Initially, three sixteenth and seventeenth century books were identified in the Herlufsholm Special Collection of the University Library of Southern Denmark, the bindings of which were partly decorated with green paint found to contain arsenic. This was reported in Denmark [1] and projected to the public, internationally, via The Conversation [2]. The matter received considerable public attention due to the apparent resemblance of the three green books to the deadly book of Aristotle that plays a vital part in the plot of Umberto Eco’s 1980 novel The Name of the Rose. This media coverage precipitated the discovery of another book of the same period, also with green paint at the Smithsonian Libraries in Washington DC, USA. It became clear very quickly using portable X-ray fluorescence (XRF) that the latter also contained arsenic. Originally, relying only on µ-XRF in Denmark it was speculated that the paint could perhaps be Emerald Green (Cu(CH3COO)2·3Cu(AsO2)2), which the present work shows is not the case. This seems to be the first report on poisonous green book bindings in the scientific literature. The question of the nature of the green colour, its original purpose, its chemistry, the particular history of the physical objects, as well as issues related to the handling and keeping of the particular books—and of similar painted works—is of potential importance to academic and national libraries, archives, museums, collectors, as well as to historical chemistry and physics.
The results of the present work are contextualized with a brief discussion of the materials used to create the paint, as well as sixteenth and seventeenth century binding practice. Finally, this paper addresses what the University of Southern Denmark and the Smithsonian Libraries are doing to reduce the threat of poisoning to staff and researchers, and what this discovery of arsenical books means to other libraries who may hold similar collections items.
The samples
Four books have been identified as having arsenic rich paint applied to the book bindings. Three are from University of Southern Denmark University Library; one is from the Smithsonian Libraries in Washington DC, USA. Photographs of the book bindings, the title pages, and the sampling sites are shown in Fig. 1. Descriptions of the books are listed below.
KLR-11920: Herlufsholm 768.6 (Fig. 1a)
Titles (two works bound together):
- 1.
Historia Boiemica. A CL. V. Thoma Iordano Medico nouis Genealogiarum, Episcoporum, Regum, Ducum Catalogis, necessariis, quinètiam Annotationibvs sic ornata & illustrata, vt nunc demùm edita dici possit.
- 2.
De Bohemorum, et ex his Imperatorum Aliquot origine ac gestis historia.
Authors:
- 1.
Johannes Dubravius (1486–1553).
- 2.
Aeneas Silvius (Pope Pius II) (1405–1464).
Publisher: Pietro Perna (1519–1582), Basel.
Year of publication: 1575.
Book block size in cm (height, width, depth): 31.5 × 20 × 3.
Binding: Contemporary sixteenth century blind-tooled alum-tawed half-pigskin with a palmette frieze border. Blind-tooled (rolled) biblical motifs and texts in two centred columns, encased by blind-tooled lines. Seven raised spine bands. Head, foredge and tail in red. The texts: (1) ECCE AGNVS DEI, QUI TOLL (-is peccata mundi, miserere nobis)—John 1:29: Behold the Lamb of God that taketh away the sin of the world. (2) ECCE VIRGO CONCIPIET—Isaiah 7:14: Behold a virgin shall conceive. (3) HIC EST FILIVS MEVS DILECT (-us)—2 Pt 1:17–18: This is my son, the beloved. (4) (O) MORS ERO MORS TVA MORSVS—Hosea 13:14: O Death, I will be thy death [3, 4]. Heavy wear on the biblical motifs and texts. On top of the front cover, the blind-tooled letters H. H. D.(?) Bottom: the year 1581. Green pigment on parchment fragments (front and back cover), obscuring medieval text (unidentified). Blind-tooled diamond pattern in rolled lines on parchment fragments.
