Hair drug testing is considered the gold standard in toxicological analyses. This long-established method can provide a history of drug abuse and is routinely used in family law.
Why test hair?
Testing oral fluid and urine can only give a short-term measure of drug use (usually a few days). The advantage of hair is that it is a strong, stable matrix, is less affected by contaminants and requires no special conditions for storage, such as refrigeration. Drugs remain relatively stable in hair and can thus be stored indefinitely. As such, hair strand testing can effectively confirm long-term exposure to drugs over a defined period depending on the length of hair collected.
All samples need to be collected under chain of custody conditions to support legally defensible results. This would require either an appointment with one of our trained sample collectors at a place convenient to the donor or at one of our 11 nationwide Walk in Centres. Because all of the samples are tested at our UK-based laboratory, we can be confident of offering the fastest results.
How are drugs detected?
The hair drug testing process is made up of five steps:
- Sample collection
- Sample decontamination
- Drug extraction
- Simultaneous drug screening
- Identification and quantitation using liquid chromatography–tandem mass spectrometry (LC–MS/MS)
Any substances of misuse that have been ingested will be absorbed into the bloodstream and broken down in the liver to produce specific metabolites. These metabolites will become incorporated into the growing hair shaft from blood supplying the hair follicle.
Hair drug testing measures the drug molecules embedded inside the hair shaft. Since head hair grows at an average rate of 1 cm each month, a retrospective record of an individual’s historical record of drug use can be established, depending on the length of hair sample available.
Hair samples are examined using a powerful analytical tool called liquid chromatography with tandem mass spectrometry (LC–MS/MS). This enables AlphaBiolabs to confirm and quantify the presence of illicit drugs and their various metabolites.
How is a sample taken?
The accuracy of any hair drug analysis depends on both the sampling procedure and the laboratory techniques employed. Hair strand samples are normally collected by a trained sample collector. The hair sample needs to be cut from the highest point of the scalp (the vertex) as this region is associated with least variation in growth rates.
Ideally, the sample needs to contain around 200 individual strands (about the width of a pencil) and should always be taken from a discreet area.
Hair samples are usually taken from a person’s head; however, if head hair is not available alternative collection sites could be considered including chest, back, arm, underarm and leg hair. The growth rate of hair from these alternate sites differs from head hair and as such body cannot be used to determine a specific timeframe of drug use. Beard hair grows at a rate of 0.7 cm a month, so analysis of this type of hair can provide a more specific timeframe.
If an individual has been in an environment heavily laden with a drug, detectable levels could be found on the hair sample due to smoke. In addition, it could be present due to direct transfer (such as by hands). To avoid any such false positive results, each hair sample is chemically washed three times to remove or reduce any drug present prior to analysis.
In addition, the Society of Hair Testing (SoHT) Guidelines for Drug Testing in Hair provide recommended cut-off levels to follow . The washing solution can also be analysed if required. For example, if an individual admits to being surrounded by cannabis smokers, the washing solution could be used to back up the test results.
Any external exposure to drugs should be declared at the time of sample collection, excessive shampooing, some cosmetic treatments (such as dyeing, bleaching, perming and relaxing), and the use of thermal straighteners may reduce drug concentrations in hair to varying degrees. The extent of the loss will depend on the cosmetic treatment used and the drug present. All hair treatments should therefore be declared at the time of sample collection and taken into consideration when reviewing the findings of a hair test.
What drugs can be detected?
The standard drugs we test for in head hair are:
- Ecstasy (MDMA)
- Phencyclidine (PCP)
We can also arrange hair drug testing for GHB, LSD, Spice, Steroids, Tramadol and other less common drugs for an additional fee.
Types of hair drug tests
There are two types of hair drug tests available: overview or segmented analysis. As head hair grows at an average rate of 1 cm each month, drug use can be established over a defined period depending on the length of hair selected.
An overview analysis is beneficial to obtain a general indication of drug use. This could range from 3 cm to identify drug use within that 3-month time period, up to 6 (2 x 3) or even 12 (4 x 3) months, dependent on the length of hair available. Differing results from the 3-month overviews can help highlight patterns in drug use.
If a more detailed analysis is needed, segmented would be the preferred option.
By segmenting head hair samples into monthly 1 cm sections, a month-by-month profile of drug use can be attained to provide a detailed historical profile of an individual’s drug exposure.
Instead of instructing us on particular drugs to detect, our Drug Screen Plus is a standalone service which analyses hair samples for any drugs present. We will then issue a report on exactly what we find and in what quantities.
For more information about hair drug testing
 Society of Hair Testing guidelines for drug testing in hair. Forensic Science International 2012;218(2012):20–24.
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AlphaBiolabs is an accredited laboratory offering a range of drug testing services.