How does hair testing work?
Hair offers the ability to stop more than twice as many drug users at the door, before they are employed. There is a growing interest in replacing abstinence monitoring urine programs with routine 90 day hair analysis, thereby reducing the number of times a donor must submit to a drug test and improving fidelity of detection.
Why use hair analysis for pre-employment testing in the workplace?
Urine appears to be more susceptible to adulteration, hydration and substitution. Hair analysis provides a greater challenge to these applicants who try to cheat for a number of reasons.

- The applicant cannot replace his or her hair with someone else’s.
- The applicant cannot adulterate hair by placing anything in or on the sample while in the specimen collection area.
- The collector takes the hair directly from the applicant and the sample is never out of the sight.
- The applicant cannot eat or drink anything that will dilute a hair sample.
- We often hear of people who strip, bleach, and re-dye their hair to its original color. This may be effective if the applicant is an occasional user and his/her levels were at or near the cutoff. In most cases, the cutoff level used by the more sophisticated laboratories is low enough that stripping the hair will not remove the entire drug that has be deposited.
Is hair analysis appropriate for post accident or
No: Because hair testing detects drug use over a long period of time, usually from 10 to 90 days prior to collection, it is not an appropriate method for post-accident or reasonable suspicion testing. In both of these situations, the result should detect the drug use of an individual as close as possible to the time of the incident. Urine combined with a breath, oral fluid, or blood alcohol specimen is the appropriate sample for this type of testing.
How do drugs deposit in or on hair?
Current scientific research indicates that drugs deposit in hair by several methods. The principle method is transmission from the blood supply. Deposition through perspiration and skin oil is a second important method. In addition, drugs are externally deposited on the hair by environmental smoke or, more reasonably, by smoke from the users own ingestion. As with the smoke from tobacco users, an individual’s hair will be more susceptible to environmental smoke from his or her own drug use activity.
What are the issues of environmental contamination?
Cocaine has been the principal focus of studies on environmental contamination. Cocaine seems to be the drug most attracted to hair. Cocaine, in its smokable form (crack), can deposit on hair. As mentioned above, the crack smoker will not only ingest cocaine, but will add more cocaine to his/her hair by mere proximity to the smoke during use. Most individuals who do not use cocaine will also not be around smoked cocaine. If an individual lives with a cocaine user, he or she could be subject to cocaine exposure in the living environment. The cocaine residue left by the user could result in both a urine and hair drug test positive if accidentally ingested by a non-user. If the donor lives with or spends time with a cocaine smoker, it is possible that the non-user may have some cocaine smoke deposited in his or her hair. If external exposure is limited, the cocaine will wash out of hair using normal hygienic methods. If the exposure is more intense, normal hygiene may not be sufficient to remove all of it.
How does the laboratory avoid reporting an environmentally contaminated sample as a positive from a user?
When metabolites of drugs are detected in the hair along with the parent compound, we can be sure that the drug entered the hair from the blood stream after being ingested. A sample positive for the parent drug, but negative for metabolites is presumed to be externally contaminated and is reported as negative. In addition, the hair samples are chemically washed before testing to remove contamination. Finally, the cutoff levels for reporting a positive are set conservatively high to avoid reporting traces of external contamination.
How are hair samples collected?
Compared to urine collection, hair collection is a simple, non-intrusive process. There are, however, some important things to remember:

In order to be fair to the donor, we must have enough hair to repeat assays if necessary. If the hair is over 1 1/2 inches long, then we require a width of 1/2 inch when spread out flat on a ruler. If the hair is shorter than 1 1/2 inches in length, more hair is required (1 inch length requires 3/4 inch width; 1/2 inch length requires 1 1/2 inch width). The reason for this is that although the laboratory describes the sample quantity in width of sample for collectors, the test requirements are actually 100 mg of hair by weight.
Will the test results really reflect 90 days use of drugs?
Approximately: Head hair grows approximately 1/2 inch per month. If you cut the hair close to the scalp and test the first 1 1/2 inch from the root end, you would be testing a 90 day period. The problem with this is that it takes hair approximately one to two weeks to grow from the hair follicle through the scalp to a level above the scalp accessible to scissors. Therefore, a hair analysis of a 1 1/2 inches covers a time span of approximately 90 days one to two weeks after drug use.
Can you go back further than 90 days?
Theoretically it is possible to test the entire length of hair in segments. This type of testing is of questionable validity. Since the distribution of drugs through the hair includes sweat and body oil, the drugs will diffuse along the shaft. In addition, normal hygiene and treatment of hair removes drugs slowly over a period of time. Therefore, at this time, the lab only tests the first inch from the root end.
Will the laboratory defend hair analysis results in court, if necessary?
Yes, as with all testing performed, our professional toxicologists are available to all clients in interpreting drug test results and provide expert witness testimony should results be questioned in administrative or legal hearings.