Bielefeld University Library has taken tens of thousands of books out of circulation. Arsenic compounds could have been used in the production of publications in the 19th century.
The exact number of copies affected by the 60,000 volumes remains uncertain. According to the library, it could be less than ten percent. The German Library Association confirms that this problem has also been known in other libraries for a long time. Up to 18,000 books could be contaminated with arsenic at the University of Duisburg-Essen.