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Will a workplace hair follicle drug screening test positive…

second opinion] Will a workplace...
second opinion] Will a workplace hair follicle drug screening test positive for an infrequent marijuana user?
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Customer reply replied 10 months ago
Also, how does the cutoff threshold standard of 50ng/ml relate to infrequent marijuana users for hair follicle tests and whether or not it binds to hair?
Answered in 16 minutes by:
10/12/2017
Dr. Huynh
Dr. Huynh, Board Certified Physician
Category: Drug Testing
Satisfied Customers: 125
Experience: Assistant Director / Medical Officer at Howard University
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Hello, I'm Dr. Huynh, a board certified physician. Please allow me a moment to review your question and I will reply shortly.

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As you mentioned, the cutoff threshold is 50ng/ml. There are several variables to consider. Frequency of use is one factor. But, the hair itself is also a factor. Hair drug testing measures a metabolite embedded inside the hairshaft. So as your hair grows, it can be detected in there. Depending on which hair they choose from your body, shorter hairs that grow fast may not have the metabolite in them as long. Whereas hair that grows slow and is long, may have the metabolite in there longer.

One time and infrequent users of marijuana are much less likely to be detected by a hair follicle test compared to those who use frequently. A 2006 Forensic Science International study, Cannabinoid Concentrations in Hair from Documented Cannabis Users, found that 85% of daily users tested positive for THC use, but only 52% of smokers who used 1-5 times per week were detected.

So there is a risk, but less of a risk. I hope that is helpful. Best regards.
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Please let me know if you have any other questions or would like to discuss further. Otherwise, please rate me a 5 or let me know how I can improve. Best regards.

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Customer reply replied 10 months ago
The screener used the hair on my lower legs. That hair is short, but I do not know the rate of growth because I've never shaved my legs before. I have one last question about the cutoff threshold: what does 50 ng/ml mean in terms of detection?

There are a number of cutoffs for detection used in courts : 20, 50, 100 ng/ml.

The lower the cutoff concentration is; the more sensitive the test is to detect cannabis metabolites; the longer the window of last use is for detection.

Hair on the body grows at a slower rate than hair on the head. Based on the information you provided here and in the previous question requests, it seems that you would fall into the category of less risk where half of those tested were positive.

Dr. Huynh
Dr. Huynh, Board Certified Physician
Category: Drug Testing
Satisfied Customers: 125
Experience: Assistant Director / Medical Officer at Howard University
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