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Isotope Analyses of Hair as a Trace Evidence Tool To Reconstruct Human Movements: Combining Strontium Isotope With Hydrogen/Oxygen Isotope Data

NCJ Number
Date Published
March 2014
51 pages
This study determined whether the 87Sr/86Sr ratios of human hair tissues are linked to geographically controlled variables.

Research has previously established that the 87Sr/86Sr ratios of human tissues composed of hydroxyapartite (e.g., bones and teeth) are related to geography/environment; however, the application of 87Sr/86Sr ratios of keratinous human tissues (e.g., hair and fingernails) has not been attempted due to low strontium concentrations within these tissues; however, recent technological advances have made strontium isotope analysis of keratin-based tissues possible. This has proven useful in reconstructing animal geospatial histories. Since human hair is structurally similar to non-human keratinous tissues, its 87Sr/86Sr value should also record environmental information. The current study has demonstrated that the 87Sr/86Sr ratios of human hair are related to geographical features, thus enabling the further development of strontium isotope ratios of human hair as a forensic tool. Such an analysis is complicated, however, by the fact that Sr abundance and 87Sr/86Sr ratios of human hair are also influenced by both endogenous (i.e., dietary sources) and exogenous (i.e., external deposits) Sr contributions. This requires separating the external Sr environmental signals from the internal Sr dietary indicators prior to the application of 87Sr/86Sr ratios of human hair for detecting environmental features of places where the subject has been. The relevance of the study's findings to forensic interests is shown by observing that hair studies revealed large variations in the 87Sr/86Sr ratios of tap waters available to an individual in different locations across the United States. This developed the foundation for wider geospatial applications of the 87Sr/86Sr ratios of human hair in determining whether a suspect has been in the vicinity where a crime at issue was committed. Extensive tables and figures and 48 references

Date Published: March 1, 2014