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Hair follicle drug testing, or hair screening, is a test procedure that is used to detect drugs and other substances taken by a person, using sample of hair taken from that person. This test can be used to detect specific drugs, and it is the most accurate among all tests used for detecting substance abuse, especially in low level users.

It is commonly used by many employers for determining if anybody has been indulging in drugs in the past 90 days. It is also done by parents, using a hair follicle test kits to keep a check on their children. Interested in knowing more? Well, here are a few quick facts to keep you hooked.

Intriguing Facts About Hair Follicle Drug Testing

The procedure of hair follicle drug testing involves the use of enzyme-immunoassay, which is nothing but a method to measure the traces of drug in the hair follicles. The drug molecules that are adsorbed by the bloodstream, get deposited in the hair follicles.
If you have been wondering all this while about the type of drugs that can be successfully detected by this test method, then here they are Cocaine (Cocaine & Benzoylecgonine), Marijuana, Opiates (Codeine, Morphine & 6-Monacteyl Morphine), Methamphetamine (Methamphetamine/Amphetamine & Ecstasy), and Phencyclidine (PCP).
Just like the food is broken down in the body to produce nutrients, the molecules of drug are also broken down into its metabolites, which are adsorbed by the blood. Once these metabolites enter the cells of the hair follicle, they remain trapped in the hair shaft. This makes it possible to detect the presence of the drug by analyzing the hair sample.
The approximate time covered by the test is close to 90 days. While collecting the hair samples for testing, hair is cut very close to the scalp. For body hair, the time covered is 12 months.
For the affected hair to grow above the scalp, it takes about a week. Thus, hair follicle testing can successfully detect the presence of a drug, 7-10 days after its consumption.
It is not very successful when it comes to determining the exact day or week when the drug was consumed. This is due to the difference in hair growth rates in individuals, and also the limitations of the test procedure.
For standard hair screening, close to 60 milligrams of hair is required. This comes close to around 100 strands of hair. The minimum length of the hair strand is 1.5 inch, cut from the root.
For people with sparse hair on the head, hair can be collected from different locations on the head. For people with no hair, the test is conducted with hair collected from other parts of the body like hands, legs, and underarms. However, test conducted using body hair poses certain limitations.
Interestingly, external exposure to drugs cannot affect the test results. This is because the hair samples are thoroughly washed before they are used for the test, to remove all traces of external contaminants. However, washing cannot remove the traces of the drug present within the shaft of hair. Thus, using shampoo on one's hair cannot yield a negative test result!
The procedure of hair screening involves a two-tier process. The first step involves screening a part of the sample using Enzyme Linked Immunosorbent Assay (ELISA), which is an effective method for testing the presence of drugs. The second step is to confirm the result by screening the remaining part of the collected sample, using either of the two methods, as given below.
  • Gas chromatography/mass spectrometry (GC/MS)
  • Gas chromatography/mass spectrometry/ mass spectrometry (GC/MS/MS)
The excess hair that has not been utilized for testing is stored in the chain-of-custody sample acquisition pouch, for a mandatory period of two years.
The shortest time period that can be accurately evaluated is one-month.
The color of the hair or the use of any chemical treatments on the hair, have no effect on the test results.
The Law makes it mandatory to maintain a record of all the test results, both positive and negative, for a period of three years.

Interesting facts, weren't they? Such is the advancements in technology these days that people should think twice before tricking the officials about the drug use.

Disclaimer: This Buzzle article is for informative purposes only, and should not be used as a replacement for expert medical advice. In case of any serious illness, please seek immediate medical help.