E ditorial For reprint orders, please contact [email protected]
Hair analysis for forensic applications: is the future bright? “…the unique characteristics of hair, make it extremely valuable in certain scenarios where the use of other biological specimens would be unsuitable.” Keywords: drug-facilitated crimes n forensic toxicological analysis n hair
Role of hair in toxicological analysis The detection and quantitation of drugs and their metabolites in biological specimens is the ultimate form of assessing substance abuse by individuals. Drugs have been determined in blood and urine specimens for several years, because of their advantages, namely the possibility to correlate the levels to the observed signals and symptoms in the case of blood, and the high concentrations usually detected in urine. However, these specimens present several drawbacks, including the invasiveness of their collection procedures and the need for supervised collection. It is therefore not surprising that there has been a trend in utilizing alternative biological specimens, which would allow the collection of high-quality information regarding drug use while being less onerous to the tested person. From those alternative biological specimens, hair, is by far, the most extensively studied, and routinely used worldwide in toxicology laboratories, helping both clinical and forensic scientists in the assessment of drug-abuse situations. Hair as a forensic specimen: pros & cons Hair analysis presents several advantages, particularly when one compares its features to those characteristic of other biological specimens. Indeed, hair is collected in an almost noninvasive fashion, without the need for needles or supervised collections, which makes the test more bearable for the specimen donor. In addition, sampling does not need to be carried out by specialized personnel. There is also no valid reasons for the tested individual to manipulate the sample after its collection, making hair specimens unlikely to be tampered with, which often does occurs with urine [1–3]. Hair offers the possibility of ‘building up’ individual histories of drug consumption by
means of segmental analysis, therefore establishing patterns of long-term exposure. This will allow collecting more information on the tested individual, which can help in investigating certain forensic scenarios, for instance in those situations where blood and/or tissue concentrations of a particular drug alone cannot justify an individual’s death. Another important feature for forensic examinations is that it is possible to collect an identical sample, or more accurately, a sample representing the same time window, in case of suspicions regarding sample identity and/or breaches in the chain of custody. This will allow retesting of the individual at similar original conditions, and this is not possible when blood, urine or any other biological specimen is concerned. In addition, it is not possible to ‘beat the test’ in hair analysis, meaning that drug abstinence a few days before sample collection will not remove drugs from the hair. However, the main advantage presented by this biological specimen is the wide detection window for most drugs. Indeed, it is possible to detect drugs in hair for weeks, months or even years after the drug was last consumed, which is in contrast with the detection windows of blood or urine (from a few hours to a few days). This is a great advantage in many forensic applications but, undoubtedly, has most impact on the so called drug-related crimes, which will be addressed below. There are however, several drawbacks often associated with hair analysis, which are sometimes difficult to handle at manageable proportions. To start with, there is no known correlation between hair concentrations and the administered dose for most drugs, which means that it is not possible to calculate, for instance blood or plasma concentrations based on hair results. Indeed, too many factors have influence on drug
10.4155/BIO.13.291 © 2014 Future Science Ltd
Bioanalysis (2014) 6(1), 1–3
Mário Barroso
Author for correspondence: Serviço de Química e Toxicologia Forenses, Instituto Nacional de Medicina Legal e Ciências Forenses, Delegação do Sul, Rua Manuel Bento de Sousa, 3, 1169–201 Lisboa, Portugal E-mail: [email protected]
Eugenia Gallardo
CICS-UBI - Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, 6201–556 Covilhã, Portugal
ISSN 1757-6180
1
E ditorial |
Barroso & Gallardo disposition in hair, which are not within the scope of this article. Hair is a very complex matrix (and substances are strongly bound to inner-hair constituents) and, as such, its analytic processing is often laborious and time-consuming. In addition, drug concentrations in hair are often small, which demands for highly sensitive techniques, and MS detection is mandatory. These techniques also provide the required selectivity for forensic purposes, since they allow analysts to identify the present drugs, unequivocally. This is extremely important, since a positive result for a drug in a forensic context may have legal implications for the examinee’s life or freedom.
