Hair analysis: back to the future



John Wicks, Lizzie Wicks and I were very privileged to attend the Scientific Celebration held in Strasbourg, France on November 27, 2015 for the 20th Anniversary of the Society of Hair Testing (SoHT), which  brought together world-leading specialists in the field.

A display of cutting-edge hair analysis science

The celebration consisted of a series of lecturers that were very helpful both as a retrospective of developments over the last 20 years and in looking forward to future challenges for that will improve hair testing analysis even more in the years to come.


Amongst the most important developments of the last 20 years that we were reminded of were:

The emergence of hair as a matrix

From being regarded as an ‘alternative matrix’ two decades ago, hair testing has gone mainstream.

The opening presentation by one of the founders and former President of the SoHT, Dr. Christian Staub, reminded us that In 1995, hair was a new matrix, often classed in conferences and scientific meetings in the section for “Alternative Matrices”, requiring 50 to 100 mg for analysis.

Some of us, who are old enough to remember the trouble we had with derivatisation techniques in the 1990’s, are now grateful for the much simpler LC-MS/MS approach that we use now. In 2015 we need no more than 20 mg of hair for a relatively simple extraction and analysis of drugs, biomarkers for evaluation of alcohol consumption, exposure to chemicals and evaluation of diseases.

Indeed, hair biomarkers are not restricted to alcohol use; the detection of acetylcodeine indicates use of illicit heroin whilst cortisol evaluates stress and long term exposure to depression and less common but with valuable applications in hair of dioxine, organic pollutants and chemical warfare agents.

Dr. Pascal Kintz, also a founder and a former President of the SoHT, enriched this retrospective/historical session and added his experience and assessment of the current state of the science of hair analysis. He added a glimpse into the future, of the next 20 years. He reminded us that in 1995 urine was the most common matrix used with very few hair samples analysed and that whilst it does not assess impairment it does provide evidence of recent and historical  drug use.  Hair collection and storage of samples are much more easier than urine and the potential of hair analysis in doping is an upcoming application that will enable the differentiation between single use and chronic use, potentially revealing doping during training.

Hair Analysis has limitations too

Toxicologists need to understand the limitations of hair analysis and that sometimes ‘the answer’ will not be clear-cut. For example, sometimes it is not possible to determine the minimal detectable dose, i.e., what is the smallest dose of a drug that we can detect in the laboratory?

Hair colour may affect the result, as can race and cosmetics, only segmental analysis of one individual’s hair can assess if usage is increasing or decreasing. The possibility of self-contamination from sweat resulting from a single dose or contamination from external or passive inhalation are also points to be considered when interpreting hair results. Different laboratories have different approaches and sometimes their results of samples from the same individual are different.

All this means that although the advantages of the detection of drugs in hair are greater due to the long window of detection, we require expert and honest interpretation of these results, which is only possible when we are aware of the limitations and understand the results and recognize clearly what we don’t know. Sometimes results are not black and white or clear cut.

Further awareness of what can affect results

Dr. Robert Konstrand added his views on the pitfalls of hair analysis stressing the risks of over-interpretation of the results.

Classical examples are the differences in metabolism, drug half-lives, physical properties, and transport over the membranes, pigmentation (melanine), segmentation and procedures that differ between different laboratories. For example, the possible inaccuracies of dates reported due to variation of hair growth rate between individuals added to the variation on how close to the scalp the sample was cut or even when re-aligned in the laboratory when it shouldn’t.

We  need scientists that understand these limitations and give accurate interpretation of the results that are comprehensible to the customer.

Applications of hair analysis

Dr. Fritz Pragst, also known as the “inventor of the hair alcohol marker”, presented the milestones from very early research and the earliest scientists who firstly detected EtG and FAEE in hair samples. EtG and FAEE were initially used as markers of chronically elevated alcohol consumption but now are often used to indicate abstention from use. One point he made  was about the benefits of cooperation between the different groups in Europe, which was the catalyst for the progress in the area. Interestingly, false positive results for ETG in hair are a rare occurrence, meaning that only when alcohol is consumed EtG is detectable in hair.

The lecture presented by Dr. Donata Favretto confirmed the wide variety of applications of hair analysis from forensic to clinical, from treatment and prevention of drug use and in work and in the family environment. The use of hair to detect substances other than drugs and alcohol, is increasing, examples are cortisol, elements, retrovirus and the detection of organic pollutants, particularly in occupational health.

Challenges for the Future

Dr. Volker Auwärter interestingly addressed the challenges and the future of hair analysis on his presentation on NPS (new psychoactive substance) and by Dr. Thomas Kraemer on the revolutionising MALDI technique. All of us involved in hair analysis are faced with this problem of the constantly changing drug market with the continuously changing NPSs. We are also faced with exciting prospect of a future, when we will be able to analyse one single strand of hair and eliminate the issues of hair growth rate and alignment. This means that potentially we would be able to analyse a single strand of plucked hair and know when drugs were used with more confidence!

Harmonisation of technologies between laboratories, participation in proficiency testing schemes and strict standards of accreditation have significantly improved the overall results of the analysis in the last few years. The challenge now is the harmonisation of the interpretation of the results between all laboratories and experts, which does not happen at the moment due to over interpretation or lack of understanding of hair analysis science by a few less experienced scientists.

New technologies and more sensitive techniques might help address some of the difficulties in understanding the results but education and guidelines will be key for a correct and honest interpretation of results.

On reflection

The day of lectures was a very realistic snapshot of the science of hair analysis. The lectures summarised well the advances made on the technology and the knowledge of hair analysis in the last 20 yearsleading to improved  interpretation of results.

Hair analysis is definitely an important tool used in many areas of life and will only get better in the future with new techniques to explore and develop to further advance our quest.

We have a lot to do and to develop in the next 20 years!


Strasbourg Cathedral
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