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.

Comments

Polonium 210

[rilister]

This has been done before: in the investigation of the poisoning of Alexander Livinenko, the traces of Polonium 210 left wherever the poisoner(s) went gave the UK authorities a very detailed trail to work with - one that not only showed the exact teapot used for the poisoning, but also provides a fingerprint of where the Po-210 was produced and at what date.

It's quite a fascinating story:
http://en.wikipedia.org/wiki/Alexander_Litvinenko_poisoning#Polonium_trails

Simply substitute Po-210 for something not deadly and you have a wonderful tracking mechanism.