Trace DNA Presence, Origin, and Transfer within a Forensic Biology Laboratory and Its Potential Effect on Casework

• NCJ Number: 214954
• Journal: Journal of Forensic Identification Volume: 56 Issue: 4 Dated: July/August 2006 Pages: 558-576
• Author(s): Adam L. Poy; Roland A. H. van Oorschot
• Date Published: July 2006
• Length: 19 pages
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

This article describes the materials, methods, and findings of an assessment of the presence, origin, and transfer of background DNA within the forensic laboratory environment and its potential to contaminate casework.

Abstract

Various amounts of DNA were found on objects commonly present in a biology laboratory; however, most were determined to be of medium or low risk for the contamination of casework. Significant amounts of DNA were found on gloves used during routine casework duties, especially from examining large items. This has the potential to transfer DNA from a glove to other regions of the exhibit and to examination equipment. Thus, it is important to decontaminate thoroughly and regularly all laboratory equipment and frequently change gloves. A review of laboratory procedures and staff training regarding the handling of exhibits and samples can significantly reduce the likelihood of casework contamination. Further studies should be conducted on the transfer of DNA-containing material in the laboratory setting, so as to identify all risks of contamination and develop improved laboratory procedures for reducing those risks. In order to collect any DNA present on laboratory surfaces, 195 laboratory sites were swabbed or tape lifted for DNA analysis. The sites selected had either direct contact with casework samples or were involved in possible secondary or tertiary pathways of contact. None of the sites were cleaned prior to collection. To determine whether DNA is transferred to a glove during either routine examination or DNA analysis, seven staff members were selected to have the outside palm region of their gloves (latex) swabbed directly after they finished the task they were conducting or before they routinely changed gloves during their task. Staff members were not informed of this experiment prior to being swabbed. The DNA analysis of the various types of samples is described. 3 tables, 10 references, and appended diagram that shows potential modes of DNA transfer that can contaminate DNA casework