Abstract

Objectives: This cohort study aims to assess the health effects of exposure to chronic intermittent hypoxia of very high and high-altitude mining compared to similar work at lower altitude in Chile. Methods: We designed a prospective cohort of 483 miners, 336 working at very high or high altitude (247 over 4,000 m, 89 over 3,000 m) and 147 below 2,000 m. Subjects were randomly selected in two stages from a census of mines for each altitude stratum and within the selected mines a census of workers <50 years with a minimum of two years of employment. The main outcomes measured at baseline were mountain sickness, sleep alterations, hypertension, body mass index and neurocognitive functions. Results: Prevalence of acute mountain systems reached 28.4% in the very high-altitude stratum (p=0.000). 71.7% presented sleep disturbance (0.02). Precision in motor skill and visuospatial memory were also lower for this group. Hypertension was lower for the highest altitude subjects, which may be attributed to pre-occupational screening. Obesity which increases health risks is a concern. Conclusions: We found that despite longer periods of acclimatization to CIHH, subjects continue to present manifestations, particular acute mountain sickness and sleep disturbance, consistent with the conclusions of other studies. Perception of the health effects attributed to work and report of ailments in the past year are particularly suggestive in a population selected for aptitude, following health guidelines. Further rigorous research is warranted to understand long term health impacts of high-altitude mining and to provide evidence-based policy recommendations.