Hello Dr. Bill,
I have a similar question to a query placed a couple months ago regarding marijuana usage and hair testing, however, my situation is a tad bit different:

10 days ago, I ate 1/2 of a cookie infused with marijuana. I did not feel anything from ingesting, and I was told that they weren't very potent to begin with. Just a few days later, an extremely good job opening fell into my lap but I found out I had to be submitted for a hair test. Yesterday (9 days after the initial ingestion of marijuana) I underwent the hair test and have been stressing over the results since. I should note that before I ate the 1/2 cookie, I had not smoked marijuana since May of 2011 and was not a very frequent user before then.
Would you be so kind to let me know what my odds are of passing the drug test?

Thank you kindly.

Hello Dr. Bill,
I have a similar question to a query placed a couple months ago regarding marijuana usage and hair testing, however, my situation is a tad bit different:

10 days ago, I ate 1/2 of a cookie infused with marijuana. I did not feel anything from ingesting, and I was told that they weren't very potent to begin with. Just a few days later, an extremely good job opening fell into my lap but I found out I had to be submitted for a hair test. Yesterday (9 days after the initial ingestion of marijuana) I underwent the hair test and have been stressing over the results since. I should note that before I ate the 1/2 cookie, I had not smoked marijuana since May of 2011 and was not a very frequent user before then.
Would you be so kind to let me know what my odds are of passing the drug test?

Thank you kindly.

Disallowing for false positive your chances of passing are 99.9%.

There is an interesting aspect to THC and hair testing. Even when THC and metabolites are detectable at high amounts in blood and urine orally ingested cannabis does not seem to infuse into hair*.

You can relax given the information provided there was no THC or other metabolite incorporated into your hair. Additionally, even if it were the amount would fall below level of detection.

*Huestis, M Cannabinoid Concentrations in Hair from Documented Cannabis Users (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2274831/), Forensic Sci Int. 2007 July 4; 169(2-3): 129–136.