Gamma irradiation for the inactivation of Aspergillus niger in aged cotton fabric

Abstract

Abstract To address the problem of biodegradation of fiber-based museum natural textiles, several decontamination methods are being used; the most common of which is chemical fumigation. However, the use of toxic chemicals presents not only occupational health hazards, but also challenges in terms of legal restrictions regarding environmental release and waste disposal. Methods that eliminate toxic pollutant release while offering low resource (energy and water) requirements and faster and effective treatment are desirable. This study investigated the use of gamma irradiation as an alternative fungal decontamination method for aged undyed 100% cotton fabric. Fabric samples inoculated with Aspergillus niger were irradiated at increasing doses of gamma radiation from a Co-60 source in the irradiation facility of the Philippine Nuclear Research Institute to determine its radiation sensitivity. The decimal reduction value (D10) was determined to be 0.21\u202fkGy, which is sufficient to inactivate 90% of the total colony forming units initially obtained. The minimum dose required for high level disinfection (6-log reduction) of the textile material is 1.26\u202fkGy. To determine the effects of gamma radiation to strength and color properties, fabric samples were irradiated at doses 0.1–25\u202fkGy then subjected to breaking strength and elongation and color measurement tests. Physical property testing reveals that cotton fabrics of similar composition and construction as the one used in the study do not undergo significant degradation in terms of breaking strength up to 10\u202fkGy dose. This may be regarded as the maximum dose of irradiation, which is well above the minimum dose of 1.26\u202fkGy required to effectively decontaminate the textile material from A. niger. Gamma irradiation with cobalt-60 is an effective decontamination method for cotton fabrics that may be used for museum applications.