MERCURY, MINING, AND THE ECOLOGICAL COST OF EMPIRE

Between 1564 and 1974, approximately 85,000 metric tons of mercury was produced in and around the city of Huancavelica, Peru, from cinnabar extracted from the nearby Santa Barbara Hill. At least 25,000 tons of elemental mercury vapor, or an average of 62 tons per year, escaped during processing. Much of this deposited and bound with the soil, or was released into the Rio Ichu which runs through the city. Air dispersion modeling suggests that mercury vapor air concentrations in 1680, a point of high production, could exceed the EPA’s IRIS RfC by up to a factor of 1,000. While all inhabitants of the city breathed mercury vapor, the indigenous forced workers who operated the smelters were most exposed.

Today, Huancavelica’s 42,000 residents shoulder this toxic burden on a daily basis while living in both Peru’s poorest departmental capital and one of the most mercury contaminated urban areas. The situation is exacerbated as over 80% of the city’s residents live in adobe homes constructed with contaminated materials. In 2010, the Environmental Health Council (EHC) sampled 60 adobe homes with a mercury vapor analyzer. Atmospheric elemental mercury vapor concentrations in 40% of tested homes were between 0.50 and 5.51 µg/m³ and 23% were between 1.00 and 5.51 µg/m³. To put this in context, the WHO Air Quality Guideline for mercury vapor is an annual average of 1 µg/m³, whereas the EPA mercury action level 2 calls for officials to “schedule relocation for the residents as soon as possible” when concentrations range between 1 and 10 µg/m³. Additionally, 75% of adobe and 77% of dirt floor samples exceeded the EPA soil screening, or “safe,” level of 23 mg/kg for residential exposure to mercury from contaminated soil. This presentation will focus on the origins and health effects of mercury contamination in Huancavelica, the results of the Environmental Health Council research on legacy contamination there, and the challenges of, and need for, mitigation and remediation.