Iodine deficiency a cause of breast cancer?

My Lovely Wife gets all kind of books, including one of hers that I read recently:

I found it fascinating, for a few reasons:

• I never thought of iodine as something humans need internally, just as that pink stuff that used to get painted on wounds, but even that is supposed to be a bad idea
• But according to this book, we need iodine not just in the "iodized salt" amount to prevent goiter
• In fact, iodine was baked into bread (in the form potassium iodate) until around 1970 such that one slice was enough for humans ... but some sketchy research published in the 70's that implied (without any proof whatsoever) that iodine was dangerous to human health ... and iodine was removed from bread in favor of bromine ...

Which binds to the same receptors and blocks iodine uptake by the body and seems to be implied in the rise of breast cancer.

Unfortunately the word hasn't gotten around to the Indians:

Potassium bromate and iodate: Why the presence of these chemicals in bread can harm you

From "firstpost" in India ...

I found one other note in the book of personal interest: there appears to be some association with Afib (which I have) and iodine deficiency, so I started taking:

... in addition to my potassium and magnesium heavy regimen ...