- Email: [email protected]
Quantification of mercury in XVIII century books by Energy Dispersive X-Ray Fluorescence (EDXRF)
Journal of Cultural Heritage 10 (2009) 435–438
Case study
Quantification of mercury in XVIII century books by Energy Dispersive X-Ray Fluorescence (EDXRF) Maria-Luisa Carvalho ∗ , Marta Manso , Sofia Pessanha , Ana Guilherme , Fernando Rodrigues Ferreira Centro de Física Atómica, Universidade de Lisboa, Faculdade de Ciências, Avenue Prof. Gama Pinto 2, 1649-003 Lisbon, Portugal Received 25 January 2008; accepted 27 November 2008
Abstract This work describes the quantitative analysis of mercury present in the ink used to colour some books of XVIII century. The mercury content was determined by Energy Dispersive X-ray Spectrometry. This is a non-destructive technique which allows elemental identification and quantification (Z > 13) by atomic physics processes. The organic pigments cannot be identified by this technique, taking into account that its composition is mainly C, O and H. Levels of 2 wt.% and 4.5 wt.% were measured in 1756 and 1753 books respectively. No significant amount of mercury was observed in other red books, on a total of 11, all from XVIII century: 1720, 1732, 1753, 1756, 1780, 1798, 1800. More than one book for each year were analysed. The studied books belong to a private collection, and were selected taking into account the age and the reddish colour of their external parts. High content on Fe were observed in some of the books. This work highlights the application of a physics technique in a very important aspect for art and cultural heritage conservation and restoration, considering that high levels of toxic elements might be found in ancient documents. It is of great importance that preliminary elemental analyses are performed on ancient documents before handling them, because they might constitute some danger for restorers, conservators and collectors. This work highlights, for the first time, the danger of some ancient books. They might contain a very high concentration of mercury, which is toxic for the organism. This is also a particularly important problem of public health never mentioned in literature before. © 2009 Elsevier Masson SAS. All rights reserved. Keywords: Mercury; Document paper; X-ray spectrometry
1. Introduction Vermilion, also known as cinnabar, is an opaque orangeish red pigment originally derived from the powdered mineral cinnabar. Throughout history, vermilion has been used in several art works. It can be found in oil on canvas [1], icons [2,3], sculptures [4] or wall paintings [5]. This pigment has also been found in several graphic documents [6–9] namely on the head, fore edge and tail of books [10]. Nowadays, vermilion is no longer used due to its toxicity. Chemically, the pigment is mercuric sulphide, HgS. One can be exposed to mercury from breathing in contaminated air, from swallowing or eating contaminated water or food, or from having skin contact with it [11]. Not all forms of mercury easily enter our body, even when in contact with it. The most dan∗
Corresponding author. Tel.: +351 21 7904700; fax: +351 21 7954288. E-mail address: [email protected] (M.-L. Carvalho).
1296-2074/$ – see front matter © 2009 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.culher.2008.11.003
gerous form, from a toxicological viewpoint, is the metallic form [12]. Inorganic mercury compounds like HgS do not generally vaporize at room temperature like elemental mercury does. If it is inhaled, it is not expected to enter in human body as easily as inhaled metallic mercury vapor. When inorganic mercury compounds are swallowed, generally less than 10% are absorbed through the intestinal tract; however, in some instances, up to 40% may enter the body through the stomach and intestines [13]. Some inorganic mercury can penetrate in the organism through the skin, but only a small amount is absorbed when compared to the amount that gets into the organism from swallowing it. Once inorganic mercury enters into the bloodstream, it moves to several tissues. Inorganic mercury accumulates mostly in the kidneys and does not reach the brain as easily as metallic mercury [14]. Nevertheless, a small amount of the inorganic mercury can be changed by the organism into metallic mercury and leave in the breath as a mercury vapour [13].
