# Biological Risk for Hypogea: Shared Data from
## 3 Results
### The Etruscan Tombs
#### 3.1.2 Conservation Treatments  
Variations in temperature and humidity inside the burial chambers of Etruscan tombs over lengthy periods of time have created significant deterioration [2; 82; 23]. Indirect control methods were also carried out, stabilising the microclimatic conditions after a partial reconstruction of overlaying tumuli and the creation of a system of double doors to close off the burial chambers, hence preventing entrance to visitors [51]. Glass barrier protection systems were put in place to prevent condensation at the tomb entrance and to allow for good visibility of the interior [23]. A cold light illumination system that does not modify the internal temperature of the chamber was also installed to prevent microclimatic changes and growth of photoautotrophic organisms [51]. In the case of Tarquinia, tests on the possible use of new vegetation cover to reduce the effects of summer heat are still underway [51]. To keep biodeterioration phenomena in check, the most common biocide compounds utilised were quaternary ammonium salts. The product that was initially used was Desogen, and then Needesogen (both based on benzalkonium chloride), and more recently Preventol R80 (Bayer) Preventol(R) RI 80 (Lanxess) (dodecyl dimethyl dichlorobenzyl ammonium chloride) [25; 47; 81]. However, the disinfection of tombs with these biocidal compounds occasionally gave rise to a certain extent of interference with materials and to unexpected problems. In fact, after treatment with Desogen (10%) in the Cerveteri tombs (in particular, a painted relief in the Banditaccia Necropolis), a huge growth of a white fluffy mycelium  
Figure 3: Biodegradation patterns in the Italian tombs from the Monterozzi Necropolis in Tarquinia. was observed due to the development of _Mortierella alpina_, _Mucor racemosus_, _Verticillium bulbilosum_, _Mortierella ramantimiana_, _Penicillium_ sp., and _Gliomastix cereals_. This last mentioned was darker than others and the most difficult to eradicate [25]. Instead, species belonging to _Acremonium_, _Geotrichum_ and the _Penicillium_ genera were found in the Tomb of the Triclinium at the same necroolis, as a recolonisation effect following this kind of treatment [27]. Similarly, in the Tomb of the Ducks (Veio), the newly formed white mycelium was associated to _Penicillium miczynskii_, _Fusarium_ sp., and _Paecilomyces_ sp. [27]. Such a phenomenon was interpreted as the consequence of treatment in limiting the competition of these fungi with more sensitive bacteria. After several tests, only treatment with orto-phenylphenol was effective in blocking their growth [25]. In tests sites, the use of Metatin 58/I0 (Acima Chemicals) a broad-spectrum biocide, resulted as the most effective method of eliminating all microorganism species definitively [27]. The authors suggested to improve tests and not removing the residuals of biocides as usual methods during restoration [27]. In fact, in several further ISCR reports [80; 81], treatment with benzalkonium chlorides compounds was suggested since the secondary effect of provoking further colonisation were not observed in several cases. Restorers also consider such treatment as a common practice in case of microbiological attacks, using them at doses of 2% [51]. Some recent studies also looked into identifying microorganisms capable of surviving biocide treatment with ammonium quaternary salts (Preventol RI80) by producing biofilms and/or spores [40]. An analysis carried out one month from the biocide treatment in various places of the tomb showed that it was effective on most bacteria, but not so on species capable of producing resistant forms of life like spore-forming bacteria, such as _Bacillus_ sp. and moulds which were still alive [40]. Furthermore, microwave heating treatment was also applied as a new methodology to control biodeterioration phenomena [46]. The prototype system used a 2.45 GHz microwave generator with an adjustable output power of up to 1 kW and an optimal application dose of 65 \({}^{\circ}\)C for 3 min.