Provenance (modern labels of ownership excluded):
KLR-11971: Herlufsholm 775.2 (Fig. 1b)
Title: Anglica Historia Libri Vigintiseptem. Ab ipso autore postremùm iam recogniti, ádq[ue]; amussim, salua tamen historiæ veritate, expoliti. Indices rerum singularum et vtiles et copoisos, in operīs calce adiectos reperies. Simon Grynaevs Lectori. […]
Author: Polydore Vergil of Urbino (c. 1470–1555).
Publisher: Thomas Guarin (1529–1592), Basel.
Year of publication: 1570.
Book block size in cm (height, width, depth): 34 × 21 × 5.
Binding: Contemporary sixteenth century blind-tooled alum-tawed half-pigskin with a palmette frieze centre column (rolled), flanked by blind-tooled (rolled) biblical motifs and texts in two columns, encased by blind-tooled lines. Seven raised spine bands. The texts: (1) APPARVIT BENIGNI D—Epistle of St Paul to Titus 3:4: But when the goodness and kindness of God our Saviour appeared. (2) ECCE AGNUS DEI—John 1:29: Behold the Lamb of God that taketh away the sin of the world. 3) DATA EST MICHI OM [nis potesta in calo]—Matthew 28:18: All authority in heaven and on earth has been given to me. 4) DE FRVCTV VENT (-ris: VENT is rolled with a reversed N)—Psalm 131:11: The Lord hath sworn truth to David, and he will not make it void: of the fruit of thy womb I will set upon thy throne [3, 4]. Green pigment on parchment fragments, obscuring medieval text (front cover: Corpus Iuris Canonici, De rescriptis, Sexti Decret. Lib. I. Tit. III. Cap. XII-XIV. Back cover: Corpus Iuris Civilis (Justinian), Feudorum Lib. I, Tit. IX-XIII.). Blind-tooled lines on parchment fragments (front and back cover).
Provenance (modern labels of ownership excluded):
R. V. D. M. Valentino Schachtio fratri, in(?) Ch. Ani. ddt Henricus Schinkius.
Heinrich Schinke (died 1593) was second vicar in Güstrow, Mecklenburg [5, 6]. Valentin Schacht (1540–1607), was a professor of theology at the University of Rostock (est. 1419) [7], archdeacon/pastor at St. Jakobi in Rostock, rector of the University of Rostock 1570, 1582, 1588, 1594, and 1600. The abbreviation “R. V. D. M.” could stand for” Rector Universitatis Dominus Magister”. It would appear that the older Heinrich Schinke gave (lat. dedit) this book to his brother of the church, Valentin Schacht.
G. Sorterup.
Possibly the Danish vicar, Jørgen Jørgensen Sorterup (1662–1723). Jørgen = Georg.
KLR-11972: Herlufsholm 186.6 (Fig. 1c)
Title: Vitæ Patrvm Das ist: Das Leben der Altväter/Zu Nutz Den Predigern Göttliches Worts/Erstlich/So viel müglich/vernewert vn besser zugerichtet […] mit einer Vorrede Doctor Martin Luther. Sampt dem Büchlein Hermanni Bonni, von den Aposteln/Martyrern/Bischoffen vnd H. Vätern. Nun aber Auss dem Lateinischen zu Wittenberg Anno Christi 1578. letzt gedruckten Exemplar verteutschet/Durch M. Sebastianum Schwan/Pastoren zu Ratzeburg im Fürstenthumb Nidersachsen. […]
Author: Georg Major (1502–1574).
Publisher: Laurentz (Lauritz) Albrecht (deceased before 1605), Lübeck.
Year of publication: 1604.
Book block size in cm (height, width, depth): 19 × 15.5 × 5.
Binding: Early seventeenth century blind-tooled alum-tawed half-pigskin with rolled flowers and intertwining leaves and diamond shaped figures, encased by blind-tooled lines. Six raised spine bands. Medieval manuscript fragments on the front and back cover. Green pigment on parchment fragments, obscuring medieval text (parts of Sancti Gregorii Homiliarum in Ezechielem, Liber I, Homilia X i.a.). Blind-tooled lines on parchment fragments.
