Screening Books for Arsenic and other Toxic Pigments

The toxicity of  books presents a previously unknown yet significant hazard within the realms of literature collection and conservation science.

This hazard can derive from two different sources: The first of these is the original book binding itself, as throughout history, various materials have been used for bookbinding such as leather, cloth, and paper. These materials are often colored using different dyes with additional decorative layers painted or applied onto their surface.

Some of the pigments that were historically used in book decorations contain hazardous materials such as the heavy metals arsenic, lead and mercury. These pigments were favored for their vibrant colors and durability. Aside from the contact hazards from handling, book coatings that contain these pigments can flake or chip, releasing harmful particles into the surrounding environment and spreading contamination to neighboring surfaces. Therefore the preservation and handling of books adorned with toxic decorations, also known as "Poison Books", demands careful consideration.

The second potential hazard source is pesticides used to preserve books. Books are sometimes preserved with pesticides to prevent pests and fungi from damaging them. These days, the pesticides in use do not pose any risks, however historically organochlorine as well as salts of heavy elements based on arsenic, lead, copper and mercury were used. These substances are harmful not just to pests, but to the human body too (Angelova et al., Cultural Heritage, 2023).  

X-Ray Fluorescence (XRF) Analysis using a handheld system is an ideal solution for the screening and identification of books containing toxic heavy elements. Handheld XRF systems are rapid tools for the determination of the presence of such hazardous materials in a non-invasive way that can be applied to a huge collection with little effort.

Discover more about the pigments of interest, recommended methods for poison book screening and the benefits that Handheld XRF can bring to collections and libraries below. 

The identification of poison books in a collection takes place over several stages - the first of which is a visual inspection to determine which books are at risk of being poisonous.

Certain pigments with characteristic colors are known to contain toxic heavy metals. The most prolific and toxic of these pigments is Paris Green – a copper acetoarsenite pigment with a vivid emerald green color that was popular in the Victorian Era. Other known pigments that contain heavy metals include another arsenic-containing compound, Orpiment, as well as the lead-containing Chrome Yellow. The distinctive colors of these pigments can help with the identification of potentially poisonous books.

In addition to the visual identification of suspicious pigments, conservation scientists can also use other information to identify books that could potentially be decorated with toxic pigments. This includes identifying other visual features on the books cover (gilding, patterns on the binding material such as leather etc.) and checking the date of publication of the book.

Regarding books decorated with arsenic pigments more information on the features to look out for is provided on the website of the Poison Book Project of the University of Delaware. 

Pesticides may not be that easily trackable. Sometimes historic documentation on conservation campaigns may provide information, but often no visible change is notable. 

Verifying if a Book Binding is Toxic

Following the identification of books that are at risk of containing poisonous pigments they must be screened using a scientific testing method. Guidelines issued by the German Librarians Association  (Deutscher Bibliotheks Verband) recommends to start the analytical approach by conducting  X-Ray Fluorescence (XRF) analysis, followed by chemical testing using a test kit, or inspection using a polarization microscope.

The initial use of XRF analysis is based on it's non-invasive nature, high sensitivity for a wide range of elements, and simple operation that facilitates an easy handling and offers quick results.

As discussed above, X-Ray Fluorescence (XRF) spectroscopy is a fitting method for the screening of books to determine if they contain, or are contaminated with, toxic heavy metals. XRF is a non-invasive analytical method that uses X-rays to determine which elements are present in a sample being analyzed.

Determination of mass deposition of toxic pigments as well as pesticides is still a desideratum and requires ground research, but can be accessed using XRF analysis even though the materials in questions are of a non-infinite nature. For more information, you can watch the on-demand webinar:

XRF can be carried out using handheld XRF systems, meaning the analysis can be brought to the sample and not the other way round. Bruker's TRACER is a handheld XRF instrument designed for use in cultural heritage environments such as libraries, museums and archaeological sites.

The TRACER is an easy-to-use tool that provides users with data on the elemental composition of a sample in seconds. Elements from sodium to uranium can be detected, meaning common toxic pigments containing arsenic, lead or mercury can easily be identified.