Hair follicle drugs Tests?

Question

A friend of mine has asked me for some advice and I didn't know how to answer. She has just taken a hair follicle drug test for a job she has applied for. She is stressing out because about 3 years ago she took cocaine on a one off occasion and thinks this may show up in her hair. She has quite long hair, gets is cut and highlighted every couple of months. The test company took quite a long piece of hair off her about 15 inches. The staff member who cut the hair made a comment that she wasn't sure which end was the root end when she put it on the test sheet suggesting that she may have got mixed up. My friend is dead against drugs now and regrets ever being stupid enough to take them. This is her dream job. Does anyone know if there is a chance that this will show in the test and she will fail?

Answer 1

This is possible, but not very likely.

Only the inch or two closest to the scalp should have been removed for testing.  This corresponds to about 90 days which is what is mandated by law.  If a 15 inch piece was obtains, the staff member who took it does not know her job very well.

The average growth rate for scalp hair is about 1/2 inch per month.  Three years would be 36 months * 1/2 inch = 18 inches of hair.  If her hair grew slowly, the 15 inch strand might be long enough, but this is not likely.

A single dose of cocaine could be found by a competent technician who knew it was there and was looking specifically for it.  It might very possibly be missed during a routine screen.

If she really wants the job and gets called back for another test (for conformation), tell her to get her hair cut to about 12 inches.  This is plenty long enough for testing (and avoiding suspicion), but not long enough to contain anything from 3 years ago.