Provenance (modern labels of ownership excluded):
Hedewig: Von: Allefeldt.
This previous owner is most likely of the noble family line Ahlefeldt with numerous members in Schleswig–Holstein and Denmark. Several women go by the name of Hedevig or Hedvig.
KLR-12109: Smithsonian QH41.A43 1602 Barcode 39088002066793 (Fig. 1d)
Title: De animalibus insectis libri septem: cum singulorum iconibus ad viuum expressis autore Vlysse Aldrovando in almo Gymnalio Bonon, rerum naturalium professore ordinario, ad sereniss, Franc. Mariam, secundum, vrbini, ducem sextum: cum indice copiosissimo.
Author: Ulisse Aldrovandi.
Publisher: Bapt. Bellagambam, Bologna.
Year of Publication: 1602.
Book block size in cm (height, width, depth): 35 × 23 × 5.6
Binding: Contemporary three-quarters binding of blind-tooled pigskin with acanthus leaves and classical busts and green-stained manuscript waste. Five raised bands. Title in ink on spine. Pigskin corner on lower back board absent, displaying unstained manuscript waste. The text of the manuscript waste is as-yet unidentified.
Provenance:
Unfortunately, not much is known about how or when this book came into the collection of the Smithsonian Libraries. The presence of a blind-embossed “Smithsonian Institution National Museum” stamp indicates that the book was in the collection prior to the opening of the Natural History Museum in 1911.
There are a few other small annotations on the front and rear pastedowns that appear to indicate a contemporary shelfmark.
Analytical methods
Sample mounting and use
Samples of ca. 5 × 5 mm were procured by cutting with a scalpel from the inside of the bookbindings. The sample size was considered necessary in order to perform the array of analytical techniques described below, the large sample size mainly due to have sufficient area for XRD. A ca. 5 × 2 mm piece was cut of each sample and embedded edge-up in Struers Epofix Resin. The embedded sample was ground on a Struers LaboForce 100 grinding and polishing machine using 500 and 1200 SiC abrasive foils, followed by diamond polishing with 9, 3, and 1 µm diamond paste.
Optical microscopy
Optical images were recorded in polarized light using a Zeiss Axioscope microscope equipped with an Axiocam 105 Color camera.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS)
Laser ablation (LA) was performed with a CETAC LXS-213 G2 equipped with a NdYAG laser operating at the fifth harmonics at a wavelength of 213 nm. A 10 µm circular aperture was used. The shot frequency was 20 Hz. The scans were performed with a scan speed of 10 µm/s. The helium flow was 600 mL/min. The laser operations were controlled by the DigiLaz G2 software provided by CETAC [8].
Inductively coupled plasma mass spectrometry (ICP-MS) analyses were carried out using a Bruker Aurora M90 equipped with a frequency matching RF-generator. The basic parameters were as follows: radiofrequency power 1.30 kW; plasma argon gas flow rate 16.5 L/min; auxiliary gas flow rate 1.65 L/min; sheath gas flow rate 0.18 L/min. The following isotopes were measured all without skimmer gas: Na23, Mg24, Al27, Ca44, Fe57, Cu65, As75, Rb85, Sr88, Ag107, Sb121, Ba137, Au197, Hg202 and Pb208. The analysis mode used was peak hopping with 3 points per peak, and the dwell time was 1 ms for Na23, Ca44, Mn55 and Fe57, and 10 ms for the rest of the analysed isotopes. The total scan time for all the selected isotopes was approximately 280 ms.
LA-ICP-MS analyses were performed on the Epoxy embedded samples.
