Linking social and scientific efforts to address arsenic and heavy metals pollution in a mining area in Central Mexico

For many years, the high concentration of arsenic (As) in deep groundwater, up to 1.2 mg/L, has posed a health risk to the residents of Zimapán, a mining town in Mexico with a population of about 40,000. Additionally, ore processing, mainly through selective flotation, has resulted in the production of thousands of tons of tailings, which have accumulated in the outskirts of the town, causing damage to soils and shallow wells. To address this environmental issue, Mexican and international scientists have conducted studies focused on various environmental compartments. Since the earliest studies, whose aim was to identify the source of As pollution, the local authorities and people of Zimapán have been involved in the research activities.

Three years ago, a collaborative working group was formed, including local authorities, scientific and social researchers from various universities, local social organizations, and individuals who were committed to the environment (Environmental Research Network, REA). Their participation has included support for field activities, communication and exchange of knowledge, and the promotion of alternatives identified by scientific and social efforts to high-level authorities.

The outcomes of their work have been significant. They have rehabilitated the As removal treatment plant, which was installed about 15 years earlier as a result of this science-social collaboration. Additionally, they have identified local limestone as an option to treat tainted water and acid mine drainage. They have also supported the municipality in building rain harvesting systems in two schools to provide safe water to students. Moreover, they have interacted with miners to propose alternatives to minimize the impact of the tailings, among other achievements. The quality of drinking water supplied to downtown Zimapán is not yet in line with the national As drinking water standards, which require the arsenic level to be below 0.025 mg/L. The current level of arsenic in the water varies between 0.2 and 0.4 mg/L, which is a significant improvement from the previous level of 1.2 mg/L. However, efforts are still underway to achieve a safe water supply that meets the national standards. The REA has been effective in reducing the arsenic concentration in the water and has proven to be a viable social-scientific method for creating a healthier environment in the locality. It is also a model for other areas in Mexico that are impacted by arsenic contamination.