title: Global spatial distributions of nitrogen and carbon stable isotope ratios of modern human hair.
abstract: BACKGROUND
  Natural stable carbon (δ(13)C) and nitrogen isotope ratios (δ(15)N) of humans are related to individual dietary habits and environmental and physiological factors. In forensic science the stable isotope ratios of human remains such as hair and nail are used for geographical allocation. Thus, knowledge of the global spatial distribution of human δ(13)C and δ(15)N values is an essential component in the interpretation of stable isotope analytical results.
  
  
  METHODS
  No substantial global datasets of human stable isotope ratios are currently available, although the amount of available (published) data has increased within recent years. We have herein summarised the published data on human global δ(13)C andδ(15)N values (around 3600 samples) and added experimental values of more than 400 additional worldwide human hair and nail samples. In order to summarise isotope ratios for hair and nail samples correction factors were determined.
  
  
  RESULTS
  The current available dataset of human stable isotope ratios is biased towards Europe and North America with only limited data for countries in Africa, Central and South America and Southeast Asia. The global spatial distribution of carbon isotopes is related to latitude and supports the fact that human δ(13)C values are dominated by the amount of C4 plants in the diet, either due to direct ingestion as plant food, or by its use as animal feed. In contrast, the global spatial distribution of human δ(15)N values is apparently not exclusively related to the amount of fish or meat ingested, but also to environmental factors that influence agricultural production.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Köln, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Hülsemann
authors.affiliation: Institute of Forensic Medicine, Ludwig-Maximilians-University Munich, Nußbaumstr. 26, 80336, München, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Lehn
authors.affiliation: Forensic Science Institute, Federal Criminal Police Office, Unit Central Analytics II, Thaerstraße 11, 65193, Wiesbaden, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Schneider
authors.affiliation: Forensic and Investigative Science, C. Eugene Bennett Department of Chemistry, West Virginia University, 308 Oglebay Hall, Morgantown, WV, 26506-6121, USA.
authors.forename: Glen
authors.initials: G
authors.lastname: Jackson
authors.affiliation: LGC, Queens Road, Teddington, TW11 0LY, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Hill
authors.affiliation: isolab GmbH, Laboratorium für Stabile Isotope, Woelkestrasse 9/I, 85301, Schweitenkirchen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Rossmann
authors.affiliation: Forensic Science Institute, Federal Criminal Police Office, Unit Central Analytics II, Thaerstraße 11, 65193, Wiesbaden, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Scheid
authors.affiliation: LGC, Queens Road, Teddington, TW11 0LY, UK.
authors.forename: Philip J H
authors.initials: PJ
authors.lastname: Dunn
authors.affiliation: Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Köln, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Flenker
authors.affiliation: Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Köln, Germany.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Schänzer
mesh_terms: D000818:Animals; D002247:Carbon Isotopes / Q000032:analysis*; D016208:Databases, Factual; D014943:Global Health; D006197:Hair / Q000737:chemistry*; D006736:Horses; D006801:Humans; D013058:Mass Spectrometry; D009262:Nails / Q000737:chemistry; D009587:Nitrogen Isotopes / Q000032:analysis*; D062206:Spatial Analysis
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes