Conversations with Silica Gel

I just found a packet of silica gel in a suitcase I recently purchased. On the packet were the words:
SILICA GEL
"Do not eat."
Throw away.
And I ask myself... why the quotation marks? Are they implying some sort of irony? According to Wikipedia, they must be. Unless, "Do Not Eat" is the title of an artistic work.

Or, more likely, it is a direct quote from the silica gel, itself.