436
M.-L. Carvalho et al. / Journal of Cultural Heritage 10 (2009) 435–438
Table 1 Comparison of elemental concentration (g g−1 ) in orchard leaves (NBS standard reference material 1571) measured in this work (± standard deviation) and the certified values. K
Ca
Mn
Fe
15,300 ± 900 14,700 ± 300
21,500 ± 1000 20,900 ± 300
95 ± 5 91 ± 4
310 ± 20 300 ± 20
Present work Certified values
Quantitative analyses of Hg present in the ink used to colour the head, fore edge and tail of several books were performed. These analyses were also performed on the covers of the books. The elemental concentrations were obtained by Energy Dispersive X-Ray Fluorescence (EDXRF) spectrometry. This technique has the main advantage of being non-destructive, which makes it the perfect tool for elemental analyses of cultural heritage [15–18]. 2. Experimental The spectrometer used in this work for EDXRF analysis consisted of a commercial X-ray tube (PW 1140; 100 kV, 80 mA) equipped with a changeable secondary target of molybdenum (Mo). With this setup, it was possible to obtain virtually a monochromatic source, with energies of the K␣ and K lines of Mo of 17.44 and 19.60 keV, respectively. The X-ray tube, the secondary target and the sample were in a triaxial geometry [19]. By thus taking advantage of the effect of polarization of the incident X-ray beam from the tube, the background was decreased. Both X-ray beams emitted by the secondary target and the sample were collimated throughout two silver apertures, in order to reduce the scattered radiation and improve the detection limits. The characteristic radiation emitted by the elements present in the sample was detected by means of a Si (Li) detector, with a 30 mm2 active area and 8 m beryllium window. The energy resolution was 138 eV at 5.9 keV and the acquisition system was a Nucleus PCA card. The pulse processing and dead time corrections were automatically adjusted by a commercial pulse processor (Oxford). The characteristic radiation from the lighter elements was strongly absorbed in the air and in the beryllium window of the detector, which made the present setup less suitable for light elements. The quantitative evaluation was made by the fundamental parameters methods [20], which makes use of fundamental parameters such as cross-sections for absorption and X-ray production, transition intensities, fluorescence yields, etc. The relation between the measured peak intensity (Ii ) and the concentration of an element (Ci ) is given by the equation:
Ni ≤ 1.5 1.3 ± 0.2
Cu
Zn
As
Rb
Pb
13 ± 1 12 ± 1
26 ± 2 25 ± 3
12.5 ± 2.5 14 ± 2
12.5 ± 0.8 12 ± 1
42 ± 2 45 ± 3
tered radiation with a normalizing condition, which means that all concentrations within a sample should add up to unity, i.e. i Ci = 1. Ai is the self-attenuation factor which can be obtained iteratively by constructing a virtual matrix of three elements representing the matrix. In the present study (light element matrix, which accounts for 80% of the absorption in biological samples), the chosen elements were hydrogen, carbon and oxygen. The X-ray generator was operated at 50 kV and 20 mA, and a typical acquisition time of 1000 seconds was used. A collimator of silver was placed in front of the detector in order to restrict the effective area of the detector by excluding regions close to the edges. The accuracy was checked by analysis of reference material orchard leaves (NBS standard reference material 1571) which matrix is cellulose. The element concentrations obtained for the standard reference material are shown in Table 1. The results obtained in the present work were in very good agreement with the certified values. The standard deviation was obtained considering the error resulting from the fitting process and the differences in concentration for three pellets analyzed repeatedly five times, respectively. In the present work, head, fore edge, tail and cover of several books from 1753 to 1800 books were directly measured by EDXRF, without any kind of sample preparation. A minimum of 10 measurements were undertaken for each part of them. 3. Discussion and results In this study, we present the results for two of the analyzed books (Fig. 1). These books were from 1753 and 1756. Mercury lines are evidenced in an EDXRF spectrum obtained for the fore edge of the 1756 book in Fig. 2. The mean concentration of Hg present in the fore edges, heads and tails of both books is presented in Table 2. These areas of the book are most frequently in contact with the skin. These levels are extremely high, especially in the head of the 1756 book, where 4.5 wt.% was measured. Standard deviation levels over 10% are due to the inhomogeneity of the sample and ink distribution. The poor
Ii = I0 mKi Ci Ai where I0 is the intensity of the X-ray beam, m is the sample thickness (g cm−2 ), Ki is an experimental calibration factor which depends on the spectrometer geometry, detector efficiency, detector solid angle and cross-sections for producing characteristic X-rays, and together with I0 is obtained by analysis of standard reference samples. The sample mass is obtained through the information in the coherent and incoherent scat-
Fig. 1. Picture of 1756 book.
