Katie Axwik, Broc Glover & Jory Schlitt

Hair testing is not a decisive method for convicting someone of drug use or exposure to external toxicants.

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.”

“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 drug-free volunteers who are only externally exposed to the drugs, right?

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.

*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

-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.

*“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)”

-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).

*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

*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.

*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

*Hair samples are hydrolyzed in concentrated NaOH overnight.

*Appropriate for extraction of morphine, amphetamines and cannabinoids.

*Analytes of interest are extracted with hydrochloric or sulphuric acid in a process similar to alkaline digestion.

*Often used for heroin and its metabolites.

*Several specific enzymes are added to a hair-containing mixture.

*These proteases break down the protein structure of the hair, releasing the bound contents into the extraction solvent.

*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.

*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.

*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.

*Many different extraction methods have been tested; the recoveries of standards range from 35% to 120%.