Used primarily as a biomarker for monitoring human exposure to polycyclic aromatic hydrocarbons (PAHs), especially from tobacco smoke, grilled foods, and environmental pollutants. It is a metabolite of benzo[a]pyrene, formed in the body after exposure, and can be measured in urine or blood to assess recent or chronic exposure to carcinogenic PAHs. Due to its role in metabolic studies, it helps researchers evaluate detoxification pathways and cancer risk associated with PAH exposure. Also used in laboratory settings to study oxidative metabolism and DNA adduct formation linked to carcinogenesis.