The Forensic Limits Of Hair Drug Testing: A Critical Assessment Of Drug Intake And Hair Concentration Relationships

Hair analysis is effective for confirming drug exposure but not for quantifying drug dose due to inconsistent dose-concentration relationships across drug classes. Factors like melanin content, sweat, and cosmetic treatments confound drug levels in hair. While some pharmaceuticals show moderate associations, most illicit drugs exhibit weak or inconsistent correlations. Ethical constraints limit controlled studies, which show trends but are not definitive. Hair analysis should be used qualitatively in forensics, and future research should aim to standardize protocols and address confounding factors.