Molecular Toxicological Mechanisms of Occupational Cadmium Exposure and Renal Dysfunction Among Battery Smelter Workers in Lagos State

Cadmium nephrotoxicity from occupational exposure represents a serious and irreversible occupational disease, with mechanisms involving oxidative stress, mitochondrial dysfunction, and tubular apoptosis that have not been characterized in Nigerian occupational populations. This doctoral molecular toxicological study investigated the mechanisms of cadmium-induced renal dysfunction among battery smelter workers in Lagos State, South West Nigeria. A prospective cohort of 200 smelter workers and 80 unexposed controls was followed over 36 months with comprehensive biological sampling at six-monthly intervals. Urinary cadmium, blood cadmium, and urinary biomarkers of early tubular injury (NGAL, KIM-1, beta-2-microglobulin, and N-acetyl-beta-D-glucosaminidase) were measured. Oxidative stress markers, mitochondrial function parameters in peripheral blood monocytes, and apoptotic pathway activation (caspase-3, Bcl-2) were assessed using validated molecular methods. Urinary cadmium levels exceeded the ATSDR reference value in 67.5 percent of workers at 36 months. KIM-1 elevation preceding clinical GFR decline was detected as the earliest renal injury biomarker, appearing at mean cadmium exposure concentrations below clinical threshold. Longitudinal mitochondrial dysfunction scores correlated significantly with proximal tubular injury marker trajectories (r=0.67, p less than 0.001). These findings establish the temporal molecular sequence of cadmium nephrotoxicity in this population and validate KIM-1 as an early surveillance biomarker. The study delivers original mechanistic molecular data and recommends biological cadmium monitoring programs, early KIM-1-based screening, and engineering controls for battery smelter facilities. Keywords: cadmium nephrotoxicity, molecular mechanisms, battery smelting, biomarkers, Lagos State.