Sources of DNA contamination and decontamination procedures in the forensic laboratory

The sensitivity of forensic DNA typing techniques can cause problems when evidence samples are inadvertently contaminated with DNA from another source. Therefore, precautions need to be taken to minimize the risk of contamination. In this study, laboratory air and surfaces, tools and equipment were evaluated as potential sources of contaminating DNA. Subsequently, two decontamination procedures, i.e. the conventionally used sodium hypochlorite and the commercially available DNA decontamination solution DNA ZAPTM (Applied Biosystems), were compared for their use in removing potentially contaminating DNA from the laboratory working environment. From our results, it can be concluded that air is unlikely to be the source of observed DNA contamination in the laboratory whereas DNA accumulating on surfaces, tools and equipment within the laboratory environment may potentially be transferred to evidence samples. DNA ZAPTM outperformed the conventionally used sodium hypochlorite decontamination procedure. Stringent preventive measures and decontamination of equipment and laboratory surfaces is important to avoid secondary transfer of this contaminating DNA to evidence samples.

Publication year:2011

Accessibility:Open