Are you in Canada? Apparently this is put in distilled water that is used to mix anti-freeze to prevent animals(and kiddies) from drinking same because of the bitter taste. I think I'd use something else for my humi! Doubt too much harm has been caused yet, but might be a good ieea to change water! Or, just buy Boveda packs!
http://www.cheaphumidors.com/BOVEDA.html