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Chapter 3―Preparing for Drug Testing
in sweat include tetrahydrocannabinol
(THC), amphetamine, methamphetamine,
methylenedioxymethamphetamine (MDMA,
or “Ecstasy”), codeine, morphine, heroin
metabolite, phencyclidine (PCP), and cocaine
and its metabolites (e.g., benzoylecgonine,
ecgonine methyl ester) (Barnes et al., 2009;
Dasgupta, 2008).
Because sweat can be collected only in
limited quantities, there may not be sufcient
specimen for repeat or conrmatory testing.
Sweat is less susceptible to tampering or
adulteration than is urine. The accuracy
of sweat testing is not standardized. Its
accuracy remains somewhat controversial
(Chawarski, Fiellin, O’Connor, Bernard, &
Schottenfeld, 2007; Watson et al., 2006) and
more research is needed (Barnes et al., 2009;
Huestis et al., 2008; Kacinko et al., 2005;
Schwilke et al., 2006). However, the sweat
patch is used extensively in the criminal
justice system, and its use to identify relapse
or violations of conditions of probation has
been upheld by the courts.
Blood
Blood testing detects alcohol or drug use
starting shortly after use, depending on the
substance and the route of administration. In
general, blood has a shorter detection period
than urine (Warner, 2003). Blood collection
is more invasive than other procedures and
requires trained personnel to collect the
specimen and perform laboratory testing. For
people who inject drugs, or those with poor
venous access, drawing blood may be difcult.
Hair
In theory, the presence of drugs in hair
is based on a simple principle: Drugs or
their metabolites circulate in a person’s
bloodstream, and the hair follicles absorb the
drug and/or metabolites from the bloodstream
and from secretions of the sebaceous and
sweat glands in the scalp (Cone, 1996;
Musshoff & Madea, 2006). Trace amounts
of drug become entrapped in the core of the
hair as it grows, at a rate of approximately
1 cm per month (Dolan et al., 2004). Drug
metabolites can be detected in the hair
shaft approximately 7–10 days after drug
ingestion. Hair is unique in that it may
provide retrospective information on drug
use, versus the point-of-time information
provided by urine, blood, and breath. (Kintz,
Villain, & Ludes, 2004). In some cases,
drugs were found to move down the hair
shaft via sweat (Henderson, Harkey, Zhou,
Jones, & Jacob, 1996), which would disrupt
the use of hair testing’s ability to determine
the historical use. Another unfortunate
aspect of interpreting hair test results of
drugs and their metabolites is that drugs
may be incorporated into hair by simple
environmental drug exposure (Ropero-Miller
& Stout, 2008; Wang & Cone, 1995).
The hair sample is usually taken from the
back of the head, cut with scissors as close to
the skin as possible (Wong & Tse, 2005). Hair
can be collected from other parts of the body
(e.g., face, armpit) of patients who are bald or
have shaved heads.
Hair testing appears to be most reliable for
detecting prior frequent, heavy use of cocaine,
opioids, amphetamine, PCP, and Ecstasy,
but is not suited for detection of very recent
use, or occasional drug use. Musshoff and
Madea (2006) report that hair tests can
detect the presence of the THC metabolite,
tetrahydrocannabinol carboxylic acid. Hair
analysis can often distinguish between
heroin and morphine use—a distinction that
is sometimes difcult to make with blood or
urine analysis (Dolan et al., 2004) because
of the short half-life of heroin metabolite in
these matrices. Hair testing for alcohol is
inappropriate; alcohol does not incorporate
into hair. However, the minor metabolites of
ethanol, ethyl glucuronide, and ethyl sulfate
in hair show promise as markers of alcohol
use (Wurst, Skipper, & Weinmann, 2003).