Assessing the Predictability of Existing Water-to-enamel Geolocation Models Against Known Human Teeth: Do We Need Tissue-Specific δ 18O Reference Maps?

Stable isotope analysis of human tissues has become a valuable tool for mapping human geolocation. This study adds to the existing knowledge of the relationship between oxygen stable isotopes in human enamel ( δ 18 O enam ) and drinking water ( δ 18 O dw ) by presenting δ 18 O enam values in clinic-extracted human dental enamel with known provenance. The results from this study indicate that the theoretical isotopic relationship between 18 O enam and 18 O dw is valid although weak at the city and country-level. However, differences of up to 15‰ were observed between predicted δ 18 O dw values using existing models and observed values, highlighting the complexity of using enamel-to-water conversion equations. A city-specific range of δ 18 O enam values is now understood for Metro Vancouver [ δ 18 O carbonate  = − 9.7‰ to − 7.2‰] and presents the possibility of both including within the city of Vancouver and excluding individuals, utilizing stable oxygen analysis as an exclusionary tool. Overall, this study’s results support the development of tissue-specific d 18 O enam geographical reference maps for human geolocation.