General Question

Jack79's avatar

Can a DNA test reveal when you last smoked hash?

Asked by Jack79 (10984points) June 23rd, 2009

I heard this story a few years back when I was in Germany. There was this famous football player who was accused of having used drugs in the past (I think it was hash only, but it could have been something harder). He insisted he hadn’t, and agreed to take a DNA test, using hair. It turned out he was lying, and from what I remember it can go up to 3 years back.

My memory is hazy on this, so the question is: can a DNA test tell for sure whether you’ve smoked hash in the past? And how far back can it go? Is it related to how often the person smoked? eg if one is a regular user and stops for 3 years will it come out completely clean?

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15 Answers

MrGV's avatar

No….Drugs does not alter DNA or anything like that.

arnbev959's avatar

It can be detected by testing hair, but the test doesn’t look at DNA.

robmandu's avatar

Here’s some explanation how hair testing for drug-use works.

Jack79's avatar

thanks guys, I learnt a lot :)

bummer that the guy I’d like tested will just stall it for 90 days and then have a haircut

Darwin's avatar

He’ll only stall for 90 days and then get a hair cut if he knows what you now know. Might be worth a shot if it is really important.

LexWordsmith's avatar

No. DNA is not affected by THC on a time-readable basis, and hair is only protein (keratin)—it does not contain DNA, iirc. Maybe some other kind of test, maybe a toxicology test, but not a DNA test.

Jack79's avatar

ah well, not really that important, we’ve got them on several other charges anyway. And yes, you’re all right, it couldn’t obviously be a DNA test, silly me. It’s the hair test pete and rob mentioned. I just remember the thing about the German footballer wrong. He was probably still a user. And I thought it went back 3 years instead of 3 months.

galileogirl's avatar

However DNA can mutate due to environmental exposure to chemicals so maybe you won’t get busted tomorrow but what might you be setting up for your grandchildren. But then most tokers are not known for long term thinking

sandystrachan's avatar

Even after a hair cut is it not still possible, the affect the drug has is still visible .

BhacSsylan's avatar

@Jack79 Just to say, wikipedia had this to say, too, should your suspect shave their heads: “Some people attempt to circumvent this through shaving their heads. This does not usually work. In the absence of the required amount of hair on the scalp, body hair can be used as an acceptable substitute in the order of face, chest, arm pit, and on some occasions the police use leg hair that has a shorter slower growth rate.”

Darwin's avatar

@BhacSsylan – Well, then, there is always full-body waxing.

However, I suspect simply giving up drugs would be less painful.

sandystrachan's avatar

Watches for all the mega bald dope smokers

Darwin's avatar

I know several guys who go in for full-body waxing. They are catalog models. Ever notice how all those guys in the catalogs never seem to have any body hair? That’s why. Of course, whether they do drugs or not, I don’t know.

Val123's avatar

My DNA is hallucinating, man.

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