Its oral LD50 was tested to be more than 5000mg/kg according to Shepherd Color Company's MSDS for Blue 10G513 (as it is known commercially). That's well into "non-toxic" as categorized by the EPA. For perspective, that's more than ten times less toxic than caffeine.

So, probably pretty safe when used appropriately. I wouldn't go inhaling it, since any fine powder's not great for the lungs, but that shouldn't be news to anyone. Just wear your N95 when mixing dry pigments as you always should.