A Comparative Study of Biological Samples (Blood, Urine, and Hair) Used in Forensic Laboratories for Drug Detection: A Narrative Scientific Review of Their Nature, Differences, Forensic and Clinical Applications, and Diagnostic Efficacy

Abstract

Background: Various biological samples from the precise scientific basis for detecting drug abuse in forensic medicine, with blood, urine, and hair being among the most commonly used samples in this field. However, each of these biological samples possesses distinct characteristics regarding detection windows, diagnostic accuracy, and legal value. Despite the importance of this subject, specialized studies on the matter in Arabic are scarce at both local and regional levels.

Objective: This study aims to conduct a comprehensive scientific narrative comparison of blood, urine, and hair biological samples in drug detection in Arabic, by analyzing their biological characteristics, diagnostic efficacy, forensic applications, and the challenges associated with interpreting their results.

Methodology: The current study employs a descriptive-analytical approach, reviewing recent scientific literature and international guidelines in the field of biological samples and forensic toxicology.

Results: The results of the current study indicate that biological samples—specifically blood—are the most suitable for detecting recent drug use and assessing pharmacological effects, as they reflect the actual concentration of substances shortly after consumption. In contrast, urine is the optimal choice for routine drug screening due to the ease of collection and analysis, serving as an effective means to detect drug metabolites over a longer period. Hair is distinguished by its ability to document chronic drug use over extended periods—potentially spanning months—by providing a long-term chronological record; this makes it valuable for assessing chronic or repeated use, rendering it highly significant in criminal cases and monitoring programs.

Conclusion: It cannot be definitively stated that any single biological sample is the best in all cases; rather, the choice of sample depends on the purpose of the test, the expected timeframe of substance use, and the nature of the case. Combining multiple types of biological samples with modern confirmatory analysis techniques enhances the accuracy and reliability of the results.