“This is extremely important, since a positive result for a drug in a forensic context may have legal implications for the examinee’s life or freedom.” However, the most important drawback of hair as a specimen of forensic interest is the possibility of providing false-positive results, particularly in those situations where the individual is exposed to, but does not actively consume, the drugs (for instance in the case of drugs that are smoked). Therefore, pre-analytical and analytical measures, as well as extreme care in the interpretation of the obtained results, must be followed. Indeed, reporting a false-positive is a stigma for any laboratory, which assumes particular relevance in the forensic field, where the consequences of such a result may have serious implications on the individual’s life and freedom, as already stated. Several decontamination procedures have been published in the scientific literature, but a general consensus regarding these procedures does so far not exist; in fact, it is assumed that the elimination of the totality of the externally deposited drug is not achieved even after laborious washing procedures [4]. The external contamination of hair can occur at any level. As such, establishing cut-off levels may not be sufficient to prevent reporting a false-positive result. For instance, the Society of Hair Testing recommends detecting drug metabolites, which in principle derive solely from endogenous metabolism, and the use of parent drug to metabolite ratios [5]. Another way to deal with external contamination is to evaluate the reproducibility of the results (including segmental analysis) using a newly collected hair specimen [4]. 2
Bioanalysis (2014) 6(1)
Applications of hair analysis Hair analysis was first reported in the late 1970s [6], and has aided toxicologists in several fields ever since. Drugs are highly stable in this specimen, allowing, for instance, the assessment of drug-use histories that took place hundreds of years ago, particularly detecting drug metabolites in ancient hair samples from South America [7,8]. This kind of analysis has a large anthropological interest and is also important in the resolution of forensic cases where hair is the unique specimen obtained from a corpse. Hair analysis can also provide useful information, for instance, in situations of driving license renewals and evaluation of compliance with drug substitution therapy; the latter is justified, since in many cases the individuals under treatment still use drugs. Hair analysis can also be used to document alcohol abuse, and this can assume relevance both in the clinical and forensic fields. Indeed, alcohol is one of the most abused substances worldwide, and the detection of specific metabolites can provide a unique type of evidence for abuse. Fatty acid ethyl esters and ethyl glucuronide are the most commonly used biomarkers [9]. As previously stated, hair analysis assumes high importance in the so-called drug-facilitated crimes, due to its particularly high window of detection for most drugs (weeks, months and in some cases years) [10]. This fact allows specimen collection, some time after the alleged event (e.g., 3–4 weeks), which is important since some of the drugs used in those crimes provoke amnesia in the victim, which can delay presenting charge at police authorities. Sometimes the involved substances are no longer present in blood or urine specimens at the time of sample collection, and hair may be the only specimen that can help assess the situation. In addition, the analytes should be detected after a single exposure, which can be associated to the event by means of segmental analysis (also differentiating a single exposure to the drug from consumption in a regular basis). This application of hair ana lysis calls for highly sensitive technology and, MS technology, is for obvious reasons a prerequisite. Future perspective Most forensic laboratories are now using hair analysis to document drug exposure, mainly due to the advantages that this specimen presents over the most traditionally used blood and urine. Moreover, the unique characteristics of hair, make it extremely valuable in certain scenarios future science group
Hair analysis for forensic applications: is the future bright? where the use of other biological specimens would be unsuitable. However, despite those particular situations, hair should not be regarded as an ultimate substitute of blood and/or urine in documenting drug exposure, but rather as a source of complimentary and important information. It is therefore expected that hair testing will continue to grow in the near future, and perhaps new applications will be discovered.
“…it is expected that hair testing will continue to grow in the near future, and perhaps new applications will be discovered.” MS procedures are now considered the gold standard for hair analysis, because of the high sensitivity and selectivity achieved, which are mandatory for forensic purposes. More sensitive equipment allow detecting single exposures to drugs and also reduce sample amounts.
| E ditorial
However, a problem that remains unsolved is the real possibility of false positive results arising from external contamination of hair. Perhaps this point deserves further research, and it would be beneficial if ‘greener’, inexpensive and efficient decontamination procedures were available for laboratories. This could improve laboratory throughput and would definitely reduce the risk of reporting false-positives, the main problem associated with hair analysis. Financial & competing interests disclosure The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript.
