You will immediately notice contamination for its muddy brown colour. The basic solution and np solvent are totally immiscible, so it will show up as little brown globules. It can show as a rusty stain in the finished product. In this case you can recrystallize, although you'd have to do a real hack job of pulling to get so much water in your nps.
To my knowledge the greatest risk is to your alveoli.
I don't want comfort. I want God, I want poetry, I want real danger, I want freedom, I want goodness. I want a clever signature.