Is Hair Analysis Accurate for Drug Testing?

A recent paper published in the Journal of Analytical Toxicology reported on the use of ultra-high performance chromatography – tandem mass spectrometry to test nightclub users for drug use. The researchers were interested in new drugs entering the market. The samples they relied on were taken from the heads of the attendees — hair. How reliable is hair for drug testing and what did the team find?

It’s not just nits you find in hair

Hair is important to many people (especially those that have some left!). You only need to count the number of hairdressers and barbers in town or see how much shelf-space is given over to hair care products to realise its value socially. It is a relatively simple structure made from a protein called keratin. But our hair can reveal much more than is visible to our friends and lovers.

Can’t wash that drug away

Forensic testing of hair for possible drug use is a useful tool when you want to know about someone’s drug history. Hair is relatively inert when compared to other parts of the body. There is no metabolism taking place and no excretion occurs — so there is nothing to remove the drugs when they get into the hair. For a forensic scientist — this has huge benefits when compared to blood or urine.

Although blood and urine might tell you what has been consumed last night — hair can tell the analyst what drugs you were taking months ago. This is one of the reasons why hair analysis is popular for workplace assessments of drug use — particularly pre-employment checks.

It takes between five and ten days for a drug to become detectable in a hair sample. Many hair analysis tests sample the hair approximately 3 cm from the root. Since hair grows approximately 1 cm per month — the hair will contain samples of the drugs and metabolites that you have taken in the past three months.

New York psychoactive

With many new psychoactive substances (NPS) entering the drug market, a team at New York University (NYU) used the reliability of hair analysis to assess drug exposure in New York nightclubs and dancehalls. In a press release from NYU, Dr Salomone one of the paper’s authors stated:

“Hair analysis represents a reliable and well-established means of clinical and forensic investigations to evaluate drug exposure. Hair is the most helpful specimen when either long-time retrospective information on drug consumption is of interest.”

NPS cannot be detected in blood or urine samples after a few days, so hair samples provide a more reliable medium-to-long term indicator of drug use. Using chromatography, the team found that a quarter of club users had used an NPS in the last three months, with several new drugs detected. The analysis of NPS is discussed in the article, Tackling the chromatographic analysis of novel psychoactive substances with High Resolution Mass Spectrometry.

So, short back n’ sides before the job interview.