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Hair Strand Testing: the validity of results

Recent guidance has been provided to practitioners on the use of hair strand testing in proceedings. Peter Jackson J (as he then was) has handed down judgment in the case of H (A Child : Hair Strand Testing) [2017] EWFC 64 in respect of the validity of hair strand testing in light of multiple criticisms made by a jointly instructed trichologist.

These proceedings concerned a mother of a baby girl who was 8 months old at the time of the final hearing. The mother had a history of drug abuse, and when she was 21 years old, she was regularly using heroin and crack cocaine. The mother’s baby was removed from her care when she was born due to a positive hair strand test, but was returned to her care when she was 6 weeks old under an interim supervision order. By the time of the final hearing, the local authority’s plan was to place the baby for adoption due to their concerns of the mother’s substance misuse.

The hearing was heard over 5 days due to the evidence, addressing the underlying factual issue of whether the mother had been using drugs, albeit it at a low level, during the past two years. The mother adamantly denied doing so. The evidence supported her save for one exception.

That exception was the hair strand tests taken over a 2 year period. The tests showed a low level cocaine use for at least some of the time. This was challenged by the mother. The evidence heard by the court was from five expert witnesses, comprising of three different testing organisations, a trichologist and a forensic toxicologist.

If there is a question about a person’s drug use, a toxicologist may be instructed to carry out hair strand testing. The toxicologist can test for a variety of drugs, and can provide a month by month breakdown of substance misuse if detected. When testing for the presence of a drug in hair, the toxicologist will test for the metabolite. After a drug has entered the body, it is metabolised (broken down) into compounds (metabolites) derived from the drug; therefore the parent drug and the metabolite are present in the blood stream. As a hair follicle grows, it is provided with a good blood supply, and this is how drugs are incorporated into hair.

There are differences with the experts instructed within these proceedings. A toxicologist is instructed to carry out scientific testing to establish whether a person has consumed illicit drugs. A trichologist will help people who have problems with their hair or scalp, and do not have expertise in scientific testing of drugs.

The local authority argued at the hearing that as total abstinence had not been achieved, there was a level if risk that the child could get caught up in the mother’s future drug use. Further, as the tests showed the mother was still misusing cocaine, albeit at a low level, she could not be fully trusted as she had maintained that was not misusing cocaine.

At the early stages of the proceedings, Dr Rushton, a trichologist, was instructed. Dr Rushton’s first report raised questions as to the validity of the hair strand testing process. As a result, a further expert, Dr McKinnon, a forensic toxicologist was instructed. Dr MacKinnon agreed to some extent with Dr Rushton as to the risks associated with external contamination and the nature and significance of industry guidelines. Both experts identified that the samples needed to be washed to measure external contaminants before being able to establish if cocaine and/or its metabolites within the hair itself could indicate use.

Peter Jackson J identified the following issues:

1) The significance, if any, of the variability of the results as between the different laboratories.
2) The nature and significance of industry guidelines.
3) The significance of findings of cocaine or its metabolites below cut-off levels.
4) The significance of the comparison between wash samples and test samples

The judgment concludes that the variability of findings from hair strand testing does not call in to question the underlying science, but underlines the need to treat numerical data with proper caution.

The experts debated the industry guidelines as to the necessary requirements to establish a positive hair strand test. The cut off levels are described as safety mechanisms, which Dr Rushton and Dr McKinnon insisted are strictly adhered to. The hair strand test providers suggested that readings below cut off levels could still be informative and should not be disregarded.

Peter Jackson J noted the evidence of the interveners (the three testing organisations) to be evidence-based, carefully considered and that they have a combination of expertise and experience that enabled them to deal satisfactorily with the issues under consideration. The Judge accepted the evidence from the toxicologist and found that the mother had misused cocaine in 2016, albeit at a low level.

Despite the court making a finding that the mother had misused cocaine at a low level in 2016, the Judge was not satisfied that the mother had misused cocaine in 2017 as alleged by the local authority. As the local authority had not proved its case that the mother had misused drugs in 2017, and along with other evidence supporting the mother that she had not recently misused drugs, the court made a supervision order with the child remaining in her care.

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