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Family Physician
Family Physician, Board Certified MRO
Category: Drug Testing
Satisfied Customers: 12816
Experience:  Medical Review Officer - Physician Trained and certified in drug test interpretation
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How does thc stay in hair follicle

Resolved Question:

how long does thc stay in hair follicle
Submitted: 6 years ago.
Category: Drug Testing
Expert:  Family Physician replied 6 years ago.
The THC and THC metabolites are deposited into the shaft of the hair as it grows. Think of this as mixing something in concreted as it is being poured. These chemicals remain in the hair indefinitely.

The standard collection process for hair drug tests uses a length of hair closest the scalp equal to approximately 90 days growth. Drugs in the more distant portions of the hair shaft are not included in the collection. For this reason, your hair testing for marijuana reflects your use (or lack of use) over the last 90 days. Hair testing is most sensitive for chronic/regular use rather than a single isolated use.
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