Bright green books from the 19th century may contain a hidden danger — arsenic

A handful of books published in the mid-19th century, bound and covered with a pigment known as emerald green, are both rare and potentially deadly.

The verdant hue, also known as Paris green, contained arsenic — a toxic mineral which created its distinctive colour.

Emerald green was en vogue at the time, widely used in paintings and as a pigment for clothing. Confections were even painted striking shade. 

While it's unlikely that simply handling these books today would cause significant harm, acute symptoms of arsenic exposure can include gastrointestinal symptoms. Long-term effects can lead to lesions and cancer.

"I knew about wallpapers that had arsenic pigment and I knew of book illustrations that had arsenic pigment in them, but you don't expect poison to be covering the outside of a book where you're going to hold it to read it," said Melissa Tedone, a conservator at Delaware's Winterthur Museum.

Tedone first discovered arsenical pigments on book covers while examining a copy of Rustic Adornments for Homes of Taste by Shirley Hibberd — a "gorgeous" book in a "sort of gaudy Victorian way," published in 1857.

Tedone was repairing the book's spine and boards when she found green pigment flaking off, which struck her as unusual.

"It really seemed like the colour was in a thick coating that was just on the surface of the book cloth, rather than a dye which would have penetrated the textile fibres of the book cloth and coloured the fibres themselves," said Tedone. 

Testing the pigment with X-ray fluorescence and raman spectroscopy, two techniques used to examine the structure of a chemical compound, confirmed the pigment contained arsenic.

Now, Tedone is working to bring attention to potentially-toxic titles with the Poisonous Book Project. 

"We're sort of following that path of looking at all the toxic components that could be in book cloth," she told CBC Radio's Day 6. "But then we're also trying to document all of the 19th century mass-produced book bindings that might contain any kind of arsenic in them."

These are precious objects, usually even before we discovered they are arsenical.- Allie Alvis, rare book cataloguer

Arsenic's toxicity was known by the Victorian era, according to National Geographic, but the chemical made emerald green cheap to produce — and popular. 

The colour also wasn't alone in its toxicity. Scheele's green, another popular pigment of the time, also contained arsenic, while chrome yellow was a mix of chromium and lead.

'It was just a nice colour of green'

Allie Alvis, a rare book collections cataloguer for Washington, D.C., book dealer Type Punch Matrix and a former special collections reference librarian at the Smithsonian Libraries, has researched books containing arsenic dating back to the 17th century.

Back then, book binders covered second-hand vellum with a pigment known as vergaut — a colour made by mixing indigo and orpiment, a yellow-orange arsenic sulfide mineral. 

Despite salacious backstories peddled by some booksellers, Alvis says it's unlikely that these books contained toxins for nefarious or security purposes.

"They weren't trying to keep people from putting their hands on these books," she recalled. "Some people speculated in the early days of our looking at these books, was it an insecticide?

"No, it was just because it was green. It was just a nice colour of green."

Alvis is part of a working group with Tedone that aims to provide information to libraries and other institutions on how best to handle books containing arsenical pigments. 

The Poison Book Project suggests wearing nitrile gloves when handling books that may have been painted with emerald green and storing them in isolated polyethylene bags. Winterthur, Tedone said, now stores emerald green books in a rare books collection, away from open stacks. 

So far, the project has identified 92 books that use emerald green on their covers. Tedone notes that not all green-covered books published in the 19th century contain arsenic, and people with older books at home shouldn't panic. 

"We are not aware of any cases of anyone getting seriously ill from handling a book like this," she said. "We just want to make people aware of the potential hazards so that we can avoid any tragedy ever happening from one of these books."

Those who believe their books may contain emerald green can request a Poison Books Project bookmark which includes a colour swatch to help identify the specific shade. 

But despite their potential danger, Alvis says the books shouldn't simply be tossed. Instead, they can offer unique insight into bookbinding techniques and practices from the past.

"These are precious objects, usually even before we discovered they are arsenical," Alvis said.

Written by Jason Vermes. Interview with Melissa Tedone produced by Laurie Allan.