Transcript Hair as an Indicator of Drug Use

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Katie Axwik, Broc Glover & Jory Schlitt
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Hair testing is not a decisive method for convicting someone of
drug use or exposure to external toxicants.
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2 types
1) Deposition of drugs on the surface of the hair
2) Passive inhalation
“Passive inhalation of substances that are
smoked would result in the incorporation of the
substances with the same mechanisms as the
active use of substances.”
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“Hair decontamination procedures rest on the assumption that
drugs, transferred into hair by passive environmental exposure,
are loosely bound to the surface of the hair or to the hair
matrix and therefore can be removed by appropriate washing
procedures.”
So you would expect results to come back negative for drugfree volunteers who are only externally exposed to the drugs,
right?
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It is difficult to determine systemic (true) exposure to cocaine over
exposure to external sources such as smoke.
In Forensic Science International, they attempted to determine if a single
external contamination would last sufficiently long to make a contaminated
subject indistinguishable from active users, even after conventional
decontamination and washing procedures.
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* The study was conducted on four drug-free volunteers.
* Each subject was asked to apply 10 mg of powdered cocaine
hydrochloride to their hands for 5 min so that it was uniformly
distributed. Subjects were then instructed on how to
contaminate their hair with their hands, as uniformly as
possible, from the roots to the ends.
* The results obtained using the decontamination methods
suggested in literature demonstrate that significant
concentrations of cocaine (>1 ng/mg) and moderate quantities
of benzoylecgonine (the main metabolite of cocaine) (generally
<0.5 ng/mg) are still detectable up to 10 weeks after
contamination
* The decontamination procedure was able to effectively remove
passive contamination, but only if done within 1 hour of
contamination
* Applied 1 day after contamination, they did not get the same
results and the results were well above the cut off value
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-Aim was to verify if a 5 consecutive day contamination with a small amount of a
powdered mixture of heroin hydrochloride and acetylcodeine hydrochloride will
last sufficiently long to make a contaminated subject indistinguishable from
active users, and if normal washing practices together with the decontamination
procedure are sufficient to completely remove the external contamination.
-The study was conducted on six drug-free volunteers, three males and three
females
-Results suggest that decontamination procedures are not sufficient to remove
drugs penetrated into hair from an external source  All contaminated subjects
were positive for opiates for at least 3 months.
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* “Another criterion used to distinguish active use from
environmental contamination has been the presence of
drug metabolites in hair however for some substances
like cocaine and heroin has been shown that metabolites
could be produced by other means than drug ingestion
(hydrolysis of the parent drug onto the hair shaft)”
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-Testosterone: epitestosterone ratio should be about 1:1. If the
participant were doping, the ratio would be off.
-When analyzing, the peaks must be well separated to determine
the ratio and it is possible for them to overlap. If this is the case,
the computer will take this into account, but accuracy and
precision will suffer.
-Additionally, if peaks are too small there is also a high uncertainty
(concentration in hair is very low, making the signal to noise ratio
very small).
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* Forensic Science International states that “a differentiation
between training and competition period is impossible by means of
hair analysis due to the uncertainty of short term kinetic
considerations related to hair growth”
* Effects of anabolic agents such as testosterone last longer than the
excretion, making it important to determine a time frame for
consumption
* “An analytical approach to the identification of exogenous steroids
in hair requires consideration of the presence of many other
steroids in the hair matrix interfering with the analysis at trace
levels”
* Identifying endogenous steroids is even more complicated as the
metabolites must be accounted for
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* To prevent contaminants on the hair from causing
false positives, hair samples generally have to be
washed.
* A wide variety of different wash methods are
available:
* Methanol, ethanol, acetone, etc.
* SDS or other detergents
* Dichloromethane
* Combined procedures using organic solvents and
repetitive washing with phosphate buffers
* Studies have found that different solvents are
appropriate for only certain analytes.
* Some wash methods will damage or alter
specific analytes.
* Prevents the use of any “general” wash
procedures.
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* Hair samples must be chemically digested prior
to sampling for analysis.
* Digestion protocols are split into three main
categories:
1) Alkaline Digestion
2) Acidic Digestion
3)Enzymatic Digestion
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* Hair samples are hydrolyzed in concentrated
NaOH overnight.
* Appropriate for extraction of morphine,
amphetamines and cannabinoids.
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* Analytes of interest are extracted with
hydrochloric or sulphuric acid in a process
similar to alkaline digestion.
* Often used for heroin and its metabolites.
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* Several specific enzymes are added to a haircontaining mixture.
* These proteases break down the protein
structure of the hair, releasing the bound
contents into the extraction solvent.
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* Each different extraction method works for
several different compounds, but there are no
comprehensive methods.
* Acid or base exposure may cause
decomposition or alteration of a chemical
structure.
* Enzymatic extraction is expensive and error
prone.
* Prevents detection of peptide hormones.
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* Immunoassays require that antibodies not be
denatured or destroyed.
* Detergents and highly alkaline matrices will
result in both of these.
* This may explain the discrepancies between
reported RIA and GC/MS results.
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* To ensure that extraction procedures result in
quantitatively reliable results, both positive
and negative controls are required.
* This requires the use of hair samples that have
known concentrations of different chemicals
present in them.
* This is difficult to accomplish, and relies on
extensive testing of these controls.
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* Many different extraction methods have been tested;
the recoveries of standards range from 35% to 120%.
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