Hair Testing in Forensic Toxicology: Recent Insights From Root to Tip

ABSTRACT Hair testing is a powerful tool in forensic toxicology, particularly for identifying past substance exposure when blood or urine samples are collected too late. Its extended window for substance detection enables the identification of previously consumed substances and patterns of exposure. Hair, from the root to the tip, has frequently been used in forensic toxicology to assess both a single dose and long‐term exposures in drug‐facilitated crimes, as well as in investigations of the cause of death. The ongoing development and increasing use of hair testing underscore the need for a fresh assessment of its evolving potential. This focus article provides insight into the field of hair testing, focusing on recent applications, emerging trends, and advancements in the hair testing workflow from sampling to interpretation. Recent trends to address factors influencing substance levels in hair involve new protocols for micro‐segmentation, longitudinal hair scanning, assessment of melanin content and verification of cosmetic hair treatments. Advancing the field of hair testing requires the continuous development and refinement of processes to reveal forensic relevant substances such as psychoactive substances, toxins, doping agents, and environmental contaminants and their distribution in the hair. It is generally agreed that standardized hair testing procedures are necessary to promote a shared framework for interpretation that can assist forensic toxicologists in evaluating substances in hair. This may enhance reliability and broaden the applications of hair testing. This article is categorized under: Toxicology > Analytical Toxicology > Hair Toxicology > Drug Analysis