Hair analysis in forensic toxicology

Testing for drugs is important for most clinical and forensic toxicological situations, both for assessing the reality of the exposure/intoxication and for evaluation of the level of drug circulating in the body over a determined period of time. This review will focus on the evolution over the last three decades and the perspectives of hair analysis science. The presence of a drug analytes in a biological specimen can be used to document exposure. The standard in drug testing is the immunoassay screen, followed by chromatographic‐mass spectrometric confirmation conducted on a blood or a urine sample. In recent years, remarkable advances in sensitive analytical techniques have enabled the analysis of drugs in unconventional biological specimens such as hair. The advantages of this sample over traditional media, such as urine and blood, are obvious: collection is noninvasive, relatively easy to perform, and in forensic situations it may be achieved under close supervision of law enforcement officers to prevent adulteration or substitution. The window of drug detection is dramatically extended to weeks, months, or even years when testing hair. It appears that the value of alternative specimens analysis for the identification of drug users is steadily gaining recognition. This can be seen from its growing use in pre‐employment screening, in forensic sciences, in clinical applications and for doping control. The aim of this review is to document toxicological applications of hair analysis in various situations over the last years, focusing on major improvements, including screening of drug addicts (for ethanol, pharmaceuticals and drugs of abuse), child abuse, drug‐facilitated crimes, including sexual assaults under the influence of drug(s), doping control in sport and workplace drug testing for safety reasons. The detection of a single drug exposure in hair (doping offense, drug‐facilitated crime) will also be addressed by the author, who has more than 25 years of experience in the field. Despite late sampling or even lack of collection of traditional biological fluids, such as blood and/or urine, results for hair testing allow to document exposure to a drug. This article is categorized under: Toxicology > Hair Toxicology Toxicology > Toxicology in Sport Toxicology > Post‐Mortem Toxicology