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FAQs
How long can drugs be detected in head hair?
Once a drug is incorporated into hair, it begins to slowly leach out due to normal daily hygiene and exposure to the elements. Most drugs have disappeared by three months. Furthermore, the laboratory only analyzes the first 1.5 inches (3.9 centimeters) nearest the scalp. Hair grows at an average rate of 0.5 inches per month.
How long can drugs be detected in body hair?
Body hair has a different growth cycle compared to head hair. Body hair may go dormant and remain in place up to one year. A positive result reflects exposure up to 12 months.
Can someone test positive because of passive or environmental exposure?
Yes, drugs are incorporated into hair by three major routes: environmental exposure, sweat and sebum from the scalp and blood flow through the follicle. Environmental exposure however will only generate a positive for the parent drug. Example: methamphetamine only. The other two mechanisms lay down drug and drug metabolites. Example: amphetamine/methamphetamine positive.
Can a hair test be manipulated by the donor?
Yes. Bleaching, perming, dyeing and straightening can affect the outcome of a hair test. Cosmetically treated hair should not be collected.
Can a hair test determine how much or how often someone is using a drug?
No. Hair is a reservoir matrix, where drugs can collect and/or degrade over time. When testing any reservoir matrix, you are unable to back-track and determine time, dosage or frequency because there are simply too many variables involved.
What does a positive hair test result mean?
The only interpretation that can come from a positive hair test is that the individual used or was exposed to drug during the three months prior to collection.
Does race make a difference in hair testing results?
Hair color, not race, is one of the most important variables in determining the quantity of drug found in the hair. Dark hair binds drug tighter than light hair.
Can a hair test be used to prove that a previously taken urine test was inaccurate?
No. The results of any second collected specimen have absolutely no bearing on the validity of the results of the first collected specimen. Furthermore, each matrix has its own advantages, disadvantages and limits of interpretation.
What is ChildGuardSM, and how is it different from regular hair drug tests?
ChildGuardSM is a modified hair drug test designed to increase environmental exposure detection in children. The assay is often used by social service agencies involved in custody cases.
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