References 1
2
Jaffee WB, Trucco E, Levy S, Weiss RD. Is this urine really negative? A systematic review of tampering methods in urine drug screening and testing. J. Subst. Abuse Treat. 33(1), 33–42 (2007). Jaffee WB, Trucco E, Teter C, Levy S, Weiss RD. Focus on alcohol and drug abuse: ensuring validity in urine drug testing. Psychiatr. Serv. 59(2), 140–142 (2008).
3
Villena VP. Beating the system: a study of a creatinine assay and its efficacy in authenticating human urine specimens. J. Anal. Toxicol. 34(1), 39–44 (2010).
4
Musshoff F, Madea B. Analytical pitfalls in hair testing. Anal. Bioanal. Chem. 388(7), 1475–1494 (2007).
future science group
5
Society of Hair Testing. Recommendations for hair testing in forensic cases. Forensic Sci. Int. 145(2–3), 83–84 (2004).
6
Baumgartner AM, Jones PF, Baumgartner WA, Black CT. Radioimmunoassay of hair for determining opiate-abuse histories. J. Nucl. Med. 20(7), 748–752 (1979).
7
Cartmell LW, Aufdemide AC, Spinfield A, Weems C, Arriaza B. The frequency and antiquity of prehistoric coca-leaf chewing practices in Northern Chile: radioimmuno assay of a cocaine metabolite in hair. Lat. Am. Antiq. 2(3), 260–268 (1991).
8
coca leaf chewers. Forensic Sci. Int. 63(1–3), 269–275 (1993). 9
Pragst F, Rothe M, Moench B, Hastedt M, Herre S, Simmert D. Combined use of fatty acid ethyl esters and ethyl glucuronide in hair for diagnosis of alcohol abuse: interpretation and advantages. Forensic Sci. Int. 196(1–3), 101–110 (2010).
10 Barroso M, Gallardo E, Vieira DN, López-
Rivadulla M, Queiroz JA. Hair: a complementary source of bioanalytical information in forensic toxicology. Bioanalysis 3(1), 67–79 (2011).
Springfield AC, Cartmell LW, Aufderheide AC, Buikstra J, Ho J. Cocaine and metabolites in the hair of ancient Peruvian
www.future-science.com
3
Hair analysis for forensic applications: is the future bright? “…the unique characteristics of hair, make it extremely valuable in certain scenarios where the use of other biological specimens would be unsuitable.” Keywords: drug-facilitated crimes n forensic toxicological analysis n hair
Role of hair in toxicological analysis The detection and quantitation of drugs and their metabolites in biological specimens is the ultimate form of assessing substance abuse by individuals. Drugs have been determined in blood and urine specimens for several years, because of their advantages, namely the possibility to correlate the levels to the observed signals and symptoms in the case of blood, and the high concentrations usually detected in urine. However, these specimens present several drawbacks, including the invasiveness of their collection procedures and the need for supervised collection. It is therefore not surprising that there has been a trend in utilizing alternative biological specimens, which would allow the collection of high-quality information regarding drug use while being less onerous to the tested person. From those alternative biological specimens, hair, is by far, the most extensively studied, and routinely used worldwide in toxicology laboratories, helping both clinical and forensic scientists in the assessment of drug-abuse situations. Hair as a forensic specimen: pros & cons Hair analysis presents several advantages, particularly when one compares its features to those characteristic of other biological specimens. Indeed, hair is collected in an almost noninvasive fashion, without the need for needles or supervised collections, which makes the test more bearable for the specimen donor. In addition, sampling does not need to be carried out by specialized personnel. There is also no valid reasons for the tested individual to manipulate the sample after its collection, making hair specimens unlikely to be tampered with, which often does occurs with urine [1–3]. Hair offers the possibility of ‘building up’ individual histories of drug consumption by
means of segmental analysis, therefore establishing patterns of long-term exposure. This will allow collecting more information on the tested individual, which can help in investigating certain forensic scenarios, for instance in those situations where blood and/or tissue concentrations of a particular drug alone cannot justify an individual’s death. Another important feature for forensic examinations is that it is possible to collect an identical sample, or more accurately, a sample representing the same time window, in case of suspicions regarding sample identity and/or breaches in the chain of custody. This will allow retesting of the individual at similar original conditions, and this is not possible when blood, urine or any other biological specimen is concerned. In addition, it is not possible to ‘beat the test’ in hair analysis, meaning that drug abstinence a few days before