Hair Testing THC Cutoff Value?

Discussion in 'Blood, Hair & Saliva Testing' started by pinkrope, Feb 22, 2004.

  1. pinkrope

    pinkrope New Member

    Does anyone know what the Hair Test cutoff value is for THC etc.
    I know someone who FAILED with a value below 0.5 ng/mg.
    They had not smoked for 8 months.

    I need to know whether this is only just a fail or whether it is 10 times over the limit.

    Can smoke or a dust particle cause a (false) POSITIVE if the hair is not washed first?

    Thanks.
  2. ChibaKeepa

    ChibaKeepa New Member

    Does anyone know what the Hair Test cutoff value is for THC etc.

    Well, that depends. Most likely you are getting a Psychemedics hair test. If so, then there are two different types of Psychemedics hair tests.

    The first one, (negative results are known within 48 hours, positive results known within 6 or 7 days), does mass spectrometry. The cutoff level for THC is 1pg/10mg

    The second type of Psychemedics hair test is a 'Safety Net' test. Results are known within 7 to 14 days. This is the test where they can supposedly pinpoint at what time (ex. last 30 days, last 60 days, last 90 days) you have been using the drug. Usually this is the test they give to someone if they complain about the first hair test coming up as a false positive. The RIA cutoffs for this are:
    Cocaine: 5ng/10mg
    Opiates: 2ng/10mg
    Phencyclidine (PCP): 3ng/10mg
    Amphetamines: 5ng/10mg
    Marijuana: 2ng/10mg



    I know someone who FAILED with a value below 0.5 ng/mg.
    They had not smoked for 8 months.

    I have no idea why this happened. Maybe he didn't have a Psychemedics test? Not sure..
  3. ChibaKeepa

    ChibaKeepa New Member

    Can smoke or a dust particle cause a (false) POSITIVE if the hair is not washed first?


    By what Psychemedics and other hair testing facilities claim, they wash the hair thoroughly with cleaning agents before testing it. As far as how true this is or how thorough the cleansing process is, I can't say. I know that Psychemedics claims that they do not test for the parent drug (The drug before it is processed through your body), they test for CarboxyTHC, which is only present after being processed through your body. Hope this helps.
  4. pinkrope

    pinkrope New Member

    Thanks ChibaKeepa,

    just to check, did you mean 1pg/10mg or is it nanogrammes like the rest
    rather than picogrammes?

    It was not a Pyschemedics test, it was done by an unregulated lab in
    Germany.

    Also I believe the test was looking for THC, Cannabinoids and Cannabinidiol
    and not the Carboxy-THC metabolate which is less prone to contamination
    Also, unlike other "reputable" tests I am not sure they washed and I am sure
    that they did not measure the Abnormal Wash Ratio AWR to check for
    contamination.

    The hair was also a dreadlock which I believe contained coiled hairs in it
    longer than 8cm, the length of the dread.

    Very very roughly (I know it's not simple), but is 2ng/10mg equivalent to
    1 joint in 3 months or what?
    Maybe somebody who failed a test could post the result and how many joints they had had.

    Big thanks once again.
    Pinkrope

  5. IamN2pot

    IamN2pot Seasoned Activist

    PR, while as I posted a link to in my last post to you, some hair test do claim cutoff levels of 50ng/ml, while researching another matter I came across this page where it clearly speaks of hair test cutoff levels measured in ng/mg. I hope it will help you with your search. http://www.tiaft.org/tiaft2001/posters/p63.doc
    N2
  6. sergato

    sergato New Member

    ok how may i pass these test??

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