Principles and Procedures in Forensic Toxicology
Introduction
Forensic toxicology concerns the application of toxicology to situations that may have medicolegal review, and as a consequence, results must stand up to scrutiny in a court of law.1 There are primarily three subdisciplines of forensic toxicology:
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Postmortem toxicology, more recently referred to as death investigation toxicology.
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Behavioral or human performance toxicology, which concerns
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Impaired driving as a result of alcohol and/or drugs consumption.
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Drug-facilitated sexual assault cases.
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Doping control. Screening of athletes for performance-enhancing substances is monitored by the World Anti-Doping Agency.2 In this category must be included equine and canine toxicology testing, because entire laboratories are dedicated to this specific purpose.
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Forensic workplace drug testing or drug urinalysis, which is performed as a preemployment and/or random monitoring of employees for illicit drugs or court-ordered testing of convicted drug offenders.
Closely related but in a category of its own is forensic drug chemistry.3 This discipline is concerned with drug and chemical analysis, as is toxicology, but in regard to nonbiological specimens such as seized bales of marijuana, packets of synthetic cannabinoids, pills, “meth lab” reagent analyses, rocks of crack cocaine, and the like. Toxicology and drug chemistry laboratories often work together on different aspects of a case, especially when the laboratories are housed in the same facility. An important consideration when laboratories are in the same building is that extraction of drugs by each discipline must be accomplished in different rooms to avoid possible contamination of toxicology specimens by the relatively massive quantities of drug chemistry specimens.
To assist with the practice of forensic toxicology, a guide as to how the discipline should be performed is provided in the form of forensic toxicology laboratory guidelines, prepared by the Society of Forensic Toxicology (SOFT) and the Toxicology Section of the American Academy of Forensic Sciences (AAFS).4 Also, at the time of this writing, a “draft” document entitled Scientific Working Group for Forensic Toxicology (SWGTOX) Standard Practices for Method Validation in Forensic Toxicology has been released for public comment. The practice of urine drug testing is defined by Mandatory Guidelines for Federal Workplace Drug Testing Programs, issued by the Department of Health and Human Services.5 This review is restricted to the subdisciplines of postmortem and behavioral toxicology.
Section snippets
How Forensic Toxicology Differs from Clinical Toxicology
Clinical toxicology is typically hospital-based, with the emergency room physicians being the primary customers. Analytical results must be obtained with speed to help confirm the therapeutic regimen for living patients, and an initial screen result by itself is sufficient for use in medical evaluation. Clinical analysts rarely are called about judicial matters, compared with forensic analysts. Quantification and confirmation of drug findings are not usually relevant to the treatment and often
Certification and Accreditation
Forensic toxicology and all fields of forensic science are currently experiencing a period of accelerated change. The impetus for change came in 2009 with the National Academy of Sciences report6 on the need for overhaul of forensic sciences in the United States. A major recommendation of this report was that forensic scientists should be certified in their specific discipline and laboratories should be accredited. Forensic toxicology certification is available primarily through two
Chain of Custody
In that the results of forensic toxicology testing may be used in court proceedings, the first necessary component of the testing process is to demonstrate the validity of test specimens. This demonstration is accomplished through the chain of custody,14 which documents the chronologic disposition and condition of specimens from the time of collection to the time of disposal. The person initiating the chain of custody would typically provide the identity of the individual from whom the specimen
Principles of Quality Assurance
A quality assurance (QA) program is required to ensure that the laboratory produces consistently reliable drug/chemical identification and quantitation. Aspects of a QA program include
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Competent analyst with access to continuing education. The number of analysts must be sufficient to handle the workload and provide testing services requested. If resources allow it, each analyst would ideally attend a national or international meeting each year. Certification in forensic toxicology should be
