Detection criteria and preventive measures for occupational disease in the mines of Almaden (Spain)

This research focuses on the metallurgy and underground mining job positions in the historic mines of Almaden (Spain). We introduce a preventive methodology for hydrargyrism in work environments known by the name of Methodology for Operational Units Action Levels for Health Indicators (MUONAIS). The methodology allows critical levels to be established using environmental and clinical–biological indicators. The prevention plan concentrated on 15 job positions in the metallurgy department that employed more than 100 workers between the years 1986 and 1997. The development of this preventive methodology managed to keep workers’ mercury levels below 60 μg/l in blood and 200 μg/l in urine, values that present no negative effects on human health. MUONAIS has proven very effective in protecting workers’ health. During this period, some cases of micro-mercurialism were detected, yet were completely reversible, allowing us to affirm that the terrible disease of hydrargyrism was totally eradicated.