Long-Term Occupational Lead Exposure and Neurocognitive Function Among Battery Smelter Workers in Ogun State

Chronic occupational lead exposure is a well-established cause of progressive neurocognitive impairment, with dose-dependent effects on memory, executive function, and processing speed. Yet controlled studies from Nigerian industrial settings documenting the neurocognitive sequelae of prolonged lead exposure remain scarce. This analytical cross-sectional study examined the relationship between long-term occupational lead exposure and neurocognitive function among lead-acid battery smelter workers in Ogun State, South West Nigeria. One hundred and sixty smelter workers and 80 demographically matched unexposed controls were recruited. Blood lead levels (BLLs) were measured using atomic absorption spectrophotometry. Neurocognitive function was assessed using a locally adapted battery including the Trail Making Test (A and B), digit span, verbal fluency, and the Montreal Cognitive Assessment. Mean BLL in smelter workers was 52.3 micrograms per deciliter versus 4.8 micrograms per deciliter in controls. Smelter workers demonstrated significantly worse performance on all neurocognitive domains compared to controls (p less than 0.001). BLL was the strongest predictor of Trail Making Test B performance and verbal fluency scores. Cognitive impairment classified as mild cognitive impairment or worse was detected in 41.9 percent of smelter workers. Duration of exposure above 15 years and BLL above 60 micrograms per deciliter were critical risk thresholds. The study recommends mandatory BLL monitoring, removal protocols for workers exceeding critical BLL thresholds, lead chelation referral programs, and engineering controls at battery smelting facilities in Ogun State. Keywords: lead exposure, neurocognitive function, battery smelting, biological monitoring, Ogun State.