The Prevention of Contamination in a Laboratory

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Recommended: Ethical issues surrounding forensics

Contamination in the lab has been discussed multiple times before but remains a major issue in laboratories. The importance of evidence in any criminal case is evident and aids in telling a story of the events that happened at a crime scene. The reliability of DNA evidence to convict or clear an individual has become a major analytical tool in investigations and court presently. DNA analysis is a scientific method for human identification but if the integrity of the evidence comes into question then important information is lost. This information plays a major role in an inclusion or exclusion of an individual. Precautions must always be taken while handling evidence and each substance should be seen as hazardous while assuming a blood borne pathogen exists.1

Why Contamination Happens

Contamination in the laboratory and at the location of the scene occasionally occurs due to improper techniques and untrained individuals during the collection and analysis of evidence. A standard procedure for analyzing any evidence especially with biological samples includes the use of personal protective equipment (PPE).1

Personal protective equipment protects individuals from contaminating themselves with diseases present in evidentiary samples as well as protecting the evidence of contamination from the individual. The use of this equipment includes disposable jackets, gloves, goggles, foot covers, and face masks while forgetting any of these items will increase the risk of contamination. The validity of DNA found in a profile pertaining to the crime will be used to link the criminal to the event and must show to be statistically accurate to include or exclude an individual.

Since the investigation of a crime requires the coll...

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...cessed April 2014)

3. NCR II. Ensuring High Standards of Laboratory Performance. The Evaluation of Forensic DNA Evidence. (accessed March 2014)

4. Gill P., et al. DNA commission of the International Society of Forensic Genetics: Recommendations on the evaluation of STR typing results that may include drop-out and/

or drop-in using probabilistic methods. Forensic Science International: Genetics 6 (2012) 679–688. (accessed April 2014)

Gill P., Kirkham A. Development of a simulation model to asses the impact of contamination in casework using STRs. Journal of Forensic Sciences (2004) 49: 485-491. (accessed April 2014)

6. Lowe A., Murray C., Whitaker J., Tully G., Gill P. The propensity of individuals to deposit DNA and secondary transfer of low level DNA from individuals to inert surfaces. Forensic Science International 129 (2002) 25–34 (accessed May 2014)

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