Damage Caused by Destructive Insects to Cellulose Previously Subjected to Gamma-Ray Irradiation and Artificial Ageing
| Main Authors: | , , |
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| Format: | Article |
| Language: | English Slovak |
| ISSN: | ISSN 0034-5806 |
| Online Access: | http://www.viks.sk/chk/res_4_01_242_250.doc |
| Abstract: | Summaries. The aim of the present paper is to develop a new system that is able to kill insects and microscopic fungi responsible for the destruction of books and documents, using gamma radiation. The authors particularly wanted to verify if the increase of depolimerization of cellulose, that is accelerated by gamma radiation and is related to the absorbed dose, could make treated material more susceptible to attack by chewing insects. For the trials a cockroach (Periplaneta americana) was selected as the insect and Whatman paper selected as a source of pure cellulose. The phenomenon is particularly evident with doses higher than 10 kGy but this dosage is much higher than that necessary for a practical application in libraries and archives. Artificial ageing does not cause cellulose to become more susceptible to insects attack. Conclusions. Irradiated Whatman paper (filter paper) subjected to the action of destructive insects shows in our experimental conditions more erosion than the non irradiated control paper. This phenomenon could be related to the depolymerization of the macromolecules of the cellulose, which as has been shown previously2,5,6, is proportional to the gamma dosage absorbed by the material. On the other hand, the ageing treatment seemed to have no influence. For those who are interested in using radiation as a method for disinfecting/ disinfesting paper material, it is necessary to make a distinction between the radiation dosages necessary for the relevant treatment of the material - which in experiments did not cause appreciable negative effects - and the much higher dosage used intentionally by us only for speculative purposes. Experimenting with extremely high radiation dosages enabled us to demonstrate that when the phenomena we want to measure are present, our analytical instruments are able to detect them. Already, two days after the start of the experiment, the sheets of Whatman paper subjected to extremely high radiation dosages appeared to be attacked by the cockroaches to a greater extent than the control sheets (Fig. 1). In other words, the accuracy of these analytic instruments allows us to assert the harmlessness of the treatment if the radiation dosages are around 3 kGy, which is what we would recommend. Moreover, it should be taken into account that the differences in the degree of erosion are measurable only if they are observed during the days immediately after the treatment since, as time goes on, even the non-irradiated control samples and those irradiated with low doses as well as the samples submitted to ageing only, were also irremediably attacked and destroyed by the insects. As has been said several times in the past that destructive living organisms become truly harmful for collections of organic based materials such as books, when the environmental conditions exceed known control parameters. Though cockroaches are described in literature as responsible for the biodeterioration of paper, it goes without saying that these insects should be not in libraries! Negative environmental conditions are always the main reason for the development of a pest problem. Only after having paid rigorous attention to the correct environmental conditions for keeping books and paper documents, may disinfection/ disinfestation measures be considered, knowing that the expected benefit of any chemical or physical treatment on that material must be weighed against the risk of a negative side-effect, which even if minimal or even immeasurable, is always present In the case of gamma-ray irradiation used to kill destructive insects, the treatment proved to be very effective even at the maximum dosages of 300 Gy1. The depolymerization induced by the irradiation of the cellulose did not cause any negative effects at dosages lower than 10 kGy. This is pertinent mainly to the susceptibility of the material to the attack of insects that may come into contact with it after the treatment, even after long periods of time. |
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| ISSN: | ISSN 0034-5806 |
