In reference to iodized salt, you would die of salt overdose before there are ill effects from iodine.
e.g. manufacturing error such that a dangerous amount of iodine is accidentally added.
It's probably reasonable for 999 999 people to benefit in exchange for 1 person being very unlucky, but that's a different argument that needs to be made.
And nobody, in this post at least, has made that argument, nor has anyone even linked to such.