Legal FAQ’s

FAQ’s – Hair Testing for Alcohol & Drugs (Legal Services)

FAQ’s – Hair Testing for Alcohol & Drugs (Legal Services)

Why is Hair Testing for Drugs so useful?


Drugs are incorporated into growing hair. Because scalp hair grows at an average rate of approximately 1 cm per month, the analysis of a hair sample can provide retrospective evidence for drug use. Therefore, analysis of a 3 cm of scalp hair should detect drug abuse during the previous 3 months approximately (it takes a week or so for drugs to get into the hair).



Is the analysis sensitive?


Yes. Modern technology has advanced so much in the previous few years, it is possible to detect the low concentrations of drugs present in hair.



Is hair testing regulated?


Hair testing is not regulated by government. Testing organisations however adhere to the practices recommended by the Society for Hair Testing (



What information do they put on the forms that go with my sample?


In the absence of a specific drug request, hair samples are tested for ‘standard panels’ of drugs which includes ranges of commonly abused drugs.



What kinds of tests would I have to take? What drugs would be tested for?


In the absence of a specific drug request, hair samples are screened for a ‘standard panel’ which includes a range of commonly abused drugs.



How reliable is hair testing?


When both screening and confirmatory tests are conducted, the combined tests themselves become virtually 100% dependable. This is due mainly to accreditation requirements and modern analytical instrumentation used in the analysis.



Where would I be tested?


Hair samples are sampled by trained collectors at a central Belfast location, although collections can also be arranged at other locations.



What actually happens when I go to be tested?


A sample of hair (preferably 2 samples of scalp hair strands) about the width of a thin pencil is collected from the back of the head.


Non-scalp hair can also be used (body, axilla) in the absence of scalp hair.  hair is not suitable for alcohol metabolite analysis.


Testing is a two-stage process. First, an initial (screening) test is administered. If it is positive for one or more drugs, then a second, confirmatory test is usually conducted for each identified drug. The confirmation test uses a different, more sophisticated chemical process. A person, who is trained in the collection process, seals and labels the specimen, then prepares both the specimen and its accompanying paperwork for shipment to the laboratory. Each step of the process is documented on a “chain of custody” form. The collection and chain of custody procedures ensure the specimen is properly identified and tracked throughout the testing process.



How long after use can drugs be detected in hair?


Drug abuse can be detected many months after the last instance of use (3 cm/3 months is standard analysis practice. The detection window is longer with non-scalp hair.



Can I test positive for environmental exposure?


Yes, it is possible. In the absence of drug metabolites there will be some possibility that the drug presence in hair was due to environmental exposure. This is of course less likely with non-powdered drugs (tablets). The presence of metabolite(s) and the concentrations of drugs detected can preclude this possibility.



What will be done to me if I test positive?


The presence of the drug will be reported to the organisation requesting the test – usually solicitor or social worker.



What are the alternatives to hair testing?


Hair testing is the best way to demonstrate retrospective drug abstention. Urine analysis can also be used but the detection window is much shorter. The use of both hair and urine is often used – the urine picks up more recent use.



How can alcohol be detected in hair?


Alcohol itself cannot be detected in hair, due to its volatility. However there are a number of minor alcohol metabolites, which do become incorporated into hair. The measurement of these metabolites can be used to provide evidence of excessive alcohol consumption.



What are these metabolites?


There are 2 types:

  1. Ethyl glucuronide (EtG)
  2. Fatty acid ethyl esters (FAEE’s)



How reliable is this testing for alcohol?


If the concentration of EtG in scalp hair lies above a defined cutoff value, then this representsstrong evidence for regular alcohol consumption and chronic excessive alcohol consumption. It can be used to support a declaration of abstinence.


The presence of FAEE’s above the cutoff provides additional evidence in cases of chronic excessive consumption  and can be useful in cases where the hair has been treated with harsh chemicals (like bleaching)


Hair analysis is not totally definitive and each case should be judged on its own merit. Hair markers in hair should not be used in isolation.



Can hair alcohol analysis be carried out with drug analysis ?


Yes. The sample selected for EtG analysis can also be used for drug analysis.


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