10.6092/issn.1973-9494/1403
application/pdf
1973-9494
1403
en
Lucia Cecilia Lorusso
Conservation Science in Cultural Heritage
A new technology with potential interest for conservation of cultural heritage: vaporized hydrogen peroxide sterilisation (VHPS)
Text.Serial.Journal
https://conservation-science.unibo.it/
8
Articles
2009-04-17
2008-04-17
2015-11-02
147-154
CSCH
Lucia Cecilia Lorusso
2008
10.6092/issn.1973-9494/1403
147
1973-9494
en
154
A new technology with potential interest for conservation of cultural heritage: vaporized hydrogen peroxide sterilisation (VHPS)
https://conservation-science.unibo.it/article/download/1403/772
8
A
    NEW TECHNOLOGY WITH POTENTIAL INTEREST
    FOR CONSERVATION OF CULTURAL HERITAGE:
    VAPORIZED HYDROGEN PEROXIDE STERILISATION (VHPS)

Karl M. Hellemann
Director Consulting International-Environment & Health, Graz, Austria
Franco Palla
Dipartimento di Scienze Botaniche, Laboratorio di Biologia Molecolare
Università degli Studi di Palermo
Lucia Cecilia Lorusso
Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), Roma




1. Introduction

   Deterioration of cultural assets, is strictly related to the characteristics of constitutive
materials and to both environmental parameters (U.R., temperature, light) and presence
of macro-micro biological systems. Microbial colonization (fungi, bacteria) induce deep
alteration of materials up to molecular level, modifying the structure also under the
macroscopic plane. Moreover, many microbial species are able to growth in different
habitat, colonize inorganic/organic material, easily adapting to the changes of environ-




                                                                                                    Conservation Science in Cultural Heritage, 8/2008
mental conditions. At present the procedures utilized to block or control the biodeteriora-
tion of materials, are in relationship to the microbial species and to biocide chemical com-
pounds, but frequently inadequate. In addition, sterilization procedures are usually
impracticable in the indoor environments where the collections are stored, such as muse-
um, library, archives, since it is impossible avoid contamination events that could be dan-
gerous for the operators and the environment.

2. Sterilization by Vaporised Hydrogen Peroxide (VHPS)

   The vaporised hydrogen peroxide represents a safe and repeatable sterilisation
method, useful for the healthcare and life sciences sectors. The effectiveness of this
methodology was showed by KIDA et al. (2007) using five kinds of carriers, contaminat-
ed with Geobacillus stearothermophilus spores, utilised as biological indicator [1].
Actually, this method useful for microorganisms (bacteria, fungi, virus) and spores is per-
formed following different protocols, where efficiency and promptness of action is strictly

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                                                                                                            related to concentration and exposure time. Moreover, one peculiarity is the low degree
                                                                                                            of toxicity but, in contrast, negative aspects are the effectiveness during the time, the
                                                                                                            reactivity with metals (iron) and related corrosion phenomena. In this work we combine
                                                                                                            scientific information coming from the application of sterilization procedure in different
                                                                                                            fields such as medicine, pharmacology, nanotechnology, in order to develop a new
                                                                                                            applicative protocol focused on conservation/restoration of cultural heritage. The applica-
                                                                                                            tion of this technology allowed that:
Karl. M. Hellemann, F. Palla, L.C. Lorusso - A new technology with potential interest for conservation...




