I was thinking, “Prussic acid?” for a joke post, when this came up in your link:
A Berlin police spokesman confirmed that laboratory analysis of the bills had identified traces of sulfuric acid.
“To date we do not have any indication that a crime has been committed,” the spokesman said, adding that it was possible that an accident led to the contamination of the bills.
Close enough!
Your contract, should you choose to accept it, is worth €500. This money will self-destruct in 10 seconds.