What is your hair hiding?

Since becoming widely accepted throughout courts in the UK - testing of hair for the presence of drugs and alcohol is finding more and more applications

Hundreds of thousands of hair tests are performed every year throughout the world by a small number of forensic toxicology laboratories to identify drug and alcohol misuse. Although this is a field not without its controversy, hair test results are now widely accepted in criminal and civil courts.  

Whilst statistics on the total number of hair tests in the UK are not published, we estimate the figures to be between five and six thousand a year for alcohol and slighter more for drugs, with around one-in-three testing positive to substance abuse. The majority of hair tests are performed in support of divorce and child custody litigation and so are typically requested by social services, family law specialists and by the courts themselves. Elsewhere, other common applications include:

•    Employee screening for safety-critical jobs such as commercial aviation
•    ‘Fit to practice’ employment tribunals (e.g. Nursing & Midwifery Council)
•    Professional sports organisations to identify steroids and recreational drugs
•    To determine whether sedatives have been used in cases of child abuse
•    Pre-requisite for convicted drink-drivers re-applying for their licences
•    Surgeons assessing a patient’s suitability for an organ transplant
•    To confirm cases of Foetal Alcohol Syndrome among newborn babies

The conventional approach to alcohol and drug testing involves taking blood or urine and submitting these liquid samples for forensic tests. However, even when accurate, these traditional tests only relate to recent consumption: approximately 24 hours in blood and approximately three to five days in urine. This short-term window of detection puts children at risk in relation to parental care, public safety at risk in relation to workplace testing and patients at risk from themselves if being treated for alcoholism. Furthermore addicts are more often than not in denial, embarrassed or simply lie when asked to self-report their substance abuse (we find, for example, that over half of heavy drinkers underestimate their consumption of alcohol). As such, it has long been acknowledged by the medical profession that a reliable test to detect alcohol and drug consumption is required and hair is fast-becoming their preferred method.

Whilst hair testing is not intended to replace ‘under the influence’ impairment type tests taken at the time of a particular incident, its real value is in differentiating between social and excessive drinkers – or recreational and habitual drug users. Samples can be collected non-invasively and will provide an accurate record of any alcohol or drugs dependency over a three to 12 month period. From a practical point of view, hair is much easier to handle in the ‘chain of custody’ than blood or urine as it does not need to be stored under any special conditions. It also avoids the embarrassment of chaperones ‘observing’ urine collection. Plus, if a urine sample is in any doubt, it is always possible to take a fresh, identical hair sample and eliminate any false positives or false negatives.

Since hair growth is fed by the bloodstream, the ingestion of drugs or excess alcohol in the blood is revealed by analysing chemical markers absorbed by the hair. As the hair grows, it absorbs these markers into its structure, which remain in the hair indefinitely. These markers are only produced when there is alcohol or drugs in the bloodstream. The more markers there are the more has been consumed. A tuft of hair about the diameter of a pencil is required and the industry standard is to test a length of 1.5 inches, which provides a 90 day history. If no head hair is available, body hair can be used instead. Samples must be taken by a trained collector (usually a visiting nurse) on behalf of clients. Results are generally available in seven to 10 working days for alcohol and as little as 36 hours for drugs from receipt of a sample and the results can be provided in a standard legal statement. This is accepted, if required, by all UK courts – although in some cases it may be necessary to also provide ‘expert witness evidence’ to support the results.

A significant breakthrough in hair alcohol testing came last year when the two most common types of tests – known as FAEE (fatty acid ethyl esters) and EtG (ethyl glucuronide) – were combined to provide a higher standard of results for any case requiring unequivocal evidence.

In contrast to other drugs consumed, alcohol is not deposited directly in the hair. For this reason the investigative procedure looks for direct products of ethanol metabolism. FAEEs, for example, are formed in blood and all tissues while EtG is formed almost exclusively in the liver and deposited into hair mainly via sebum – or sweat. Interestingly, EtG is the chemical responsible for making someone ‘reek of alcohol’. It has been technically possible to measure FAEEs in hair since 1993, whereas the technique for measuring the relevant range of EtG is still in its infancy. Both markers are deposited in hair during chronically high alcohol consumption but are analysed with different methods. So, by combining these two types of testing, they complement each other in an optimum way and the accuracy of the combined results increases beyond all doubt.

Based on hair samples from a large number of donors with known drinking behaviour (teetotallers, social drinkers, alcoholics in withdrawal treatment, and death cases with known alcohol abuse), the following scale can be used:

 FAEE is measured in nanograms per milligram

Guidelines from the World Health Organisation are that excessive alcohol drinking corresponds to consumption higher than 60 grams of pure ethanol per day over several months. In the UK, alcohol is based on units to allow drinkers to establish their alcohol consumption. One unit is eight grams of pure alcohol. However, the amount of drink that equates to 60 grams depends on how strong the drink is. On average, one small pub measure of wine, one half of average strength beer, and one measure of spirit are all one unit. So seven of these units provide 56 grams of alcohol. A 750ml bottle of wine with 13% alcohol by volume would contain 9.75 units.

Merseyside law firm, Burd Ward Solicitors, has used hair alcohol tests in a successful bid to reunite children with their parents. In January, hair samples were collected from both parents who had admitted excessive use of alcohol. Both adults reported abstinence in the four day period prior to hair samples being collected, but it was too short a timeframe for the hair alcohol test to yield a negative result. Further testing one month later did however give a negative result, showing that the donors had significantly reduced their alcohol intake. A third and final hair alcohol test carried out one month after that yielded a negative EtG result of less than 4ng/mg, which is typical of teetotallers. This clearly showed that the parents had abstained from drinking in the three month period covered by all three tests.

It is hard to see the demand for hair testing waning. Not only are more countries – such as Portugal and Brazil – now willing to adopt the hair testing phenomenon but we are constantly being asked to test for different things. Our new lab in Manchester, for example, will be the first in the world to test the hair samples of HIV and TB sufferers to see if they have been taking anti-retroviral drugs prescribed to them. Tragically, in countries such as South Africa, these drugs are frequently sold on to the black market by patients or even smoked to obtain a ‘high’ instead of being swallowed.