Stable ²H isotope analysis of modern‐day human hair and nails can aid forensic human identification

Abstract

Continuous-flow isotope ratio mass spectrometry (CF-IRMS) was used to compare (2)H isotopic composition at natural abundance level of human scalp hair and fingernail samples collected from subjects worldwide with interpolated delta(2)H precipitation values at corresponding locations. The results showed a strong correlation between delta(2)H values of meteoric water and hair (r(2) = 0.86), while the corresponding correlation for nails was not as strong (r(2) = 0.6). Offsets of -180 per thousand and -127 per thousand were observed when calculating solutions of the linear regression analyses for delta(2)H vs. delta(18)O correlation plots of hair and nail samples, respectively. Compared with the +10 per thousand offset of the global meteoric water line equation these findings suggested that delta(18)O data from hair and nail would be of limited diagnostic value. The results of this pilot study provide for the first time tentative correlations of (2)H isotopic composition of human hair and nails with local water. Linear regression analyses for measured delta(2)H values of human hair and nails vs. water yielded delta(2)H(hair) = 0.49 x delta(2)H(water) - 35 and delta(2)H(nails) = 0.38 x delta(2)H(water) - 49, respectively. The results suggest that (2)H isotopic analysis of hair and nail samples can be used to provide information regarding an individual's recent geographical life history and, hence, location. The benefit of this technique is to aid identification of victims of violent crime and mass disasters in circumstances where traditional methods such as DNA and fingerprinting cannot be brought to bear (or at least not immediately).

Multi-element stable isotope analysis of H, C, N and S in hair and nails of contemporary human remains

“…Since both finger and toenail tissue of each individual had almost the same δ 2 H value over the whole growth time, δ 2 H values along the hair strand changed distinctly with a remarkable enrichment in younger hair segments. An enrichment of 2 H values in human hair compared to nail tissue by a mean value of 6‰ can also be seen in the results of Fraser and Meier-Augenstein [9]. Contrary to our study, the authors took hair samples directly from the scalp, which were compared with nail samples clipped off at the distal edge of the nail.…”

“…Although there is a tendency for a 'global supermarket' diet, isotope signatures in human tissues hold dietary information directly related to both food sources and dietary practices in a region [5][6][7]. Several studies have demonstrated the potential of multi-element stable isotope analysis as a tool for determining the place of origin of living humans, unidentified humans and the identification of disaster victims [8][9][10][11][12]. Description of regional differences is possible using stable isotope ratios of bio-(H, C, N, O and S) and geo-elements (Sr and Pb).…”

Stable isotope analysis of modern human hair collected from Asia (China, India, Mongolia, and Pakistan)

“…H and O isotope ratio analysis has been applied to questions of origin or migration in nonhuman keratin tissues such as bird feathers (Hobson et al, 1999a(Hobson et al, , 2004 and butterfly wing keratin (Hobson et al, 1999b). However, data from human hair (Sharp et al, 2003;O'Brien and Wooller, 2007;Ehleringer et al, 2008) and nail keratin (Fraser et al, 2006;Fraser and Meier-Augenstein, 2007) have recently been published.…”

Recent Advances in the Application of Stable Isotope Ratio Analysis in Forensic Chemistry

“…Abundances of these isotopes, therefore, provide an indication of the dietary lifestyle and geographical origin of an individual. Following on from some of the fundamental studies of Ehleringer et al [27] investigating the links between stable isotope signatures in hair of US residents and geographic provenance, Fraser et al [26,28] developed isotope profiling methods for hair and nails.They conducted studies yielding information about the intra-and inter-variability of individuals within a geographical area [26] and have demonstrated that information regarding recent geographical whereabouts can be obtained from 2H isotope profiling of hair and nail samples. [28] Meier-Augenstein and Fraser [29] reported the first use of isotope analysis in aiding the identification of an unknown victim.…”

“…They examined hair and nail samples from a dismembered body. Using data obtained from their previous longitudinal study, [27] as well as data from the Global Network for Isotopes in Precipitation, they were able to provide sufficient information about the likely geographical origin of the victim and approximate time period of entry into the country. This allowed investigators justification for DNA analysis that resulted in identification of the victim.…”