I used a small amount of cocaine last week at a party with some old friends. By 'small' I mean two tiny key bumps that combined would have been a small bump. Prior to that, the last time I used any was one time more than a year ago.

I have a couple of interviews coming up in the next couple of weeks and don't know what kind of drug screening they do. They may test hair.

I have medium brown, fine textured, wavy hair with about 10% gray; I color my hair and need to touch up my roots before the interviews. Am I likely to be above the 500 pg/gr threshold for positive because of those two tiny key bumps? And does coloring hair have any effect?

Thanks!

You are a study in hair drug testing.

Cocaine (COC) is incorporated into hair at the very highest rate of all drugs (1). This is influenced by hair color (eumelanin content) and hair structure. The lighter the hair color the less likely the drug will be absorbed. This applies to basic drug including COC. (2)

Therefore grey hair (containing no eumelanin) is unlikely to absorb COC.

Dyeing hair is known to reduce drug content but this is (seems to be) related to method. Superficial coloring having less affect than permanent hair color. (4)

The most important factor is that low level use (of even basic drugs) is seldom detected by HDT. (3)

With primary reliance on the findings of Kleber (3) and other similar findings it is unlikely that the use you describe will be detected by HDT.

1) Nakahara, Y (1999) Hair analysis for abused and therapeutic drugs. Journal of Chromatography B, 733 (1999) 161–180, [p 174 contains graph of incorporation by drug type]

2)Ropero-Miller

3) Galanter & Kleber, 2011 Psychotherapy for the Treatment of Substance Abuse, American Psychiatric Publishing, Wash, DC, p. 58

4) Norchem Laboratories

Thanks for your answer, dr. bill, and also for the links. It's hard to find accurate information about this.

Hey there, I am trying to find the same answer you were looking for. Did you happen to do the test? How long after use? And did you pass or fail?