The multifaceted role of hair as a biospecimen: recent advances in precision medicine and forensic science.

Hair specimens are vital in precision medicine, forensics and environmental monitoring owing to their ability to retain biochemical data over time. Their noninvasive collection and long-term storage suitability make them ideal for diagnostics and investigations, offering historical insights into health and exposure records. In medicine, hair analysis provides a long-term biochemical profile, aiding in monitoring health conditions, nutritional deficiencies, toxin exposure and treatment efficacy. Advances in mass spectrometry, chromatography and spectroscopy have expanded their applications to cancer diagnostics, tuberculosis, HIV, neurological disorders and mental health assessments. In forensic science, the resistance of hair to decomposition and its ability to absorb substances help identify individuals, detect drug use and reconstruct crime scenes. Omics techniques such as genomics, proteomics and metabolomics enhance forensic accuracy by enabling precise substance detection and timeline reconstruction. Despite its potential, challenges such as hair growth variability, contamination and lack of standardized techniques limit the current impact of hair analysis. Addressing these issues could advance its role in diagnostics and forensic investigations. This review explores recent advancements and applications of hair analysis in precision medicine, infectious diseases, mental health, stress assessment and forensic science.