1 Garden CourtAlpha BiolabsCoram ChambersFamily Law Week Email Subscription

Home > Articles > 2013 archive

Alcohol Testing - What are the options?

Julie Stather, barrister, of 42 Bedford Row and Farooq Ahmed, barrister, of 7 Bedford Row consider the advantages and disadvantages of the various methods available for alcohol testing.

Julie Stather, barrister, 42 Bedford RowFarooq Ahmed, barrister, 7 Bedford Row

Julie Stather, barrister, 42 Bedford Row and Farooq Ahmed, barrister, 7 Bedford Row

It is now three years since the judgment in LB Richmond v B & W & B & CB [2010] EWHC 2903 (Fam) in which Moylan J provided guidance as to the evidential value of hair strand testing. Finally, the options for alcohol testing are widening. This article sets out the current testing methods and compares their relative probative values before the courts.

Breathalyser tests are often used as a cheap, effective and quick method of testing. Their usefulness is however limited in that the results provide evidence only of alcohol consumption in the hours leading up to the testing appointment. Further, the scientific limitations of such tests are well known, particularly in the criminal courts: the results vary depending on the rate at which the individual metabolises the alcohol, which can in turn be affected by exercise and can be distorted by use of products such as mouthwash. In family proceedings, results can be valuable when they form part of the fuller evidential picture. They can be used to support consistent results obtained by other forms of testing, but their limitations are such that they can rarely be relied upon with any force to undermine contrary evidence.

Urine testing
Urine samples are of more evidential value than breathalyser tests in that they provide results covering a longer period, to a maximum of 72 hours. Urine tests results are also compromised in similar fashion to breathalyser results in that they are also affected by the rate at which the individual metabolises alcohol. Additionally, subjects suffering from candida albicans (thrush) may also show a false positive result as the sugar excreted by the yeast ferments sugar into alcohol. Further, there have been numerous instances of samples being dishonestly provided from a person other than the correct donor. For these reasons, urine tests may be helpful to corroborate other results, but are so open to tampering and arguments of scientific inaccuracy that their reliability as a sole indicator of use or lack of use of alcohol is severely compromised.

Blood testing
Blood testing is more widely used and can detect alcohol between 14 and 28 days after its consumption. The result provides a snapshot of an individual's alcohol consumption at any given time. Laboratories use two indicators when examining blood: the variation of the proteins in the blood produced by the liver (the liver function test or LFT) and the presence or elevation of a marker known as carbohydrate deficit transferrin (CDT). Both of these indicators are present when an individual has consumed moderate to heavy amounts of alcohol and the results are therefore not helpful in those cases where the concern is around the use of alcohol per se (namely, where the individual is required to be abstinent because of long standing problematic use). One of the main limitations of blood testing is that results can be abnormal where the individual has liver damage for reasons other than alcohol consumption (e.g. cirrhosis, hepatitis and so on). Blood testing is most often used to provide another evidential source to confirm the results of hair strand testing where those results are disputed. It is also useful to seek to disprove drinking because the combination of alcohol markers in the LFT test in particular have a high negative predictive value of between 83 and 91%.

Hair strand testing
Hair strand testing is, and has been in recent years, the most common form of testing for alcohol and other drugs. The results cover a period up to 12 months, although the test most often requested is 6 months. The test looks at two specific markers, ethyl glucuronide (EtG) and fatty acid ethyl esters (FAEE), both of which identify ethanol within the body. EtG is formed within the liver and deposited into the hair from sweat. FAEE is formed in blood and other tissues and gets into the hair by means of diffusion from the external sebum layer.

The Society of Hair Strand Testing issued a Consensus in 2011 relating to testing for chronic excessive alcohol consumption. Such consumption is defined by the World Health Organisation as being 60g of pure alcohol per day over several months. In the UK, alcohol is measured in units. One unit is 8g of alcohol. Therefore, the test is measuring whether a person is consuming more than 7 units (7 x 8g= 56g) of alcohol per day, which equates to 7 pub measures of wine, 7 half pints of normal strength beer or 7 shots of spirit.

The cut off levels identified in the Consensus are 0.5ng/mg in the 0-3 cm proximal segment of hair and 1.0ng/mg if a 0-6 cm hair sample is used. A hair sample of less than 3 cm provides results which should be interpreted with caution, making the test virtually redundant for those with very short hair, although it may be possible to use body hair.

Drawing upon material published by the Society of Hair Strand Testing, the information on the websites of providers of hair strand testing and the judgment of Moylan J in the London Borough of Richmond case, the following limitations of hair strand testing emerge:

  1. EtG is water soluble and can be washed out of the hair over time, potentially leading to false negative results if the donor shampoos very frequently.
  2. Both EtG and FAEE are sensitive to cosmetic hair treatments. Ethanol containing lotions and sprays can lead to false positive results, whereas dying of hair and over washing can lead to false negative results.
  3. Either EtG or FAEE can be used independently to determine chronic excessive alcohol consumption. However for mutual confirmation and for exclusion of false positive or false negative results both parameters should be used, which can be expensive.
  4. The testing is designed to identify chronic excessive alcohol consumption, not abstinence or moderate or social consumption. This is because ethanol can find its way into hair from the environment (for example, just from being in a pub) and can therefore be present in the hair of teetotallers.
  5. It is not advisable to use the results of hair strand testing in isolation. They should be used with other clinical data and the results of other tests (e.g. blood tests) where possible.
  6. The results of both EtG and FAEE do not equate to the amount of alcohol consumed; the results cannot be interpreted in a linear fashion. This is because of differences in metabolism, hair growth and hair care (both frequency of shampooing and the use of hair products). The tests merely confirm whether or not consumption is above or below the cut off point.
  7. The results of both EtG and FAEE do not provide information as to the method or timing of consumption. They cannot identify binge drinking or a pattern of drinking which has escalated or decreased over the testing period. This is because the FAEEs can migrate in the sebum through the hair follicle, and EtGs can be picked up from the scalp and deposited along the hair shaft. Therefore, both forms of testing can provide only a level of average consumption over the testing period. The only way to gain a comparison of drinking habits is to conduct a number of tests over time.
  8. Hair grows on average only 1 cm per month, so the time between tests may not be compatible with the timescales for the child.
  9. Moylan J concluded that research evidence suggests that 10% of the results will be false positives. All results must therefore be treated with caution.

