I believe the pink is from red dye. Traces of lead, mercury, other heavy metals and arsenic can be found in various food sources as well as table salt. Talking pink curing salt #1
I do not get the pink salt thing. It is pink because it contains impurities in the form of minerals. Unfortunately, some of those are lead, mercury and arsenic.
I've definitely heard of certain sources of "pink salt" (ie: Himalayan Salt) that have been found to contain some of the impurities you mention.
However, in the discussion here, we're talking about "pink curing salt" which is artificially colored to aid in distinguishing it from regular salt (not a good idea to put curing salt on your eggs....) "Pink curing salt" should NOT have any of the trace impurities you mention.
I'm not a salt/minerals expert by any means, but pretty sure I've got this right.