Chemicals in your hair can track where you've been

[Paradox]

http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/jf1003539?cookieSet=1

Essentially, scientists have found a way to examine the trace chemicals deposited in hair after water is processed in the body to discover where that water came from, so if you had a lager in Boston or Scotch in Scotland or water in Mexico (assuming your hair didn't fall out after drinking it), they can track where you've been or where your beverage came from by the residual chemicals in your hair.

My problem with this study is the fact that most beverages are bottled and shipped elsewhere. People around the country drink Samuel Adams, and people around the world drink Scotch whisky, so actually using this to track people seems a bit far-fetched; still, it's an interesting idea.

Edit: Some people dislike reading actual scholarly journal articles, so a simpler explanation is here:
http://news.sciencemag.org/sciencenow/2010/06/scienceshot-this-beer-knows-wher.html

[Trieste]

This is a current subject of research. I was just speaking to a professor not long ago about the possible forensic use of seawater isotopes. We have core samples collected from most of the world's seas and their isotope profiles are known to us. The only thing is that not all of them are different enough to provide a differentiation for, say, a floating corpse.

I think a more accurate assessment would be probably what's in the skin, maybe the hands. The hands tell a story just as much, if not more than, the hair. If you think about it, people very seldom wash their hands in bottled water.

[electrichigh]

This came up in a evolutionary bio lecture last semester as a wee side track, my lecturer has a tendancy to go off in huge unrelated but really interesting tactics. He was talking about how the same technique was used to track a group of nomadic people where they had been etc. It is highly interesting just how much of your suroundings end up residing in your body. For example they did a study on children in cities and towns over a period of fifty years and by the end of it could track what road (with a mile radius) these children had grown up on by the size of the lead rings around their eyes. If you look in the mirror there is a dark band around your iris where it meets the corona. Thats lead desposits from the air when lead was commonly used in petrol. At least that was why it was banned in the UK they didn't realise that it ended up in everyones bodies.

Though the more prevalent case with this is just the proof that most chemicals we put through our body don't leave!

[Trieste]

'Chemicals' is used with a pretty negative tone. Keep in mind that some of the 'chemicals' we take in are things that help us. Dihydrogen monoxide is a chemical compound, as are threonine and tryptophan. Of course the chemicals we take in stick around. Most of the time, our bodies need them.

[Oniya]

They've been using hair samples to determine when victims of poisoning were dosed for quite a while.  Essentially, hair grows something like 1/2 inch every month, so they section off the hair sample into 1/2 inch lengths starting at the root (which would be 'time zero').  Each section is basically dissolved, and run through a mass spectrometer to separate it into the various components.  Then, it's compared against the peaks for 'what we're looking for', be it arsenic, lead, or a selection of isotopes of benign components.

[NotoriusBEN]

Along with this line of talk, about hair samples, you can track when a person indulged in a drug of their choice (well duh... chemicals). If a company *really* wants to nail you for doing drugs, they can ask for a hair sample along with a urinalysis. Shoot, they can even track what *day* you took the drug based on your hair sample.

Not that I touch the stuff. I just work in heavy industrial environments that require these on a random basis...

[Oniya]

Along with this line of talk, about hair samples, you can track when a person indulged in a drug of their choice (well duh... chemicals). If a company *really* wants to nail you for doing drugs, they can ask for a hair sample along with a urinalysis. Shoot, they can even track what *day* you took the drug based on your hair sample.

Not that I touch the stuff. I just work in heavy industrial environments that require these on a random basis...

Day?  Given the rate of growth that I've heard quoted, that would require a sample of 1/60th of an inch long, or under 0.5 mm.  That sounds like pretty sensitive equipment for a random sample.

[NotoriusBEN]

indeed. usually with samples they just check to see if you test positive or negative on chems. If you test positive, they go to more exact tests if a timeframe is required for certain incidents. Of course, as your hair gets longer the bands can get fuzzy. You'll still be tested positive, but it becomes weekly or even monthly.

scarey tech in the realm of drug testing...

[Trieste]

Day?  Given the rate of growth that I've heard quoted, that would require a sample of 1/60th of an inch long, or under 0.5 mm.  That sounds like pretty sensitive equipment for a random sample.

*headshake* .5 or even .25mm is massive for a chemical sample. Even at the undergrad level, I've personally done testing that involved literally counting how many cells out of the population on the slide stained a certain color. (Talk about making your eyes cross.)

You could look that over under nothing more complex than a bead of water caught in a washer, really, and it doesn't take a whole lot to run it through GC, mass spec, NMR, etc.