More and more evidence of toxic books with toxic dyes

If you come across brightly colored, cloth-bound books from the Victorian era, you should handle them with caution or even avoid them altogether. Some of their attractive hues come from dyes that could pose a health risk to readers, collectors or librarians.

The latest investigation into these toxic books used three techniques – including one not previously used on books – to identify dangerous dyes in a university collection and found that some volumes may not be safe to handle.

The researchers will present their results at the fall meeting of the American Chemical Society.

“These old books with toxic dyes can be found in universities, public libraries and private collections,” says Abigail Hoermann, a chemistry student at Lipscomb University. Users can be at risk if the pigments from the cloth covers rub against their hands or become airborne and inhaled.

“So we want to find a way for anyone to easily find out how much contact they have with these books and how to keep them safe.” Hoermann, recent graduate Jafer Aljorani and student Leila Ais conducted the study together with Joseph Weinstein-Webb, an assistant professor of chemistry at Lipscomb University.

The study began after Lipscomb librarians Jan Cohu and Michaela Rutledge contacted the university's chemistry department about testing colorful, cloth-bound books from the 19th and early 20th centuries from the school's Beaman Library. Weinstein-Webb was intrigued to learn that the Winterthur Museum, Garden & Library had previously tested its own 19th-century books for the presence of an arsenic compound called copper acetoarsenite.

This emerald-green pigment was used in Victorian-era wallpaper and clothing and, as Winterthur discovered, in fabric book covers. This discovery led to the creation of the Poison Book Project, a crowdsourced research initiative that uses X-ray fluorescence (XRF), Raman spectroscopy and other techniques to track down toxic pigments in books around the world. Weinstein-Webb and the Lipscomb students he recruited launched their own investigation in 2022.

For the Lipscomb book project, the team used three spectroscopic techniques:

• X-ray fluorescence was used to qualitatively check whether arsenic or other heavy metals were present in any of the book covers.
• Inductively coupled plasma optical emission spectroscopy (ICP-OES) to determine the concentration of these metals.
• X-ray diffraction (XRD) to identify the pigment molecules containing these metals.

Although XRD has been used before to examine paintings and wallpaper, this is the first time it has been used to check books for toxins, Ais says. The XRD tests are being conducted in collaboration with Janet Macdonald of Vanderbilt University.

Recently, researchers used XRF data to prove that some of the Lipscomb books contained lead and chromium. To quantify the amounts, they cut samples the size of a small paper clip from the cloth covers and then dissolved them in nitric acid.

Their analysis by ICP-OES showed that lead and chromium were present in high concentrations in some samples. Subsequent XRD tests showed that in some cases these heavy metals were present in the form of lead(II) chromate, one of the compounds that contribute to the chrome yellow pigment that Vincent van Gogh favored in his sunflower paintings.

However, the book covers contained far more lead than chromium, which is a bit puzzling since lead(II) chromate contains equal amounts of lead and chromium. The researchers suspect that the dyes used to color the books contain other lead-containing pigments that lack chromium, such as lead(II) oxide or lead(II) sulfide. The team is working to identify these other compounds in the yellow pigments.

Weinstein-Webb and the students also wanted to determine whether the heavy metal levels in the Lipscomb books could be harmful to librarians who work with them. In some of the book covers, the researchers discovered metal levels that exceeded the acceptable limits for chronic exposure set by the Centers for Disease Control and Prevention (CDC).

In the dissolved sample from the most contaminated ceiling, the lead concentration was twice the CDC limit and the chromium concentration was almost six times higher. Chronic exposure to inhaled lead or chromium can lead to health effects such as cancer, lung damage, or fertility problems.

“I find it fascinating to learn what previous generations thought was safe, and then we learn that maybe it wasn't such a good idea to use these brilliant dyes,” says Weinstein-Webb.

The results prompted the Lipscomb Library to seal colorful 19th-century books that had not yet been tested in zip-lock plastic bags for handling and storage. Meanwhile, books that were found to contain dangerous dyes have also been sealed in bags and removed from public circulation.

After the researchers conduct further testing, they plan to share their results with the Poison Book Project and help raise awareness among librarians and collectors about the safe handling, preservation and storage of these books.

They also hope that others will follow their example and use XRD, as it does not require researchers to take samples from books. “In the future,” says Hoermann, “we want to give libraries the opportunity to test their collections without destroying them.”