Hair Drug Testing FAQs

AlphaBiolabs offers hair drug testing services for members of the public, the legal profession, social workers and employers. Below you will find some frequently asked questions about hair drug testing.

How does head hair grow?

Normal head/scalp hair growth occurs in a cycle consisting of four phases. After continuous growth in the anagen (growing) phase which lasts for several years, cell division stops, and the hair bulb begins to degenerate within about 2 weeks (catagen phase).

The hair then stops growing but remains in the skin for 2-6 months (telogen phase) until a new hair is formed and pushes the old one out (exogen).

It is estimated that 10-15% of all hairs are in the telogen phase at any given time with the length of time increasing with age and dependent on the hair type.

Scalp hair from the posterior vertex is the preferred sample for time-resolved testing as it has the most consistent growth rate, with the highest percentage of follicles in the anagen phase.

The Society of Hair Testing (SoHT) recommends utilising an average growth rate of 1 centimetre a month for head hair. However, rates of scalp hair growth can vary from person to person, and this does not take into account all possible factors such as age, sex, race, and even seasonal fluctuations.

It takes approximately two weeks for newly formed hair containing the drug to be available for inclusion within a cut hair sample.

How does body hair grow?

Body hair has much more variable growth and resting cycles than scalp hair.

With body hair, 40–60% of the hair remains in the resting phase, making it unsuitable for segmented analysis. This means that deriving an accurate time frame of drug use from body hair is not possible.

It can be assumed that any drug use occurs within the total life cycle of the body hair; however, it is not possible to tell more precisely when the sample donor has consumed these drugs.

If a substance is detected using a drug test, this may represent very recent or older drug use/exposure. It may also represent drug use/exposure throughout the entire period of growth.

Consequently, it is not possible to determine if the pattern of drug use disclosed by the sample donor is consistent with the analytical findings.

How are drugs incorporated into hair?

Drugs can be detected in both sweat and sebum, and as both secretions bathe the hair shaft as it grows, they will contribute to the drugs incorporated into hair.

Consequently, drugs are incorporated into the hair:

  • directly from the blood supply and
  • from sebum and sweat bathing the hair

In contrast to blood, parent drugs are more commonly detected in hair. For example, 6-monoacetylmorphine (6-MAM), the primary compound of heroin and cocaine, is generally found in higher concentrations in hair than the respective metabolites, morphine and benzoylecgonine.

Basic drugs, such as amphetamines and cocaine, incorporate into hair to a greater extent than neutral or acidic drugs and are present in higher concentrations in hair compared with benzodiazepines and cannabinoids.

Cocaine metabolites (benzoylecgonine, norcocaine and cocaethylene) have a lower cut-off (0.05 ng/mg) when compared to the parent compound cocaine (0.5 ng/mg). Therefore, it is not uncommon for cocaine metabolites to be above the cut-off, but for the parent compound cocaine to be below the cut-off and reported as ‘negative’.

In addition, chemical hydrolysis of cocaine (within the body) occurs at alkaline pH, producing the metabolite benzoylecgonine: a product of chemical hydrolysis.

Unlike some other hair testing laboratories, AlphaBiolabs runs cocaine benzoylecgonine hydrolysis on every run, ensuring that our benzoylecgonine result is a true benzoylecgonine result.

We have strict criteria within the toxicology laboratory, and we will not report anything that does not pass.

Consequently, if the internal hydrolysis fails for cocaine/benzoylecgonine and they are the only cocaine compounds detected, AlphaBiolabs does not report the cocaine results, and the sample will be repeated. However, if there is no hair remaining, a further sample will be required, and a recollection organised.

What are the different levels for hair drug testing?

The low, medium, or high range provided is derived from statistical analysis of positive samples analysed at AlphaBiolabs:

  • Low – lies below the 25th percentile*
  • Medium – lies between the 25th and 75th percentile*
  • High – lies above the 75th percentile*

*Of dynamically updated positive cases

However, the level does not refer to the amount of drug consumed and is provided for guidance only.

The test results provided by AlphaBiolabs are obtained using High Performance Liquid Chromatography tandem Mass Spectrometry (HP-LC/MS/MS).

This is a highly sensitive and specific analytical technique which means that analyte identification is unequivocal, and it can only be that compound.

