Current Environmental Health Challenges
in Huancavelica, Peru and Potosí, Bolivia:
For additional information concerning our work in Huancavelica, Peru, please click here
The highland cities of Huancavelica, Peru, and Potosí, Bolivia, share not only a mining history, but also some of the highest levels of urban mercury contamination in the world. Between 1564 and 1974, when mining in Huancavelica ceased, over metric 72,000 tons of mercury were produced in and immediately around the city from cinnabar ore extracted from the nearby Santa Barbara Hill. Due to inefficiencies in the production process, at least 25,000 additional tons of mercury vapor escaped the smelters and condensing systems to settle in the vicinity, where it bound with the soil or was washed into the Ichu River.
Until the late 1700s, most of Huancavelica’s production was shipped to Potosí, in present day Bolivia, where it was used to refine silver through the amalgamation process. Other mining center destinations included Castrovirreina, Hualgayoc, and Cerro de Pasco in Peru, and Oruro in Bolivia.
In all cases, the final step of the amalgamation technique involves volatizing the mercury from the amalgam to yield high-grade silver. Between 1574 and 1900, a minimum of 30,000 metric tons of mercury also literally went up in smoke in Potosí. By 1900, the use of mercury amalgamation for producing silver was increasingly replaced by cyanide leaching processes in Potosí and elsewhere, and Huancavelica’s production was destined to meet the growing international demand for quicksilver for use in many industrial applications.
Today, the 48,000 residents of Huancavelica and the 150,000 inhabitants of Potosí shoulder this toxic burden as they go about their daily lives, and as they sleep at night. For many, toxicity has turned into tragedy as their homes are built on or near mercury smelter or silver refining sites which date to colonial times.
Detail of silver refining mill from”Descripciòn del Zerro Rico e Imperial. Villa de Potosí,” painting by Gaspar Miguel de Berrío Bravo, 1758.Located in the Museo Colonial Charcas de la Universidad San Francisco Xavier, Sucre, Bolivia.
In these neighborhoods, many residents have constructed their modest dwellings from adobe, or mud bricks, using dirt and other materials from or near their home site. In Huancavelica, these bricks often contain the tailings of cinnabar, from which mercury is refined, as well as lead and arsenic Similarly, in Potosí, our research has demonstrated that adobe homes constructed from local soils are also contaminated
Health Effects of Mercury Intoxication
Individuals respond differently to mercury poisoning, and effects also depend on the species of mercury, as well as the dose and manner in which it enters the body. Common results among children include physical and mental developmental abnormalities, compromised immune systems and increased susceptibility to infections and allergies. General physical symptoms of chronic elemental and inorganic mercury poisoning include tremors, a loss of appetite, weight and muscular control, speech impairment, anemia, pallidity, uncontrollable salivation, gingivitis, and gum discoloration.
These symptoms are often accompanied by a range of persistent and even irreversible neuropsychological effects. These include personality alterations including psychoses, irritability, impatience, violent outbursts, hypercriticism, depression, anxiety, obsessive-compulsive behaviors, memory loss, problems concentrating, diffidence, indecision, and lack of affect.