µ-X-ray fluorescence spectrometry (µ-XRF)
An ARTAX-800 µ-XRF manufactured by Bruker-Nano was used for the µ-XRF measurements. The beam diameter was between 60 and 64 µm in diameter. A high tension of 50 kV and a current of 600 µA were used. For each sample, 200 scans were measured with a 30 s live time under a constant He flow of 1 mL/min. The penetration of 50 keV X-rays is several µm and based on absorption calculations for the outgoing low energy X-rays (NIST-XCOM) it can be seen, that the analyses reflect a layer of approximately 1–20 µm thickness depending on the chemistry of the outermost layer.
Absolute calibration of the concentrations has been performed by the DCCR-method (Direct Calibration from Count Rates) provided by the Bruker software using the standard reference material NIST-2711. For the determination of S, a NIST-610 standard was used with the assumed S concentration value of 570 ± 70 µg/g [9]. The quantitative results can only be considered semi-quantitative because of the difference between the matrix of the samples (paint layer on parchment) and the matrix of the standard materials (glass for NIST-610 and pressed pellet from NIST-2711).
The µ-XRF measurements were performed perpendicular to surface area of the cut samples from the four books.
X-ray diffraction (XRD)
The analysis was performed using a PANalytical X’Pert PRO MPD system (PW3050/60) diffractometer with Cu Kα radiation as the source (λ = 1.54 Å) and a PIXcel3D detector. The X-ray generator was set to an acceleration voltage of 45 kV and a filament emission to 40 mA. The samples have been placed in a sample-holder and was sealed between two sheets of Kapton polyimide foil. All measurements were performed with a 2Θ angle step size of 0.013° and a counting time of 1500 s per step in a range from 5° to 75° 2Θ. An empty sample holder with the Kapton polyimide foil was also measured in the same conditions in order to subtract the background caused by the foil. Data were collected using X’Pert Data Collector. The qualitative analysis was performed using Highscore Plus software and Crystal Impact Match software linked to the ICDD PDF-2 database. The semi-quantitative results have been measured using the reference intensity ratio method (RIR).
The XRD measurements were performed on the painted surface of the cut out samples.
Raman spectroscopy
Raman measurements were conducted using a Thermo Scientific DXR Raman microscope equipped with a 633 nm laser and a 10× objective. The laser power was 3 mW, the spectral resolution was 5 cm−1 at full width at half maximum (FWHM) and the spot size had a diameter of 2.1 µm.
The Raman spectroscopy was performed on the painted surfaces of the cut out samples.
Mass spectrometry
A sample of surficial scrapings of less than 0.1 mg of the green paint was dissolved in acetonitrile and a mass spectrum acquired on a Bruker micro TOF QII. The instrument was operated with electrospray ionization in positive mode. The capillary voltage was set to − 4200 V.
Air samples
At the Smithsonian Libraries, air samples were collected for both arsenic and arsine to help determine exposure to library staff, and to provide information for developing appropriate storage and handling protocols. The air sampling was performed for only one of the four books in this study, the KLR-12109.
Two types of air samples were collected, personal exposure and ambient air. Air monitoring for personal exposure was performed on a Smithsonian Library staffer during the procurement of the book binding sample for this study. A laboratory chemical fume hood was used to control exposure during the book sampling. Ambient air samples were collected, subsequently, near the surfaces of the book while the book was unhandled and left inside the laboratory chemical fume hood, with the sash positioned down and the fan turned off, to produce “worst-case scenario” air concentrations. Air samples were also collected, at the same time, on another Smithsonian Libraries conserved book that had arsenic-containing edge staining. This book was handled, and pages were thumbed through by the staffer during the sampling. While this book was not part of this study, the results are included in this paper to provide additional information to the reader on potential exposure levels from other types of arsenic-containing books.
Personal exposure air monitoring samples for arsenic (inorganic) particulate and arsenic trioxide vapor were collected using calibrated air sampling pumps, connected via Tygon@ tubing to 37 mm mixed cellulose ester filter cassettes (MCEF) with treated backup pads, and positioned in the staffer’s breathing zone (BZ) at collar level. Ambient air samples were similarly collected, with sampling cassettes positioned in close proximity to the book’s surface. The air sampling pumps were calibrated at a flow rate of 3 L per minute. All samples, including field blanks, were analyzed for arsenic using OSHA Method ID105 M (ICP-MS) by Analytics Corporation, an accredited industrial hygiene laboratory.
