As hair grows from the root (at approximately 1 cm per month),
the byproducts of alcohol metabolizm are deposited along the
shaft of the hair. From hair clippings, the detection of these
byproducts are delayed to a certain extent; and therefore,
they cannot be detected until the hair grows out a bit (2-4
The distance from the scalp of the hair portion
containing drugs allows us to estimate the approximate time
of drug consumption. The deposited substances are relatively
stable in the face of external influences such as hair treatments,
cosmetics and sunlight. Due to the way in which drugs are
deposited in the hair, hair analysis provides us with a detailed
view of drug consumption over the past weeks or months. Consumption
on a day-to-day basis can be detected by analyzing blood and
urine samples. Trace amounts of ethanol from the environment
are present in all hair including in the hair of teetotalers.
Simply being in a pub or laboratory is enough for traces of
ethanol to find their way into the hair.
There are two (2) types of Hair Alcohol Tests, FAEE
"FAEE" stands for fatty acid ethyl
esters, a direct and very specific metabolite of alcohol,
produced in the body when alcohol is consumed. It provides
a greatly specific indicator of excessive alcohol consumption
over a 0-6 month period of time. Studies have showed that
FAEE markers are relatively stable in hair, and that the effect
of hair care and hair cosmetics on FAEE concentrations did
not significantly decrease concentrations. However, recent
studies have shown elevated levels of FAEE in hair could be
the result from hair treatment products containing alcohol
Science International, 2011). This is because the cells
around the hair are capable of metabolizing alcohol and leading
to an FAEE byproduct. As a result, this FAEE marker is sensitive
to false-positive results, therefore testing in tandem with
the EtG delivers a more accurate report on alcohol abuse.
"EtG" stands for ethyl glucuronide,
a direct and very specific metabolite of alcohol, produced
in the body when alcohol is consumed. It provides a good indicator
of excessive alcohol consumption over a 1-3 month period of
time. It is recommended that EtG testing is performed on the
most recent 1-3 months of hair growth (approximately 0 - 3cm
from the scalp). That is due to the fact that using the EtG
test in isolation carries the risk of the 'wash-out' effect
whereby the frequent washing and intense shampooing of a donor's
hair slowly removes the EtG marker that has been deposited
onto the hair. As a result, this marker is sensitive to false-negative
results. It is recommended that the EtG test always be combined
with the FAEE test.
In contrast to other drugs consumed, alcohol is not deposited
directly in the hair. For this reason the investigation procedure
looks for direct products of ethanol metabolism. The main
part of alcohol is oxidized in the human body. This means
it is released as water and carbon dioxide. One part of the
alcohol reacts with fatty acids to produce esters. The sum
of the concentrations of four of these fatty acid ethyl esters
(FAEEs: ethyl myristate, ethyl palmitate, ethyl oleate and
ethyl stearate) are used as indicators of the alcohol consumption.
The amounts found in hair are measured in nanograms (one nanogram
equals only one billionth of a gram), however with the benefit
of modern technology, it is possible to detect such small
In the mass spectrometer the substances are fired with an
electronic beam. Every molecule decomposes into specific fragments.
It is possible to determine which substance is present on
basis of its molecular weight.
However there is one major difference between most drugs
and alcohol metabolites (FAEE) in the way in which they enter
into the hair: on the one hand like other drugs FAEEs enter
into the hair via the ceratinocytes, the cells responsible
for hair growth. These cells form the hair in the root and
then grow through the skin surface taking any substances with
them. On the other hand the sebaceous glands produce FAEEs
in the scalp and these migrate together with the sebum along
the hair shaft (Auwärter et al., 2001, Pragst et al.,
2004). So these glands lubricate not only the part of the
hair that is just growing at 0.3 millimeters per day on the
skin surface, but also the more mature hair growth, providing
it with a protective layer of fat.
1: Possible ways of incorporation of FAEEs into hair (based
on Auwärter, 2006).
This means the glands supply the whole length of hair with
sebum, which in turn carries FAEEs into the hair, resulting
in an accumulative increase of FAEEs from proximal to distal
hair sections, see next figure (Auwärter et al., 2001).
This phenomenon has one important consequence: whilst most
other drugs are mainly stored in the hair via the root alone,
allowing toxicologists to establish time-resolved patterns
of consumption according to the length of hair provided, this
is not possible with alcohol (FAEEs) with respect to previous
drinking and abstinence. This would only be possible using
alcohol markers which enter the hair solely through the hair
root, but these have not yet been discovered.
