Hair strand testing | Are children at risk from substance misuse?

Are children at risk from substance misuse, is an all too familiar question facing the family courts.

Hair strand testing (HST) is the most common form of testing used to produce evidence for the courts in these cases. Despite guidance from the High Court and compelling evidence accumulated over the past 25 years confirming that current industry practices used to produce HST reports for court is significantly flawed, HST results are often taken as definitive. A positive test will often lead the court to conclude drug usage has taken place, notwithstanding the fact there may be little corroborating evidence to support that conclusion and compelling evidence confirming the conclusions are wrong in an unacceptably high proportion of cases.

In this podcast, Forensic toxicologist Paul Hunter and Sarah Branson explored the limits of hair strand testing, how it works and some of the pitfalls in relying solely on this form of testing.

A sample of hair is taken from the scalp by a collecting agent, then logged and packed to ensure the chain of custody is maintained.  The hair is decontaminated in the laboratory and often cut into sections, representing approximate monthly periods. The hair is then tested for instructed drug and metabolites, (by-products produced in the body). The presence of both the drug and the metabolite above a pre-defined arbitrary level (the ‘cut-off’) usually leads to a conclusion that there is a positive association with the drug, i.e. it’s been used.

The analytical testing process and extracting material from the hair, is now mostly robust and very reliable. However, the processes used by almost all HST providers at all stages, from instruction to reporting, is significantly flawed leading to misleading evidence presented to the courts, which regularly results in miscarriages of justice. Given the industry all understand the failings in the process, this is clearly unacceptable, however, because the recipients of the evidence are ignorant of these issues there is no commercial incentive for them to change.

By way of example, many drugs (eg. cocaine, heroin and other opiates) are incorporated into the dark melanin in hair, and the darker the hair the higher melanin content. Dark hair incorporates more drug for the same amount and frequency used. Almost all companies apply standardised cut off levels to report results, above which a positive test will be reported (drug use) and below which a negative result will be reported (non-use. Afro-Caribbean and particularly Asian black hair incorporates significantly more drug into the hair than Caucasian black hair and significantly more than someone with red or blonde hair.  Therefore, two people using the same amount of drug over the same period produce very differing results – one positive for drug use who would lose custody of their child and the other negative, who retains custody.  Plainly this is neither fair nor of forensic value to the court.

Current industry practices, completely ignore all influencing factors and context relying solely on this binary, above or below, reporting, which has been proved to be unreliable and leads to misleading reporting in a high proportion of cases. What is needed top produce reliable and fair evidence is a full forensic investigation, starting at the instruction stage, to establish all factors that influence the presence, levels, and profile of drugs in the samples and their interpretation of results. Instructing an expert under Practice Direction, (not a drug test) allows the expert to inform the court and parties in detail what investigation and testing is needed specifically for each case, i.e. is nail and/or body hair testing needed in conjunction with hair testing; does the client use hair straighteners (a factor that leads to misreporting crack cocaine use).

Given the reliance placed on drug testing within the family courts, and necessity for the Court to have as accurate and reliable a picture as possible, and how high the stakes can be, it is essential that the testing and reporting process is reliable and fair.  Current practices do not provide reliable or fair results in all cases and while this is understood by the industry, its ignored and not only do children and families continue to suffer unnecessary catastrophic disruption to their lives, but public money continues to be misused and wasted.

With thanks to Sarah Branson, Barrister, Coram Chambers and Paul Hunter, Technical Director, Forensic Testing Service Ltd