Geographic Patterns of Hydrogen and Oxygen Isotopes in Human Hair

sci-policy-hd…from Science Insider

[Reaction about the scientific validity of a plan by the U.K. Border Agency to use DNA and isotope analysis of tissue from asylum seekers to evaluate their nationality and help decide who can enter the United Kingdom...]

Jane Evans, NERC Isotope Geosciences Laboratory: I can’t imagine how you use [isotope evidence] to define nationality….It worries me as a scientist that actual peoples’ lives are being influenced based on these methods.

James Ehleringer, University of Utah: In 2008 we published a paper establishing a relationship between the hydrogen and oxygen isotope of human hair and geographic patterns…To the best of my knowledge, we are the only laboratory that has taken the hair isotope patterns and explicitly placed them onto a GIS display (i.e., map). As you see from that map, there are not unique relationships in the USA, only banding patterns. I am unaware of any substantive regional and/or global pattern analyses other than those out of our lab. Thus, I find it surprising that scientists in the UK have not only acquired the data to develop global maps but also that this technique has been refined to the point that it is a viable, reliable screening tool with the specificity implicit in the document. There are not unique global distribution patterns for hydrogen and oxygen isotopes of water. Instead there are repeatable patterns across continents in a general sense. We would expect hair hydrogen and oxygen isotopes to exhibit the same pattern.  Thus, a unique specificity that would be appropriate for the proposed application seems unlikely. Now the additional analyses of heavy isotopes in hair may further constrain the possible regions of origin, but I do not believe that our science has reached the point where we can be specific at the country or within country scale.

“Now to the bigger challenge…Hydrogen and oxygen isotopes of hair reveal recent regional geographic patterns. Assuming that hair grows at about 1 cm per month,  a 10-cm hair length might record the last 10 months of that person’s travel…this 10-month period is not necessarily synonymous with where that person may have originated from.”