A small amount of kelp taken for short periods of time won't hurt you. If you want to take plenty though, and use it for a long period of time, you might run into problems. There are articles about one woman who got arsenic poisoning from taking 2 to 4 kelp tablets a day for 2 years. Since there are better forms of iodine to take, and other fibers can be used for detoxification, I don't really see a reason to take it.