Insights from a six-year hair drug analysis compendium in drug-facilitated crimes involving vulnerable population cases.

Hair analysis is a well-established matrix in forensic toxicology, offering a valuable alternative or complement to traditional matrices in diverse contexts, including drug-facilitated crimes (DFC), elder abuse, and accidental exposure in children. However, objective interpretation of hair drug concentrations remains challenging due to significant inter-study variability, even for identical compounds. This study included hair analysis results upon the prosecutor's request over six years in the Grenoble Forensic Laboratory in France. Hair analysis was performed using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) on Sciex® 5500QT and Waters® TQ-XS mass spectrometers, following the French Society of Analytical Toxicology (SFTA) guidelines. Hair proficiency quality testing ensured reproductive results. This compendium describes 38 cases with hair analysis, including child's exposure and chemical abuse involving both children and the elderly. The study population predominantly involved female victims (84.2%), aged 5 months to 90 years. At least one substance was detected in hair in 26 cases. In twelve cases, hair analyses supplemented blood or urine testing. Substances identified were cocaine, THC, and levamisole in child exposure cases; alprazolam, diazepam, loprazolam, and tiapride in chemical abuse; and mainly MDMA, cocaine, paroxetine, and THC in other cases. This compendium contributes valuable data to the literature, enhancing the interpretation of hair drug concentrations across a broad spectrum of cases characterized by diverse age ranges, hair characteristics, timeframes, and circumstances. This work provides critical comparative data for interpreting findings in forensic cases.