Long-Term Health Effects of Multiple Occupational Hazard Co-Exposure Among Artisanal Miners in North Central Nigeria: A 10-Year Retrospective Cohort Study

Artisanal miners in North Central Nigeria are uniquely exposed to multiple simultaneous occupational hazards including heavy metals, silica dust, physical injury, noise, and psychosocial stress, yet longitudinal evidence on the cumulative health effects of co-exposure is entirely absent from the literature. This doctoral 10-year retrospective cohort study examined the long-term health effects of occupational hazard co-exposure among artisanal miners in Zamfara, Niger, and Plateau States, North Central and North West Nigeria. Medical records, occupational health assessment data, and government health facility records for 1,200 miners were reconstructed and linked across a decade using record linkage methodology. Exposome profiling was conducted using blood and urine archive samples from cross-sectional surveys conducted between 2014 and 2018. The study examined mortality, incident chronic disease, and disability outcomes over the cohort period, adjusted for confounders using time-varying covariate Cox proportional hazard regression models. All-cause mortality among artisanal miners was 2.7 times higher than the national age-standardized mortality rate. Synergistic interactions between silica and heavy metal co-exposure significantly accelerated pulmonary fibrosis progression, exceeding the effects of either hazard alone. Lead and mercury co-exposure demonstrated additive neurocognitive decline effects. Psychosocial hazard co-exposure interacted with chemical exposure to amplify cardiovascular disease incidence. The study provides the first multi-hazard longitudinal health outcomes evidence from Nigerian artisanal mining and contributes a novel co-exposome analysis framework for mining occupational epidemiology in Africa. Keywords: multiple hazard co-exposure, artisanal mining, longitudinal cohort, health outcomes, North Central Nigeria.