Multi-Element Exposure in a High-Altitude Páramo Mining District and Oxidative Stress Biomarkers in Gold Miners

Artisanal and small-scale gold mining (ASGM) generates complex metal mixtures, yet their biological effects remain poorly characterized in high-altitude populations, where occupational exposure occurs against a hypoxic environmental background. This study evaluated 49 occupationally exposed gold miners from the Vetas–California mining district, near the Santurbán páramo in Colombia, and 25 non-exposed individuals from a comparable high-altitude area. Hair concentrations of essential and toxic elements were quantified by ICP-MS, and serum catalase (CAT), superoxide dismutase (SOD), reduced glutathione (GSH), oxidized glutathione (GSSG), and the GSH/GSSG ratio were assessed. Miners showed a distinct multielement profile, with a higher toxic-metal burden and a dominant mixture mainly characterized by Fe, Mn, As, Pb, Cd, and Hg. CAT and SOD activities did not differ markedly between groups, although SOD activity decreased along the main exposure gradient among exposed workers. In contrast, glutathione-related biomarkers showed a more consistent exposure-related pattern, with higher GSSG and a lower GSH/GSSG ratio, suggesting a shift toward a more oxidized glutathione redox status. Together with positive within-group associations between selected elements and the GSH/GSSG ratio, these results are consistent with a mixture-associated perturbation of glutathione redox homeostasis, with heterogeneous adaptive responses. Overall, this study supports the use of integrated biomonitoring strategies and highlights glutathione-related markers as potential indicators of early redox perturbation in high-altitude mining populations.