Integrated Exposure Assessment and Toxicogenomic Characterisation of Polycyclic Aromatic Hydrocarbon-Induced DNA Damage in Petroleum Refinery Workers in Warri, Delta State

Petroleum refinery workers in Warri, Delta State, are occupationally exposed to polycyclic aromatic hydrocarbon mixtures through inhalation and dermal contact, with potential genotoxic consequences including DNA adduct formation and gene expression alterations linked to occupational cancer risk. Biomonitoring and toxicogenomic characterisation of this exposure are critical for occupational health risk management in Nigeria's oil sector. This study conducted an integrated exposure assessment and toxicogenomic investigation of PAH-induced DNA damage in 120 refinery workers at the Warri Refining and Petrochemical Company and 60 unexposed community controls. Personal air sampling quantified inhalation PAH exposure using HPLC-fluorescence. Urinary 1-hydroxypyrene was determined as a biomarker of internal exposure. Peripheral blood lymphocytes were analysed for DNA strand breaks by the comet assay, chromosomal aberrations by cytogenetic analysis, and PAH-DNA adducts by 32P-postlabelling. Transcriptomic profiling by whole blood RNA-seq characterised gene expression differences between high-exposure, low-exposure, and control groups. Refinery workers showed significantly elevated urinary 1-hydroxypyrene compared to controls. DNA strand breaks and chromosomal aberration frequencies were significantly higher in high-exposure workers. Transcriptomic analysis identified upregulation of DNA damage response and xenobiotic metabolism pathway genes including CYP1A1, CYP1B1, and NQO1. A toxicogenomic signature of 64 differentially expressed genes distinguished high-PAH exposure workers from controls with high classification accuracy. This study provides original integrated molecular evidence for occupational PAH genotoxicity in Nigerian refinery workers and contributes a biomarker panel for occupational surveillance. Keywords: polycyclic aromatic hydrocarbons, genotoxicity, petroleum refinery workers, toxicogenomics, Warri.