Society of Hair Testing
published in: Forensic Science International 84 (1997) 3-6
1 Statement of the Society of Hair Testing concerning the examination of drugs in human hair
The first meeting of The Society of Hair Testing met in Genoa, Italy from June 17 to June 19, 1996. In attendance were scientists from all over the world. Most came from Western Europe and the United States, but some were from Japan, Abu Dhabi, Argentina, Chile and Romania. Their scientific presentations, posters and discussion sessions made significant contributions to the science of hair analysis. Approximately one-fourth of the meeting was devoted to discussions of three basis issues:
(1) Legal aspects of hair analysis
(2) Criteria for obtaining a positive result
(3) The relationship between drug dose and hair concentration.
The group met one afternoon to hear selected moderators present their proposals for resolving each issue. The attendees then divided into three groups. Led by the respective moderators, each group discussed its issue in detail. At the end of their respective sessions, the moderators prepared a summary statement of the group's positions. These summaries then served as the basis for another session the following afternoon. Attendees were encouraged to voice their agreement to the statements or to suggest modifications. Point by point the statements were then summarized and a consensus was obtained.
2 Legal aspects of hair analysis
2.1 Sample collection
Sample collection should be performed by a responsible authority respecting the legal, ethical and human rights of the person to be tested for drugs of abuse. Hair samples should be obtained in a non drug contaminated environment by an appropriately trained individual, not necessarily a physician. A sufficient amount of sample should be collected so that a repeat analysis or a confirmation analysis by another laboratory can be performed should it be needed.
2.2 Reference material
Reference material should be produced from hair samples collected from drug users. Homogeneity must be controlled and the best estimate of concentration has to be determined by the average results from reference laboratories' analyses.
2.3 Drivers under drug influence
Hair analysis is not a suitable test to prove driving under the influence of drugs. A positive result should lead to a psycho-medical examination (Italy, Germany),but not to the immediate withdrawal of the driving licence.
3 Criteria for obtaining a positive hair test result
It is recommended that the following criteria should be utilized when employing hair as a specimen in testing for drugs:
(1) Hair should be collected from the posterior vertex region of the scalp. The hair should be collected in such a manner as to enable identification of the proximal (scalp) to the distal orientation.
(2) Standard hair analysis should be performed on a measured segment of hair.
(3) All hair samples should undergo a decontamination procedure.
(4) A decontamination procedure should consist of a first wash with organic solvent, a second wash using water or aqueous buffer, and a third wash, with an organic solvent for example.
(5) The washes should be analysed for the drug which is under investigation, if necessary.
(6) All positive screening tests should be confirmed by alternative methods, for example by chromatography coupled to mass spectrometry or any other technology of comparable or greater specificity and selectivity.
(7) In order to evaluate the possibility of passive contamination, four criteria are recommended:
- The identification of metabolites
- The use of metabolite-to-parent drug ratios
- The assay values of the decontamination washes
- Threshold values
(8) The determination of the following metabolites can be recommended:
- Cocaine: Benzoylecgonine and Cocaethylene;
- Heroin: 6-monoacetylmorphine and morphine;
- THC: Carboxy-THC;
- Amphetamines: none.
(9) The following metabolite-to-parent drug ratios may be used
- Cocaine: benzoylecgonine/cocaine > 0.05 (since BE is not always present, hydrolysis controls should be used)
- Heroin: 6-monoacetylmorphine/morphine > 1.3 (corrected for hydrolysis)
4 Relationship between drug dose and hair concentration
The positive result of a hair analysis may be used to confirm if a person has used or was exposed to a drug. A negative result does not refute use of or exposure to the drug. To ascertain the time of exposure and the extent of drug use is difficult and needs further research. For some drugs, data now exist which indicate that, in very controlled clinical studies, a positive dose-concentration relationship exists. Hair testing is acceptable for forensic applications:
- If a chain of custody is maintained
- If external contamination is considered
- If a proper definition of a positive result is established
- If performed in qualified laboratories with acceptable analytical methodology
- If the laboratory participates in an external proficiency testing program, has achieved a satisfactory performance, and has established an internal quality assurance and quality control program
This document represents the official position of the society for hair testing. The society forbids partial citation of this document. This statement represents the initial step in the creation of a complete set of guidelines for hair analysis. Because of time limitations not every subject could be discussed in sufficient detail. One of these was the applicability and suitability of hair testing for the various legal systems of the countries represented at the meeting. The most extensively discussed point was the introduction of threshold values or cut-offs. Different legal situations in the different countries lead to different questions in court proceedings which require different cut-offs. The society will therefore set up a committee in which every concerned country will be represented by one member. This committee will have the task to develop a list of cut-offs with respect to:
- purpose of hair analysis
- substance of abuse
- GC/MS method
We expect thereby to complete the guidelines which will not only satisfy the requirements of forensic toxicologists, but also the requirements of the different administrations and courts dealing with drug abuse.
Officers of the SHT: Dr. Hans Sachs (President), Dr. Christian Staub (Vice-president), Dr. Pascal Kintz (Secretary), Dr. Michael Uhl (Treasurer).
Conseil d Ádministration (Board of Directors): Dr. Mario Cassani (Italy), Dr.Carmen Jurado (Spain), Prof. Marcello Chiarotti (Italy), Prof. Patrice Mangin (France), Prof. Thomas Mieczkowski (USA), Dr. Yuji Nakahara (Japan), Prof. Manfred Moeller (Germany), Dr. Jordi Segura (Spain), Dr. Irving Sunshine (USA), Prof. Robert Wennig (Luxembourg).