Information to back Iodine in high dosages..

I wasn't sure if anyone had any good links to articles explaining why websites state Iodine supplementing is limited to 250mcg any anything over can be toxic?? I find when I talk to friends/family about Iodine they don't believe me too much because they Google Iodine and 99% of the "reputable" medical sites state most people get plenty of Iodine from iodized salt and then my info is thrown out the window. I would like to have websites or links I could forward to them. Thanks! Tweet