A study carried out by two US researchers, Bryn Thoms and Nicholas Robins, and two Peruvian counterparts, Enrique Ecos and Rubén Espinoza, reveals the scale of mercury contamination in the city of Huancavelica. From colonial times, Huancavelica was the centre for producing the mercury used to refine silver from Potosí. The study shows how the walls and floors of homes in poor neighbourhoods reveal serious levels of contamination. Many of these houses were built with mud blocks gleaned from close to the site where mercury was mined. The most serious contamination is to be found in the district of Yananaco, but also to a lesser extent in the districts of Ascensión, San Cristóbal and Santa Ana. Ecos, a medical doctor from Huancavelica, has called for a thorough investigation into the problem.

The study is the result of collaboration between the US Environmental Health Council and the University of Huancavelica. It involved the collection of blood and urine samples, as well as soil analysis and that of household water supplies.