I'm not sure if Iodine can cause that, I know that when I was juicing carrots and other veggies, I had orange palms and feet and people thought I had a natural tan. It did kinda of worry me. It lasted for a couple of years. One thing I have noticed about callouses on the bottom of my feet is that one side is getting softer and seems to be going away, and the other side is less calloused, but you can still tell they are there. I attribute that to oilpulling since I've been doing it a little over a year. It could possibly be both Iodine coupled with oilpulling as I just noticed it last week.