NCJ Number
227809
Journal
International Journal of Legal Medicine Volume: 122 Issue: 1 Dated: January 2008 Pages: 29-33
Date Published
January 2008
Length
5 pages
Annotation
This study examined the effectiveness of four sterilization techniques (ultraviolet [UV], gamma radiation, beta radiation, and ethylene oxide treatment) in effectively degrading extraneous DNA on items used at crime scenes and when handling exhibits within the laboratory.
Abstract
The most effective method for reducing contaminating DNA was ethylene oxide treatment. None of the contaminated samples treated with ethylene oxide and subsequently subjected to DNA analysis met the DNA profile criteria necessary for acceptance on the British National DNA Database, indicating the samples were no longer contaminated. Contaminated cotton swabs and micro-centrifuge tubes treated with ethylene oxide showed a marked decrease in amplifiable DNA posttreatment. Ethylene oxide treatment of sterile swabs and tubes did not significantly influence subsequent DNA analysis. Ethylene oxide gas treatment is not corrosive to metal, so it can be used to clean plastic and metal laboratory equipment. The disadvantage of using ethylene oxide is that items must be sent away for treatment over several days. This means that large fixed items such as laboratory bench surfaces cannot be sterilized in this manner; however, this study showed that ethylene oxide is the best sterilization method for small items compared with other tested methods. Beta and gamma radiation had the ability to reduce the number of full DNA profiles after their application, but not consistently. UV radiation was the least effective in eradicating unwanted DNA. The authors recommend that ethylene oxide be used to reduce the amount of unwanted amplifiable DNA on items used in forensic procedures. Additional work is underway in examining the various cycling parameters of the ethylene oxide sterilization treatment, so as to determine the optimal conditions for DNA decontamination and validate the process. 1 table, 2 figures, and 9 references