I don't think there is any limit on kelp but if that were straight iodine you'd be in big trouble.

Most Americans are deficient in iodine. When Fukushima first went off I put a drop or two of iodine on my feet every day but my girlfriend borrowed the bottle for her dog and I never seen it again. I would continue to do so again if I ever find the bottle.

I used to use ground kelp as a spice in cooking. I imagine something like a 50/50 mix with salt in the salt shaker would be a really good idea.