Possibly this play sand is found on the west coast? Majority of postings I have read regarding play sand from either Lowe's or Home DePot the name is "Quickrete"? (as well as what is carried in my local area as well) And another note that was also stated on the older CSJ host, one must also take into consideration where the sand was manufactured at. (I will search through some of the archives on the older host that was saved to see if I can find further info on this...) The query (sp) that mined/packaged the one sold in Calif. May not also sell that sand further east.
And I am quite aware that the site is to a reef site. Is not other creatures and sites how some of the information has been found regarding hermies in the past? If a substrate would be considered safe in a fish/reef aquarium chances are super high it is safe for our hermies. There has been a LOT more research done regarding fish as opposed to our hermies, they are not considered by majority of the public or scientific fields as disposable pets.
A little note too, originally majority of the foods on the do not feed list were listed because they were poisonous to cats, dogs, birds, human, reptiles, etc. Same as many of the safe foods.
Edited to add:
I would be curious to see a close up picture of the play sand as the one was done in this link to compare it to:
http://crabbywiki.com/tiki-index.php?pa ... Substrates