Validation of a dual cycle ethylene oxide treatment technique to remove DNA from consumables used in forensic laboratories

Validation of a dual cycle ethylene oxide (EO) approach to removing DNA contamination from consumables has been undertaken. The limits of the technique were investigated resulting in evidence that the DNA from up to 50 μl of blood and saliva can be removed to a level where the consumable can be considered DNA free. DNA from semen was more resilient and some allelic peaks remained that would have prevented the consumable being classed as suitable for use in low template DNA analysis. No residual effect on consumables resulting in inhibition of subsequent DNA analysis was noted. However, if consumables had been previously treated with gamma or electron beam irradiation then slight inhibition of the downstream STR process was observed.Dual cycle EO treatment was effective at removing recoverable DNA from swabs and stain cards and consideration should be given to the suitability of EO treatment for use on critical consumables used in the forensic laboratory.