However there exists a significant correlation between the
intensity of the alcohol intake and the concentrations of
the FAEEs in hair. Results between 0.05 and 30 ng/mg were
found in hair (Pragst et al., 2006).
Fig. 2: Profile of FAEE concentrations (based on
Pragst, 2004). Case 1 is a strictly abstinent person.
Case 2 is a social drinker. Case 3 is a patient in alcohol
rehabilitation (self-reporting 60 grams ethanol per day for
at least 6 months). The increase in FAEE concentrations from
proximal to distal sections up to a length of 5-10 cm found
in most cases could be explained by the sebum deposition route.
The hair is continuously bathed by sebum, and this leads to
an accumulation of the concentrations with increasing age,
i.e., distance of hair from skin.
As a consequence of the increasing FAEE concentrations from
proximal to distal it is preferable to always analyze, if
possible, a standard length of hair. For example analysis
of a 1cm hair sample taken close to the scalp will give a
much lower result than the analysis of a 6 cm long sample
also taken close to the scalp from the same person. For this
reason we standardly use the proximal 0-6 cm segment of head
hair in exactly the same procedure. For samples analyzed under
these standard conditions the cutoff level is set at 1.0 ng/mg.
The same holds true for body hair of any length (length is
genetically determined, body hair grows more slowly and has
different growth cycles, etc.). However for shorter head hair
the analysis changes (e.g.: for only 3 cm we reduce the cut
off level to 0.5 ng/mg). The closer the conditions (i.e. hair
length) are to the standard procedure, the more certain we
can be of the accuracy of the result.
A 6 cm long hair sample can be used to look back over one
to 6 months (this is commonly used in Germany to test drivers).
If head hair is not available or is too short (minimum: 2
cm); underarm, chest, leg and pubic hair may be analyzed.
Body hair also gives us a picture going back up to 6 months.
Pragst F., Balikova M.A.: State of the art
in hair analysis for detection of drugs and alcohol
Practical experiences in application of hair fatty acid ethyl esters and ethyl glucuronide for detection of chronic alcohol abuse in forensic cases.
abuse; Forensic Sci Int. 2011 Oct 27. [Epub ahead of print].
abuse; Clinica Chimic Acta 370 2006 17-49.
Auwärter V.: Fettsäureethylester
als Marker exzessiven Alkoholkonsums – Analytische Bestimmung
im Haar und in Hautoberflächenlipiden mittels Headspace-Festphasenmikroextraktion
und Gaschromatographie-Massenspektrometrie. Dissertation Humboldt-Universität
Pragst F., Auwärter V., Kiessling B.,
Dyes C.: Wipe-test and patch-test ror alcohol misuse based
on the concentration ratio of fatty acid ethyl esters and
squalen CFAEE/CSQ in skin surface lipids. Forensic Sci Int
Yegles M., Labarthe A., Auwärter V.,
et al.: Comparison of ethyl glucuronide and fatty acid ethyl
esters concentrations in hair of alcoholics, social drinkers
and teetotalers. Forensic Sci Int 2004; 145:167-173.
Madea B.,Mußhoff F.(Hrsg.): Haaranalystik
- Technik und Interpretation in Medizin und Recht. Deutscher
Ärzteverlag Köln 2004.
Hartwig S., Auwärter V. and Pragst F.:
Effect of hair care and hair cosmetics on the concentrations
of fatty acid ethyl esters in hair as markers of chronically
elevated alcohol consumption. Forensic Sci Int 2003a; 131:90-97.
Hartwig S., Auwärter V. and Pragst F.:
Fatty acid ethyl esters in scalp, pubic, axillary, beard and
body hair as markers for alcohol misuse. Alcohol Alcohol 2003b;
Auwärter V.: Fattty acid ethyl esters
in hair as markers of alcoholconsumption. Segmental hair analysis
of alcoholics, social drinkers, and teetotalers. Clin Chem
2001; 47: 2114-2123.
Pragst F., Auwärter V., Sporkert F.,
Spiegel K.: Analysis of fatty acid ethyl esters in hair as
possible markers of chronically elevated alcohol consumption
by headspace solid-phase microextraction (HS-SPME) and gas
chromatography-mass spectrometry (GC-MS). Forensic Sci Int
Spiegel K.: Untersuchungen zum Nachweis alkoholspezifisch
metabolisierter Substanzen aus menschlichen Haaren mit Gaschromatographie-Massenspektrometrie;
Dissertation Humboldt-Universität Berlin 1997.