This document came with the insurance bill.
There was also a disclaimer re alcoholic beverages.

Yeah, one article I read said that in order to get enough heavy metals from sea salt to be dangerous, you'd have to consume an on-the-verge-of-fatal amount of salt daily for a very long time.  The salt would cause organ failure before the heavy metals had a chance to do much.

I think the only real warning would be for lead in very young children.  Just like lead-based paint, it would not be fatal, but it can contribute to stunted mental development and neurological problems.