Determination of substances subject to control in human hair

Abstract

Introduction: Currently, the determination of controlled substances in hair is a method used in forensic toxicology laboratories, due to its specific characteristics, which provide information that cannot be obtained from the analysis of other biological samples, mainly because of the long detection time achieved with this sample, as well as the ability to establish a chronological profile of drug consumption. Drugs are deposited in human hair through blood circulation by different mechanisms after ingestion or administration, being more stable and therefore can be detected after prolonged periods of time compared to other biological samples, studies indicate that the drug varies along the hair shaft, which is related to the period of abuse.  A number of licit and illicit substances can be detected in human hair, depending on the case, most studies focus their attention on commonly used drugs such as opiates, amphetamines, stimulants, marijuana, cocaine and heroin. Objective: The objective of this study was to determine which controlled substances and methods of analysis are used in the laboratory using human hair as biological material, focusing on a bibliographic review of updated high impact articles.  Methodology: The study used a literature review with a descriptive approach, documentary design, non-experimental, cross-sectional with retrospective chronology. Results: After the analysis it was determined that the toxic substances reach the human hair thanks to the blood circulation being stored in these for long periods of time, to determine a minimum of 1 cm of growth is required, and it is subjected to a treatment which varies according to the protocol used by each laboratory where it is intended to perform it. After the analysis it was determined that the toxic substances reach the human hair thanks to the blood circulation and are stored in them for long periods of time. To determine this, a minimum of 1 cm of growth is required, and it is subjected to a treatment which varies according to the protocol used by each laboratory where it is intended to be performed. To perform this analysis, most laboratories have Gas Chromatography/Mass Spectrometry as the method of choice. The search allowed the consultation of scientific articles and theses obtained from fifteen online databases, published between 2020-2024. Conclusion:  The determination of controlled substances in human hair by various detection methods is a crucial forensic process that provides a unique window to assess an individual's drug use history over time. The combination of advanced analytical techniques allows the identification and quantification of specific substances.