Relationship Between Occupational Exposure to Benzene and Hematological Parameters Among Petroleum Downstream Workers in Rivers State

Benzene, a ubiquitous solvent in petroleum refining and distribution operations, is a confirmed human leukemogen and hematotoxin requiring strict occupational monitoring. This analytical cross-sectional study investigated the relationship between occupational benzene exposure and hematological parameters among workers in petroleum downstream facilities in Rivers State, South South Nigeria. Two hundred and twenty downstream workers from three refineries and petroleum product distribution depots, along with 80 unexposed administrative controls, were recruited by stratified random sampling. Urinary trans,trans-muconic acid (tt-MA), a validated benzene biomarker, was measured by high-performance liquid chromatography. Complete blood count and blood film analysis were performed on all participants. Mean urinary tt-MA levels in exposed workers (1.23 mg/g creatinine) significantly exceeded controls (0.18 mg/g creatinine). Hematological abnormalities including leucopenia, thrombocytopenia, and microcytic anemia were significantly more prevalent in exposed workers. Linear regression models confirmed significant inverse relationships between tt-MA levels and both white blood cell and platelet counts. Duration of benzene exposure above 10 years was an independent predictor of hematological suppression. The study contributes rigorous biomonitoring evidence to the Nigerian petroleum occupational health literature and recommends mandatory periodic benzene biomonitoring, hematological surveillance, engineering controls to reduce benzene exposure, and regulatory review of OELs in Nigerian downstream petroleum operations. Keywords: benzene exposure, hematological effects, petroleum workers, biomonitoring, Rivers State.