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The evaluation and validation of Phadebas® paper as a presumptive screening tool for saliva on forensic exhibits

Wornes, Danielle (2017) The evaluation and validation of Phadebas® paper as a presumptive screening tool for saliva on forensic exhibits. Masters by Coursework thesis, Murdoch University.

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Abstract

Biological evidence originating from saliva can be of considerable significance to criminal investigations. However, the localisation of saliva is inherently challenging, due to the fact that saliva, and its associated stains, do not contain readily visible constituents. Under such circumstances, it is necessary to adopt screening techniques in order to isolate potential saliva stains. There are a limited number of screening tools available for this purpose; currently, the state DNA forensic laboratory of Western Australia (PathWest) utilises alternate light source technology. However, this method has demonstrated ineffectiveness, with a fail rate of 40% or greater. Thus, PhadebasR paper has been suggested as an alternative. This test detects the activity of the α- amylase enzyme, which is present in high concentrations in saliva. The limitations of PhadebasR paper for use as a presumptive screening tool need to be understood for the correct interpretation and inclusion of test results in forensic investigations. Thereby, the following review aims to assess the suitability of PhadebasR paper as a presumptive screening test for saliva. In this review, current screening techniques for saliva have been examined, as well as the reported sensitivity and specificity of PhadebasR paper. Furthermore, the factors affecting sensitivity and specificity have been explored. The use of PhadebasR paper in the greater context of forensic examination has also been considered. Finally, suggestions have been made pertaining to experimental design and methodology for studies concerning this topic; recommendations for future studies have also been advised. This review found that the limitations of PhadebasR paper as a presumptive screening tool are poorly reported and attempts to validate this test lack scientific rigour. Consequently, five crucial areas have been identified for consolidation; specifically, the sensitivity, specificity, effects of temperature on sensitivity and specificity, detection of saliva in mixed body fluid stains, and influence of the substrate on PhadebasR paper need to be subjected to experimental validation.

Publication Type: Thesis (Masters by Coursework)
Murdoch Affiliation: School of Veterinary and Life Sciences
Supervisor: Speers, Samuel and Murakami, J.A.
URI: http://researchrepository.murdoch.edu.au/id/eprint/37890
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