                                                                                                            a) the procedure has to be performed on site; the procedure can be repeated in several
                                                                                                               runs;
                                                                                                            b) the procedure performs microbial biocide and sporocide activity;
                                                                                                            c) the human toxicity has to be controllable (safe working environment);
                                                                                                            d) the gaseous mixture has to avoid creating a cumulative chemical toxic burden;
                                                                                                            e) the validation and reproducibility of the decontamination process.
                                                                                                               Utilizing this new ultrasonic technology, a multiple mixtures of gaseous solutions of
                                                                                                            hydrogen peroxide is produced, that: start to work at a very low humidity level already;
                                                                                                            avoid the condensation on cold surface spots (e.g. wall anchors); show a quick distribu-
                                                                                                            tion within the treated compartment, reaching also the countless tiny sub-compartments.
                                                                                                            Particular interesting is the application of this technique for delicate works of art, and for
                                                                                                            microstructure of paper or textiles, which have to be handled very careful because of their
                                                                                                            mechanical instability. The development of treatment boxes (clean-rooms, airflows, etc.)
                                                                                                            and related sluice systems, allows the application of the method in a wide range of situ-
                                                                                                            ations and works of art, avoiding contact with decontaminating gaseous substances dur-
                                                                                                            ing the manipulation.
                                                                                                               The following example showed the reduction of spots, produced by fungi activity on
                                                                                                            cellulose and lignin molecules [2-3], identified on paper surface of ancient book page.
                                                                                                               The documents (dated back to 1710 to 1790) involved in this study, belong to the bib-
                                                                                                            liotheca of the Castle of Bärnegg1 in der Elsenau in eastern Styria (Austria), forgotten and
                                                                                                            mistreated for a long time, were found and returned to Bärnegg by Mr. Di Romirer (Tech.
                                                                                                            Dir. Castle Laxenburg, Lower Austria).
                                                                                                               Most of them were in bad conservation conditions and the restoration will take a long
                                                                                                            time and, in order to guarantee the success keeping the cost at a bearable level as well, in
                                                                                                            2006 it was decided to utilize this new sterilisation technology to stop, or inhibit, the destruc-
                                                                                                            tive processes in wood, paper and walls by employing, on site, the VPHS procedure.
                                                                                                               A protocol was designed in order to perform the VHPS using a clean-room with spe-
                                                                                                            cific characteristics, such as the possibility to operate an inspection of the whole room

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system, of the wall, of the pipes that going into and out of the room, in order to put in evi-
dence other possible leaks or cold spots.
The protocol followed these steps:

Ø Pre-designed and described DECONTAMINATION CYCLE, defining the Critical
   Control Point (CCPs)
    Pre-phase of the DCC (De-Contamination Cycle)
      – Rising the concentration of the gaseous mixture to the best working concentra-
         tion as fast as possible;
      – Avoid condensation (by measurement of the humidity at CCPs).
    Decontamination – Sterilisation phase (De-Steri phase)
      – Avoid a lowering of the designed and calculated best working concentration by
         measurements at the defined CCPs;
      – Avoid a deviation of the temperature by measurements at CCPs.
    Post-Steri phase. Desorption
      – Replacement of the gaseous atmosphere by fresh and not contaminated (spores
         or microbes) air.

Important remark

   Each run has to be documented and controlled by measurements and bio-checks pre-
viously defined, in order to obtain information on about:
ü streaming conditions and their influence in room system utilized;
ü stability of concentrations and exposure conditions;
ü physical-chemical interactions with material;
ü effectivity and efficiency of the whole procedure.
                                                                                                   Conservation Science in Cultural Heritage
   This documentation guarantees the consequence of treatment, and is the most effec-
tive quality management tool to prevent mistreatment of rare and worthy pieces of art.
Moreover, it is the only way to register unexpected events and to learn about the appli-
cation of this method, in relationship with the cultural assets.


3. Results

   The first picture showed the original surface of grey and dirty first page of an old
(Arzney-buch, 1710-1730) paper manuscript, where small dark or dark brown spots,
related to microbial activity, were spread over the whole page section, (fig. 1/A). The
microbial growth was, for sure, induced by changes in humidity and temperature val-

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Karl. M. Hellemann, F. Palla, L.C. Lorusso - A new technology with potential interest for conservation...




                                                                                                            Figure 1. VPHS treatment of a degraded manuscript page.

                                                                                                            ues, during the time of the bad documents conservation. In those conditions, even
                                                                                                            spores could be reactivated by temperature variations (22°C-28°C), changing their
                                                                                                            vegetative phase, performing, again, their destructive activity on the contaminated sur-
                                                                                                            faces [2, 4].
                                                                                                                The results of the pre-check step, showed that:
                                                                                                            Ø   there is not a reactive bleaching effect,
                                                                                                            Ø   the brightness of the background is related to the mechanical cleaning (fig. 1/B);
                                                                                                            Ø   print colour and intensity didn’t changed after the contact with the gas (fig. 1/C).

