1. Ina Rennisch Anna Zappe

2. Background information analyse hair samples from 65 cities across the U.S. „you are what you eat“ model: hair isotopic compositions as a function of drinking water and dietary input meassures δ2H and δ18O maps were constructed using the information gained from the water samples to predict the isotopic composition of the human hair (across 48 states)

3. 4 potential sources dietary organic molecules dietary waters drinking waters atmospheric oxygen  influence the synthesis within the hair follicle

4. Materials & Methods hair samples randomly collected tap water samples 3 x 25mL per city mass spectrometer continuous flow mode carrier gas: He

5. Hypothesis nonexchangeable δ2H and δ18O  insights: water and diet across geographical regions  correlation: hair and water samples model: diet and water incorporate into keratin

6. Model Derivation keratin: synthesized from amino acids H atoms in keratin no isotopic exchange recorders of isotopic inputs model: sources and isotopic effects  determine H and O isotopic composition of the amino acids incorporated into hair keratin

7. Model Derivation 2 location of H and O fixation in amino acids depends on amino acids pH O atoms in carbonyl  exchanged during digestion isotopic composition of gut water oxygen of keratin: relates to gut water H atoms in carboxyl, amide and sulfhydryl groups exchange with the H in water H atoms in C-H bonds cannot be exchanged

8. Model Derivation 3 H atoms in amino acids: essential: C-H atoms in keratin should reflect the δ2H values of food sources nonessential: nonexchangeable H atoms may reflect: δ2H values of dietary amino acids amino acids synthesized in the body  δ2H of nonexchangable H in keratin in human hair should relate to water of the hair follicle

9. Influence H and O in follicle and gut water: multiple sources δ2H difference of cells and their surrounding water: exchange of intra- and extracellular water 2 water pools in human: describe influence of H ratio of tap water on water in the follicle H isotopic composition of hair follicle water is a mixture of extracellular (blood) water produced through the metabolism of dietary foods body water: other composition as drinking water  mixture of drinking water water derived from metabolism

10. Predictions and Implications observed slope: evidence that H and O atoms in hair derived from secondary water pools scatter exceeded measurement prediciton could be related to continental supermarket diet robustness of model predicitons was tested analysed a second set of hair samples  barbershops predict isotope ratio of tap water

11. Mapping maps of δ2H and δ18O values (496 locations) heaviest hair expected in the southern parts: Gulf coast, Texas, Oklahoma lightest hair predicted in region of the northern Rockies

12. Results hair and tapwater samples from 18 states standard deviations within a city were generally small lightest values were from nothern Montana heaviest values were from southern Oklahoma Conclusion: water samples from same city are isotopically similiar

13. Results 2 linear relationship between these two parameters interpretation: 27% and 35% of the H and O in hair were derived from local drinking water

14. Detecting Movements Beijing, China to Salt Lake City, Utah hair: sequential recorder of changes in diet changes: detected in the first interval after arriving in Utah detectable: geographic movements locations with contrasting isotope ratios in tap water

15. Discussion: Deviation nonregional water sources bottled water juices barbershop visitors

16. Discussion: Scatters dietary differences H and O composition influenced by dietary inputs drinking water O also influenced by atmospheric O

17. Discussion near „constancy“ of dietary input continental supermarket diet not only locally derived foods stronger local water and hair isotope relationships: historical populations geographically isolated populations

18. Future research specifying regions of origin in anthropological archaeological forensic studies  estimating the region-of-origin not sufficiently explored yet

19. Referenzen Ehleringer J. R., Bowen G. J., Chesson L.A., West A. G., Podlesak D. W. & Cerling T. E. (2007): Hydrogen and oxygen isotope ratios in human hair are related to geography. In: Proceedings of the National Academy of Sciences of the United States of America, Feb. 2008, pp. 2788 – 2793. The National Academy of Sciences of the USA.

20. Thank you for your attention!