However, due to the sensitivity of the analysis, occasionally only a qualitative result can be reported i.e. detailed as ‘detected’ rather than a numerical value. This does not affect the overall interpretation of the findings.

In such cases, we will be unable to provide a level for that analyte but will provide a level for any associated compounds such as heroin and cocaine and their respective metabolites, morphine or benzoylecgonine.

How accurate is a hair drug test?

Our hair drug testing is 100% accurate and reliable based on the samples we receive at our laboratory.

We are accredited by UKAS to the quality technical standard of ISO 17025 (No. 2773) and certified to ISO 9001.

We follow cut-off guidelines for hair drug testing as set by the Society of Hair Testing, and our toxicologists also work within the framework of Family Law, following Part 25 of the Family Procedure Rules (2010).

When testing hair, how can external exposure to drugs be ruled out?

External contamination has been extensively investigated by researchers, with the greatest challenge in attempting to recreate realistic contamination scenarios.

Consideration is given to the condition of the hair sample, which may be damaged through natural wear and tear or chemical treatment, and to the porosity of the hair. All these factors will affect the incorporation of drugs from external contamination and, conversely, the loss of drugs from the hair following use.

Passive exposure to a drug through smoke and/or direct contamination (i.e. the drug being in direct contact with the hair, such as through contaminated hands) may result in the presence of detectable levels.

Therefore, the method used by AlphaBiolabs for the analyses of drugs in hair samples involves the decontamination of the hair samples through a series of three chemical washes, which are kept by AlphaBiolabs for further analyses if requested.

Although these washes may not, on occasion, remove 100% of a drug (particularly after heavy contamination of the surface of the hair), the monitoring of the washes may allow the discrimination between the active direct use of a drug and environmental exposure.

How does hair dye affect my client’s test results?

It is well documented that chemical hair treatments such as bleach and dye can damage the hair shafts and have the potential to reduce the levels of any drugs, metabolites and alcohol biomarkers present in hair, possibly to a level below the cut-off.

However, it is not possible to specifically determine to what extent the treatment may affect the results obtained in a specific case.

Consequently, although increasing concentrations towards the scalp could indicate an increase in drug use, when treatments have been used, it is not possible to rule out that the concentrations in the oldest hair segments have been decreased due to the chemical treatment exacerbated by the washout effect.

Is it possible for a client to get a residual positive result on a drug test, after a period of abstinence?

One of the major advantages of hair testing is that it provides a retrospective time frame of an individual’s drug use or period of abstinence.

Normal scalp hair consists of approximately 85% of actively growing hair (anagen phase) and approximately 10-15% of hair not actively growing (catagen and/or telogen phase).

The catagen/telogen phase can last up to six months in some cases. Therefore, the hairs that were not actively growing prior to the collection could still contain residual drugs from earlier use.

Segmental hair analysis can address any changes in drug use. Studies have shown that the duration for which a drug is no longer detected in a hair sample after abstinence can also be influenced by the extent to which that drug was originally consumed, i.e. if an individual has not consumed a drug heavily prior to ceasing its consumption, then a drug hair result may be negative relatively quickly.

However, after heavy use, it may take up to six months to completely disappear from the hair segments closest to the root.

Therefore, if the date of abstaining from drug use was over six months prior to the sample collection, a positive residual drug result is unlikely, as the hair sample collected would not be expected to contain any of the resting phase hair during the active use.

It is only when negative results are obtained for a hair segment that the findings support drug use ceasing.

How much does a hair drug test cost?

The cost of a hair drug test varies depending on the requirements of the instructing party.

If you have received a quote for hair drug testing from another testing laboratory, we will match their price and reduce it by a further 5%. This makes AlphaBiolabs the most cost-effective solution for your legal drug testing needs.

To request a quote for hair drug testing, simply complete our online form, and a member of our Legal sales team will be in touch to discuss your needs.

You can also call 0333 600 1300 or email for more information.

How can I get a quote for a hair drug test?

It’s easy to request a quote online now. Simply complete our online quote form and a member of our Legal team will be in touch to discuss your requirements.

Alternatively, call us on 0333 600 1300 or email and a member of the Legal team will be happy to discuss your case and provide a quote.

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