These green books are poisonous – and there might be one on a shelf near you

Libraries and rare book collections often contain volumes with poisons on their pages, from famous murder mysteries to seminal works on toxicology and forensics. The poisons described in these books are just words on a page, but some books scattered around the world are literally poisonous.

These poisonous books, produced in the 19th century, are bound in vivid cloth colored with a notorious pigment known as emerald green which is mixed with arsenic. Many of them go unnoticed on the shelves and in collections. So Melissa Tedone, the laboratory head for library materials preservation at the Winterthur Museum, Garden & Library in Delaware, has started an effort called the Poison Book Project to locate and catalog these harmful volumes.

To date, the team has discovered 88 books from the 19th century that contain emerald green. Seventy of them are covered with a bright green paper cloth, and the rest have the pigment incorporated on paper labels or decorative elements. Tedone even found an emerald green book on sale at a local bookstore, which she bought.

While these poisonous books would likely cause only minor damage unless someone decided to devour a nearly 200-year-old tome, the seductive and vibrant books aren’t entirely without risk. People who handle them frequently, such as librarians or researchers, may accidentally inhale or ingest arsenic-containing particles, which could make them lethargic and dizzy or suffer from diarrhea and stomach cramps. Against the skin, arsenic can cause irritation and lesions. Severe cases of arsenic poisoning can lead to heart failure, lung disease, neurological dysfunction and, in extreme situations, death.

So how common are these poisonous green books? “It’s a bit hard to predict because our dataset is still small, but I would definitely expect there to be thousands of these books around the world,” Tedone says. “Any library that collects mid-19th century cloth publishers’ bindings is likely to have at least one or two.”

A color to die for

Emerald green, also known as Paris green, Vienna green and Schweinfurt green, is the product of the combination of copper acetate and arsenic trioxide, producing copper acetoarsenite. The poisonous pigment was commercially developed in 1814 by the Wilhelm Dye and White Lead Company in Schweinfurt, Germany. It was used everywhere, from clothing and wallpaper to fake flowers and paint. To say that Victorian England was bathed in emerald green is an understatement: by 1860, over 700 tons of the pigment had been produced in the country alone.

The toxicity of arsenic was known at the time, but the vibrant color was nonetheless popular and inexpensive to produce. Wallpapers spread poisonous green dust that covered food and smeared floors, and clothing stained with the pigment irritated the skin and poisoned the wearer. Despite the risks, emerald green was ingrained in Victorian life – a color to literally die for.

As toxic green products flooded parts of Europe and the United States, another invention transformed the bookmaking industry. Early 19th century books were handmade, leather-bound creations, but the Industrial Revolution soon provided a way to mass-produce books for a growing population of readers.

Traditional dress fabric cannot withstand the book binding process, and it is not strong enough to function as a cover. In the 1820s, publisher William Pickering and bookbinder Archibald Leighton developed the first commercially viable process for coating fabric with starch, filling the gaps in the weave and producing a strong material: the first book cloth.

“It was a game-changer,” says Tedone. “Fabric was so much cheaper than leather, which meant you could sell books at different prices.” The process affected more than the publisher’s bottom line; it changed the way books were read. “They were making the books accessible to a much wider demographic, catering to people at all levels of the economic spectrum.”

Cloth-bound books took off in the 1840s, and the process of creating book cloth became a closely guarded secret. “It meant a lot of money for the publishers, so unfortunately there’s not a lot of documentary evidence of slick making,” Tedone says.

What we do know is that book covers could suddenly take on a wide range of hues. Bookmakers have produced a colorful range of books with dyes, which are solutions that chemically bind to the substance they are applied to, and pigments, which are materials that physically coat the substance, like mud dried on a Sunday dress. As such, the most fashionable shade of green pigment at the time could grace the covers of popular books.

The problem with pigments, however, is that they tend to crack, peel and flake over time.

