when i made calculations in my head about just how much exposure most of us have to the bad halogens and how much Iodine would be needed to keep them at bay, my estimate was 100mg per day. i think anything less than that in this environment would be ill advised. more than that depends on the individual person and environment. i would not take more than a gram a day for any extended length of time unless you were convinced it was warranted. 300mg per day seems to be a sweet spot that delivers the energy in spades along with rapid detox, if either of those strike your fancy.
chances are if youre questioning it then you should trust yourself and find another level of supplementation. i get along fine here in dallas with 400mg. that leaves me lots of room for more in case of gulf contamination coming in on a hurricane or some similar. i am maintaining my health but its nasty here. its a petrochemical tsunami.