Personal exposure air monitoring samples for arsine were collected using calibrated air sampling pumps, connected via Tygon@ tubing to charcoal sampling tubes, and positioned in the worker’s BZ at collar level. Ambient air samples were similarly collected, with sampling tubes positioned in close proximity to the book’s surface. The air sampling pumps were calibrated at a flow rate of 0.2 L per minute. All samples, including field blanks, were analyzed for arsine using NIOSH Method 6001 M by Analytics Corporation, an accredited industrial hygiene laboratory.
Arsenic exposure air monitoring results were compared with the OSHA Permissible Exposure Limit (PEL) of 0.01 milligrams per cubic meter of air (mg/m3) and the action level of 0.005 mg/m3, which is used to determine the need for inclusion in an occupational medical surveillance program. Arsine results were compared with the OSHA PEL of 0.05 parts per million parts air (ppm) and the action level of 0.025 ppm. All OSHA PELs and action levels are calculated as 8-h time-weighted average (TWA) exposure concentrations.
The exposure air monitoring results were also compared to the non-regulatory exposure limits recommended by ACGIH and NIOSH. ACGIH and NIOSH limits are considered best practice, “health-based” exposure limits that nearly all workers may be repeatedly exposed to without adverse health effects, based on the available scientific information. The ACGIH Threshold Limit Value (TLV) for arsenic is the same as the OSHA PEL. The ACGIH TLV for arsine is 0.005 ppm. The NIOSH Recommended Exposure Limit (REL) for arsenic is 0.002 mg/m3 for a 15-min exposure, and the REL for arsine is 0.0006 ppm, also for a 15-min exposure.
Wipe samples
At the Smithsonian Libraries, surface wipe samples were also collected for arsenic to assess surface contamination, which could pose an arsenic exposure hazard to staff, in addition to handling the books themselves. Detectable arsenic concentrations on wipe samples indicate contamination on surfaces contacted by the book, which would need to be addressed by handling and storage protocols The wipe sampling was performed for only one of the four books in this study, the KLR-12109.
The arsenic wipe samples were collected, using a Ghost Wipe kit, from the blotter paper placed under the book in the laboratory chemical fume hood, and from gloved hand surfaces of the Smithsonian Library staffer after the book was handled and the binding sample procured for this study. The samples were collected using NIOSH 9102 protocol. The samples were analyzed using NIOSH 7082 M/7300 by Analytics Corporation, an accredited industrial hygiene laboratory. Wipe samples were also collected, at the same time, on the other Smithsonian Libraries conserved book with the arsenic-containing edge staining. This book was handled, and pages were thumbed through by the staffer prior to the wipe sampling. While this book was not part of this study, the results are included in this paper to provide additional information to the reader on potential exposure levels from other types of arsenic-containing books.
The level of risk posed by the arsenic concentrations reported on the wipe samples was assessed by comparing the concentrations to the “health-based” settled dust screening value for arsenic of 387 µg/m2, as OSHA, ACGIH, and NIOSH do not currently have regulatory/recommended limits for surface wipes. The screening value, based on an assigned toxicity value for arsenic, was developed by the World Trade Center (WTC) Indoor Air Task Force Working Group to be protective of long-term habitability of residential buildings, post 9/11, to evaluate potential inhalation and ingestion risk from surface contamination levels reported for various contaminates, including arsenic. This screening value is published in the “World Trade Center Indoor Environmental Assessment: Selecting Contaminants of Potential Concern and Setting Health-Based Benchmarks” (Mark A. Maddaloni et al. 2003, https://epa-prgs.ornl.gov/radionuclides/copc_benchmark.pdf) [10].