Poison in the library

In the spring of 2019, Tedone received a request from a Winterthur gallery curator to borrow a book from the library for exhibition: Rustic ornaments for homes and tastepublished in 1857.

“This book in particular was very beautiful, bright green with lots of gold stamps. It was visually very stunning, but it was in very poor condition,” says Tedone. broken, so it had to be preserved before it could be exhibited.”

With the beautiful book still broken under the microscope, Tedone looked at the front of the painting. “There was a black, waxy excretion on the surface, and I was trying to brush it off the tablecloth with a porcupine quill,” she says. “And then I noticed that the dye on the canvas was flaking off very easily around the area where I was working.”

To the untrained eye this might seem normal for a 162 year old book, but to Tedone it was surprising. “It didn’t look like the fabric was dyed,” she said. “It looked to me like the starch layer on the fabric was maybe mixed with some pigment.”

To learn the identity of the mysterious green pigment, Tedone turned to Rosie Grayburn, head of the museum’s scientific research and analysis laboratory.

Grayburn first studied the sample with an X-ray fluorescence spectrometer, which bombards the material with X-rays and measures the energies of the emitted photons to determine its chemical composition. This technique can tell you what elements are present, but not how they are arranged in a molecule. Another technique using a Raman spectrophotometer measures how light from a laser interacts with target molecules, moving the laser’s energy up or down. Just as each person has unique fingerprints, each molecule has a characteristic Raman spectrum.

The sensitivity of these techniques is essential, but it is equally important that they are non-destructive. “You shouldn’t damage the artwork,” says Grayburn.

X-ray fluorescence revealed the presence of copper and arsenic in the green pigment, a key finding, and the unique fingerprint of Raman spectroscopy positively identified the pigment as the infamous emerald green.

Handling Poisoned Literature

The team then used the soil laboratory at the University of Delaware to measure the amount of arsenic in the cover of rustic ornaments. They found that the blanket contained an average of 1.42 milligrams of arsenic per square centimeter. Without medical care, a lethal dose of arsenic for an adult is about 100 milligrams, the mass of several grains of rice.

“What are the implications of having so much arsenic in the books, on your gloves, during treatment? What does this mean for your health and safety? asks Grayburn.

To answer these questions, Tedone and Grayburn reached out to Michael Gladle, director of environmental health and safety at the University of Delaware. “Arsenic is a heavy metal and has some toxicity associated with it, mostly through inhalation or ingestion,” he says. The relative risk of emerald green book web “is frequency-dependent,” Gladle says, and is a major concern “for those in the conservation business.”

Gladle suggests that anyone handling these tomes should isolate the books and work on them on tables with fume hoods to control arsenic particles. “People who have access to these old books for research purposes should wear gloves and use a designated space to examine these books,” he says.

Following Gladle’s recommendations, the Winterthur Library removed nine arsenic-coated green books from circulation and placed them in large, sealable polythene plastic bags. When handling or storing distressed books, they wear nitrile gloves, then wipe down hard surfaces and wash their hands.

The team then launched a search for more books, traveling 25 miles northeast to America’s oldest library, the Library Company of Philadelphia. There they identified 28 more emerald green cloth books. With a larger sample, they found that most of the books featuring emerald green canvas containing arsenic were published in the 1850s.

To help others identify arsenic-covered books and their potential risks, the team designed color bookmarks with images of emerald green covers along with handling and safety precautions. They sent more than 900 of these bookmarks across the United States and to 18 other countries, which allowed six other institutions to identify books containing arsenic in their collections.

Despite the toxicity of arsenic-based emerald green in household items, articles, and clothing, it was never banned. Instead, its use died out naturally, either because of its toxic reputation or because the color simply went out of fashion, much like avocado green appliances in the 1970s.

And the most important message from ever-conservative Tedone is don’t throw away the pounds of poison. “You don’t have to panic and throw them away,” she says. “We just want people to take this seriously.”