Hidden danger

The good news is that unless you lick or eat old books, accidental contact with heavy metals will not release enough poison into your body to seriously harm you.

But longer-term contact with such books poses a greater threat. Librarians and booksellers who work extensively with antiquarian publications are at high risk. The results of a study on these hazards were presented at a meeting of the American Chemical Society.

These old books containing toxic paint can be found in universities, public libraries, and private collections. So we wanted to find a way to make it easy for everyone to determine how much of these books have been exposed and how to store them safely.
– says Abigail Hoermann from Lipscomb University in the USA.

But let’s go back a bit. In the 19th century, a new class of dyes was invented. Bright hues could no longer be achieved with the help of hard-to-find natural ingredients alone. Arsenic produced gorgeous, almost neon greens and purples. Aniline was used to create deep blacks and striking purples. Other heavy metals help dyes become more stable and retain their shine longer.

The price was many unpleasant deaths, especially among factory workers. But these colors were not only added to books. They appeared in the wallpaper, clothes, cosmetics and other everyday objects that surrounded people. Today, of course, we do not use items from that period, but various antiques can still be found all over the world.

Experiments begin

In 2019, restorers Melissa Thedon and Rosie Greyburn of the Winterthur Museum, Garden and Library in the US noticed a book whose cloth cover had been stained with a pigment known to contain arsenic. Since then, many more books stained with the same toxic pigment have been discovered around the world as part of the “Toxic Book” project.

Hearing about the initiative, Lipscomb University librarians Ian Kohu and Michaela Rutledge approached Lipscomb University chemist Joseph Weinstein-Webb to find out if the brightly colored books in the library’s collection contained toxic dyes. So the scientist and his team subjected a series of samples to a variety of tests, including X-ray fluorescence to check for arsenic and heavy metals, and inductively coupled plasma optical emission spectroscopy to determine the concentration of these metals. They also used X-ray diffraction to identify pigment molecules that contain the toxin. This is the first time this method has been applied to books.

All these checks came out high and even dangerous concentrations of lead and chromium In some cases, these were in the form of lead(II) chromate, the yellow pigment best known for the vibrant colors of Vincent Van Gogh’s Sunflowers. But lead(II) chromate contains equal parts lead and chromium, and books show a much higher concentration of lead than chromium. This likely means that other paints were used that contained different concentrations of the metal. Researchers are still working to figure out which ones.

Meanwhile, the books were sealed in plastic and free access to them is now closed: Some examples contained twice as much lead and six times as much chromium as standards allowed by the U.S. Centers for Disease Control and Prevention.