M.-L. Carvalho et al. / Journal of Cultural Heritage 10 (2009) 435–438
437
Fig. 4. Comparison of the mean Hg concentration (g g−1 ) in the cover and fore edges of both books. Fig. 2. Spectrum obtained by EDXRF for the fore edge of the 1756 book. Table 2 Mean concentration and standard deviation (wt.%) of Hg present in the fore edge, head and tail of the two studied books. Book part
Book 1756 Mean ± SD
Book 1753 Mean ± SD
Fore edge Head Tail
2.4 ± 0.2 4.5 ± 0.1 2.5 ± 0.1
1.8 ± 0.4 1.9 ± 0.2 1.6 ± 0.2
state of conservation of the analyzed books (Fig. 3) may also contribute to the fluctuation of Hg levels. Values ranging from 68 to 550 g g−1 were obtained in the books of 1756, 1780 and 1798, respectively. No mercury was found in the remaining books. In Fig. 4, we compare the Hg concentration in the fore edges and covers of both books. In this study, the levels of Hg are much lower in the covers than in the corresponding fore edges, however, it is remarkable the extremely high concentration levels of Hg for the fore edge of the books. There is limited information currently available on the dermal absorption of the inorganic form of mercury. Not even guidelines for skin contact with mercury have been established yet. However, directives for other potential exposure routes do exist. The Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA) set a limit of two parts inorganic mercury per billion parts of water in drinking water (2 × 10−7 wt.%) [13,22]. Furthermore, FDA set that fish which presents more than one part
Fig. 3. Picture of the head of the 1753 book.
of methylmercury per million (1 × 10−4 wt.%) are not allowed to be sold in public [13]. The RoHS Directive stands for “the restriction of the use of certain hazardous substances in electrical and electronic equipment” [21]. This Directive bans the placing on the EU market of new electrical and electronic equipment containing more than agreed levels of mercury, amongst other elements and compounds. The agreed value for Hg is 0.1 wt.% [22]. As the health effects of dermal exposure are not fully understood, contact with mercury should be avoided, though it is already known that dermal contact with inorganic mercury compounds may lead to dermatitis and other dermal effects, in addition to respiratory problems [23]. 4. Conclusion The research performed in this study is unique and allowed, for the first time, the quantification of huge amounts of mercury in the head, fore edge and tail of XVIII century books, in a non-destructive way. X-ray fluorescence was the used technique. Besides Hg, other toxic elements like As, Ba, Ni, Bi and Pb have already been found in high concentrations in old paper documents [16,24]. In this way, paper conservators and restorers, as well as any person that deals regularly with ancient books and other graphic documents, should be aware that they are not innocuous. When handling a book with the same characteristics as the ones in the present study, one can be mostly exposed to mercury from having skin contact with the ink. Residual mercury on hands can lead to straight intake into the organism. Other ways of exposure could be from paper cuts and, in this situation, it could enter directly in the blood stream. Gloves and other personal protection equipment would be strongly recommended when handling these books. Paper conservators and restorers should first make sure that the documents do not represent any risk to their health. This can be achieved by multidisciplinary teams where paper conservators and scientists merge their knowledge together in order to obtain more accurate results [25]. Finally, this work highlights the contribution of EDXRF technique in public health, particularly conservators, restorers and collectors of cultural heritage.
438
M.-L. Carvalho et al. / Journal of Cultural Heritage 10 (2009) 435–438
Acknowledgments The authors wish to acknowledge F. Rodrigues Ferreira for lending the books for analysis.
