Hair

Hair is composed of keratin and consists of three layers: medulla, cortex, and cuticle. The cortex contains melanin, which determines hair color, with eumelanin and pheomelanin being the primary pigments. Toxic substances can alter melanin production, changing hair color. Hair serves as an excretory tissue for testing toxicants, providing valuable information on chemical exposure. Hair analysis is significant in forensic toxicology for detecting substances like opioids, antidepressants, antipsychotics, and amphetamines. Despite the availability of reliable detection methods, challenges include the specific growth cycles of hair, result interpretation, and the high cost of techniques.