Drug Testing

Ok, here’s the situation:

I hadn’t smoked grass in years (about ten). Back in the college days I was an occasional smoker, and never did any other drugs.

About a week ago an opportunity presented itself and I smoked a little pot for old times sake. As an aside, the immediate sleepiness reminded me why I stopped.

Today I had a job offer out of the blue. However, there is a drug test.

Here is what I have been able to determine: 1. urinalysis will only show positive for a few days after a one-time user uses. No sweat. Besides, for light users the solution is dilution, as in drink lots of water and coffee (the effects of dilution can be compensated for by the tester with multiple tests to get the baseline of other analytes, but since pre-employment screens are one-shot deals, this isn’t an issue). 2. For urinalysis, there is a cutoff level below which the presence of THC metabolites is not considered positive (this allows for casual contact, such as attending a Greatful Dead concert without actually smoking). 3. Hair testing is all the rage, and a MA company recently got 510(k) approval for a hair test. Hair testing can pick up use from between 5 days (the time required for the contaminated part of the hair to exit the scalp) and 90 days.

Finally, here are the questions:
-Is there a lower cutoff level for hair testing (a level below which the presence of THC metabolites is not considered a positive result)?
-Is the hair test sensitive enough to detect one use in three to six months worth of hair growth?


Does the test, test for marijuana? The last few drug tests I took, didn’t do that. So if all you did was marijuana well they wouldn’t be looking for it.

And my last company was one of the largest in the hotel industry so, that would be interesting to know which companies test for which.

Ah, here we go again…

First, while it is true that most drug tests for employment have a cut-off level below which an indication of a substance is not considered positive, and below which it can’t detect the substance, this varies from test to test. So there’s no one right answer to that part of the question.

Second, THC lingers in the body and is detectable for up to 3 weeks - even if you smoke just one joint.

Thirdly, THC hangs out in the body fat, not the fluids. It’s not very water soluable. So no matter how much water/fluid you consume it will do nothing to flush it out of your body. It is possible to consume enough water to make your urine so dilute that there not enough THC to register, however, that takes more fluid than most people realize, there are tests that will detect even the most minute presence of THC, and some places test for overly dilute urine and, if they find it, they count it as a postive for something under the assumption you are hiding something.

As has already been pointed out, they may not even be testing for THC. Not everyone does. Sometimes, they don’t even use the sample, they just want to see if you’re willing to pee in a cup. You just don’t know. Inquiring may raise suspcions.

I’m not as famillar with hair testing - back when I was in the business hair testing was seen as unreliable. And too many guys showed up for the test shaved bald.

Now, after all that - if you took just one hit on the joint then maybe you can slide by. If you smoked the whole thing you’ll show positive for THC on just about every test there is. Now, it’s too bad that your once-a-decade lapse took place so close to this employment opportunity. You have three choices here:

  1. Don’t apply for the job
  2. Apply for the job, take the test, and deal with the results, which may or may not be positive for THC
  3. Apply for the job and try to scam the test.

Good luck.

Do hairs (I presume we’re talking about scalp hair here … otherwise this is just gross) really only stay around for 90 days? If you’ve got really long hair, is it possible to detect years-old drug use?

For the record, I got my information on hair testing here:

and my information on urinalysis here:


Both of which are the information pages of companies performing the tests.

You could claim your rastafarian and then say its discrimination by religion or something:cool:

You can’t just make blanket statements like that. I know a very heavy smoker who quit five days before the test. She knows her sample was sent off to the lab, rather than just chucked in the trash. She knows they tested for marijuana. She passed.

I know at least a dozen people who smoked a day or two before the test and passed with detox products, which are mostly just diuretics. I’ve known one (or was it two? My memory is hazy.) people who failed with the detox stuff. There is no guaranteed way to beat a drug test, but a hell of a lot of people do get lucky.

Perhaps I should clarify:

First, I do realize that the methodology can detect minute levels of the metabolites, but all tests have a lower cutoff level not of detection, but of where they assign a positive. For example, thanks to automatic money counting machines, trace levels of drugs are often found on currency. Obviously, a cutoff must be assigned or anyone’s wallet could land him in jail. The feds have assigned a cutoff for THC metabolites in urine, so I wondered if there was a similar assignment for hair, and if one use would bring a person to that level.

As for the 90-day cutoff, well, I used to design clinical assays for a large company. What actually happens is that the data are reliable only to a certain point. So it might be that the test was designed to a confidence level of 95%, and at 90 days that confidence level has dropped below 95%. So it could be that long-haired folks leve a record out five years, but at the end of the five years the confidence level is 66% and therefore not acceptable.

Here’s another thought. If hair grows 1/4 inch per month, the technician collecting the sample would have to get right down to the scalp to collect the last week or two. That’s about .009 inches per day.

Sure I can. I just did.

I worked in the drug rehab industry for four years, and how the tests worked (and didn’t work) was a topic of some interest. I stand by my statements.

I might also note that the last time we talked about scamming drug tests we all wound up in the Pit. I don’t really feel like doing that again.

“Passed” in what sense? Getting a “hit” for THC does not automatically mean you will be fired, reprimanded, or even informed of the result. If she took the test and never heard anything further that doesn’t mean her use was undetected.

Please do a search of the board on the term “drug test”. There have been several prior threads.

What about exercise?

It might have some effect, as would the amount of body fat a person actually has. That’s why it’s always phrased up to three weeks. In some, it might be two. But it won’t “clean” you up in just a day or two.

Hey, as long as you won’t face prosecution or have something go on a permanent record somewhere, if you’re faced with the situation in the OP I’d say apply and take the test. If you don’t apply you don’t get the job. If you do apply, maybe you’ll get the job and maybe you won’t (depending on testing or policy at the company), but I don’t see where you’d lose out.

Now, if you’re applying to the CIA or FBI or DEA, that might be a different matter.

Unfortunately, I’m in a small, incestuous industry where reputations are important, and everyone knows everyone else. The good side is that I make good money, and there isn’t much that the powers that be can do about it. The bad side is that, once you damage yourself, you’re screwed.