sample collection will not remove drugs from the hair. However, the main advantage presented by this biological specimen is the wide detection window for most drugs. Indeed, it is possible to detect drugs in hair for weeks, months or even years after the drug was last consumed, which is in contrast with the detection windows of blood or urine (from a few hours to a few days). This is a great advantage in many forensic applications but, undoubtedly, has most impact on the so called drug-related crimes, which will be addressed below. There are however, several drawbacks often associated with hair analysis, which are sometimes difficult to handle at manageable proportions. To start with, there is no known correlation between hair concentrations and the administered dose for most drugs, which means that it is not possible to calculate, for instance blood or plasma concentrations based on hair results. Indeed, too many factors have influence on drug
10.4155/BIO.13.291 © 2014 Future Science Ltd
Bioanalysis (2014) 6(1), 1–3
Mário Barroso
Author for correspondence: Serviço de Química e Toxicologia Forenses, Instituto Nacional de Medicina Legal e Ciências Forenses, Delegação do Sul, Rua Manuel Bento de Sousa, 3, 1169–201 Lisboa, Portugal E-mail: [email protected]
Eugenia Gallardo
CICS-UBI - Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, 6201–556 Covilhã, Portugal
ISSN 1757-6180
1
E ditorial |
Barroso & Gallardo disposition in hair, which are not within the scope of this article. Hair is a very complex matrix (and substances are strongly bound to inner-hair constituents) and, as such, its analytic processing is often laborious and time-consuming. In addition, drug concentrations in hair are often small, which demands for highly sensitive techniques, and MS detection is mandatory. These techniques also provide the required selectivity for forensic purposes, since they allow analysts to identify the present drugs, unequivocally. This is extremely important, since a positive result for a drug in a forensic context may have legal implications for the examinee’s life or freedom.
“This is extremely important, since a positive result for a drug in a forensic context may have legal implications for the examinee’s life or freedom.” However, the most important drawback of hair as a specimen of forensic interest is the possibility of providing false-positive results, particularly in those situations where the individual is exposed to, but does not actively consume, the drugs (for instance in the case of drugs that are smoked). Therefore, pre-analytical and analytical measures, as well as extreme care in the interpretation of the obtained results, must be followed. Indeed, reporting a false-positive is a stigma for any laboratory, which assumes particular relevance in the forensic field, where the consequences of such a result may have serious implications on the individual’s life and freedom, as already stated. Several decontamination procedures have been published in the scientific literature, but a general consensus regarding these procedures does so far not exist; in fact, it is assumed that the elimination of the totality of the externally deposited drug is not achieved even after laborious washing procedures [4]. The external contamination of hair can occur at any level. As such, establishing cut-off levels may not be sufficient to prevent reporting a false-positive result. For instance, the Society of Hair Testing recommends detecting drug metabolites, which in principle derive solely from endogenous metabolism, and the use of parent drug to metabolite ratios [5]. Another way to deal with external contamination is to evaluate the reproducibility of the results (including segmental analysis) using a newly collected hair specimen [4]. 2
Bioanalysis (2014) 6(1)
Applications of hair analysis Hair analysis was first reported in the late 1970s [6], and has aided toxicologists in several fields ever since. Drugs are highly stable in this specimen, allowing, for instance, the assessment of drug-use histories that took place hundreds of years ago, particularly detecting drug metabolites in ancient hair samples from South America [7,8]. This kind of analysis has a large anthropological interest and is also important in the resolution of forensic cases where hair is the unique specimen obtained from a corpse. Hair analysis can also provide useful information, for instance, in situations of driving license renewals and evaluation of compliance with drug substitution therapy; the latter is justified, since in many cases the individuals under treatment still use drugs. Hair analysis can also be used to document alcohol abuse, and this can assume relevance both in the clinical and forensic fields. Indeed, alcohol is one of the most abused