There are still a large proportion of countries, especially in Africa, where there are no available data for human carbon and nitrogen isotope ratios. Although the interpretation of modern human carbon isotope ratios at the global scale is quite possible, and correlates with the latitude, the potential influences of extrinsic and/or intrinsic factors on human nitrogen isotope ratios have to be taken into consideration.

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Analysing the isotope ratio of light elements in human tissue of an unknown person helps to reconstruct the life history with regard to geographical origin and/or typical food supply. In this study the isotope ratios of the bio-elements in hair samples of 111 persons from 13 different countries all over the world were measured with the aim of provenance determination. The results indicated that individuals from Costa Rica and Brazil can be differentiated from typical European individuals by delta(13)C, Australians by delta(34)S and delta(2)H in hair samples. The combination and evaluation of the data by multivariate statistical analysis considerably improved origin assignment. Investigation of hair samples from a number of individuals from one particular region (southern Germany) yielded remarkable variation of isotopic values indicating different nutritional habits. The possibilities and limitations of this method in its current state are demonstrated and discussed.

This paper presents a comparison of the isotopic ratios of hydrogen, carbon, nitrogen and sulphur of three pairings of hair and nail tissue taken from contemporary human remains. Our aim was to examine the possibility of a direct comparison of isotopic data in hair with that of nail tissue for forensic purposes. The results indicate that stable isotope ratios of the elements were best comparable between human scalp hair longer than 3 cm and the distal end of the nails. There were no distinct variations between finger and toenails. Our isotopic data for bulk hair and nail confirmed that hair samples were slightly enriched in (13)C but depleted in (15)N compared to nail samples. Furthermore, our data reveal that δ(34)S values in nail samples were more variable than in hair samples. Direct comparison of the corresponding segments of hair and nail samples may be difficult due to individual differences especially for δ(15)N and δ(2)H. Hair may have an isotopic composition more consistent with the ingested food within a specific time than is provided by nail. It can be concluded that once a hair is formed, no further metabolic changes of the isotopic pattern should occur. Nevertheless, our data suggest that there was a change in isotope ratios particularly for δ(2)H along the hair shaft. Interpretation of the isotope data in corresponding segments of hair and nail for forensic purposes must consider particular variations, especially for chronological considerations.

Multi-element stable isotope analyses of δC, δN, δS and δH values were performed along scalp hair strands to detect isotopic changes resulting from different stays abroad. One hair strand with a hair length of more than 50 cm originated from a German woman, who frequently made long-distance travels of 1 to 4 weeks. The second hair strand with a length of 15 cm was taken from a Japanese woman who went to Germany for a period of some months. Stable isotopic influences due to the stays abroad were clearly reflected in the 5-mm segments along the proximal part of the hair strand; whereas in the more distal parts, the isotopic influences were blurred. This can be regarded as the result of the highly variable intra-individual hair growth rate of single hairs of at least ± 30% compared to the mean growth rate. Consequently, the initial isotope signal obtained by short stays abroad became rapidly attenuated in the more distal parts of the hair strand. Furthermore, decreasing sulphur content associated with higher sulphur isotope values was observed with increasing hair length. The isotope shifts along the scalp hair strand, provoked by dietary changes at new locations, appeared at such points of hair length, which correspond well with the maximum growth rate of single hairs. Consequently, the exact date for any changes coming along with isotopic shifts may be calculated by best approach considering a hair growth value of 1.4 cm per 30 days, instead of the commonly used mean monthly hair growth rate of 1.1 cm. This may be important in forensics, if detailed information about a person's recent lifetime should be figured out by segmental scalp hair analyses.

To receive information about the duration of a person's stay abroad related to those questions in forensics, stable isotopes of H-C-N-S were analysed in beard hair samples from four young soldiers, who went from Fürstenfeldbruck (Bavaria, Germany) to Phoenix (Arizona, USA) on the same date for their pilot training over a time period of 3 months. All study subjects were almost of the same age, had similar physical constitutions and stayed at the same military bases for the whole study period. However, the results showed considerable individual variabilities. In Arizona, hair δ(13)C increased by 2.3‰ (±0.6) and δ(34)S decreased by 1.8‰ (±1.2). No remarkable shifts of hair δ(15)N and δ(2)H were observed. Significant shifts of δ(13)C or δ(34)S in the shaved beard hair samples occurred 8 or 9 days after arrival in Arizona, respectively. The time lag to receive the isotope signals in hair due to US diet correspond to the growth period that hair needs to cover the distance of 2-3 mm from its root to the surface of the skin. This implies that isotopic changes due to the consumption of food and drinks were incorporated almost immediately into the hair protein. Consequently, if connected with an isotopic change of the diet, short-term stays for only a few days might be clearly recognizable within the first millimetres of a scalp hair strand which includes the hair roots.

The consumption of the offal of noncastrated pigs can lead to the excretion of 19‐norandrosterone (NorA) in urine of humans. In doping control, GC/C/IRMS is the method of choice to differentiate between an endogenous or exogenous origin of urinary NorA. In some cases, after the consumption of wild boar offal, the δ13C values of urinary NorA fulfill the criteria of an adverse analytical finding due to differing food sources of boar and consumer. However, consumption of wild boar's offal is not very common in Germany, and thus, the occurrence of such an analytical finding is unlikely. In contrast, the commerce with wild boar meat has increased in Germany within the last years. Up to 20,000 tons of wild boar meat are annually consumed. In order to probe for the probability of the occurrence of urinary NorA after consumption of wild boar meat, human urine samples were tested following the ingestion of commercially available game. In approximately half of the urine samples, traces of NorA were detected postadministration of 200 to 400 g boar meat. The highest urinary concentration was 2.9 ng/ml, and significant amounts were detected up to 9 h after the meal. δ13C values ranged from −18.5‰ to −23.5‰, which would have led to at least two adverse analytical findings if the samples were collected in an antidoping context. IRMS analysis on German boar tissue samples showed that δ13C values for wild boar's steroids are unpredictable and may vary seasonally.