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Validation of a Dual Cycle Ethylene Oxide Treatment Technique To Remove DNA From Consumables Used in Forensic Laboratories

NCJ Number
Forensic Science International: Genetics Volume: 4 Issue: 4 Dated: July 2010 Pages: 239-243
Emily Archer; Heather Allen; Andy Hopwood; Diane Rowlands
Date Published
July 2010
5 pages
This paper reports on efforts to optimize the ethylene oxide (EO) technique for the removal of DNA from disposable plastic consumables so they can be used in the most sensitive DNA analysis techniques; further work tested the limits of performance of this technique and tested for inhibition of PCR following treatment both with virgin consumables and on pretreated (sterilized) consumables.
EO is a colorless, flammable, organic gas that was patented for sterilization use in 1938. It is used as a fumigant or sterilizing agent for a wide variety of facilities. The current work used a dual cycle EO approach in attempting to remove DNA contamination from consumables. In order to mimic the method of introduction of contamination with human DNA during the manufacturing or packaging process of the disposable plastic consumables, the tested components were spiked with blood, saliva, or touch DNA. Following treatment with the dual cycle EO process, testing showed that the DNA from up to 50 ml of blood and saliva had been removed to a level so low that consumables could be considered DNA free. DNA from semen applied to the consumable was more resilient, with some allelic peaks remaining to prevent the consumable from being suitable for use in low template DNA analysis. No residual effect on consumables that resulted in inhibition of subsequent DNA analysis was noted; however, if a consumable had been previously treated with gamma or electron beam irradiation, then a slight inhibition of the downstream STR process was observed. Since dual cycle EO treatment was effective in removing recoverable DNA from swabs and stain cards, consideration should be given to using this treatment on critical consumables used in DNA procedures in the forensic laboratory. The materials and methods used in this work are described in detail. 2 tables, 6 figures, and 14 references