[12] [13]
References
[14] [15] [16] [17] [18]
[1] A. von Bohlen, e-Preservation Science 1, 23 (2004). http://www.moranartd.com/e-preservationscience/. [2] L. Burgio, R.J.H. Clark, K. Theodoraki, Spectr. Chimica Acta A 59 (2003) 2371. [3] N. Civici, J. Cult. Her 7 (2006) 339. [4] W. Devos, L. Moens, A. von Bohlen, R. Klockenkämper, Stud. Conserv. 40 (1995) 153. ˇ [5] A.S. Skapin, P. Ropret, P. Bukovec, Mater. Charac. 58 (2007) 1138. [6] R.J.H. Clark, C.R. Chimie 5 (2002) 7. [7] D. Bersani, P.P. Lottici, F. Vignali, G. Zanichelli, J. Raman Spectrosc. 37 (2006 1012). [8] F. Magistro, M. Domenico, P. Migliardo, R. Ponterio, M.T. Rodriquez, J. Cult. Her. 2 (2001) 191. [9] M. Bicchieri, M. Nardone, A. Sodo, J. Cult. Her. 1 (2000) S277. [10] M.M. Ayala, El arte de la encuadernación, ed. Clan, Madrid, 1995. [11] HSE, Health and Safety Laboratory, Mercury and its inorganic divalent compounds in air: Laboratory method using Hydrar diffusive badges or pumped sorbent tubes, acid dissolution and analysis by cold vapor atomic
[19] [20] [21] [22]
[23] [24]
[25]
absorption spectrometry or cold vapor atomic fluorescence spectrometry, HSE Books, (2002) pp. 1–2. H. Satoh, Ind. Health 38 (2000) 153. Agency for Toxic Substances and Disease Registry, Public Health Service, U.S. Department of health and human services, Toxicological Profile for mercury, March (1999). S.A. Counter, L.H. Buchanan, Toxicol. Appl. Pharmacol. 198 (2004) 209. M. Mantler, M. Schreiner, Xray Spectrom. 29 (2000) 3. M. Manso, M.L. Carvalho, J. Anal. At. Spectrom. 22 (2007) 164. R. Cesareo, Nuc. Instr. Meth. B 211 (2003) 133. G. Vittiglio, K. Janssens, B. Vekemans, F. Adams, A. Oost, Spectr. Chimica Acta B 54 (1999) 1697. T. Magalhães, A. von Bohlen, M.L. Carvalho, M. Becker, Spectr. Chim. Acta B 61 (2006) 1185. A. Rindby, Xray Spectrom. 18 (1989) 113. National primary drinking water regulations. US Environmental Protection Agency. Website: http://www.epa.gov/safewater/contaminants/index.html. Directives for the Restriction of the use of certain hazardous substances in electrical and electronic equipment. Website: http://www.rohs.gov.uk/ (2006). National primary drinking water regulations. US Environmental Protection Agency. Website: http://www.epa.gov/iris/subst/0692.htm (2006). V.F. Hanson, in: J.C. Williams (Eds.) Preservation of paper and textiles of historic and artistic value II, American Chemical Society Advances Washington, D.C., 1981 pp. 53–78. M. Pérez-Alonso, K. Castro, M. Álvarez, J.M. Madariaga, Analytica. Chimica. Acta 524 (2004) 379.
Case study
Quantification of mercury in XVIII century books by Energy Dispersive X-Ray Fluorescence (EDXRF) Maria-Luisa Carvalho ∗ , Marta Manso , Sofia Pessanha , Ana Guilherme , Fernando Rodrigues Ferreira Centro de Física Atómica, Universidade de Lisboa, Faculdade de Ciências, Avenue Prof. Gama Pinto 2, 1649-003 Lisbon, Portugal Received 25 January 2008; accepted 27 November 2008
Abstract This work describes the quantitative analysis of mercury present in the ink used to colour some books of XVIII century. The mercury content was determined by Energy Dispersive X-ray Spectrometry. This is a non-destructive technique which allows elemental identification and quantification (Z > 13) by atomic physics processes. The organic pigments cannot be identified by this technique, taking into account that its composition is mainly C, O and H. Levels of 2 wt.% and 4.5 wt.% were measured in 1756 and 1753 books respectively. No significant amount of mercury was observed in other red books, on a total of 11, all from XVIII century: 1720, 1732, 1753, 1756, 1780, 1798, 1800. More than one book for each year were analysed. The studied books belong to a private collection, and were selected taking into account the age and the reddish colour of their external parts. High content on Fe were observed in some of the books. This work highlights the application of a physics technique in a very important aspect for art and cultural heritage conservation and restoration, considering that high levels of toxic elements might be found in ancient documents. It is of great importance that preliminary elemental analyses are performed on ancient documents before handling them, because they might constitute some danger for restorers, conservators and collectors. This work highlights, for the first time, the danger of some ancient books. They might contain a very high concentration of mercury, which is toxic for the organism. This is also a particularly important problem of public health never mentioned in literature before. © 2009 Elsevier Masson SAS. All rights reserved. Keywords: Mercury; Document paper; X-ray spectrometry
1. Introduction Vermilion, also known as cinnabar, is an opaque orangeish red pigment originally derived from the powdered mineral cinnabar. Throughout history, vermilion has been used in several art works. It can be found in oil on canvas [1], icons [2,3], sculptures [4] or wall paintings [5]. This pigment has also been found in several graphic documents [6–9] namely on the head, fore edge and tail of books [10]. Nowadays, vermilion is no longer used due to its toxicity. Chemically, the pigment is mercuric sulphide, HgS. One can be exposed to mercury from breathing in contaminated air, from swallowing or eating contaminated water or food, or from having skin contact with it [11]. Not all forms of mercury easily enter our body, even when in contact with it. The most dan∗
Corresponding author. Tel.: +351 21 7904700; fax: +351 21 7954288. E-mail address: [email protected] (M.-L. Carvalho).