                                                                                                            4. Relationship between gas mixture-temperature-contacts time

                                                                                                                During the process, the constant needs of fluid mixture is directly related with:
                                                                                                            •   temperature;
                                                                                                            •   the volume of the micro spaces consuming the gas in the structure;

                                               150
Figure 2

•   adhesion and adsorbing ratio of the gas at the accessible surfaces and
•   binding rate by the components of the layers (e.g. painting).
    Moreover, a standard can be defined by using technical structures with a well defined
surface area. Because of the changed behaviour of those particles with a diameter far
below 2.5 µm, the control and test area can be packed within a spongiform material. A
test bodies can be loaded with biological test organisms and a count of the redetected
active organisms gives us the limit of this method. In parallel, for safety reasons too – the
measurements of various physical and chemical parameters have to be done.
    The binding / desorption ratio is the leading parameter to calculate the total exposure
time and even more important to estimate the (WPCmax) workplace2 concentration you
have to expect over the time.




                                                                                                  Conservation Science in Cultural Heritage




Figure 3. This graph
reflects the needs for
fluid in an artificial test
environment           with
wood and plastic sur-
face (1:1) and can be
modified ad hoc.

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                                                                                                            5. Conclusions

                                                                                                                 As demonstrated on two samples the VHPS-Method is a sophisticated method to
                                                                                                            decontaminate pieces of art and to stop further destruction by microbial activity.
                                                                                                                 The application of this method can be performed:
                                                                                                            a) in an isolated workplace, with an high protective effect for the working expert and
                                                                                                                 handcraft;
Karl. M. Hellemann, F. Palla, L.C. Lorusso - A new technology with potential interest for conservation...




                                                                                                            b) in an total network of rooms as in an archive system;
                                                                                                            c) that firstly occurs the decontamination of assessments, under isolated conditions, fol-
                                                                                                                 lowed by the decontamination of the storage rooms. After this two steps it guarantees
                                                                                                                 a refilling of the archive with the already decontaminated sealed pieces;
                                                                                                            d) in these conditions a recontamination can be excluded.

                                                                                                                 Despite a toxic burden, an adequate personal protection (mask, avoiding direct con-
                                                                                                            tact to epidermal and mucodermal tissues) is required. The decontamination process can
                                                                                                            be adjusted to the needs on site and it is reproducible, controllable and validated and it
                                                                                                            fulfils the requirements of a safe working area.



                                                                                                            Notes
                                                                                                            1   Old way of writing: Perneckh; therefore you have two interpretations of the name Bärnegg deduct-
                                                                                                                ed from the name of the Perner or the bear also a figure in the nearby villages symbol.
                                                                                                            2   Maximal Concentration of toxic substance in the air on site = MAK (Maximale Arbeitsplatz
                                                                                                                Konzentration).



                                                                                                            Bibliography
                                                                                                            [1] KIDA N., MOCHIZUKI Y., TAGUCHI F. 2007, Sporicidal Activity of the KMT reagent
                                                                                                                in its vapor phase against Geobacillus stearothermophilus spores, Microbiol.
                                                                                                                Immunol., 51, 99-103.
                                                                                                            [2] SINGH A., GANGULI M., SING A.B. 1995, Fungal spores are an important compo-
                                                                                                                nent of library air, Aerobiologia, 11, 231-237.
                                                                                                            [3] VALENTIN N. 2003, Microbial contamination in museum collections: Organic mate-
                                                                                                                rial, In C. SAIZ-JIMENEZ (ed), Molecular Biology and Cultural Heritage, Lisse
                                                                                                                /Abingdon/Exton (PA)/ Tokyo, A.A, Balkema Publishers, 85-91.
                                                                                                            [4] ELSE T.A., PANTLE C.R., AMY P.S. 2003, Boundaries for biofilm formation: humidity
                                                                                                                and temperature, Applied Environmental Microbiology, 69, 5006-5010.


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Summary
The VHPS technology can be considered as a safer and more environmentally friendly method for
decontamination of works of art, and environments, colonized by microorganisms (fungi, bacteria).
The application of this technology allowed that:
• the procedure has to be performed on site;
• the procedure has to be repeated in several runs;
• the procedure has to perform microbial biocide and sporocide;
• the human toxicity has to be controllable (safe working environment);
• the gaseous mixture has to avoid creating a cumulative chemical toxic burden;
• the validation and reproducibility of the decontamination process.
In the present work we put together the information coming from the application of sterilization pro-
cedure from different field such as medicine, pharmacology, nanotechnology, in order to develop new
applicative protocols, particularly for cultural heritage field.


