Biochemical Mechanisms of Arsenic-Induced Oxidative Toxicity in Rural Communities Using Contaminated Groundwater in Ogun State

Arsenic contamination of groundwater poses chronic health risks in selected rural communities in Ogun State where geological arsenic mobilization has been documented, but the biochemical mechanisms of arsenic-induced oxidative toxicity in affected human populations have not been empirically characterized in this region. This study investigates biochemical mechanisms of arsenic-induced oxidative toxicity in rural residents using arsenic-contaminated groundwater in Odeda LGA, Ogun State. A comparative design enrolled sixty chronic groundwater-exposed residents (urinary arsenic above 50 micrograms per litre confirmed by graphite furnace AAS) and fifty unexposed residents from adjacent arsenic-safe water areas. Blood and urine samples were collected. Oxidative toxicity biomarkers including plasma MDA, protein carbonylation, DNA oxidative damage marker 8-hydroxy-2-deoxyguanosine (8-OHdG) in urine, and lymphocyte DNA strand breaks by alkaline comet assay were measured. Antioxidant status was assessed by erythrocyte SOD, catalase, GPx, plasma GSH, and total antioxidant capacity. Arsenic methylation capacity was assessed by urinary inorganic arsenic, monomethylarsonic acid, and dimethylarsinic acid speciation by HPLC-ICP-MS. Results show significantly elevated MDA, protein carbonyls, urinary 8-OHdG, and DNA strand breaks in exposed individuals. Antioxidant enzyme activities and total antioxidant capacity were significantly reduced. Inefficient arsenic methylation, characterized by high urinary inorganic arsenic proportion, correlated with the most severe oxidative damage biomarker levels. The study provides mechanistic biochemical evidence of arsenic genotoxicity in the Ogun State population. Keywords: arsenic toxicity, oxidative stress, groundwater contamination, DNA damage, Ogun State.