1296-2074/$ – see front matter © 2009 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.culher.2008.11.003
gerous form, from a toxicological viewpoint, is the metallic form [12]. Inorganic mercury compounds like HgS do not generally vaporize at room temperature like elemental mercury does. If it is inhaled, it is not expected to enter in human body as easily as inhaled metallic mercury vapor. When inorganic mercury compounds are swallowed, generally less than 10% are absorbed through the intestinal tract; however, in some instances, up to 40% may enter the body through the stomach and intestines [13]. Some inorganic mercury can penetrate in the organism through the skin, but only a small amount is absorbed when compared to the amount that gets into the organism from swallowing it. Once inorganic mercury enters into the bloodstream, it moves to several tissues. Inorganic mercury accumulates mostly in the kidneys and does not reach the brain as easily as metallic mercury [14]. Nevertheless, a small amount of the inorganic mercury can be changed by the organism into metallic mercury and leave in the breath as a mercury vapour [13].
436
M.-L. Carvalho et al. / Journal of Cultural Heritage 10 (2009) 435–438
Table 1 Comparison of elemental concentration (g g−1 ) in orchard leaves (NBS standard reference material 1571) measured in this work (± standard deviation) and the certified values. K
Ca
Mn
Fe
15,300 ± 900 14,700 ± 300
21,500 ± 1000 20,900 ± 300
95 ± 5 91 ± 4
310 ± 20 300 ± 20
Present work Certified values
Quantitative analyses of Hg present in the ink used to colour the head, fore edge and tail of several books were performed. These analyses were also performed on the covers of the books. The elemental concentrations were obtained by Energy Dispersive X-Ray Fluorescence (EDXRF) spectrometry. This technique has the main advantage of being non-destructive, which makes it the perfect tool for elemental analyses of cultural heritage [15–18]. 2. Experimental The spectrometer used in this work for EDXRF analysis consisted of a commercial X-ray tube (PW 1140; 100 kV, 80 mA) equipped with a changeable secondary target of molybdenum (Mo). With this setup, it was possible to obtain virtually a monochromatic source, with energies of the K␣ and K lines of Mo of 17.44 and 19.60 keV, respectively. The X-ray tube, the secondary target and the sample were in a triaxial geometry [19]. By thus taking advantage of the effect of polarization of the incident X-ray beam from the tube, the background was decreased. Both X-ray beams emitted by the secondary target and the sample were collimated throughout two silver apertures, in order to reduce the scattered radiation and improve the detection limits. The characteristic radiation emitted by the elements present in the sample was detected by means of a Si (Li) detector, with a 30 mm2 active area and 8 m beryllium window. The energy resolution was 138 eV at 5.9 keV and the acquisition system was a Nucleus PCA card. The pulse processing and dead time corrections were automatically adjusted by a commercial pulse processor (Oxford). The characteristic radiation from the lighter elements was strongly absorbed in the air and in the beryllium window of the detector, which made the present setup less suitable for light elements. The quantitative evaluation was made by the fundamental parameters methods [20], which makes use of fundamental parameters such as cross-sections for absorption and X-ray production, transition intensities, fluorescence yields, etc. The relation between the measured peak intensity (Ii ) and the concentration of an element (Ci ) is given by the equation:
Ni ≤ 1.5 1.3 ± 0.2
Cu
Zn
As
Rb
Pb
13 ± 1 12 ± 1
26 ± 2 25 ± 3
12.5 ± 2.5 14 ± 2
12.5 ± 0.8 12 ± 1
42 ± 2 45 ± 3
tered radiation with a normalizing condition, which means that all concentrations within a sample should add up to unity, i.e. i Ci = 1. Ai is the self-attenuation factor which can be obtained iteratively by constructing a virtual matrix of three elements representing the matrix. In the present study (light element matrix, which accounts for 80% of the absorption in biological samples), the chosen elements were hydrogen, carbon and oxygen. The X-ray generator was operated at 50 kV and 20 mA, and a typical acquisition time of 1000 seconds was used. A collimator of silver was placed in front of the detector in order to restrict the effective area of the detector by excluding regions close to the edges. The accuracy was checked by analysis of reference material orchard leaves (NBS standard reference material 1571) which matrix is cellulose. The element concentrations obtained for the standard reference material are shown in Table 1. The results obtained in the present work were in very good agreement with the certified values. The standard deviation was obtained considering the error resulting from the fitting process and the differences in concentration for three pellets analyzed repeatedly five times, respectively. In the present work, head, fore edge, tail and cover of several books from 1753 to 1800 books were directly measured by EDXRF, without any kind of sample preparation. A minimum of 10 measurements were undertaken for each part of them. 3. Discussion and results In this study, we present the results for two of the analyzed books (Fig. 1). These books were from 1753 and 1756. Mercury lines are evidenced in an EDXRF spectrum obtained for the fore edge of the 1756 book in Fig. 2. The mean concentration of Hg present in the fore edges, heads and tails of both books is presented in Table 2. These areas of the book are most frequently in contact with the skin. These levels are extremely high, especially in the head of the 1756 book, where 4.5 wt.