The Linus Pauling Institute link which mrsD has provided is worth a careful read.

The Linus Pauling Institute is a reliable source of information - it is independent of any commercial entities.

From that link, the Tolerable Upper Intake Level (UL) for iodide is about 1 mg/day.

Consuming iodide in excess of this UL can lead of hypothyroidism, for reasons which are explained in the link.

In my opinion, this is something which people who choose to self-medicate with iodide at levels which are significantly above the UL should give careful attention to.