[Investigations on disinfection and sterilization of surfaces by ultraviolet radiation (author's transl)].

Some model investigations have been made in order to find out if disinfection or sterilization in an ultraviolet radiation cabinet (fig. 1) is effective. The reduction rate of spores of Bacillus anthracis dried to germ carriers of aluminium, ceramics or wood was used for indicating the germicidal effect. It was found, that a 7.5 times higher dose of radiation was necessary to reach a similar reduction rate of spores on germ carriers of ceramics as it was found for the ones of aluminium (tab. 1 and 2). Very high dosage of radiation was necessary to get a safe reduction of spores on each germ carrier (fig. 2 and 3). On wooden germ carriers an average logarithmical reduction (R) of no more than 0.67 was found after 30 h of exposure (tab. 3). Unreliable results have been found in the sterilization experiments with spore bearing germ carriers of aluminium and ceramics. In a few rare cases sterility could be obtained by an ultraviolet radiation dose of 2.000.000 microW s/cm2 (tab. 4). But generally a dosage of even 222.600.000 microW s/cm2 was not sufficient to sterilize the copntaminated germ carriers. The ultraviolet radiation cabinet cannot be recommended for disinfection or sterilization.