% was measured. Standard deviation levels over 10% are due to the inhomogeneity of the sample and ink distribution. The poor
Ii = I0 mKi Ci Ai where I0 is the intensity of the X-ray beam, m is the sample thickness (g cm−2 ), Ki is an experimental calibration factor which depends on the spectrometer geometry, detector efficiency, detector solid angle and cross-sections for producing characteristic X-rays, and together with I0 is obtained by analysis of standard reference samples. The sample mass is obtained through the information in the coherent and incoherent scat-
Fig. 1. Picture of 1756 book.
M.-L. Carvalho et al. / Journal of Cultural Heritage 10 (2009) 435–438
437
Fig. 4. Comparison of the mean Hg concentration (g g−1 ) in the cover and fore edges of both books. Fig. 2. Spectrum obtained by EDXRF for the fore edge of the 1756 book. Table 2 Mean concentration and standard deviation (wt.%) of Hg present in the fore edge, head and tail of the two studied books. Book part
Book 1756 Mean ± SD
Book 1753 Mean ± SD
Fore edge Head Tail
2.4 ± 0.2 4.5 ± 0.1 2.5 ± 0.1
1.8 ± 0.4 1.9 ± 0.2 1.6 ± 0.2
state of conservation of the analyzed books (Fig. 3) may also contribute to the fluctuation of Hg levels. Values ranging from 68 to 550 g g−1 were obtained in the books of 1756, 1780 and 1798, respectively. No mercury was found in the remaining books. In Fig. 4, we compare the Hg concentration in the fore edges and covers of both books. In this study, the levels of Hg are much lower in the covers than in the corresponding fore edges, however, it is remarkable the extremely high concentration levels of Hg for the fore edge of the books. There is limited information currently available on the dermal absorption of the inorganic form of mercury. Not even guidelines for skin contact with mercury have been established yet. However, directives for other potential exposure routes do exist. The Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA) set a limit of two parts inorganic mercury per billion parts of water in drinking water (2 × 10−7 wt.%) [13,22]. Furthermore, FDA set that fish which presents more than one part
Fig. 3. Picture of the head of the 1753 book.
of methylmercury per million (1 × 10−4 wt.%) are not allowed to be sold in public [13]. The RoHS Directive stands for “the restriction of the use of certain hazardous substances in electrical and electronic equipment” [21]. This Directive bans the placing on the EU market of new electrical and electronic equipment containing more than agreed levels of mercury, amongst other elements and compounds. The agreed value for Hg is 0.1 wt.% [22]. As the health effects of dermal exposure are not fully understood, contact with mercury should be avoided, though it is already known that dermal contact with inorganic mercury compounds may lead to dermatitis and other dermal effects, in addition to respiratory problems [23]. 4. Conclusion The research performed in this study is unique and allowed, for the first time, the quantification of huge amounts of mercury in the head, fore edge and tail of XVIII century books, in a non-destructive way. X-ray fluorescence was the used technique. Besides Hg, other toxic elements like As, Ba, Ni, Bi and Pb have already been found in high concentrations in old paper documents [16,24]. In this way, paper conservators and restorers, as well as any person that deals regularly with ancient books and other graphic documents, should be aware that they are not innocuous. When handling a book with the same characteristics as the ones in the present study, one can be mostly exposed to mercury from having skin contact with the ink. Residual mercury on hands can lead to straight intake into the organism. Other ways of exposure could be from paper cuts and, in this situation, it could enter directly in the blood stream. Gloves and other personal protection equipment would be strongly recommended when handling these books. Paper conservators and restorers should first make sure that the documents do not represent any risk to their health. This can be achieved by multidisciplinary teams where paper conservators and scientists merge their knowledge together in order to obtain more accurate results [25]. Finally, this work highlights the contribution of EDXRF technique in public health, particularly conservators, restorers and collectors of cultural heritage.
