Concerns on the Misinterpretation of Very Low Drug Concentrations in Hair

Establishing effective interpretation criteria in hair analysis to distinguish between passive and active cocaine exposure: Insights from authentic hair samples collected from professional individuals exposed to cocaine

Interpretation results of hair analysis, particularly for cocaine, can be challenging due to the need to differentiate between active use or passive contamination. Our study aimed to assess the impact of varying degrees of passive cocaine exposure hair analysis results and their interpretation. Hair samples (n = 25) were categorized based on the declared cocaine exposure of volunteers: (a) high, involving handling up to several kilograms of cocaine powder from dismantling illegal distribution sites; (b) medium, where staff dealt with cocaine blocks (up to kilograms); and (c) low, with staff in contact with up to grams of cocaine for laboratory analysis. Hair samples were decontaminated using dichloromethane, water, and methanol. The samples and final wash were analyzed for cocaine, benzoylecgonine, norcocaine, cocaethylene, m-OH-benzoylecgonine, and ecgonine methyl ester using a validated UPLC-MS/MS method. Cocaine hair concentrations ranges were as follows (pg/mg): high (n = 53 segments) < LLOQ(32)-7046; medium (n = 91) < LLOQ-939; and low (n = 54) < LLOQ-292. All hair samples had concentrations below the LLOQ for cocaethylene, ecgonine methyl ester, and m-OH-benzoylecgonine. Applying the SoHT cocaine cut-off in combination with a hair/wash ratio criterion identified 97% of the samples as contaminated. This study advocates for a comprehensive approach in evaluating cocaine hair concentrations. This involves integrating the 500 pg/mg decision limit for cocaine with a criterion comparing wash and hair concentration. Additionally, confirming the presence of specific metabolites is crucial. This multifaceted method effectively distinguishes between environmental contamination and active cocaine usage. The research contributes significantly to refining cocaine exposure assessment in professional contexts.

Hair analysis for New Psychoactive Substances (NPS): Still far from becoming the tool to study NPS spread in the community?

In this review article, we performed an overview of extraction and chromatographic analysis methods of NPS in hair from 2007 to 2021, evaluating the limit of detection (LOD), limit of quantification (LOQ), limit of reporting (LOR), and limit of identification (LOI) values reported for each NPS. Our review aimed to highlight the limitations of modern hair analytical techniques, and the prerequisites for the proper evaluation and use of analytical results in relation to the objectives of NPS hair analysis. In the selected studies the detection of a total of 280 NPS was reported. The detected NPS belonged to seven classes: synthetic cannabinoids with 109 different substances, synthetic opioids with 58, cathinones with 50, phenethylamines with 34, other NPS with 15, tryptamines with ten, and piperazines with four substances. The NPS hair analysis of real forensic/ clinical cases reported the detection of only 80 NPS (out of the 280 targeted), in significantly higher levels than the respective LODs. The analytical protocols reviewed herein for NPS hair analysis showed continuously growing trends to identify as many NPS as possible; the extraction methods seem to have a limited potential to improve, while the various mass spectroscopic techniques and relevant instrumentation provide an enormous field for development and application. Hair is a biological indicator of the past chronic, sub-chronic, and, even, in certain cases, acute exposure to xenobiotics. Therefore, future research in the field could progress NPS hair analysis and aim the monitoring of NPS expansion and extent of use in the community.

Alternative matrices in forensic toxicology: a critical review

Purpose

The use of alternative matrices in toxicological analyses has been on the rise in clinical and forensic settings. Specimens alternative to blood and urine are useful in providing additional information regarding drug exposure and analytical benefits. The goal of this paper is to present a critical review on the most recent literature regarding the application of six common alternative matrices, i.e., oral fluid, hair, sweat, meconium, breast milk and vitreous humor in forensic toxicology.

Methods

The recent literature have been searched and reviewed for the characteristics, advantages and limitations of oral fluid, hair, sweat, meconium, breast milk and vitreous humor and its applications in the analysis of traditional drugs of abuse and novel psychoactive substances (NPS).

Results

This paper outlines the properties of six biological matrices that have been used in forensic analyses, as alternatives to whole blood and urine specimens. Each of this matrix has benefits in regards to sampling, extraction, detection window, typical drug levels and other aspects. However, theses matrices have also limitations such as limited incorporation of drugs (according to physical–chemical properties), impossibility to correlate the concentrations for effects, low levels of xenobiotics and ultimately the need for more sensitive analysis. For more traditional drugs of abuse (e.g., cocaine and amphetamines), there are already data available on the detection in alternative matrices. However, data on the determination of emerging drugs such as the NPS in alternative biological matrices are more limited.

Conclusions

Alternative biological fluids are important specimens in forensic toxicology. These matrices have been increasingly reported over the years, and this dynamic will probably continue in the future, especially considering their inherent advantages and the possibility to be used when blood or urine are unavailable. However, one should be aware that these matrices have limitations and particular properties, and the findings obtained from the analysis of these specimens may vary according to the type of matrix. As a potential perspective in forensic toxicology, the topic of alternative matrices will be continuously explored, especially emphasizing NPS.