The leading case in respect of hair strand testing is London Borough of Richmond v B & W & B & CB [2010] EWHC 2903 (Fam) in which Mr Justice Moylan gave clear guidance as to the evidential worth of hair strand testing, which can be summarised as follows:

Hair strand testing is therefore valuable to form part of an evidential picture when the aim of the testing is to determine whether a person has been consuming more than 7 units of alcohol a day, on average, over the testing period. However, it is only valuable when used in conjunction with other evidence such as other forms of testing and other forensic evidence.

Transdermal Alcohol Continuous Testing
Transdermal alcohol continuous testing (TACT) has been available in the UK since only February 2013. Its use is therefore not as well established here as are the more traditional methods of alcohol testing, although it has been employed in the United States in all 50 states. If one is looking for evidence of past misuse of alcohol, for example to see if someone has been truthful about their alcohol intake, TACT will not be suitable. In such cases, hair strand testing is likely to be the most appropriate method as it can go back for up to 6 months with 6 cm of hair. However, if the court wishes to monitor current and future alcohol intake, TACT is a very good option as it tests for alcohol every 30 minutes over long periods and provides information on specific drinking events and levels, which hair testing cannot do.

The principle behind TACT testing is based on how the human body metabolises alcohol. Once alcohol is absorbed and distributed through the bloodstream, it is eliminated in various forms. One to two per cent of the alcohol that is consumed is eliminated transdermally or literally through the skin in the form of sensible and insensible perspiration. The transdermal emissions are sampled every 30 minutes by the TACT device.

TACT has two main components: a base station and an ankle bracelet. The bracelet has to be fitted to the ankle by a trained person sent by the system provider to ensure that it is fitted correctly. It transmits alcohol data to the base station in the person's home, which in turn sends it for analysis and reporting. Incidents of drinking and tampering are recorded and made known. The transmission can, if desired, be done without a telephone line or internet connection.

The bracelet is not uncomfortable to wear. It is water resistant, but the wearer needs to shower rather than take a bath as it must not be submerged. If an attempt is made to tamper with the equipment by trying to remove or obstruct it, it will send an alert. Reports can be provided weekly, monthly or at the end of the testing programme. The device can pick up readings from hygiene products containing alcohol, thereby giving an environmental alcohol reading, so these should not be applied to the ankle. It is best for the bracelet to be worn for 30 days or more as that gives a good overview of the wearer's drinking behaviour.

The costs of hair strand testing and TACT are comparable. Therefore, the Legal Aid Agency is as likely to approve funding for the use of TACT testing as it is for the use of hair strand testing. As at October 2013, the daily cost is about £15. A month's testing would cost approximately £450, with fitting and removal of the bracelet costing another £198. Included is the weekly report of levels of consumption and of any tampering, as well as reports within 24 hours of any confirmed alerts, if required. That makes a total of £648 plus VAT for a month. Hair testing used in conjunction with CDT and LFT tests can cost up to approximately £720 plus VAT when one factors in expert witness reports and sample collection costs.

No alcohol testing method will prove complete abstinence. With hair strand testing, a person can have about seven glasses of wine, taking them to the cut off. Below that cut off, the evidence descends into murkiness with the results being arguably affected by, for example, metabolic rates. The cut off level with TACT is three consecutive readings above 0.02 TAC (transdermal alcohol concentration). A glass of wine with a meal is unlikely to take the TAC reading even to 0.02. The maximum level for driving in the UK is 35 micrograms of alcohol in 100 millilitres of breath. This equates to approximately 0.08 TAC. So it may be seen that TACT tests for alcohol down to quite a low level of consumption.

Testing by TACT can be clearer and more reliable than other methods of testing for current and future alcohol consumption and may be something which the courts should be invited to consider using more widely in order to make more accurate assessments of current and future alcohol use or misuse.

It can be seen that all the methods of alcohol testing have their place. Blood testing can identify where past use has been so heavy as to cause damage to the functioning of the liver. Hair strand testing can show chronic excessive use over the six months prior to testing. TACT is the only presently available method of testing for current use and obtaining instant feedback. However, in the current climate of restrictive budgets it is unlikely that the court will find favour with approving all three methods of testing.

Perhaps the way forward is to seek to obtain earlier concessions to the threshold criteria. If past excessive alcohol use is conceded as part of threshold, then there is arguably no need for blood or hair strand testing. The parties could then focus on possible current use for the welfare stage of proceedings.

In addition, given the recent judgment in Re B-S (Children) [2013] EWCA Civ 1146 and the efforts being made by all to keep families together where possible, TACT may have its place over the longer term to allow for monitoring of a carer's use of alcohol whilst the children are at home, whether under a care or supervision order. 

Finally, TACT bracelets may prove invaluable in the event of a client stopping drinking only shortly before the final hearing. A bracelet could be fitted for the weeks leading up to that hearing to provide evidence to the court of current consumption, which could assist in arguing a case for return of the children or for an adjournment to allow a period of further testing. In the current climate and under the new protocol, the delay incurred by awaiting hair growth and hair strand testing could well be unacceptable.

The authors are grateful to Alere Toxicology for providing them with scientific and technical information relating to TACT.