Although a typical 3-cm proximal length of scalp hair represents drug use averaged over a 3-month retrospective time period approximately, time boundaries can be diffuse due to growth rate variation and incorporation from sweat and sebum. For this reason, sufficient time must be allowed to elapse for a period of abstinence to be reflected in hair drug concentrations.
Although scalp hair is preferable, hair taken from other sources (eg chest & body hair) can also be used. The time period covered by a sample of non-scalp hair generally represents a longer retrospective time period than a similar length of scalp hair and as hair samples from alternative sources are analysed in their entirety, analysis can represent a much longer retrospective detection period.
Note that neither underarm nor pubic hair are suitable for alcohol marker analysis.
Also, as underarm hair drug concentrations can be lower, hair from this source should only be selected if unavailable elsewhere.
A sample of hair (roughly the width of a thin pencil) is taken from the back of the crown of the head (posterior vertex). In subjects who have poor hair distribution, several smaller locks can be obtained and combined. The most common length of head hair analysed is 3 cm (proximal), even though a longer sample is often collected; a 3-cm length of scalp hair analysed represents a retrospective time period of 3 months, approximately.
Although shorter samples of hair can also be collected, representing shorter growth periods, it is advisable that at least 3-cm is available for analysis for alcohol markers.
Collection is carried out under full chain-of-custody conditions, usually in duplicate.
In the laboratory, a sample of submitted hair is analysed for a range of target drugs & their metabolites.
The hair is washed in the laboratory using a procedure validated for this purpose to remove surface contamination prior to further analysis. Analysis is carried out using highly specific techniques capable of identifying individual drugs with absolute certainty and measuring their concentrations.
As part of the protocol, the washings may also be analysed to help assess the potential influence of environmental drug exposure.
There can be some variation in the detail of the analytical strategy depending on the laboratory used and particular drugs targeted.
Cutoff concentrations are used to distinguish which samples are to be considered negative or positive. Such interpretative cutoffs are commonly used in the drug testing industry for workplace and substance abuse casework and cutoffs for many common drugs have been defined [eg. Guidelines of the Society of Hair Testing (soht.org) and European Workplace Drug Testing Society, (ewdts.org)].
These cutoffs can be applied in the laboratory and their application enables drug test results to be used to identify drug use with a high probability; low level, occasional or historic drug use is likely to result in a negative outcome.
Quantitative results can be reported in such a way that allowance will have been made for variation in analytical measurement.
The cutoffs used can also be represented by the analytical sensitivity of the method and in such circumstances expert interpretation of the results will be provided.
Hair - Scope of Analysis
The drugs included in each analytical panel have been defined and a detailed list of the drugs/metabolites targeted is included in the laboratory report. Short descriptors for the panels are provided in the tables below.
Although the standard panels include the majority of common drugs of abuse, special targeted analysis is also available for unusual drugs. This may be appropriate in the testing for specific drugs, anabolic steroids or for New Psychoactive Substances (NPS).
Details of unusual or specific requests should be discussed with NIVHA prior to collection being arranged.
Hair - Alcohol Markers
Although analysis for alcohol in hair is not possible, analysis for its minor metabolites can be used as an indication of excessive alcohol consumption or self-declared abstinence. These metabolites are ethyl glucuronide (EtG) and FAEE’s (fatty acid ethyl esters) and their concentrations in hair can be used to support an assertion of chronic excessive alcohol consumption. They can also be used to help confirm self-declared abstinence.
EtG is the most useful metabolite used for this purpose although analysis for FAEE’s (at additional cost) can be a useful enhancement.
While EtG concentrations can be reduced by chemical treatment of the hair (eg dyeing bleaching etc), FAEE concentrations can be elevated by the use of alcohol-containing hair-care products such as hairsprays and dry shampoos.
While EtG concentrations alone will usually provide adequate interpretative value in the majority of cases (for both abstinence and chronic excessive assessment), FAEE analysis can be a useful adjunct, particularly in cases of suspected ‘false negative’ EtG results. This may occur, for example, where recent hair growth has been subjected to harsh chemical treatment, such as dyeing or bleaching. In cases of this type in particular, analysis for both EtG and FAEE’s would be recommended.
It should also be noted that EtG is the first choice in hair alcohol assessment and disproportionately elevated FAEE concentrations can only be used to prompt further monitoring. In the case of chemically treated hair, future analysis of untreated hair growth could be useful; blood & urine testing for alcohol markers can also be useful in these circumstances.
As a general approach, NIVHA recommends that EtG alone represents a cost-effective approach for self-declared abstinence assessment. Additional analysis for FAEE’s can be useful in chronic excessive alcohol consumption assessment, particularly in cases of recent harsh chemical treatment.
Hair type: the evidential value of this testing is maximised if analysis is carried out on scalp hair segments of between 3 and 6 cm in length. Body hair can also be used, but the interpretative value of the results will be associated with greater uncertainty; full interpretative support will be provided in hair alcohol cases. Pubic and underarm hair are not suitable for alcohol assessment.
Hair testing results for alcohol should not generally be used in isolation; the test should not be used to reach evidential conclusions by itself in isolation of other evidence.
Hair - Segmental Analysis
Although hair analysis results typically represent an average of drug intake during the entire growth period, segmental analysis can be useful in certain circumstances. With this technique, more detailed information on drug abuse timeline profiles can be useful. If segmental analysis is considered, NIVHA can provide expert guidance on its application for a particular case.
Hair Drug (& Alcohol) Panels
For hair drugs analysis we offer 3 standard panels, covering many of the drugs of abuse encountered, and their metabolites. Most of the common drugs of abuse are covered in standard panel 1 and this can be expanded at extra cost to include additional drugs listed in standard panel 2. All of the drugs included in standard panels 1 and 2 have industry standard cut-offs already defined.
The drugs listed in panel 3 can be requested to further expand the scope of standard panels 1 & 2 or can be requested as a stand-alone panel. Currently the drugs listed in panel 3 do not have cut-offs defined, but interpretative guidance will be provided when appropriate.
In addition to the standard panels, analysis for anabolic steroids, alcohol markers and New Psychoactive Substances is also offered.
Some minor variation in the details of drugs listed in the panels is possible; specific drugs analysed in each case is provided in individual laboratory reports.