THE APPLICABILITY OF GAMMA-RADIATION TO THE CONTROL OF FUNGI IN NATURALLY CONTAMINATED PAPER

The efficiency of treatments using gamma radiation for the disinfectio n of authentic papers naturally contaminated by fungi and bacteria was investigated. The effect of pretreatments using temperature and humid ity aiming to reduce the dose of gamma radiation applied for disinfect ion was also studied. The results obtained on the treatments using hig h doses of radiation (17.5 and 20.0 kGy) showed a reduction in the num ber of fungus colonies, indicating that the latent spores become viabl e after the irradiation germinating when exposed to favorable conditio ns. Using the same doses of radiation, pretreatments A (laboratory roo m conditions) and C (heating at 50 degrees C, 95% relative humidity, 2 4 h) reduced the frequency of fungi isolated when compared to pretreat ment B (drying at 50 degrees C, 24 h). The number of bacterium colonie s, however, increased when the paper was heated at high humidity condi tions compared with the control.