Stable isotope relationships between apatite phosphate (δ18O), structural carbonate (δ18O, δ13C), and collagen (δ2H, δ13C, δ15N, δ34S) in modern human dentine

Rationale The use of multi-isotopic analysis (delta H-2, delta C-13, delta N-15, delta O-18, and delta S-34 values) of modern human body tissues for provenancing of unknown individuals in forensics is increasing. Tooth dentine develops during childhood and adolescence, therefore providing geographical information from that period of life. Tooth apatite delta O-18 values are commonly used for the reconstruction of drinking water values, and H-C-N-S isotope ratios in collagen supply additional information about the composition of diet. We tested if dentine collagen delta H-2 values provide similar information to apatite delta O-18 values with a proof-of-concept study. Methods Tooth samples were taken from modern-day individuals born in different regions of the world. Apatite and collagen were prepared from dentine. Stable isotope analyses were performed on apatite phosphate oxygen (delta O-18(phos)); oxygen and carbon of the structural carbonate (delta O-18(carb), delta C-13(carb)); and hydrogen, carbon, nitrogen, and sulfur of the collagen (delta H-2(coll,) delta C-13(coll), delta N-15, delta S-34). Results delta O-18(phos), delta O-18(carb), and delta H-2(coll) values are highly correlated in modern human dentine. There are significant relationships of delta O-18 values in the apatite fraction and delta H-2 values in the collagen fraction with local delta O-18 and delta H-2 precipitation values, respectively. Pearson correlation coefficients indicate no direct relationship between delta N-15 values and the isotope ratios of any other element. Weak relationships exist between collagen delta S-34 values and delta O-18(carb) or delta O-18(phos) values. Conclusions The highly significant correlation of delta O-18(phos), delta O-18(carb), and delta H-2(coll) values in the modern human dentine implies that measurement of delta H-2 values in collagen or delta O-18 values in bioapatite will provide reliable information about the climate at the person's whereabouts.