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View Full Version : I smoke marijuana and did a hair follicle test, it came back negative, why?


sometimesmoker
Jul 25, 2012, 11:29 PM
I smoke a hit or two a day, maybe... I did a follicle test and it came back negative. I would assume that even though it's only a few hits a day it is still frequently enough to show a positive. What gives?

Fr_Chuck
Jul 26, 2012, 04:05 AM
One hit a day? Most likely very poor level pot, along with almost no intake with one hit.
Honestly one hit will not have any effect and is a real waste of your time, money.

DrBill100
Jul 26, 2012, 06:05 AM
I smoke a hit or two a day, maybe... I did a follicle test and it came back negative. I would assume that even though it's only a few hits a day it is still frequently enough to show a positive. What gives?

The main reason is that hair is a very poor medium for detecting THC metabolites. Far less apt to detect infrequent and low level cannabis use than urine drug testing.

It may ultimately incorporate into your hair in sufficient quantity to be detected simply due to accumulation or it may not as even chronic heavy users are detected at only around 60%.

Hair drug testing is also heavily influenced by ethnicity and hair color.

Doesn't correspond with the claims of commercial testing labs in promoting the procedure but is well documented.

Ref.
“Basic drugs such as cocaine and methamphetamine concentrate in hair due to ionic bonding to melanin, the pigment in hair that determines hair color. The more neutral and lipophilic THC is not strongly bound to melanin, resulting in much lower concentrations of THC in hair as compared to other drugs of abuse. " [183-186].
Marilyn A. Huestis (2007) Human Cannabinoid Pharmacokinetics (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2689518/). Chem Biodivers. 2007 August; 4(8): 1770–1804. Sec 3.5