Hair testing: When THC metabolites are in the blood, they go through the blood vessels in the head, and get filtered through the hair. THC metabolites remain in the hair as a permanent record. The hair test costs several hundred dollars ($150-$300) and is rarely given because urinalysis is cheaper (approximately $65) and more accurate. (The hair test equipment and setup goes for over a million). According to Jeff Nightbyrd, hair tests are widely used in the casino industry. They cut 50 strands of hair from the scalp, and send it in to the testing lab where they liquefy it.



A hair sample is disolved in a series of solvents which extract the drug metabolites and then are analyzed via GC/MS. It can take several hours to days just to extract metabolites. Average hair grows 1/4 inch per month. Typically they just use hair one and a half inches from the scalp; though some labs will take enough to test for up to 3 years. The liquid is run through the most sensitive GC/MS machines available, and can detect as little as 1 ng/mL! The hair test discriminates in that detection is easier in dark hair. Colored people may be discriminated against further because melanin is in their hair, which can be mistaken for THC. However, there is conflicting data as to whether melanin can be detected as THC.

Beating the hair test is extremely hard, and there are false positives. Bleaching or dying your hair is rumored to work, but it doesn't. I imagine you can shave every hair on your body and claim that you're a swimmer. According to NORML, Aloe Rid by Nexus is a shampoo that will aid in testing negative. Aloe Rid is available only in salons. Healthy Hair, from Sampson Health Products, is another shampoo designed to beat the hair test. Healthy Hair is sold in retail stores throughout Las Vegas. Keith Thrash from Sampson Health Products reccommends precleansing with Aloe Rid prior to using Healthy Hair. Healthy Hair is used in the morning and before going to bed. Each session takes 20 minutes.

According to Steve at Sampson Health Products, two out of a thousand people failed the hair test when using Healthy Hair. Byrd Labs is currently developing a shampoo to defeat the hair test. Some have suggested treating hair with oil because THC is oil based and oil soluble. However, there is no proven way to beat the hair test, so it's all heresay and guessing at this point. (If anyone has any success with the shampoos or the swimmer excuse, please let me know). Swimming and washing your hair removes toxins, and Keith Thrash recommends doing both as much as possible.

Fortunately, the hair test cannot be used alone as evidence because there are no forensic standards. It can only be used when substantiated by other evidence. Also, there are no intoxication standards. I believe if you tested positive for the hair test that you would probably have a good chance of fighting it. (BlockBuster Video uses the most up-to-date equipment, and passing such a test can be difficult). It takes several months of precleansing to beat the tests given by Psychemedics.