Frequently Asked Questions about Hair Testing
- How soon after use can a drug be detected in hair from the
time of use?
It takes approximately 3-7 days from the time of drug use for the affected hair to grow above the scalp. (Test is performed on the length of hair from the scalp out).
- What time period does a standard test cover?
A standard test of one-and-one-half inches of head hair cut close to the scalp can provide a several month window to detect drug ingestion.
- How fast does hair grow?
Studies indicate that hair collected at the crown of the head grows on an average approximately 1.3cm (or ½ inch) per month. This growth may vary among people; consequently the same 3.9cm length of hair may represent slightly different time periods.
- How much hair is needed to test?
A standard screen, along with a confirmation if needed usually requires a cosmetically undetectable lock of hair preferably snipped from the back of the head, just below the crown. In general, the amount needed is the thickness of a shoelace to a pencil thickness(depending on the hair available).
- Can tests be done on people with little or no hair?
Yes. Hair can be collected from several different locations on the head and combined to obtain the required amount of hair. If head hair is not available, body hair can be used as an alternative. However, the various types of hair cannot be combined.
- Do chemical treatment of the hair affect the results?
Commonly used hair procedures (e.g. shampoos, conditioners, sprays, mousses and gels) have no significant effect on results. In fact, normal hair washing helps to remove external contamination. Normal hair treatments such as bleaching, perming, and dyeing generally will not significantly lower the quantitative results.
- What is done with the excess hair that is not tested?
Excess strands of hair not used for testing, are stored at the lab in the chain of custody sample acquisition pouch. Negative hair is stored for one month. Positive hair is stored for five years.