Toxic Dyes in Victorian-Era Books May Still Harm Readers

Toxic dyes once used to give cloth-bound books their striking colours may still pose a toxic risk to readers.

A study of Victorian-era books has found toxic substances including lead and chromium. Fortunately, provided people do not lick the books, ordinary contact with these heavy metals is unlikely to result in exposure levels high enough to cause serious harm.

However, those who regularly work with antique books, including librarians and booksellers, may face a greater risk.

The results were presented on a poster at the American Chemical Society's Fall meeting.

"These old books with toxic dyes may be in universities, public libraries and private collections," says chemist Abigail Hoermann of Lipscomb University in the US. "So, we want to find a way to make it easy for everyone to be able to find what their exposure is to these books, and how to safely store them."

Toxic dyes in Victorian-era books

During the 19th century, a new range of dyes became prominent. Bright colours no longer had to come exclusively from scarce natural materials. Arsenic created spectacular, near-neon greens and magentas, while aniline produced rich blacks and vivid purples. Other heavy metals were used to make dyes more durable, helping their colours remain brighter for longer.

This led to more than a few grim deaths, particularly among factory workers. Victorian-era clothing is no longer everyday wear, and people have since learnt not to colour clothes and books with materials that can gradually poison them. Even so, some other vintage items may still be less safe than they appear.

In 2019, art conservators Melissa Tedone and Rosie Grayburn, of the Winterthur Museum, Garden & Library in the US, spotted a book with a cloth cover coloured using a pigment known to contain arsenic. Since that discovery, the Poison Book Project has identified numerous books worldwide that were dyed with the same toxic pigment.

Testing heavy metals in antique book covers

Inspired by the project, Lipscomb University librarians Jan Cohu and Michaela Rutledge asked Lipscomb University chemist Joseph Weinstein-Webb to investigate whether brightly coloured books in their own library collection also held toxic dyes.

Weinstein-Webb and colleagues examined several books using a series of tests. These included X-ray fluorescence to detect arsenic and other heavy metals; inductively coupled plasma optical emission spectroscopy to establish the metals' concentrations; and X-ray diffraction to identify the pigment molecules containing those metals. This was the first use of the latter technique on books.

The testing identified lead and chromium at high, unsafe concentrations in certain samples. In some instances, the material was lead(II) chromate, the yellow pigment best known for providing the brilliant colour in Vincent van Gogh's Sunflowers.

Yet lead(II) chromate contains equal quantities of lead and chromium, whereas the books contained far greater concentrations of lead than chromium. This probably indicates that other dyes, with differing concentrations of these metals, were also used. The researchers are attempting to establish what those dyes are.

For now, the books have been enclosed in plastic and withdrawn from circulation. According to the researchers, some samples contained lead at twice the limit and chromium at six times the limit for acceptable exposure set by the CDC.

"I find it fascinating to know what previous generations thought was safe, and then we learn, oh, actually, that might not have been a great idea to use these brilliant dyes," Weinstein-Webb says.

The team shared its findings to date at the 2024 Fall meeting of the American Chemical Society.