Poison books: first comprehensive analysis of 23 elements in suspected old books

Ancient and hazardous industrial practices have been terminated but their products are still available in the anthroposphere, including cultural heritage. The present study aims to raise unprecedented awareness about a multifaceted biblio-toxicology problem and to stimulate a paradigm shift towards a quantitative approach to the presence of toxic metals in heritage sites. For the first time, Inductively-Coupled-Plasma-Optical-Emission-Spectroscopy enabled a thorough qualitative and quantitative multi-element analysis of thirty green books of the 19th- and early 20th-century in the splendid historical civic Library Romolo Spezioli (Italy). They were suspected to contain the toxic Copper Acetoarsenite, based on the Arsenical Book database of the International Poison Book Project. Metal contents and stoichiometry were used to assess the chemical nature of the pigments and shed light on old industry secrets. Aluminium, Barium, Chromium, Lead, and Zinc are the most abundant ubiquitous elements; Copper and Iron are present in all green books even if in lower amounts. Only one book was found to contain both Copper and Arsenic in a mass ratio compatible with Paris Green. Barium and Zinc originate from Barium Carbonate and Zinc Oxide, white pigments used for lightening the final color. Aluminium is probably related to the use of Aluminium Sulfate in machine-made paper manufacture. Chromium, Lead and Iron are possibly related to the use of Chrome Green, a mixture of Lead Chromate and Prussian Blue. The present thorough qualitative and quantitative multi-element results represent a prerequisite for any occupational hygiene study. Volumes containing toxic metals should be sealed in hermetic cases, removed from the open stacks, and stored in a controlled area with restricted access. If consultation is necessary, users should be informed that the books contain heavy metals, they should wear and use Personal Protective Equipment and follow the protocol enforced by the management.