I have no idea, is the short answer! I don't think the blood system you have dictates your allergies in that way - after all, haemocyanin is copper based, but I used to wear a shitload of copper jewellery and do not have nasty reactions to it, I have stuck myself with copper wire by accident and therefore had it in contact with my blood and it's not been a problem, and on the flip-side, snails, which have haemocyanin from memory, frequently ooze up iron railings. So whatever iron allergy you come up with, it's not going to be blood related, I shouldn't think :)