University of Southern Denmark researchers have published an article in The Conversation detailing the deadly discovery.
The three rare books from the 16th and 17th century were undergoing X-ray fluorescence analysis. The idea was the radiation from the X-ray could discern different chemicals in their pages and bindings — and hopefully, uncover lost texts.
Other books in the library had previously been found to have used recycled fragments of much older parchments — such as Roman and canonical law — in their bindings.
So the university was looking for more.
The books were taken to the lab for more intensive analysis intended to peer through the paint to find the chemicals of the print below.
But the analysis threw back an unexpected result.
The green stains were arsenic.
And it was as toxic as the day it was put there.
“This chemical element is among the most toxic substances in the world and exposure may lead to various symptoms of poisoning, the development of cancer and even death,”
the researchers write.
"Now, the library stores our three poisonous volumes in separate cardboard boxes with safety labels in a ventilated cabinet,” the researchers write “We also plan on digitizing them to minimize physical handling. One wouldn’t expect a book to contain a poisonous substance. But it might.”
Source: NY Post