Preliminary Study to Test the Feasibility of Sex Identification of Human (Homo sapiens) Bones Based on Differences in Elemental Profiles Determined by Handheld X-ray Fluorescence

Abstract

Sex assignment of human remains is a crucial step in forensic anthropological studies. The aim of this study was to examine elemental differences between male and female bones using X-ray fluorescence (XRF) and determine if elemental profiling could be used for sex discrimination. Cranium, humerus, and os coxae of 60 skeletons (30 male, 30 female) from the Chiang Mai University Skeletal Collection were scanned by XRF and differences in elemental profiles between male and female bones determined using discriminant analysis. In the cranium, three elements (S, Ca, Pb) were significantly higher in males and five elements (Si, Mn, Fe, Zn, Ag) plus light elements (atomic number lower than 12) were higher in females. In humerus and os coxae, nine elements were significantly higher in male and one element was higher in female samples. The accuracy rate for sex estimation was 60, 63, and 61 % for cranium, humerus, and os coxae, respectively, and 67 % when data for all three bones were combined. We conclude that there are sex differences in bone elemental profiles; however, the accuracy of XRF analyses for discriminating between male and female samples was low compared to standard morphometric and molecular methods. XRF could be used on small samples that cannot be sexed by traditional morphological methods, but more work is needed to increase the power of this technique for gender assignment.

Elemental Analysis of Bone, Teeth, Horn and Antler in Different Animal Species Using Non-Invasive Handheld X-Ray Fluorescence

“…X-ray fluorescence (XRF) is used for routine, relatively non-destructive chemical analyses of rocks, minerals, sediments and fluids, and can provide important information on the elemental components of various biological sample types, such as bone [ 11 – 14 ], teeth [ 3 , 12 , 15 ] and antler [ 16 ], and forensically to identify the species of body remains [ 11 , 12 , 17 ]. Recent studies have examined lead levels in human bone ( in vivo ) and arsenic levels in human nail clippings by portable XRF [ 18 , 19 ].…”

“…Based on discriminate analyses, XRF was able to distinguish between dog, pig, goat, tapir, monkey, and elephant tooth samples with a 100% success rate [ 3 ]. Subsequently, we identified differences in elemental composition of human bones between male and female samples: eight (silicon (Si), S, Ca, Mn, Fe, Zn, silver (Ag) and Pb), nine (S, Ca, Fe, zirconium (Zr), Ag, Cd, tin (Sn), antimony (Sb) and Pb) and 10 (P, S, (titanium) Ti, Fe, Zn, Ag, Cd, Sn, Sb and Pb) elements differed by sex for cranium, humerus and os coxae bones, respectively [ 14 ]. The accuracy rate for sex estimation by XRF was only ~60–67%, however, so more refining of the technique is needed to make it more reliable for human bones.…”

Elemental classification of the tusks of dugong (Dugong dugong) by HH-XRF analysis and comparison with other species

“…Also, the elemental content in male and female elephant tusks is not much different25. In humans, the elemental content in bone (cranium, humerus, os coxae and their combination) has been used for sex classification, but it only gave an accuracy rate ranging from 60 to 67%21. Taken together, we have concluded that elemental analysis might not be a worthy tool for sex identification in dugongs.…”

“…bones, teeth, soft tissues or body fluids) of a particular mammal species has been studied for a wide range of purposes, such as tissue structure1314, the role of elements in physiology151617, contamination by environmental pollution1819, and forensic science202122232425. Many techniques are used for element detection, such as inductively coupled plasma mass spectrometry (ICP-MS)26, atomic absorption spectroscopy (ASS)27 and X-ray fluorescence (XRF)2829; each technique has both advantages and disadvantages.…”

“…All samples used in this study were under the authority of museums or belonged to private owners who did not allow any destruction of the samples. HH-XRF has been shown to be an appropriate technique for detection of elements in animal tissues such as horn/antler24, bone212431 or teeth/tusks222325 for either biological or forensic purposes. For example, analysis of elemental data by discriminant analysis and logistic regression models has been successful in identifying the origin of elephant tusks, i.e.…”