Postmortem Investigation
A strong forensic axiom is that no aspect of a death investigation is performed in isolation. There is communication with all staff members through a morning “viewing meeting” to discuss case history, medical records, pharmacy records, and the circumstances of the death. An important consideration is that “results of toxicology testing have to make sense” in light of the entire case findings. For example, GC/MS analysis of specimens and identification of cocaine with no detectable cocaine
Summary
This article is intended to provide the reader an overview of principles, procedures, and practices in a modern forensic toxicology laboratory. Future trends in forensic toxicology may include a change in analytical procedures where LC tandem mass spectrometry, time of flight mass spectrometry, and/or capillary electrophoresis are the standard analytical methods. Certification of analyst and accreditation of laboratories will be a universal requirement. Laboratories will be able to minimize the
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Drug toxicity and forensic pharmacokinetics
2022, Pharmacokinetics and Toxicokinetic Considerations - Vol IIThe toxicity and safety of Chinese medicine from the bench to the bedside
2021, Journal of Herbal MedicineCitation Excerpt :This facilitates the toxic biomarkers discovery and new research ideas on toxicity mechanism. Thus, it is increasingly valued by toxicologists (Blomme and Will, 2016; Kiani et al., 2016; Kimber et al., 2011; Wyman, 2012). And as a technical tool, systemic toxicology has been widely used in drug screening, new drug research and development, clinical rational drug use and other fields (Hoeng et al., 2014; Kiani et al., 2016; Rosenkranz, 2003).
Exhumation of Wistar rats experimentally exposed to the carbamate pesticides aldicarb and carbofuran: A pathological and toxicological study
2016, Experimental and Toxicologic PathologyCitation Excerpt :Similar to what has been reported in studies of drug abuse-related deaths (Carvalho et al., 2013; Hilberg et al., 1993; Kaferstein et al., 2013; Pounder and Jones, 1990; Skopp, 2010), this finding is related to the post-mortem distributions of the substances, which vary according to the collection site and PMI (Drummer et al., 2013; Gerostamoulos et al., 2012; Pounder and Jones, 1990) and also may be affected by bacterial metabolism (Drummer et al., 2013; Elliott et al., 2004; Skopp, 2010). The concentrations of substances in the viscera can dramatically increase due to dehydration and the positioning of the body, depending on the organ or site of the collected matrix (Butzbach, 2010; Flanagan et al., 2005; Skopp, 2010; Wyman, 2012). Additionally, other factors, such as incomplete distribution of a substance at the time of death and passive diffusion through blood vessels or cavities to nearby organs, influence its post-mortem concentration (Drummer et al., 2013; Gerostamoulos et al., 2012; Saar et al., 2012a; Skopp, 2010).
Poisoning of cats and dogs by the carbamate pesticides aldicarb and carbofuran
2015, Research in Veterinary ScienceCitation Excerpt :In animals, necropsies are performed by veterinary pathologists or veterinarians, which should be made aware of the possible circumstances that lead to the death of the animals, and follow established protocols, both for the necropsy and samples collection for toxicology and histopathology. A toxicologist should always be consulted about the appropriate matrices according to the pathologist's suspicions, as well as the best methods of handling of the samples, in order to obtain consistent and reliable results (Byard and Boardman, 2011; Cooper and Cooper, 2008; Drummer et al., 2013; Flanagan et al., 2005; Munro, 1998; Wyman, 2012). The majority of the animals fatally poisoned by carbamates usually presents a set of non-specific gross and histopathological findings, such as systemic congestion and multiple areas of haemorrhage (Grendon et al., 1994; Novotný et al., 2011; Xavier et al., 2007b).
The value of samples for postmortem toxicological studies
2015, Revista Espanola de Medicina LegalDrug confirmation by mass spectrometry: Identification criteria and complicating factors
2015, Clinica Chimica ActaCitation Excerpt :A large panel of drugs (e.g. 67 analytes [5]) can be included in the same run; although smaller panels are more common. If the test results may be used for forensic or civil litigation, chain of custody is required, and all aspects of specimen handling including sample collection, transportation, and analysis should be documented [6]. Despite the great performance of MS-based methods for drug confirmation, there are significant challenges due to the complexity of both the technologies and the biological matrices.
The author has nothing to disclose.