On the bag/bucket of my IO salt is says:
"Instant Ocean is not for human consumption, keep out of reach of children. Contact in dry form may cause skin or eye irritation. In case of contact throughly flush skin or eye(s) with cool water and seek medical attention".
After knowing that I would not want to eat it. Now, I have gotten it on my hands, with no irritation, and while siphoning I have gotten a mouthful of it, and I have not had any ill affects, but still, even if it wont hurt you, I would not eat it, just to be safe.