Slashdot Mirror
Things You Drink Can Be Used To Track You
sciencehabit writes with an intriguing story about the potential of figuring out where people have been by examining their hair: "That's because water molecules differ slightly in their isotope ratios depending on the minerals at their source. Researchers found that water samples from 33 cities across the United State could be reliably traced back to their origin based on their isotope ratios. And because the human body breaks down water's constituent atoms of hydrogen and oxygen to construct the proteins that make hair cells, those cells can preserve the record of a person's travels. Such information could help prosecutors place a suspect at the scene of a crime, or prove the innocence of the accused." Or frame someone by slipping them water from every country on the terrorist watchlist.
http://news.bbc.co.uk/2/hi/england/bristol/10332975.stm
Basically some bones from a German cathedral could be places as having lived in England due to isotopes in the teeth.
This helped confirm the bones were of a 10th century English princess.
This may be forensically useful, but don't think of it like a fingerprint or a DNA match. There's only one degree of freedom here -- whether the water is isotopically "heavy" or "light". All of a person's water co9nsumption history is mixed up into one number.
So you won't be able to tell the difference between, say, a person who lived all year in Illinois (with a moderate isotope ratio) and a person who flies back and forth between Montana and Florida (who'd have a mix of "heavy" and "light" water in their system.)