Riassunto
L’innovativa tecnica basata sulla sterilizzazione con perossido di idrogeno vaporizzato (VHPS) per-
mette la rimozione di alterazioni cromatiche, oltre ad inibire il degrado dei materiali costituenti manu-
fatti scrittori ad opera di microrganismi. La tecnologia VHPS presenta le seguenti caratteristiche:
• possibilità di un controllo preliminare delle interazioni;
• applicazione in situ;
• assenza di ricontaminazione di materiali già sterilizzati in archivi, biblioteche e/o unità culturali,
   includendo anche l’ambiente di deposito nella procedura di decontaminazione;
• processo convalidato e ripetibile che, dopo l’avvio, procede automaticamente;
• nessun effetto tossico a lunga durata;
Inoltre, migliora le condizioni negli ambienti di lavoro per coloro che operano nel campo della con-
servazione e del restauro dei beni culturali.


Résumé
L’innovante technique basée sur la stérilisation avec peroxyde d’hydrogène vaporisé (VHPS) permet
l’enlèvement d’altérations chromatiques, outre à interdire la détérioration des matériaux constituant
des ouvrages écrivains grâce à des microorganismes. La technologie VHPS présente les caracté-
ristiques suivantes:
• possibilité d’un contrôle préliminaire des interactions;
• application en situ;                                                                                        Conservation Science in Cultural Heritage
• absence de recontamination de matériaux déjà stérilisés dans des archives, bibliothèques et/ou
   unités culturelles, incluant aussi le milieu de dépôt dans la procédure de décontamination;
• processus validé et répétable qui, après le démarrage, procède automatiquement;
• aucun effet toxique de longue durée.
En outre, elle améliore les conditions dans les milieux de travail pour ceux qui opèrent dans le
domaine de la conservation et de la restauration des biens culturels.


Zusammenfassung
Durch die innovative Sterilisationstechnik mit dampfförmigem Wasserstoffperoxid (VHPS) kann man
Verfärbungen entfernen und dem von Mikroorganismen verursachten Verfall der Materialien von
schriftlichen Artefakten entgegenwirken. Die VHPS- Technologie hat folgende Merkmale:
• die Möglichkeit, eine Vorkontrolle der Interaktionen durchzuführen;
• Anwendung in situ;
• keine Wiederkontamination von sterilisierten Materialien in Archiven, Bibliotheken und /oder kul-


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                                                                                                              turellen Anstalten, weil der Aufbewahrungsort in der Dekontaminationsprozedur eingeschlossen
                                                                                                              wird;
                                                                                                            • es ist ein mehrmals bestätigter und wiederholbarer Prozess, der nach dem Starten automatisch
                                                                                                              läuft;
                                                                                                            • keine giftige Wirkung langfristig;
                                                                                                            Außerdem verbessert diese Technik den Zustand der Arbeitsplatzes für die Leute, die im Bereich der
                                                                                                            Konservierung und der Restauration von Kulturgütern tätig sind.


                                                                                                            Resumen
Karl. M. Hellemann, F. Palla, L.C. Lorusso - A new technology with potential interest for conservation...




                                                                                                            La innovadora técnica basada en la esterilización con peróxido de hidrógeno vaporizado (VHPS)
                                                                                                            permite la eliminación de alteraciones cromáticas, además de inhibir la degradación de los materia-
                                                                                                            les que constituyen piezas escritas por obra de microorganismos. La tecnología VHPS presenta las
                                                                                                            siguientes características:
                                                                                                            • posibilidad de un control preliminar de las interacciones;
                                                                                                            • aplicación in situ;
                                                                                                            • ausencia de recontaminación de materiales ya esterilizados en archivos, bibliotecas y/o unidades
                                                                                                               culturales, incluyendo también el ambiente de depósito en el procedimiento de descontaminación;
                                                                                                            • proceso convalidado y repetible que, después de la puesta en marcha, procede automáticamente;
                                                                                                            • ningún efecto tóxico de larga duración;
                                                                                                            Además, mejora la condiciones en los lugares de trabajo para quienes operan en el campo de la
                                                                                                            conservación y restauración de bienes culturales.




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