all potassium is radioactive. all over the world. inside of you. and in every molecule of potassium iodide. i can get a reading with my inspector geiger counter from the potassium Iodide that i take. same thing with the grocery store potassium supplement in my kitchen cabinet. and my potassium chloride for the IMAM.
salt is iodized using KI. its not radioactive from medical waste iodine, its radioactive from the potassium thats on the earth.
as for taking too much iodine, its all lies. all of those problems are caused by other things. modern humans are health basket cases. Iodine helps correct that, not the other way around. everyones mileage will vary.