substances worldwide, and the detection of specific metabolites can provide a unique type of evidence for abuse. Fatty acid ethyl esters and ethyl glucuronide are the most commonly used biomarkers [9]. As previously stated, hair analysis assumes high importance in the so-called drug-facilitated crimes, due to its particularly high window of detection for most drugs (weeks, months and in some cases years) [10]. This fact allows specimen collection, some time after the alleged event (e.g., 3–4 weeks), which is important since some of the drugs used in those crimes provoke amnesia in the victim, which can delay presenting charge at police authorities. Sometimes the involved substances are no longer present in blood or urine specimens at the time of sample collection, and hair may be the only specimen that can help assess the situation. In addition, the analytes should be detected after a single exposure, which can be associated to the event by means of segmental analysis (also differentiating a single exposure to the drug from consumption in a regular basis). This application of hair ana lysis calls for highly sensitive technology and, MS technology, is for obvious reasons a prerequisite. Future perspective Most forensic laboratories are now using hair analysis to document drug exposure, mainly due to the advantages that this specimen presents over the most traditionally used blood and urine. Moreover, the unique characteristics of hair, make it extremely valuable in certain scenarios future science group
Hair analysis for forensic applications: is the future bright? where the use of other biological specimens would be unsuitable. However, despite those particular situations, hair should not be regarded as an ultimate substitute of blood and/or urine in documenting drug exposure, but rather as a source of complimentary and important information. It is therefore expected that hair testing will continue to grow in the near future, and perhaps new applications will be discovered.
“…it is expected that hair testing will continue to grow in the near future, and perhaps new applications will be discovered.” MS procedures are now considered the gold standard for hair analysis, because of the high sensitivity and selectivity achieved, which are mandatory for forensic purposes. More sensitive equipment allow detecting single exposures to drugs and also reduce sample amounts.
| E ditorial
However, a problem that remains unsolved is the real possibility of false positive results arising from external contamination of hair. Perhaps this point deserves further research, and it would be beneficial if ‘greener’, inexpensive and efficient decontamination procedures were available for laboratories. This could improve laboratory throughput and would definitely reduce the risk of reporting false-positives, the main problem associated with hair analysis. Financial & competing interests disclosure The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript.
References 1
2
Jaffee WB, Trucco E, Levy S, Weiss RD. Is this urine really negative? A systematic review of tampering methods in urine drug screening and testing. J. Subst. Abuse Treat. 33(1), 33–42 (2007). Jaffee WB, Trucco E, Teter C, Levy S, Weiss RD. Focus on alcohol and drug abuse: ensuring validity in urine drug testing. Psychiatr. Serv. 59(2), 140–142 (2008).
3
Villena VP. Beating the system: a study of a creatinine assay and its efficacy in authenticating human urine specimens. J. Anal. Toxicol. 34(1), 39–44 (2010).
4
Musshoff F, Madea B. Analytical pitfalls in hair testing. Anal. Bioanal. Chem. 388(7), 1475–1494 (2007).
future science group
5
Society of Hair Testing. Recommendations for hair testing in forensic cases. Forensic Sci. Int. 145(2–3), 83–84 (2004).
6
Baumgartner AM, Jones PF, Baumgartner WA, Black CT. Radioimmunoassay of hair for determining opiate-abuse histories. J. Nucl. Med. 20(7), 748–752 (1979).
7
Cartmell LW, Aufdemide AC, Spinfield A, Weems C, Arriaza B. The frequency and antiquity of prehistoric coca-leaf chewing practices in Northern Chile: radioimmuno assay of a cocaine metabolite in hair. Lat. Am. Antiq. 2(3), 260–268 (1991).
8
coca leaf chewers. Forensic Sci. Int. 63(1–3), 269–275 (1993). 9
Pragst F, Rothe M, Moench B, Hastedt M, Herre S, Simmert D. Combined use of fatty acid ethyl esters and ethyl glucuronide in hair for diagnosis of alcohol abuse: interpretation and advantages. Forensic Sci. Int. 196(1–3), 101–110 (2010).
10 Barroso M, Gallardo E, Vieira DN, López-
Rivadulla M, Queiroz JA. Hair: a complementary source of bioanalytical information in forensic toxicology. Bioanalysis 3(1), 67–79 (2011).
Springfield AC, Cartmell LW, Aufderheide AC, Buikstra J, Ho J. Cocaine and metabolites in the hair of ancient Peruvian
www.future-science.com
3
