Im not sure its game over once bound... It would be my guess.. and its simply a guess... that once a bromine molecule is bound to a particular Iodine receptor that it gets used up eventually just like the Iodine would.. resulting of course in poorer performance for that body part.. (like putting water into your gastank so to speak)
but at some point the bad halogen would have to get used up just like Iodine does IMO.