoned beyond his Regenerative ability to heal, hence why River had to give up her Regenerations to heal him. So, yea, from this event, every reason to believe the Spectrox Toxin was a concern for Regeneration.
One Day I hope to be the Man my Cat thinks I am
Where are we going? And why are we in this Handbasket?