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Encyclopedia of Drugs, Alcohol & Addictive Behavior, 3rd Edition, Vol 2 - Finals/10/13/2008 20:6 PM Page 219
H
n
HAIR ANALYSIS AS A TEST FOR
DRUG USE. Because every drug taken
becomes a permanent part of the user’s hair, laboratory analysis of hair can reveal the presence of a
variety of drugs including opiates, cocaine, amphetamines, phencyclidine, marijuana, nicotine, and barbiturates. Hair analysis is widely used and accepted
by courts, law enforcement bureaus, and government agencies. It is used for a variety of purposes
including employment screening, determination of
maternal or fetal drug exposure, and validating selfreports of drug use (Kintz, 1996; Harrison &
Hughes, 1997).
Unlike urinalysis, which can only detect comparatively recent drug ingestion (e.g., depending
on the drug, between days and weeks), hair analysis
can reveal the ingestion of drugs during the past
ninety days or even longer. Because head hair
grows at a relatively constant rate of one-half inch
(1 cm) (1 inch ¼ 2.54 cm) per month, segmental
analysis of hair strands could localize the period of
drug exposure to within as little as one particular
week. Although various hair treatments such as tinting and perming may affect test readings, detectable
traces are indelible in the hair (Kintz, 1996).
DRUGS IN HAIR
Hair is nonliving tissue composed primarily of a sulfur-rich protein called keratin. Hair grows from the
follicle (a saclike organ in the skin) at a rate of 0.3 to
0.4 millimeters (0.011 to 0.012 inches) per day in
cycles of active growth followed by a resting phase.
For an adult, approximately 85 percent of scalp hair is
in the growing stage at any time. Two sets of glands
are associated with the follicle: the sebaceous glands,
which excrete sebum (a waxy substance), and the
apocrine glands, which excrete an oil that coats the
hair. Hair color is determined by genetic programming for varying amounts of melanin, a pigment that
is synthesized in hair cells called melanocytes.
Although the exact mechanism by which drugs
and drug metabolites are incorporated into hair is
still unknown, they enter into hair by multiple
processes. Drugs and drug metabolites may be
deposited from the capillaries, which supply blood
to the follicles, or they may be excreted in the
sebum, oil, or sweat that coats the hair shafts.
Drugs can also be deposited on the hair by environmental exposure (such as marijuana smoke or
cocaine powder in the air) (Kintz, 2008).
When hair is analyzed for drug use a sample is
taken from either the head or another part of the
body. It’s washed to remove dirt and any external
drug deposits (the wash medium is also tested) then
stripped of melanin. The actual analysis is performed by radioimmunoassay, which detects not
only traces of drugs but their metabolites, breakdown products that appear only when the body has
metabolized the drug. All positive samples are confirmed by gas chromatography/mass spectrometry
(GC/MS). This second test has a cutoff level to
eliminate specimens containing drug levels that
could come from environmental exposure such as
inhaling second-hand marijuana smoke or eating
food that contains poppy seeds (Kintz, 1996).
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Encyclopedia of Drugs, Alcohol & Addictive Behavior, 3rd Edition, Vol 2 - Finals/10/13/2008 20:6 PM Page 220
HALLUCINATION
SIGNIFICANCE OF HAIR DRUG TESTING
Once a drug is embedded in hair it appears to
be stable indefinitely although its concentration
diminishes somewhat over time. Cocaine metabolite,
for example, has been detected in hair from a preColumbian mummy more than 500 years old. This is
an obvious advantage over other methods of drug
testing such as urinalysis, which can detect drugs
ingested only within the past few days or weeks.
Depending on the length of the hair, analysis can
determine that drug use has occurred from months
to years. Hair is also easily collected and stored. If
more testing is required another sample may be easily
obtained. One disadvantage of hair analysis is that it
will not reveal drug use during the three to five days
before testing since hair does not grow quickly
enough to show this. Urine testing can thus be used
to complement the results of hair analysis. Hair analysis is also more expensive than urinalysis and the
results take longer to be determined.
estimates. NIDA Research Monograph, 167 (NIH Publication No. 97–4147).
Kidwell, D. A., Lee, E. H., & DeLauder, S. F. (2000). Evidence for bias in hair testing and procedures to correct
bias. Forensic Science International, 107, 39–61.
Kintz, P. (Ed.). (1996). Drug testing in hair. Boca Raton,
FL: CRC Press.
Kintz, P. (2008). Drug testing in hair. In A. J. Jenkins (Ed.)
Forensic science and medicine: Drug testing in alternate
biological specimens, (pp. 67–81). Totowa, NJ: Humana
Press.
Ledgerwood, L. M., Goldberger, B. A., Risk, N. K., Lewis, C. E.,
& Price, R. K. (2008). Comparison between self-report and
hair analysis of illicit drug use in a community sample of
middle-age men. Addictive Behaviors. Available from
http://www.science-direct.com.
Uhl, M., & Sachs, H. (2004). Cannabinoids in hair: Strategy to prove marijuana/hashish consumption. Forensic
Science International, 145, 143–147.
REVISED
CONTROVERSY
Hair drug testing techniques have been greatly
improved over time. However, quantitative detection
of some drugs and their metabolites—particularly
THC, the major active component of cannabis—is
still considered difficult (Uhl & Sachs, 2004).
Some groups have raised concerns that hair testing may be biased against minority populations such
as African Americans. Multiple cross-comparison
studies between self-report and hair testing on
cocaine demonstrate discrepancies to be correlated
with hair color (Ledgerwood et al., 2008). A number
of in vitro experiments show that hair samples from
different gender and racial groups incorporate differing amounts of drugs under identical conditions
(Kidwell et al., 2000). Hair testing labs claim that
their processes, which remove melanin from samples,
eliminate any chance of distinction or discrimination
by race or ethnic group. Combining urinalysis and
hair testing may be needed to assess a more complete
profile of the individual’s past and present drug use
for forensic and occupational applications.
See also Industry and Workplace, Drug Use in; Military,
Drug and Alcohol Abuse in the United States.
BIBLIOGRAPHY
Harrison, L., & Hughes, A. (1997). The validity of selfreported drug use: Improving the accuracy of survey
220
BY
EDWARD J. CONE
AMY LOERCH STRUMOLO (2001)
RUMI KATO PRICE (2009)
BRUCE A. GOLDBERGER (2009)
n
HALLUCINATION. The word hallucinate
is derived from the Greek halyein, meaning ‘‘to
wander in mind.’’ Hallucinations are perceptions
that occur in the absence of a corresponding external sensory stimulus. They are experienced by the
person who has them as immediate, involuntary,
vivid, and real. They may involve any sensory system, and hence there are several types of hallucinations: auditory, visual, tactile (e.g., sensations on
the skin), olfactory (smell), and gustatory (tastes).
Visual hallucinations range from simple (e.g.,
flashes of light) to elaborate visions. Auditory hallucinations can be noises, a voice, or several voices
carrying on a conversation. In command hallucinations, the voices often order the person to do
things that at times involve acts of violence.
Hallucinations have been a hallmark of mental
illness throughout history. They are an important
clinical feature of several psychiatric conditions in
which psychosis can occur, such as schizophrenia,
manic-depressive illness, major depression, and
dissociative states. Withdrawal from alcohol can
cause visual as well as other sensory hallucinations.
In alcoholic hallucinosis, a person dependent on
ENCYCLOPEDIA OF DRUGS, ALCOHOL & ADDICTIVE BEHAVIOR, 3RD EDITION