May 22, 2024

Arsenic: Zurich Central Library found no contaminated books – News


The library tested old books for the toxic substance arsenic. However, unlike other libraries, no evidence has been found yet.

Arsenic is a powerful poison. Depending on the dose, it can be fatal to humans. Because old books can also be contaminated, many libraries are currently banning some of their holdings, such as those at the German universities of Bielefeld and Düsseldorf.

We have not discovered any concrete evidence of books containing arsenic.

But Zurich Central Library is different. Their old books can still be borrowed, she confirmed when asked by the regional magazine Zurich Schaffhausen.


Old books can still be borrowed from the Zurich Central Library.

Keystone/Walter Perry

“We have not discovered any concrete evidence of books containing arsenic,” says Stefan Wiederker, senior librarian responsible for special collections and digitization. They recently took another close look at all the old books as part of a digitization project. They had never encountered arsenic in the Central Library before.

Toxic green

When it comes to the toxin, the focus is on books dating back to the 19th century, especially those with green covers. The reason: arsenic is mainly present in a certain color called “Schweinfurt green.” This bright green color was used to protect books and other objects from parasites.

A person runs a cotton swab over the top of an old book.


In studies such as the one taking place at the Düsseldorf University Library, the focus is on the books in the “Schweinfurter Grün”.

Keystone/DPA/Federico Gambarini

Because the Zurich Central Library has extensive holdings from this period, it has educated its staff. If there is any doubt, the procedure is clearly defined: “The average employee should not touch the book anymore, but should call our internal specialists,” says Wiederkahr. They would first put the book in “quarantine,” that is, lock it in a container so that no one would come into contact with it again.

If a book in the Central Library does contain arsenic, the library will have it processed by outside experts so that it is not harmful to health.

Baslund’s books were banned

Arsenic is a carcinogen. Things can get dangerous with a soiled book if someone gets their fingers wet before turning the pages. The dust should not be inhaled. As long as the book is on the shelf and not moved, the material should be safe.

Books from the 19th century cannot be accessed for free in the Zurich Central Library in any case, and must be requested.

We want to be on the safe side.

Even in the Baslund Canton Library, old books are not easily accessible. However, it has recently banned some of its historical books. About three percent of the population has doubts. “We want to be on the safe side,” the organization’s director, Susan Wafler, told the regional magazine BaselBaselund. She doesn’t believe the books actually contain arsenic. External experts with special equipment must be brought in to verify.

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