A hair follicle drug test is used “to determine the patterns of illicit drug use or prescription medication misuse over a certain period”. This test only carried out in between three months for hair sample that comes from person’s head.
This hair follicle drug test can detect many drugs includes, cocaine, phencyclidine (PCP), marijuana, heroin, amphetamines, morphine and codeine. For legal, medical and employment purposes a person undergo drug testing. Some institutes require workers to take drug test as a part of their job, but this has a high risk of injury.
Hair follicle drug test carried out in healthcare center, at home or at workplace. During this test procedure the small hair sample taken from individual’s scalp and that hair sample send to laboratory for drug testing overnight.
Recommended medication and some foods for example, poppy seeds, because of some compounds give false positive results. Two steps process in hair samples undergo, to guarantee accurate results.
Enzyme-linked immunosorbent assay (ELISA) test is the first step and this is the rapid screening method. Second step is gas chromatography-mass spectrometry (GC-MS) to check out the false positive. If ELISA gives a positive result for a substance then it undergo for a confirmatory test for used hair sample i.e. chromatographic testing.
Negative result can be determined within 24 hours of collecting hair sample. For this purpose ELISA test is used to determine if hair sample gives negative result for used drug or not. This result shows that a person hasn’t engaged in illicit drug use over the past 90 days. Positive drug test is confirmed after 72 hours.
For this purpose GC-MS test is used. It confirms a positive test results. This test also identifies the specific drugs used. The inconclusive result isn’t common. In some cases improper collection of the hair specimen may result in the test being rejected completely. So in this case test may be repeated.
Drug uptake can be detected over 90 days by hair drug test. The rate of growth of hair varies in each individual but this test cannot properly determine the drugs were used in last 90 days.
Although two step testing processes involves in testing of hair samples, these two steps are not completely accurate. Some factors affect the concentration of drug metabolites present in hair samples are.
How much a person sweats? , structure of drug compound, amount of melanin, quantity of drugs a person has consumed, coloring and bleaching the hair. Use of shampoos and typical products use for styling shouldn’t affect the results.
Head and body hair grow at the same rate. But the major difference is that body hair tends to stop growing at a shorter maximum length. In body and head hair, new hair replaces dormant strands pushes them out.
Hair samples taken from face or armpit for drug testing, in case of people who do not have hair on their heads. The length of hair must be at least 0.5-1.5 inches. If a person having shorter hair than more hair samples needed for drug testing.
In another case where people used to shave their whole bodies are not able for hair drug testing.
Cleanse your hair from any drug substance is impossible because drugs enter in person’s bloodstream and embedded in hair and it stays there until that hair is removed from your body.
According to the recent studies the results shows that the testing of drugs in hair follicle identifies 53.2% marijuana used, 2.9% opiod used, 24.2% amphetamine used and 65.2% cocaine used by people more as compared to other drugs.
Drug test of hair follicle can identify drug use up to 90 days earlier to the test date. This is because the chemicals in drugs that ends up in bloodstream which a person uptake becomes a part of hair cells with the time as the hair grows.
Testing of hair follicle may not be appropriate for determining recent drug use. That’s because it may take five to seven days for the drugs to be identifiable through a hair follicle test. Urine drugs tests are used to detect recent drug use. If you’re taking prescribed medications, let the administrator of the test know. Medications may lead to a false-positive test result.
Some advantages of hair testing includes, the long detection period, noninvasive collection process, employee briefly abstains from drugs and greater result accuracy.
Some disadvantages of hair testing includes, this test is more expensive than other test methods, can detect long-term drug use and for proper results longer processing time is required.
Authors: Aniqa Nasir , Rabia Shehzad
Department of Chemistry, Kinnaird College for Women, Lahore.