Hair testing is a fast, accurate and non-invasive means of testing for drug and alcohol use over long periods.
Collecting a hair sample is a simple process: yet the importance of cutting, packaging and testing samples in the correct way cannot be overstated. Without a secure chain of custody, the results of a hair test lose their reliability and can be dismissed in a court.
To clarify the collection process, this guide covers the importance of the chain of custody, the sampling method and the individuals who should make each collection – so you can trust your hair test result when it matters most.
The chain of custody
‘Chain of custody’ is a guarantee that a drug or alcohol test sample has been collected, transported in tamper-proof packaging and processed in a correct, reliable way – usually in the form of a paper trail documenting the collection process and the conditions for the collection itself.
Without a secure chain of custody, a hair sample cannot be used as evidence in a family court or otherwise. The method by which a sample is taken and the person overseeing the test are the two essential components of the chain itself.
Hair test results must be interpreted by the laboratory performing the test. If the toxicologist lacks reliable information about the circumstances of a sample collection, or cannot trust the chain of custody for a sample, their interpretation of the test result could be undermined.
For example: bleaching hair can affect the level of drug or alcohol traces in a donor’s hair sample. A reliable witness to the collection will record when a donor’s hair has been bleached – in turn helping the testing laboratory interpret their test results correctly. Without a secure chain of custody, details like the bleached hair would be missed – and the interpretation of the hair test result will be unreliable.
How are hair samples collected?
Hair on a human scalp grows at a rate of roughly one centimetre per month. Therefore, testing a one centimetre lock of hair closest to the scalp indicates whether a donor has used specific drugs or alcohol within the past approximate month, a two-centimetre section indicates use over the past two months, and so on.
The collection process is as follows:
- Under controlled conditions, a sample of hair – usually the thickness of a shoelace – is cut from the scalp using scissors.
- The sample is immediately deposited in a tin foil wrap provided by the testing laboratory. The collector must indicate which end of the hair came from the scalp - as this will determine which hair section reflects each period of drug or alcohol use.
- The collector seals the wrapped sample in a supplied tamper-proof envelope. On the envelope, the collector notes certain conditions about the circumstances of the sampling – including whether the donor’s hair has been dyed or otherwise.
- The sealed sample is sent to the testing laboratory, where trained staff ensure the envelope has not been tampered with in transit. The sample is logged into a computer system that records information about the donor, the sampling method and the collector to took the sample, and then it is tested.
Who can collect a hair sample?
In the first instance, the person collecting the hair sample is responsible for the integrity of the hair – not the laboratory performing the test itself. This is an essential consideration when commissioning a test or using the results of one.
Reliable laboratories – including our own here at Cansford – will insist that a trained collector or GP be employed to take the hair sample from a donor. In this way, the conditions demanded by a laboratory for sample collection are a key indicator of the quality and reliability of the laboratory itself. After all, if the chain of custody for a sample is not guaranteed, the results of the hair test will not withstand examination in a courtroom.
- You may also like: Hair testing accuracy for drug and alcohol use
Official identification of the donor must be provided. A reliable witness may also be present to guarantee the security of the sampling process.
Cansford Laboratories send our trained collectors to take samples at at a location convenient for the individual donor. For collection by a doctor, a sampling kit will be sent to the donor’s local surgery.
For workplaces or other situations where hair tests are required for multiple donors, we provide a professional group-testing service via a trusted sample collection partner.
Remember: the rigour of the chain of custody is essential to a successful hair test. Without it, hair test results – while useful – cannot be relied upon. With a guaranteed, documented chain of custody, however, hair testing offers a fast, simple and accurate means of testing for long-term drug and alcohol use.
To find out more about hair testing for family law cases – including test accuracy, costs and alternative test methods – download our free ebook: ‘The complete guide to hair testing for drug & alcohol for Family Law’.