438
M.-L. Carvalho et al. / Journal of Cultural Heritage 10 (2009) 435–438
Acknowledgments The authors wish to acknowledge F. Rodrigues Ferreira for lending the books for analysis.
[12] [13]
References
[14] [15] [16] [17] [18]
[1] A. von Bohlen, e-Preservation Science 1, 23 (2004). http://www.moranartd.com/e-preservationscience/. [2] L. Burgio, R.J.H. Clark, K. Theodoraki, Spectr. Chimica Acta A 59 (2003) 2371. [3] N. Civici, J. Cult. Her 7 (2006) 339. [4] W. Devos, L. Moens, A. von Bohlen, R. Klockenkämper, Stud. Conserv. 40 (1995) 153. ˇ [5] A.S. Skapin, P. Ropret, P. Bukovec, Mater. Charac. 58 (2007) 1138. [6] R.J.H. Clark, C.R. Chimie 5 (2002) 7. [7] D. Bersani, P.P. Lottici, F. Vignali, G. Zanichelli, J. Raman Spectrosc. 37 (2006 1012). [8] F. Magistro, M. Domenico, P. Migliardo, R. Ponterio, M.T. Rodriquez, J. Cult. Her. 2 (2001) 191. [9] M. Bicchieri, M. Nardone, A. Sodo, J. Cult. Her. 1 (2000) S277. [10] M.M. Ayala, El arte de la encuadernación, ed. Clan, Madrid, 1995. [11] HSE, Health and Safety Laboratory, Mercury and its inorganic divalent compounds in air: Laboratory method using Hydrar diffusive badges or pumped sorbent tubes, acid dissolution and analysis by cold vapor atomic
[19] [20] [21] [22]
[23] [24]
[25]
absorption spectrometry or cold vapor atomic fluorescence spectrometry, HSE Books, (2002) pp. 1–2. H. Satoh, Ind. Health 38 (2000) 153. Agency for Toxic Substances and Disease Registry, Public Health Service, U.S. Department of health and human services, Toxicological Profile for mercury, March (1999). S.A. Counter, L.H. Buchanan, Toxicol. Appl. Pharmacol. 198 (2004) 209. M. Mantler, M. Schreiner, Xray Spectrom. 29 (2000) 3. M. Manso, M.L. Carvalho, J. Anal. At. Spectrom. 22 (2007) 164. R. Cesareo, Nuc. Instr. Meth. B 211 (2003) 133. G. Vittiglio, K. Janssens, B. Vekemans, F. Adams, A. Oost, Spectr. Chimica Acta B 54 (1999) 1697. T. Magalhães, A. von Bohlen, M.L. Carvalho, M. Becker, Spectr. Chim. Acta B 61 (2006) 1185. A. Rindby, Xray Spectrom. 18 (1989) 113. National primary drinking water regulations. US Environmental Protection Agency. Website: http://www.epa.gov/safewater/contaminants/index.html. Directives for the Restriction of the use of certain hazardous substances in electrical and electronic equipment. Website: http://www.rohs.gov.uk/ (2006). National primary drinking water regulations. US Environmental Protection Agency. Website: http://www.epa.gov/iris/subst/0692.htm (2006). V.F. Hanson, in: J.C. Williams (Eds.) Preservation of paper and textiles of historic and artistic value II, American Chemical Society Advances Washington, D.C., 1981 pp. 53–78. M. Pérez-Alonso, K. Castro, M. Álvarez, J.M. Madariaga, Analytica. Chimica. Acta 524 (2004) 379.